The result of cherry-picking every commit (except ones that seemed to not
affect the compiler itself) from mono-5.10.0.179 to mono-6.12.0.206 that
touched ./mcs/mcs.

Mono seems to consistently, almost as a rule, depend on C# features before
they implement them.  This is extremely awkward for building using previous
versions, so hopefully this will allow us to jump straight to a high version.

Includes the following commits, in order of most-recent to least-recent:

b3911589b37
6700dd220fe
2a7dfb28e07
eea6f11a3e6
3fc047c6f3a
ac6666f5b0b
927b27bb9d8
4ab24d4c059
aa836b46a23
ee7dccfb320
23510f26915
d9f26547d88
9dc1c885a0f
ef558ead89a
2cb7909b13c
0390ea2e78c
b4f6659bdc0
e92d6070eaf
4c5b3fbd4f4
e6507f2da8a
656a4b1120c
9bd2fa4cf33
be2d1aeffe0
454a76cfa4a
60c1ee454d4
53f1ef506ea
d3487bfebb3
92f6e5b1a81

diff --git a/.gitignore b/.gitignore
index c6ef19a849b..c37d4fce3f0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -40,6 +40,7 @@ Ankh.NoLoad
 *.gpState
 .vscode/
 *.exp
+.vs/
 
 # Tooling
 _ReSharper*/
diff --git a/mcs/class/Commons.Xml.Relaxng/Makefile b/mcs/class/Commons.Xml.Relaxng/Makefile
index 1febae4eb1e..f9b57fea265 100644
--- a/mcs/class/Commons.Xml.Relaxng/Makefile
+++ b/mcs/class/Commons.Xml.Relaxng/Makefile
@@ -22,7 +22,7 @@ EXTRA_DISTFILES = \
 	$(RESOURCE_FILES)
 
 Commons.Xml.Relaxng.Rnc/RncParser.cs: Commons.Xml.Relaxng.Rnc/RncParser.jay $(topdir)/jay/skeleton.cs
-	$(topdir)/jay/jay -ctv < $(topdir)/jay/skeleton.cs $(CURDIR)/Commons.Xml.Relaxng.Rnc/RncParser.jay > Commons.Xml.Relaxng.Rnc/RncParser.cs
+	$(topdir)/jay/jay -ctv -o Commons.Xml.Relaxng.Rnc/RncParser.cs $< < $(topdir)/jay/skeleton.cs
 
 BUILT_SOURCES = Commons.Xml.Relaxng.Rnc/RncParser.cs
 
diff --git a/mcs/class/Microsoft.Build/Makefile b/mcs/class/Microsoft.Build/Makefile
index 2dcbefdf7f9..1a711069b0b 100644
--- a/mcs/class/Microsoft.Build/Makefile
+++ b/mcs/class/Microsoft.Build/Makefile
@@ -26,7 +26,7 @@ EXTRA_DISTFILES = \
 EXPR_PARSER = Microsoft.Build.Internal/ExpressionParser
 
 $(EXPR_PARSER).cs: $(EXPR_PARSER).jay $(topdir)/jay/skeleton.cs
-	(cd Microsoft.Build.Internal; $(topdir)/../jay/jay -ctv < $(topdir)/../jay/skeleton.cs ExpressionParser.jay > ExpressionParser.cs)
+	(cd Microsoft.Build.Internal; $(topdir)/../jay/jay -ctv -o ExpressionParser.cs ExpressionParser.jay < $(topdir)/../jay/skeleton.cs )
 
 BUILT_SOURCES = $(EXPR_PARSER).cs
 
diff --git a/mcs/class/Mono.CSharp/Makefile b/mcs/class/Mono.CSharp/Makefile
index 7b1986b78e5..3615532853d 100644
--- a/mcs/class/Mono.CSharp/Makefile
+++ b/mcs/class/Mono.CSharp/Makefile
@@ -24,7 +24,7 @@ LIB_MCS_FLAGS += $(REFERENCE_SOURCES_FLAGS)
 BUILT_SOURCES = $(PROFILE)-parser.cs
 
 $(PROFILE)-parser.cs: $(topdir)/mcs/cs-parser.jay $(topdir)/jay/skeleton.cs
-	$(topdir)/jay/jay -c < $(topdir)/jay/skeleton.cs $< > $(PROFILE)-jay-tmp.out && mv $(PROFILE)-jay-tmp.out $@
+	$(topdir)/jay/jay -c -o $(PROFILE)-jay-tmp.out $< < $(topdir)/jay/skeleton.cs && mv $(PROFILE)-jay-tmp.out $@
 
 include ../../build/library.make
 
diff --git a/mcs/class/Mono.Xml.Ext/Makefile b/mcs/class/Mono.Xml.Ext/Makefile
index dc49f816fee..16498215a38 100644
--- a/mcs/class/Mono.Xml.Ext/Makefile
+++ b/mcs/class/Mono.Xml.Ext/Makefile
@@ -29,13 +29,13 @@ Mono.Xml.XPath2/XQueryParser.jay: Mono.Xml.XPath2/ParserBase.jay $(SKELETON)
 Mono.Xml.XPath2/XPath2Parser.cs: Mono.Xml.XPath2/XPath2Parser.jay
 	echo "#define XPATH2_PARSER" > $@
 	echo "#if NET_2_0" >> $@
-	$(topdir)/jay/jay -ct < $(SKELETON) $(CURDIR)/$< >>$@
+	$(topdir)/jay/jay -ct $(CURDIR)/$< < $(SKELETON) >>$@
 	echo "#endif" >> $@
 
 Mono.Xml.XPath2/XQueryParser.cs: Mono.Xml.XPath2/XQueryParser.jay $(SKELETON)
 	echo "#define XQUERY_PARSER" > $@
 	echo "#if NET_2_0" >> $@
-	$(topdir)/jay/jay -ct < $(SKELETON) $(CURDIR)/$< >>$@
+	$(topdir)/jay/jay -ct $(CURDIR)/$< < $(SKELETON) >>$@
 	echo "#endif" >> $@
 
 Mono.Xml.XPath2/XPath2Tokenizer.cs: Mono.Xml.XPath2/TokenizerBase.cs
diff --git a/mcs/class/corlib/System/RuntimeArgumentHandle.cs b/mcs/class/corlib/System/RuntimeArgumentHandle.cs
index 216c4ea3924..c10d3f174d1 100644
--- a/mcs/class/corlib/System/RuntimeArgumentHandle.cs
+++ b/mcs/class/corlib/System/RuntimeArgumentHandle.cs
@@ -31,13 +31,9 @@
 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 //
 
-using System;
-using System.Runtime.InteropServices;
-
 namespace System
 {
-	[ComVisible (true)]
-	public struct RuntimeArgumentHandle
+	public ref struct RuntimeArgumentHandle
 	{
 #pragma warning disable 649
 		internal IntPtr args;
diff --git a/mcs/class/referencesource/mscorlib/system/typedreference.cs b/mcs/class/referencesource/mscorlib/system/typedreference.cs
index 80bef5ab852..a30541f4399 100644
--- a/mcs/class/referencesource/mscorlib/system/typedreference.cs
+++ b/mcs/class/referencesource/mscorlib/system/typedreference.cs
@@ -19,7 +19,11 @@ namespace System {
     [CLSCompliant(false)] 
     [System.Runtime.InteropServices.ComVisible(true)]
     [System.Runtime.Versioning.NonVersionable] // This only applies to field layout
-    public struct TypedReference
+    public
+#if MONO
+    ref
+#endif
+    struct TypedReference
     {
 #if MONO
 #pragma warning disable 169
diff --git a/mcs/errors/cs0151-4.cs b/mcs/errors/cs0151-4.cs
index 0e45b1a9049..c9e05589e4d 100644
--- a/mcs/errors/cs0151-4.cs
+++ b/mcs/errors/cs0151-4.cs
@@ -1,5 +1,6 @@
 // CS0151: A switch expression of type `S1?' cannot be converted to an integral type, bool, char, string, enum or nullable type
-// Line: 24
+// Line: 25
+// Compiler options: -langversion:5
 
 using System;
 
diff --git a/mcs/errors/cs0273-2.cs b/mcs/errors/cs0273-2.cs
new file mode 100644
index 00000000000..b0bdbef9e75
--- /dev/null
+++ b/mcs/errors/cs0273-2.cs
@@ -0,0 +1,9 @@
+// CS0273: The accessibility modifier of the `C.S2.set' accessor must be more restrictive than the modifier of the property or indexer `C.S2'
+// Line: 7
+// Compiler options: -langversion:7.2
+
+ class C
+ {
+	private string S2 { get; private protected set; }
+ }
+
diff --git a/mcs/errors/cs0280.cs b/mcs/errors/cs0280.cs
new file mode 100644
index 00000000000..62be8e39585
--- /dev/null
+++ b/mcs/errors/cs0280.cs
@@ -0,0 +1,22 @@
+// CS0280: `C.Fixable.GetPinnableReference(int)' has the wrong signature to be used in extensible fixed statement
+// Line: 11
+// Compiler options: -unsafe -langversion:latest -warnaserror
+
+using System;
+
+unsafe class C
+{
+	public static void Main ()
+	{
+		fixed (int* p = new Fixable ()) {
+		}
+	}
+
+	struct Fixable
+	{
+		public ref int GetPinnableReference (int i = 1)
+		{
+			throw new NotImplementedException ();
+		}
+	}
+}
\ No newline at end of file
diff --git a/mcs/errors/cs0826-9.cs b/mcs/errors/cs0826-9.cs
deleted file mode 100644
index 4e098969b8c..00000000000
--- a/mcs/errors/cs0826-9.cs
+++ /dev/null
@@ -1,16 +0,0 @@
-// CS0826: The type of an implicitly typed array cannot be inferred from the initializer. Try specifying array type explicitly
-// Line: 8
-
-class C
-{
-	static void Main()
-	{
-		object o = 1;
-		dynamic d = 1;
-		
-		var a = new[] {
-			new { X = o },
-			new { X = d }
-		};
-	}
-}
diff --git a/mcs/errors/cs1013-1.cs b/mcs/errors/cs1013-1.cs
new file mode 100644
index 00000000000..01827df4995
--- /dev/null
+++ b/mcs/errors/cs1013-1.cs
@@ -0,0 +1,8 @@
+// CS1013: Invalid number
+// Line : 6
+
+class X
+{
+    static int i = 0b;
+    static void Main () {}
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1013-2.cs b/mcs/errors/cs1013-2.cs
new file mode 100644
index 00000000000..c868cb2a769
--- /dev/null
+++ b/mcs/errors/cs1013-2.cs
@@ -0,0 +1,7 @@
+// CS1013: Invalid number
+// Line : 6
+
+class X
+{
+    static int i = 0x0_;
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1013-3.cs b/mcs/errors/cs1013-3.cs
new file mode 100644
index 00000000000..3145b1ba596
--- /dev/null
+++ b/mcs/errors/cs1013-3.cs
@@ -0,0 +1,7 @@
+// CS1013: Invalid number
+// Line : 6
+
+class X
+{
+    static int i = 1_;
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1013-4.cs b/mcs/errors/cs1013-4.cs
new file mode 100644
index 00000000000..3a5e744ff4f
--- /dev/null
+++ b/mcs/errors/cs1013-4.cs
@@ -0,0 +1,7 @@
+// CS1013: Invalid number
+// Line : 6
+
+class X
+{
+    static double i = 1_.2;
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1013-5.cs b/mcs/errors/cs1013-5.cs
new file mode 100644
index 00000000000..8082743c0b5
--- /dev/null
+++ b/mcs/errors/cs1013-5.cs
@@ -0,0 +1,7 @@
+// CS1013: Invalid number
+// Line : 6
+
+class X
+{
+    static int i = 1_e1;
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1013-6.cs b/mcs/errors/cs1013-6.cs
new file mode 100644
index 00000000000..d2cea2c72dd
--- /dev/null
+++ b/mcs/errors/cs1013-6.cs
@@ -0,0 +1,7 @@
+// CS1013: Invalid number
+// Line : 6
+
+class X
+{
+    static float i = 1_f;
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1013-7.cs b/mcs/errors/cs1013-7.cs
new file mode 100644
index 00000000000..8030d6ed095
--- /dev/null
+++ b/mcs/errors/cs1013-7.cs
@@ -0,0 +1,7 @@
+// CS1013: Invalid number
+// Line : 6
+
+class X
+{
+    static int i = 0x_1;
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1013-8.cs b/mcs/errors/cs1013-8.cs
new file mode 100644
index 00000000000..d26c7acacb7
--- /dev/null
+++ b/mcs/errors/cs1013-8.cs
@@ -0,0 +1,7 @@
+// CS1013: Invalid number
+// Line : 6
+
+class X
+{
+    static int i = 0b_1;
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1021-4.cs b/mcs/errors/cs1021-4.cs
new file mode 100644
index 00000000000..75c2ff70360
--- /dev/null
+++ b/mcs/errors/cs1021-4.cs
@@ -0,0 +1,8 @@
+// CS1021: Integral constant is too large
+// Line: 6
+
+class X {
+	public static void Main() {
+		int h = 0b11111111111111111111111111111111111111111111111111111111111111111;
+	}
+}
diff --git a/mcs/errors/cs1061-18.cs b/mcs/errors/cs1061-18.cs
new file mode 100644
index 00000000000..3ac82b7f2d3
--- /dev/null
+++ b/mcs/errors/cs1061-18.cs
@@ -0,0 +1,10 @@
+// CS1061: Type `int' does not contain a definition for `__0' and no extension method `__0' of type `int' could be found. Are you missing an assembly reference?
+// Line: 8
+
+static class C
+{
+	static void Main ()
+	{
+		int c = 0.__0;
+	}
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1525-27.cs b/mcs/errors/cs1525-27.cs
index dc184931667..d4c1f326be2 100644
--- a/mcs/errors/cs1525-27.cs
+++ b/mcs/errors/cs1525-27.cs
@@ -1,4 +1,4 @@
-// CS1525: Unexpected symbol `fe', expecting `class', `delegate', `enum', `interface', `partial', or `struct'
+// CS1525: Unexpected symbol `fe', expecting `class', `delegate', `enum', `interface', `partial', `ref', or `struct'
 // Line: 6
 
 namespace X
diff --git a/mcs/errors/cs1525-43.cs b/mcs/errors/cs1525-43.cs
index d83d4d847fa..26f466a2528 100644
--- a/mcs/errors/cs1525-43.cs
+++ b/mcs/errors/cs1525-43.cs
@@ -1,4 +1,4 @@
-// CS1525: Unexpected symbol `)', expecting `(', `[', `out', `params', `ref', `this', or `type'
+// CS1525: Unexpected symbol `)'
 // Line: 6
 
 class TestClass
diff --git a/mcs/errors/cs1527-2.cs b/mcs/errors/cs1527-2.cs
index d38945f3c89..0256ee2b354 100644
--- a/mcs/errors/cs1527-2.cs
+++ b/mcs/errors/cs1527-2.cs
@@ -1,4 +1,4 @@
-// CS1527: Namespace elements cannot be explicitly declared as private, protected or protected internal
+// CS1527: Namespace elements cannot be explicitly declared as private, protected, protected internal, or private protected
 // Line: 4
 
 protected interface IFoo {
diff --git a/mcs/errors/cs1527-3.cs b/mcs/errors/cs1527-3.cs
index 763c75958ee..469d74cbb99 100644
--- a/mcs/errors/cs1527-3.cs
+++ b/mcs/errors/cs1527-3.cs
@@ -1,4 +1,4 @@
-// CS1527: Namespace elements cannot be explicitly declared as private, protected or protected internal
+// CS1527: Namespace elements cannot be explicitly declared as private, protected, protected internal, or private protected
 // Line: 4
 
 protected internal enum E {
diff --git a/mcs/errors/cs1527.cs b/mcs/errors/cs1527.cs
index 189cc472f4c..e847fd14e11 100644
--- a/mcs/errors/cs1527.cs
+++ b/mcs/errors/cs1527.cs
@@ -1,4 +1,5 @@
-// CS1527: Namespace elements cannot be explicitly declared as private, protected or protected internal
-// Line:
+// CS1527: Namespace elements cannot be explicitly declared as private, protected, protected internal, or private protected
+// Line: 4
+
 private class X {
 }
diff --git a/mcs/errors/cs1611-2.cs b/mcs/errors/cs1611-2.cs
new file mode 100644
index 00000000000..882231378f0
--- /dev/null
+++ b/mcs/errors/cs1611-2.cs
@@ -0,0 +1,8 @@
+// CS1611: The params parameter cannot be declared as ref, out or in
+// Line: 6
+// Compiler options: -langversion:latest
+
+class Test
+{
+    public static void Error (params in int args) {}
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1611.cs b/mcs/errors/cs1611.cs
index 8df10fac0ce..469e083ec3c 100644
--- a/mcs/errors/cs1611.cs
+++ b/mcs/errors/cs1611.cs
@@ -1,4 +1,4 @@
-// CS1611: The params parameter cannot be declared as ref or out
+// CS1611: The params parameter cannot be declared as ref, out or in
 // Line: 6
 
 class Test
diff --git a/mcs/errors/cs1644-61.cs b/mcs/errors/cs1644-61.cs
new file mode 100644
index 00000000000..d58ba64c7ec
--- /dev/null
+++ b/mcs/errors/cs1644-61.cs
@@ -0,0 +1,11 @@
+// CS1644: Feature `digit separators' cannot be used because it is not part of the C# 6.0 language specification
+// Line: 9
+// Compiler options: -langversion:6
+
+class X
+{
+	int Test ()
+	{
+		var i = 1_0;
+	}
+}
diff --git a/mcs/errors/cs1644-62.cs b/mcs/errors/cs1644-62.cs
new file mode 100644
index 00000000000..5a29839610d
--- /dev/null
+++ b/mcs/errors/cs1644-62.cs
@@ -0,0 +1,10 @@
+// CS1644: Feature `private protected' cannot be used because it is not part of the C# 6.0 language specification
+// Line: 7
+// Compiler options: -langversion:6
+
+class C
+{
+	private protected enum E
+	{
+	}
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1644-63.cs b/mcs/errors/cs1644-63.cs
new file mode 100644
index 00000000000..ce61d5ce046
--- /dev/null
+++ b/mcs/errors/cs1644-63.cs
@@ -0,0 +1,22 @@
+// CS1644: Feature `extensible fixed statement' cannot be used because it is not part of the C# 7.2 language specification 
+// Line: 11
+// Compiler options: -unsafe -langversion:7.2
+
+using System;
+
+unsafe class C
+{
+	public static void Main ()
+	{
+		fixed (int* p = new Fixable ()) {
+		}
+	}
+
+	struct Fixable
+	{
+		public ref int GetPinnableReference ()
+		{
+			throw new NotImplementedException ();
+		}
+	}
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1644-64.cs b/mcs/errors/cs1644-64.cs
new file mode 100644
index 00000000000..88917a0a5d5
--- /dev/null
+++ b/mcs/errors/cs1644-64.cs
@@ -0,0 +1,13 @@
+// CS1644: Feature `expression body property accessor' cannot be used because it is not part of the C# 6.0 language specification 
+// Line: 11
+// Compiler options: -langversion:6
+
+using System;
+
+class C
+{
+	public int Integer
+	{
+		get => 0;
+	}
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1644-65.cs b/mcs/errors/cs1644-65.cs
new file mode 100644
index 00000000000..dea648b7846
--- /dev/null
+++ b/mcs/errors/cs1644-65.cs
@@ -0,0 +1,13 @@
+// CS1644: Feature `expression body property accessor' cannot be used because it is not part of the C# 6.0 language specification 
+// Line: 11
+// Compiler options: -langversion:6
+
+using System;
+
+class C
+{
+	public int this[int i]
+	{
+		get => i;
+	}
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1644-66.cs b/mcs/errors/cs1644-66.cs
new file mode 100644
index 00000000000..3f393b50d30
--- /dev/null
+++ b/mcs/errors/cs1644-66.cs
@@ -0,0 +1,17 @@
+// CS1644: Feature `expression body event accessor' cannot be used because it is not part of the C# 6.0 language specification 
+// Line: 11
+// Compiler options: -langversion:6
+
+using System;
+
+class C
+{
+	public event EventHandler Event
+	{
+		add => Ignore ();
+	}
+
+	static void Ignore ()
+	{
+	}
+}
\ No newline at end of file
diff --git a/mcs/errors/cs1763-2.cs b/mcs/errors/cs1763-2.cs
index 72f5370949a..7e4d091fc72 100644
--- a/mcs/errors/cs1763-2.cs
+++ b/mcs/errors/cs1763-2.cs
@@ -1,4 +1,4 @@
-// CS1763: Optional parameter `o' of type `object' can only be initialized with `null'
+// CS1763: Optional parameter `o' of type `object' can only be initialized with default value
 // Line: 6
 
 class C
diff --git a/mcs/errors/cs1763.cs b/mcs/errors/cs1763.cs
index d10a7bf2c20..03b5f28a19d 100644
--- a/mcs/errors/cs1763.cs
+++ b/mcs/errors/cs1763.cs
@@ -1,4 +1,4 @@
-// CS1763: Optional parameter `o' of type `object' can only be initialized with `null'
+// CS1763: Optional parameter `o' of type `object' can only be initialized with default value
 // Line: 6
 
 class C
diff --git a/mcs/errors/cs8326.cs b/mcs/errors/cs8326.cs
new file mode 100644
index 00000000000..efd3a84fea7
--- /dev/null
+++ b/mcs/errors/cs8326.cs
@@ -0,0 +1,13 @@
+// CS8326: Both ref conditional operators must be ref values
+// Line: 11
+
+class Program
+{
+	static int x, y;
+
+	public static void Main ()
+	{
+		bool b = false;
+		ref int targetBucket = ref b ? x : y;
+	}
+}
\ No newline at end of file
diff --git a/mcs/errors/cs8327.cs b/mcs/errors/cs8327.cs
new file mode 100644
index 00000000000..8d0ccd86a70
--- /dev/null
+++ b/mcs/errors/cs8327.cs
@@ -0,0 +1,14 @@
+// CS8327: The ref conditional expression types `int' and `byte' have to match
+// Line: 12
+
+class Program
+{
+	static int x;
+	static byte y;
+
+	public static void Main ()
+	{
+		bool b = false;
+		ref int targetBucket = ref b ? ref x : ref y;
+	}
+}
\ No newline at end of file
diff --git a/mcs/errors/cs0428-2.cs b/mcs/errors/cs8385-2.cs
similarity index 50%
rename from mcs/errors/cs0428-2.cs
rename to mcs/errors/cs8385-2.cs
index 5f468fd519a..cc7860faa62 100644
--- a/mcs/errors/cs0428-2.cs
+++ b/mcs/errors/cs8385-2.cs
@@ -1,4 +1,4 @@
-// CS0428: Cannot convert method group `Main' to non-delegate type `void*'. Consider using parentheses to invoke the method
+// CS8385: The given expression cannot be used in a fixed statement
 // Line: 9
 // Compiler options: -unsafe
 
diff --git a/mcs/errors/cs0213-2.cs b/mcs/errors/cs8385.cs
similarity index 54%
rename from mcs/errors/cs0213-2.cs
rename to mcs/errors/cs8385.cs
index ae72e4cd9aa..5fa9f794ccf 100644
--- a/mcs/errors/cs0213-2.cs
+++ b/mcs/errors/cs8385.cs
@@ -1,4 +1,4 @@
-// CS0213: You cannot use the fixed statement to take the address of an already fixed expression
+// CS8385: The given expression cannot be used in a fixed statement
 // Line: 9
 // Compiler options: -unsafe
 
diff --git a/mcs/errors/known-issues-net_4_x b/mcs/errors/known-issues-net_4_x
index c9ed9317350..54902e03e7b 100644
--- a/mcs/errors/known-issues-net_4_x
+++ b/mcs/errors/known-issues-net_4_x
@@ -14,6 +14,9 @@
 # Parser problems
 cs0080.cs 
 
+# Undocumented switch governing rules
+cs0151-4.cs NO ERROR
+
 # Operators
 cs0457-2.cs
 cs0457.cs
diff --git a/mcs/ilasm/Makefile b/mcs/ilasm/Makefile
index 090d1cc3231..4ca11545781 100644
--- a/mcs/ilasm/Makefile
+++ b/mcs/ilasm/Makefile
@@ -13,7 +13,7 @@ EXTRA_DISTFILES = \
 	$(wildcard tests/*.il)
 
 ILParser.cs: parser/ILParser.jay $(topdir)/jay/skeleton.cs
-	$(topdir)/jay/jay -ct < $(topdir)/jay/skeleton.cs $(CURDIR)/$< >$@
+	$(topdir)/jay/jay -ct -o $@ $(CURDIR)/$< < $(topdir)/jay/skeleton.cs
 
 include ../build/executable.make
 
diff --git a/mcs/jay/defs.h b/mcs/jay/defs.h
index 2aade48dac2..3bd3c5859ce 100644
--- a/mcs/jay/defs.h
+++ b/mcs/jay/defs.h
@@ -236,12 +236,14 @@ extern char *input_file_name;
 extern char *prolog_file_name;
 extern char *local_file_name;
 extern char *verbose_file_name;
+extern char *output_file_name;
 
 extern FILE *action_file;
 extern FILE *input_file;
 extern FILE *prolog_file;
 extern FILE *local_file;
 extern FILE *verbose_file;
+extern FILE *output_file;
 
 extern int nitems;
 extern int nrules;
diff --git a/mcs/jay/main.c b/mcs/jay/main.c
index fcac218b1df..7fb5e6c8ccb 100644
--- a/mcs/jay/main.c
+++ b/mcs/jay/main.c
@@ -63,6 +63,7 @@ char *input_file_name = "";
 char *prolog_file_name;
 char *local_file_name;
 char *verbose_file_name;
+char *output_file_name = 0;
 
 FILE *action_file;	/*  a temp file, used to save actions associated    */
 			/*  with rules until the parser is written	    */
@@ -70,6 +71,7 @@ FILE *input_file;	/*  the input file				    */
 FILE *prolog_file;	/*  temp files, used to save text until all	    */
 FILE *local_file;	/*  symbols have been defined			    */
 FILE *verbose_file;	/*  y.output					    */
+FILE *output_file; /* defaults to stdout */
 
 int nitems;
 int nrules;
@@ -106,6 +108,7 @@ int k;
     if (action_file) { fclose(action_file); unlink(action_file_name); }
     if (prolog_file) { fclose(prolog_file); unlink(prolog_file_name); }
     if (local_file) { fclose(local_file); unlink(local_file_name); }
+    if (output_file && (output_file != stdout)) { fclose(output_file); if (k != 0) unlink(output_file_name); }
     exit(k);
 }
 
@@ -137,7 +140,7 @@ set_signals()
 
 usage()
 {
-    fprintf(stderr, "usage: %s [-tvcp] [-b file_prefix] filename\n", myname);
+    fprintf(stderr, "usage: %s [-tvcp] [-b file_prefix] [-o output_filename] input_filename\n", myname);
     exit(1);
 }
 
@@ -167,9 +170,9 @@ char *argv[];
 	    if (i + 1 < argc) usage();
 	    return;
 
-        case '-':
-            ++i;
-            goto no_more_options;
+    case '-':
+        ++i;
+        goto no_more_options;
 
 	case 'b':
 	    if (*++s)
@@ -180,13 +183,22 @@ char *argv[];
 		usage();
 	    continue;
 
-        case 't':
-            tflag = 1;
-            break;
+    case 'o':
+        if (*++s)
+            output_file_name = s;
+        else if (++i < argc)
+            output_file_name = argv[i];
+        else
+            usage();
+        continue;
+
+    case 't':
+        tflag = 1;
+        break;
 
 	case 'p':
-            print_skel_dir ();
-            break;
+        print_skel_dir ();
+        break;
 
 	case 'c':
 	    csharp = 1;
@@ -217,12 +229,12 @@ char *argv[];
 		vflag = 1;
 		break;
 
-            case 'p':
-                print_skel_dir ();
-                break;
+        case 'p':
+            print_skel_dir ();
+            break;
 
-            case 'c':
-		csharp = 1;
+        case 'c':
+		    csharp = 1;
 	        line_format = "#line %d \"%s\"\n";
         	default_line_format = "#line default\n";
 
@@ -355,6 +367,17 @@ open_files()
 	if (verbose_file == 0)
 	    open_error(verbose_file_name);
     }
+
+    if (output_file == 0)
+    {
+        if (output_file_name != 0) {
+            output_file = fopen(output_file_name, "w");
+            if (output_file == 0)
+                open_error(output_file_name);
+        } else {
+            output_file = stdout;
+        }
+    }
 }
 
 
diff --git a/mcs/jay/output.c b/mcs/jay/output.c
index d1e2c14a1b2..ab9b2043be9 100644
--- a/mcs/jay/output.c
+++ b/mcs/jay/output.c
@@ -73,7 +73,7 @@ output () {
       fprintf(stderr, "jay: line %d is too long\n", lno), done(1);
     switch (buf[0]) {
     case '#':	continue;
-    case 't':	if (!tflag) fputs("//t", stdout);
+    case 't':	if (!tflag) fputs("//t", output_file);
     case '.':	break;
     default:
       cp = strtok(buf, " \t\r\n");
@@ -93,7 +93,7 @@ output () {
           fprintf(stderr, "jay: unknown call (%s) in line %d\n", cp, lno);
       continue;
     }
-    fputs(buf+1, stdout), ++ outline;
+    fputs(buf+1, output_file), ++ outline;
   }
   free_parser();
 }
@@ -103,19 +103,19 @@ output_rule_data()
     register int i;
     register int j;
 
-	printf("/*\n All more than 3 lines long rules are wrapped into a method\n*/\n");
+	fprintf(output_file, "/*\n All more than 3 lines long rules are wrapped into a method\n*/\n");
 
     for (i = 0; i < nmethods; ++i)
 	{
-		printf("%s", methods[i]);
+		fprintf(output_file, "%s", methods[i]);
 		FREE(methods[i]);
-		printf("\n\n");
+		fprintf(output_file, "\n\n");
 	}
 	FREE(methods);
 
-	printf(default_line_format, ++outline + 1);
+	fprintf(output_file, default_line_format, ++outline + 1);
 
-    printf("  %s static %s short [] yyLhs  = {%16d,",
+    fprintf(output_file, "  %s static %s short [] yyLhs  = {%16d,",
 	   csharp ? "" : " protected",
 	   csharp ? "readonly" : "final",
 	    symbol_value[start_symbol]);
@@ -126,18 +126,18 @@ output_rule_data()
 	if (j >= 10)
 	{
 	    ++outline;
-	    putchar('\n');
+	    putc('\n', output_file);
 	    j = 1;
 	}
         else
 	    ++j;
 
-        printf("%5d,", symbol_value[rlhs[i]]);
+        fprintf(output_file, "%5d,", symbol_value[rlhs[i]]);
     }
     outline += 2;
-    printf("\n  };\n");
+    fprintf(output_file, "\n  };\n");
 
-    printf("  %s static %s short [] yyLen = {%12d,",
+    fprintf(output_file, "  %s static %s short [] yyLen = {%12d,",
 	   csharp ? "" : "protected",
 	   csharp ? "readonly" : "final",
 	   2);
@@ -148,16 +148,16 @@ output_rule_data()
 	if (j >= 10)
 	{
 	    ++outline;
-	    putchar('\n');
+	    putc('\n', output_file);
 	    j = 1;
 	}
 	else
 	  j++;
 
-        printf("%5d,", rrhs[i + 1] - rrhs[i] - 1);
+        fprintf(output_file, "%5d,", rrhs[i + 1] - rrhs[i] - 1);
     }
     outline += 2;
-    printf("\n  };\n");
+    fprintf(output_file, "\n  };\n");
 }
 
 
@@ -165,7 +165,7 @@ output_yydefred()
 {
     register int i, j;
 
-    printf("  %s static %s short [] yyDefRed = {%13d,",
+    fprintf(output_file, "  %s static %s short [] yyDefRed = {%13d,",
 	   csharp ? "" : "protected",
 	   csharp ? "readonly" : "final",	   
 	    (defred[0] ? defred[0] - 2 : 0));
@@ -178,15 +178,15 @@ output_yydefred()
 	else
 	{
 	    ++outline;
-	    putchar('\n');
+	    putc('\n', output_file);
 	    j = 1;
 	}
 
-	printf("%5d,", (defred[i] ? defred[i] - 2 : 0));
+	fprintf(output_file, "%5d,", (defred[i] ? defred[i] - 2 : 0));
     }
 
     outline += 2;
-    printf("\n  };\n");
+    fprintf(output_file, "\n  };\n");
 }
 
 
@@ -309,7 +309,7 @@ goto_actions()
     state_count = NEW2(nstates, short);
 
     k = default_goto(start_symbol + 1);
-    printf("  protected static %s short [] yyDgoto  = {%14d,", csharp ? "readonly" : "final", k);
+    fprintf(output_file, "  protected static %s short [] yyDgoto  = {%14d,", csharp ? "readonly" : "final", k);
     save_column(start_symbol + 1, k);
 
     j = 10;
@@ -318,19 +318,19 @@ goto_actions()
 	if (j >= 10)
 	{
 	    ++outline;
-	    putchar('\n');
+	    putc('\n', output_file);
 	    j = 1;
 	}
 	else
 	    ++j;
 
 	k = default_goto(i);
-	printf("%5d,", k);
+	fprintf(output_file, "%5d,", k);
 	save_column(i, k);
     }
 
     outline += 2;
-    printf("\n  };\n");
+    fprintf(output_file, "\n  };\n");
     FREE(state_count);
 }
 
@@ -633,7 +633,7 @@ output_base()
 {
     register int i, j;
 
-    printf("  protected static %s short [] yySindex = {%13d,", csharp? "readonly":"final", base[0]);
+    fprintf(output_file, "  protected static %s short [] yySindex = {%13d,", csharp? "readonly":"final", base[0]);
 
     j = 10;
     for (i = 1; i < nstates; i++)
@@ -641,17 +641,17 @@ output_base()
 	if (j >= 10)
 	{
 	    ++outline;
-	    putchar('\n');
+	    putc('\n', output_file);
 	    j = 1;
 	}
 	else
 	    ++j;
 
-	printf("%5d,", base[i]);
+	fprintf(output_file, "%5d,", base[i]);
     }
 
     outline += 2;
-    printf("\n  };\n  protected static %s short [] yyRindex = {%13d,",
+    fprintf(output_file, "\n  };\n  protected static %s short [] yyRindex = {%13d,",
 	   csharp ? "readonly" : "final",
 	    base[nstates]);
 
@@ -661,17 +661,17 @@ output_base()
 	if (j >= 10)
 	{
 	    ++outline;
-	    putchar('\n');
+	    putc('\n', output_file);
 	    j = 1;
 	}
 	else
 	    ++j;
 
-	printf("%5d,", base[i]);
+	fprintf(output_file, "%5d,", base[i]);
     }
 
     outline += 2;
-    printf("\n  };\n  protected static %s short [] yyGindex = {%13d,",
+    fprintf(output_file, "\n  };\n  protected static %s short [] yyGindex = {%13d,",
 	   csharp ? "readonly" : "final",
 	    base[2*nstates]);
 
@@ -681,17 +681,17 @@ output_base()
 	if (j >= 10)
 	{
 	    ++outline;
-	    putchar('\n');
+	    putc('\n', output_file);
 	    j = 1;
 	}
 	else
 	    ++j;
 
-	printf("%5d,", base[i]);
+	fprintf(output_file, "%5d,", base[i]);
     }
 
     outline += 2;
-    printf("\n  };\n");
+    fprintf(output_file, "\n  };\n");
     FREE(base);
 }
 
@@ -702,7 +702,7 @@ output_table()
     register int i;
     register int j;
 
-    printf("  protected static %s short [] yyTable = {%14d,", csharp ? "readonly" : "final", table[0]);
+    fprintf(output_file, "  protected static %s short [] yyTable = {%14d,", csharp ? "readonly" : "final", table[0]);
 
     j = 10;
     for (i = 1; i <= high; i++)
@@ -710,17 +710,17 @@ output_table()
 	if (j >= 10)
 	{
 	    ++outline;
-	    putchar('\n');
+	    putc('\n', output_file);
 	    j = 1;
 	}
 	else
 	    ++j;
 
-	printf("%5d,", table[i]);
+	fprintf(output_file, "%5d,", table[i]);
     }
 
     outline += 2;
-    printf("\n  };\n");
+    fprintf(output_file, "\n  };\n");
     FREE(table);
 }
 
@@ -731,7 +731,7 @@ output_check()
     register int i;
     register int j;
 
-    printf("  protected static %s short [] yyCheck = {%14d,",
+    fprintf(output_file, "  protected static %s short [] yyCheck = {%14d,",
 	   csharp ? "readonly" : "final",
 	    check[0]);
 
@@ -741,17 +741,17 @@ output_check()
 	if (j >= 10)
 	{
 	    ++outline;
-	    putchar('\n');
+	    putc('\n', output_file);
 	    j = 1;
 	}
 	else
 	    ++j;
 
-	printf("%5d,", check[i]);
+	fprintf(output_file, "%5d,", check[i]);
     }
 
     outline += 2;
-    printf("\n  };\n");
+    fprintf(output_file, "\n  };\n");
     FREE(check);
 }
 
@@ -801,30 +801,30 @@ char *prefix;
 	if (is_C_identifier(s))
 	{
 	    if (prefix)
-	        printf("  %s ", prefix);
+	        fprintf(output_file, "  %s ", prefix);
 	    c = *s;
 	    if (c == '"')
 	    {
 		while ((c = *++s) != '"')
 		{
-		    putchar(c);
+		    putc(c, output_file);
 		}
 	    }
 	    else
 	    {
 		do
 		{
-		    putchar(c);
+		    putc(c, output_file);
 		}
 		while (c = *++s);
 	    }
 	    ++outline;
-	    printf(" = %d%s\n", symbol_value[i], csharp ? ";" : ";");
+	    fprintf(output_file, " = %d%s\n", symbol_value[i], csharp ? ";" : ";");
 	}
     }
 
     ++outline;
-    printf("  %s yyErrorCode = %d%s\n", prefix ? prefix : "", symbol_value[1], csharp ? ";" : ";");
+    fprintf(output_file, "  %s yyErrorCode = %d%s\n", prefix ? prefix : "", symbol_value[1], csharp ? ";" : ";");
 }
 
 
@@ -842,14 +842,14 @@ char *name;
     if ((c = getc(in)) != EOF) {
       if (c ==  '\n')
 	++outline;
-      putchar(c);
+      putc(c, output_file);
       while ((c = getc(in)) != EOF)
       {
 	if (c == '\n')
 	    ++outline;
-    	putchar(c);
+    	putc(c, output_file);
       }
-      printf(default_line_format, ++outline + 1);
+      fprintf(output_file, default_line_format, ++outline + 1);
     }
     fclose(in);
 }
@@ -862,67 +862,67 @@ output_debug()
     char * prefix = tflag ? "" : "//t";
 
     ++outline;
-    printf("  protected %s int yyFinal = %d;\n", csharp ? "const" : "static final", final_state);
+    fprintf(output_file, "  protected %s int yyFinal = %d;\n", csharp ? "const" : "static final", final_state);
 
       ++outline;
-	  printf ("%s // Put this array into a separate class so it is only initialized if debugging is actually used\n", prefix);
-	  printf ("%s // Use MarshalByRefObject to disable inlining\n", prefix);
-	  printf("%s class YYRules %s {\n", prefix, csharp ? ": MarshalByRefObject" : "");
-      printf("%s  public static %s string [] yyRule = {\n", prefix, csharp ? "readonly" : "final");
+	  fprintf(output_file, "%s // Put this array into a separate class so it is only initialized if debugging is actually used\n", prefix);
+	  fprintf(output_file, "%s // Use MarshalByRefObject to disable inlining\n", prefix);
+	  fprintf(output_file, "%s class YYRules %s {\n", prefix, csharp ? ": MarshalByRefObject" : "");
+      fprintf(output_file, "%s  public static %s string [] yyRule = {\n", prefix, csharp ? "readonly" : "final");
       for (i = 2; i < nrules; ++i)
       {
-	  printf("%s    \"%s :", prefix, symbol_name[rlhs[i]]);
+	  fprintf(output_file, "%s    \"%s :", prefix, symbol_name[rlhs[i]]);
 	  for (j = rrhs[i]; ritem[j] > 0; ++j)
 	  {
 	      s = symbol_name[ritem[j]];
 	      if (s[0] == '"')
 	      {
-		  printf(" \\\"");
+		  fprintf(output_file, " \\\"");
 		  while (*++s != '"')
 		  {
 		      if (*s == '\\')
 		      {
 			  if (s[1] == '\\')
-			      printf("\\\\\\\\");
+			      fprintf(output_file, "\\\\\\\\");
 			  else
-			      printf("\\\\%c", s[1]);
+			      fprintf(output_file, "\\\\%c", s[1]);
 			  ++s;
 		      }
 		      else
-			  putchar(*s);
+			  putc(*s, output_file);
 		  }
-		  printf("\\\"");
+		  fprintf(output_file, "\\\"");
 	      }
 	      else if (s[0] == '\'')
 	      {
 		  if (s[1] == '"')
-		      printf(" '\\\"'");
+		      fprintf(output_file, " '\\\"'");
 		  else if (s[1] == '\\')
 		  {
 		      if (s[2] == '\\')
-			  printf(" '\\\\\\\\");
+			  fprintf(output_file, " '\\\\\\\\");
 		      else
-			  printf(" '\\\\%c", s[2]);
+			  fprintf(output_file, " '\\\\%c", s[2]);
 		      s += 2;
 		      while (*++s != '\'')
-			  putchar(*s);
-		      putchar('\'');
+			  putc(*s, output_file);
+		      putc('\'', output_file);
 		  }
 		  else
-		      printf(" '%c'", s[1]);
+		      fprintf(output_file, " '%c'", s[1]);
 	      }
 	      else
-		  printf(" %s", s);
+		  fprintf(output_file, " %s", s);
 	  }
 	  ++outline;
-	  printf("\",\n");
+	  fprintf(output_file, "\",\n");
       }
       ++ outline;
-      printf("%s  };\n", prefix);
-	  printf ("%s public static string getRule (int index) {\n", prefix);
-	  printf ("%s    return yyRule [index];\n", prefix);
-	  printf ("%s }\n", prefix);
-	  printf ("%s}\n", prefix);
+      fprintf(output_file, "%s  };\n", prefix);
+	  fprintf(output_file, "%s public static string getRule (int index) {\n", prefix);
+	  fprintf(output_file, "%s    return yyRule [index];\n", prefix);
+	  fprintf(output_file, "%s }\n", prefix);
+	  fprintf(output_file, "%s}\n", prefix);
 
     max = 0;
     for (i = 2; i < ntokens; ++i)
@@ -931,7 +931,7 @@ output_debug()
 
 	/* need yyNames for yyExpecting() */
 
-      printf("  protected static %s string [] yyNames = {", csharp ? "readonly" : "final");
+      fprintf(output_file, "  protected static %s string [] yyNames = {", csharp ? "readonly" : "final");
       symnam = (char **) MALLOC((max+1)*sizeof(char *));
       if (symnam == 0) no_space();
   
@@ -943,7 +943,7 @@ output_debug()
 	  symnam[symbol_value[i]] = symbol_name[i];
       symnam[0] = "end-of-file";
   
-      j = 70; fputs("    ", stdout);
+      j = 70; fputs("    ", output_file);
       for (i = 0; i <= max; ++i)
       {
 	  if (s = symnam[i])
@@ -965,25 +965,25 @@ output_debug()
 		  if (j > 70)
 		  {
 		      ++outline;
-		      printf("\n    ");
+		      fprintf(output_file, "\n    ");
 		      j = k;
 		  }
-		  printf("\"\\\"");
+		  fprintf(output_file, "\"\\\"");
 		  s = symnam[i];
 		  while (*++s != '"')
 		  {
 		      if (*s == '\\')
 		      {
-			  printf("\\\\");
+			  fprintf(output_file, "\\\\");
 			  if (*++s == '\\')
-			      printf("\\\\");
+			      fprintf(output_file, "\\\\");
 			  else
-			      putchar(*s);
+			      putc(*s, output_file);
 		      }
 		      else
-			  putchar(*s);
+			  putc(*s, output_file);
 		  }
-		  printf("\\\"\",");
+		  fprintf(output_file, "\\\"\",");
 	      }
 	      else if (s[0] == '\'')
 	      {
@@ -993,10 +993,10 @@ output_debug()
 		      if (j > 70)
 		      {
 			  ++outline;
-		      	  printf("\n    ");
+		      	  fprintf(output_file, "\n    ");
 			  j = 7;
 		      }
-		      printf("\"'\\\"'\",");
+		      fprintf(output_file, "\"'\\\"'\",");
 		  }
 		  else
 		  {
@@ -1015,25 +1015,25 @@ output_debug()
 		      if (j > 70)
 		      {
 			  ++outline;
-		      	  printf("\n    ");
+		      	  fprintf(output_file, "\n    ");
 			  j = k;
 		      }
-		      printf("\"'");
+		      fprintf(output_file, "\"'");
 		      s = symnam[i];
 		      while (*++s != '\'')
 		      {
 			  if (*s == '\\')
 			  {
-			      printf("\\\\");
+			      fprintf(output_file, "\\\\");
 			      if (*++s == '\\')
-				  printf("\\\\");
+				  fprintf(output_file, "\\\\");
 			      else
-				  putchar(*s);
+				  putc(*s, output_file);
 			  }
 			  else
-			      putchar(*s);
+			      putc(*s, output_file);
 		      }
-		      printf("'\",");
+		      fprintf(output_file, "'\",");
 		  }
 	      }
 	      else
@@ -1043,12 +1043,12 @@ output_debug()
 		  if (j > 70)
 		  {
 		      ++outline;
-		      printf("\n    ");
+		      fprintf(output_file, "\n    ");
 		      j = k;
 		  }
-		  putchar('"');
-		  do { putchar(*s); } while (*++s);
-		  printf("\",");
+		  putc('"', output_file);
+		  do { putc(*s, output_file); } while (*++s);
+		  fprintf(output_file, "\",");
 	      }
 	  }
 	  else
@@ -1057,14 +1057,14 @@ output_debug()
 	      if (j > 70)
 	      {
 		  ++outline;
-		  printf("\n    ");
+		  fprintf(output_file, "\n    ");
 		  j = 5;
 	      }
-	      printf("null,");
+	      fprintf(output_file, "null,");
 	  }
       }
       outline += 2;
-      printf("\n  };\n");
+      fprintf(output_file, "\n  };\n");
       FREE(symnam);
 }
 
@@ -1084,19 +1084,19 @@ output_trailing_text()
 	if ((c = getc(in)) == EOF)
 	    return;
         ++outline;
-	printf(line_format, lineno, input_file_name);
+	fprintf(output_file, line_format, lineno, input_file_name);
 	if (c == '\n')
 	    ++outline;
-	putchar(c);
+	putc(c, output_file);
 	last = c;
     }
     else
     {
 	++outline;
-	printf(line_format, lineno, input_file_name);
-	do { putchar(c); } while ((c = *++cptr) != '\n');
+	fprintf(output_file, line_format, lineno, input_file_name);
+	do { putc(c, output_file); } while ((c = *++cptr) != '\n');
 	++outline;
-	putchar('\n');
+	putc('\n', output_file);
 	last = '\n';
     }
 
@@ -1104,16 +1104,16 @@ output_trailing_text()
     {
 	if (c == '\n')
 	    ++outline;
-	putchar(c);
+	putc(c, output_file);
 	last = c;
     }
 
     if (last != '\n')
     {
 	++outline;
-	putchar('\n');
+	putc('\n', output_file);
     }
-    printf(default_line_format, ++outline + 1);
+    fprintf(output_file, default_line_format, ++outline + 1);
 }
 
 
@@ -1132,22 +1132,22 @@ output_semantic_actions()
     last = c;
     if (c == '\n')
 	++outline;
-    putchar(c);
+    putc(c, output_file);
     while ((c = getc(action_file)) != EOF)
     {
 	if (c == '\n')
 	    ++outline;
-	putchar(c);
+	putc(c, output_file);
 	last = c;
     }
 
     if (last != '\n')
     {
 	++outline;
-	putchar('\n');
+	putc('\n', output_file);
     }
 
-    printf(default_line_format, ++outline + 1);
+    fprintf(output_file, default_line_format, ++outline + 1);
 }
 
 
diff --git a/mcs/mcs/Makefile b/mcs/mcs/Makefile
index dbd71a3d581..dbf040afdd6 100644
--- a/mcs/mcs/Makefile
+++ b/mcs/mcs/Makefile
@@ -32,7 +32,7 @@ BUILT_SOURCES = cs-parser.cs
 CLEAN_FILES += y.output
 
 %-parser.cs: %-parser.jay $(topdir)/jay/skeleton.cs
-	$(topdir)/jay/jay $(JAY_FLAGS) < $(topdir)/jay/skeleton.cs $< > jay-tmp.out && mv jay-tmp.out $@
+	$(topdir)/jay/jay $(JAY_FLAGS) -o jay-tmp.out $< < $(topdir)/jay/skeleton.cs && mv jay-tmp.out $@
 
 KEEP_OUTPUT_FILE_COPY = yes
 
diff --git a/mcs/mcs/argument.cs b/mcs/mcs/argument.cs
index 5b1003dbadf..4c75e41a9e5 100644
--- a/mcs/mcs/argument.cs
+++ b/mcs/mcs/argument.cs
@@ -38,6 +38,8 @@ namespace Mono.CSharp
 			// Conditional instance expression inserted as the first argument
 			ExtensionTypeConditionalAccess = 5 | ConditionalAccessFlag,
 
+			Readonly = 6,
+
 			ConditionalAccessFlag = 1 << 7
 		}
 
diff --git a/mcs/mcs/assembly.cs b/mcs/mcs/assembly.cs
index aa4c54317a2..96e43e70d99 100644
--- a/mcs/mcs/assembly.cs
+++ b/mcs/mcs/assembly.cs
@@ -554,7 +554,8 @@ namespace Mono.CSharp
 						if (prop != null) {
 							AttributeEncoder encoder = new AttributeEncoder ();
 							encoder.EncodeNamedPropertyArgument (prop, new BoolLiteral (Compiler.BuiltinTypes, true, Location.Null));
-							SetCustomAttribute (pa.Constructor, encoder.ToArray ());
+							SetCustomAttribute (pa.Constructor, encoder.ToArray (out var references));
+							module.AddAssemblyReferences (references);
 						}
 					}
 				}
diff --git a/mcs/mcs/attribute.cs b/mcs/mcs/attribute.cs
index 83d403118ad..faf2cfaa1d8 100644
--- a/mcs/mcs/attribute.cs
+++ b/mcs/mcs/attribute.cs
@@ -1064,8 +1064,10 @@ namespace Mono.CSharp {
 			}
 
 			byte[] cdata;
+			List<Assembly> references;
 			if (pos_args == null && named_values == null) {
 				cdata = AttributeEncoder.Empty;
+				references = null;
 			} else {
 				AttributeEncoder encoder = new AttributeEncoder ();
 
@@ -1138,7 +1140,7 @@ namespace Mono.CSharp {
 					encoder.EncodeEmptyNamedArguments ();
 				}
 
-				cdata = encoder.ToArray ();
+				cdata = encoder.ToArray (out references);
 			}
 
 			if (!IsConditionallyExcluded (ctor.DeclaringType)) {
@@ -1157,6 +1159,8 @@ namespace Mono.CSharp {
 					Error_AttributeEmitError (e.Message);
 					return;
 				}
+
+				context.Module.AddAssemblyReferences (references);
 			}
 
 			if (!usage_attr.AllowMultiple && allEmitted != null) {
@@ -1415,6 +1419,7 @@ namespace Mono.CSharp {
 		byte[] buffer;
 		int pos;
 		const ushort Version = 1;
+		List<Assembly> imports;
 
 		static AttributeEncoder ()
 		{
@@ -1594,7 +1599,15 @@ namespace Mono.CSharp {
 		public void EncodeTypeName (TypeSpec type)
 		{
 			var old_type = type.GetMetaInfo ();
-			Encode (type.MemberDefinition.IsImported ? old_type.AssemblyQualifiedName : old_type.FullName);
+			if (type.MemberDefinition.IsImported) {
+				if (imports == null)
+					imports = new List<Assembly> ();
+
+				imports.Add (old_type.Assembly);
+				Encode (old_type.AssemblyQualifiedName);
+			} else {
+				Encode (old_type.FullName);
+			}
 		}
 
 		public void EncodeTypeName (TypeContainer type)
@@ -1675,8 +1688,10 @@ namespace Mono.CSharp {
 			Encode (value);
 		}
 
-		public byte[] ToArray ()
+		public byte[] ToArray (out List<Assembly> assemblyReferences)
 		{
+			assemblyReferences = imports;
+
 			byte[] buf = new byte[pos];
 			Array.Copy (buffer, buf, pos);
 			return buf;
@@ -1990,7 +2005,8 @@ namespace Mono.CSharp {
 			encoder.Encode ((int) state);
 			encoder.EncodeEmptyNamedArguments ();
 
-			builder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray ());
+			builder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray (out var references));
+			module.AddAssemblyReferences (references);
 		}
 	}
 
@@ -2024,7 +2040,8 @@ namespace Mono.CSharp {
 			encoder.Encode ((int) modes);
 			encoder.EncodeEmptyNamedArguments ();
 
-			builder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray ());
+			builder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray (out var references));
+			module.AddAssemblyReferences (references);
 		}
 	}
 
@@ -2050,7 +2067,8 @@ namespace Mono.CSharp {
 			encoder.Encode ((uint) bits[0]);
 			encoder.EncodeEmptyNamedArguments ();
 
-			builder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray ());
+			builder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray (out var references));
+			module.AddAssemblyReferences (references);
 		}
 
 		public void EmitAttribute (FieldBuilder builder, decimal value, Location loc)
@@ -2068,7 +2086,8 @@ namespace Mono.CSharp {
 			encoder.Encode ((uint) bits[0]);
 			encoder.EncodeEmptyNamedArguments ();
 
-			builder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray ());
+			builder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray (out var references));
+			module.AddAssemblyReferences (references);
 		}
 	}
 
@@ -2092,7 +2111,8 @@ namespace Mono.CSharp {
 			encoder.EncodeTypeName (type);
 			encoder.EncodeEmptyNamedArguments ();
 
-			builder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray ());
+			builder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray (out var references));
+			module.AddAssemblyReferences (references);
 		}
 	}
 
diff --git a/mcs/mcs/class.cs b/mcs/mcs/class.cs
index 6b1adc297a3..dc61f6dc627 100644
--- a/mcs/mcs/class.cs
+++ b/mcs/mcs/class.cs
@@ -2117,7 +2117,8 @@ namespace Mono.CSharp
 			encoder.Encode (GetAttributeDefaultMember ());
 			encoder.EncodeEmptyNamedArguments ();
 
-			TypeBuilder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray ());
+			TypeBuilder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray (out var references));
+			Module.AddAssemblyReferences (references);
 		}
 
 		public override void VerifyMembers ()
@@ -3962,7 +3963,10 @@ namespace Mono.CSharp
 					Report.Error (4013, Location,
 						"Local variables of type `{0}' cannot be used inside anonymous methods, lambda expressions or query expressions",
 						MemberType.GetSignatureForError ());
-				} else if (MemberType.IsByRefLike) {
+				} else if (MemberType.IsSpecialRuntimeType) {
+					Report.Error (610, Location,
+						"Field or property cannot be of type `{0}'", MemberType.GetSignatureForError ());
+				} else {
 					if ((ModFlags & (Modifiers.ABSTRACT | Modifiers.EXTERN)) != 0)
 						return;
 
@@ -3975,9 +3979,6 @@ namespace Mono.CSharp
 					Report.Error (8345, Location,
 						"Field or auto-implemented property cannot be of type `{0}' unless it is an instance member of a ref struct",
 						MemberType.GetSignatureForError ());
-				} else {
-					Report.Error (610, Location, 
-						"Field or property cannot be of type `{0}'", MemberType.GetSignatureForError ());
 				}
 			}
 		}
diff --git a/mcs/mcs/convert.cs b/mcs/mcs/convert.cs
index ae153fc49e8..2c8d2a0204c 100644
--- a/mcs/mcs/convert.cs
+++ b/mcs/mcs/convert.cs
@@ -1232,6 +1232,13 @@ namespace Mono.CSharp {
 					FindApplicableUserDefinedConversionOperators (rc, operators, source_type_expr, target_type, restr, ref candidates);
 				}
 
+				if (source_type_expr == source && source_type.IsNullableType) {
+					operators = MemberCache.GetUserOperator (source_type.TypeArguments [0], Operator.OpType.Implicit, declared_only);
+					if (operators != null) {
+						FindApplicableUserDefinedConversionOperators (rc, operators, source_type_expr, target_type, restr, ref candidates);
+					}
+				}
+
 				if (!implicitOnly) {
 					operators = MemberCache.GetUserOperator (source_type, Operator.OpType.Explicit, declared_only);
 					if (operators != null) {
diff --git a/mcs/mcs/cs-parser.jay b/mcs/mcs/cs-parser.jay
index 4d6fcb44c0d..4ca3bf74f3d 100644
--- a/mcs/mcs/cs-parser.jay
+++ b/mcs/mcs/cs-parser.jay
@@ -34,13 +34,16 @@ namespace Mono.CSharp
 			Params	= 1 << 4,
 			Arglist	= 1 << 5,
 			DefaultValue = 1 << 6,
+			ReadOnly = 1 << 7,
 			
-			All = Ref | Out | This | Params | Arglist | DefaultValue,
+			All = Ref | Out | This | Params | Arglist | DefaultValue | ReadOnly,
 			PrimaryConstructor = Ref | Out | Params | DefaultValue
 		}
 		
 		static readonly object ModifierNone = 0;
-	
+		static readonly object RefStructToken = new object ();
+		static readonly object RefPartialStructToken = new object ();
+
 		NamespaceContainer current_namespace;
 		TypeContainer current_container;
 		TypeDefinition current_type;
@@ -338,6 +341,7 @@ namespace Mono.CSharp
 %token OPEN_BRACKET_EXPR
 %token OPEN_PARENS_DECONSTRUCT
 %token REF_STRUCT
+%token REF_PARTIAL
 
 // Make the parser go into eval mode parsing (statements and compilation units).
 %token EVAL_STATEMENT_PARSER
@@ -648,8 +652,8 @@ namespace_or_type_declaration
 			TypeContainer ds = (TypeContainer)$1;
 
 			if ((ds.ModFlags & (Modifiers.PRIVATE | Modifiers.PROTECTED)) != 0){
-				report.Error (1527, ds.Location, 
-				"Namespace elements cannot be explicitly declared as private, protected or protected internal");
+				report.Error (1527, ds.Location,
+				"Namespace elements cannot be explicitly declared as private, protected, protected internal, or private protected");
 			}
 
 			// Here is a trick, for explicit attributes we don't know where they belong to until
@@ -1028,7 +1032,15 @@ struct_keyword
 			FeatureIsNotAvailable (GetLocation ($1), "ref structs");
 		}
 
-		$$ = this;
+		$$ = RefStructToken;
+	  }
+	| REF_PARTIAL STRUCT
+	  {
+		if (lang_version < LanguageVersion.V_7_2) {
+			FeatureIsNotAvailable (GetLocation ($1), "ref structs");
+		}
+
+		$$ = RefPartialStructToken;
 	  }
 	;
 
@@ -1043,8 +1055,13 @@ struct_declaration
 		if ((mods & Modifiers.READONLY) != 0 && lang_version < LanguageVersion.V_7_2) {
 			FeatureIsNotAvailable (GetLocation ($4), "readonly structs");
 		}
-		if ($4 != null)
+		if ($4 != null) {
 			mods |= Modifiers.REF;
+			if ($4 == RefPartialStructToken) {
+				mods |= Modifiers.PARTIAL;
+				$3 = $4;
+			}
+		}
 
 		lexer.ConstraintsParsing = true;
 		valid_param_mod = ParameterModifierType.PrimaryConstructor;
@@ -1469,7 +1486,7 @@ method_header
 	  OPEN_PARENS
 	  {
 		lexer.parsing_generic_declaration = false;
-	  	valid_param_mod = ParameterModifierType.All;
+		valid_param_mod = ParameterModifierType.All;
 	  }
 	  opt_formal_parameter_list CLOSE_PARENS 
 	  {
@@ -1569,7 +1586,7 @@ constructor_body
 	 expression SEMICOLON
 	 {
 		lexer.parsing_block = 0;
-		current_block.AddStatement (new ContextualReturn ((Expression) $3));
+		current_block.AddStatement (CreateExpressionBodiedStatement ((Expression) $3));
 		var b = end_block (GetLocation ($4));
 		b.IsCompilerGenerated = true;
 		$$ = b;
@@ -1590,7 +1607,7 @@ expression_block
 	 lambda_arrow_expression SEMICOLON
 	 {
 		lexer.parsing_block = 0;
-		current_block.AddStatement (new ContextualReturn ((Expression) $3));
+		current_block.AddStatement (CreateExpressionBodiedStatement ((Expression) $3));
 		var b = end_block (GetLocation ($4));
 		b.IsCompilerGenerated = true;
 		$$ = b;
@@ -1794,7 +1811,9 @@ parameter_modifiers
   		Parameter.Modifier mod = (Parameter.Modifier)$1 | p2;
   		if (((Parameter.Modifier)$1 & p2) == p2) {
   			Error_DuplicateParameterModifier (lexer.Location, p2);
-  		} else {
+		} else if ((mod & ~(Parameter.Modifier.This | Parameter.Modifier.ReadOnly)) == 0) {
+			// ok
+		} else {
 	  		switch (mod & ~Parameter.Modifier.This) {
   				case Parameter.Modifier.REF:
 					report.Error (1101, lexer.Location, "The parameter modifiers `this' and `ref' cannot be used altogether");
@@ -1836,6 +1855,13 @@ parameter_modifier
 	  			
 		$$ = Parameter.Modifier.This;
 	  }
+	| IN
+	  {
+		if (lang_version < LanguageVersion.V_7_2)
+			FeatureIsNotAvailable (GetLocation ($1), "readonly references");
+
+		$$ = Parameter.Modifier.ReadOnly;
+	  }
 	;
 
 parameter_array
@@ -1871,7 +1897,7 @@ params_modifier
 		if ((mod & Parameter.Modifier.This) != 0) {
 			report.Error (1104, GetLocation ($1), "The parameter modifiers `this' and `params' cannot be used altogether");
 		} else {
-			report.Error (1611, GetLocation ($1), "The params parameter cannot be declared as ref or out");
+			report.Error (1611, GetLocation ($1), "The params parameter cannot be declared as ref, out or in");
 		}	  
 	  }
 	| PARAMS params_modifier
@@ -2004,7 +2030,7 @@ indexer_declaration
 	: opt_attributes opt_modifiers
 	  ref_member_type indexer_declaration_name OPEN_BRACKET
 	  {
-	  	valid_param_mod = ParameterModifierType.Params | ParameterModifierType.DefaultValue;
+		valid_param_mod = ParameterModifierType.Params | ParameterModifierType.DefaultValue | ParameterModifierType.ReadOnly;
 	  }
 	  opt_formal_parameter_list CLOSE_BRACKET 
 	  {
@@ -2181,6 +2207,11 @@ set_accessor_declaration
 accessor_body
 	: block
 	| expression_block
+	  {
+		if (lang_version < LanguageVersion.V_7) {
+			FeatureIsNotAvailable (GetLocation ($1), "expression body property accessor");
+		}
+	  }
 	| SEMICOLON
 	  {
 		// TODO: lbag
@@ -2331,7 +2362,7 @@ operator_type
 operator_declarator
 	: operator_type OPERATOR overloadable_operator OPEN_PARENS
 	  {
-		valid_param_mod = ParameterModifierType.DefaultValue;
+		valid_param_mod = ParameterModifierType.DefaultValue | ParameterModifierType.ReadOnly;
 		if ((Operator.OpType) $3 == Operator.OpType.Is)
 			valid_param_mod |= ParameterModifierType.Out;
 	  }
@@ -2418,7 +2449,7 @@ overloadable_operator
 conversion_operator_declarator
 	: IMPLICIT OPERATOR type OPEN_PARENS
 	  {
-		valid_param_mod = ParameterModifierType.DefaultValue;
+		valid_param_mod = ParameterModifierType.DefaultValue | ParameterModifierType.ReadOnly;
 	  }
 	  opt_formal_parameter_list CLOSE_PARENS
 	  {
@@ -2441,7 +2472,7 @@ conversion_operator_declarator
 	  }
 	| EXPLICIT OPERATOR type OPEN_PARENS
 	  {
-		valid_param_mod = ParameterModifierType.DefaultValue;
+		valid_param_mod = ParameterModifierType.DefaultValue | ParameterModifierType.ReadOnly;
 	  }
 	  opt_formal_parameter_list CLOSE_PARENS
 	  {
@@ -2850,6 +2881,11 @@ event_accessor_block
 	  }
 	| block
 	| expression_block
+	  {
+		if (lang_version < LanguageVersion.V_7) {
+			FeatureIsNotAvailable (GetLocation ($1), "expression body event accessor");
+		}
+	  }
 	;
 
 attributes_without_members
@@ -3014,7 +3050,7 @@ delegate_declaration
 	  ref_member_type type_declaration_name
 	  OPEN_PARENS
 	  {
-		valid_param_mod = ParameterModifierType.Ref | ParameterModifierType.Out | ParameterModifierType.Params | ParameterModifierType.DefaultValue;
+		valid_param_mod = ParameterModifierType.Ref | ParameterModifierType.Out | ParameterModifierType.Params | ParameterModifierType.DefaultValue | ParameterModifierType.ReadOnly;
 	  }
 	  opt_formal_parameter_list CLOSE_PARENS
 	  {
@@ -3927,7 +3963,15 @@ non_simple_argument
 	  {
 		$$ = new Argument (new Arglist (GetLocation ($1)));
 		lbag.AddLocation ($$, GetLocation ($2), GetLocation ($3));
-	  }	  
+	  }
+	| IN variable_reference
+	  {
+		if (lang_version < LanguageVersion.V_7_2)
+			FeatureIsNotAvailable (GetLocation ($1), "readonly references");
+
+		$$ = new Argument ((Expression) $2, Argument.AType.Readonly);
+		lbag.AddLocation ($$, GetLocation ($1));
+	  }
 	;
 
 out_variable_declaration
@@ -4408,7 +4452,7 @@ opt_anonymous_method_signature
 anonymous_method_signature
 	: OPEN_PARENS
 	  {
-	  	valid_param_mod = ParameterModifierType.Ref | ParameterModifierType.Out;
+		valid_param_mod = ParameterModifierType.Ref | ParameterModifierType.Out | ParameterModifierType.ReadOnly;
 	  }
 	  opt_formal_parameter_list CLOSE_PARENS
 	  {
@@ -5014,36 +5058,47 @@ null_coalescing_expression
 	  }
 	;
 
+
+conditional_oper_expr
+	: expression
+	| stackalloc_expression
+	;
+
 conditional_expression
 	: null_coalescing_expression
-	| null_coalescing_expression INTERR expression COLON expression
+	| null_coalescing_expression INTERR conditional_oper_expr COLON conditional_oper_expr
 	  {
 		$$ = new Conditional (new BooleanExpression ((Expression) $1), (Expression) $3, (Expression) $5, GetLocation ($2));
 		lbag.AddLocation ($$, GetLocation ($4));
 	  }
-	| null_coalescing_expression INTERR expression COLON THROW prefixed_unary_expression
+	| null_coalescing_expression INTERR conditional_oper_expr COLON THROW prefixed_unary_expression
 	  {
 		if (lang_version < LanguageVersion.V_7)
-			FeatureIsNotAvailable (lexer.Location, "throw expression");
+			FeatureIsNotAvailable (GetLocation ($5), "throw expression");
 
 		var expr = new ThrowExpression ((Expression) $6, GetLocation ($5));
 		$$ = new Conditional (new BooleanExpression ((Expression) $1), (Expression) $3, expr, GetLocation ($2));
 		lbag.AddLocation ($$, GetLocation ($4));
 	  }
-	| null_coalescing_expression INTERR expression error
+	| null_coalescing_expression INTERR reference_expression COLON reference_expression
+	  {
+		$$ = new Conditional (new BooleanExpression ((Expression) $1), (Expression) $3, (Expression) $5, GetLocation ($2));
+		lbag.AddLocation ($$, GetLocation ($4));
+	  }
+	| null_coalescing_expression INTERR conditional_oper_expr error
 	  {
 		Error_SyntaxError (yyToken);
 
 		$$ = new Conditional (new BooleanExpression ((Expression) $1), (Expression) $3, null, GetLocation ($2));
 	  }
-	| null_coalescing_expression INTERR expression COLON error
+	| null_coalescing_expression INTERR conditional_oper_expr COLON error
 	  {
 		Error_SyntaxError (yyToken);
 
 		$$ = new Conditional (new BooleanExpression ((Expression) $1), (Expression) $3, null, GetLocation ($2));
 		lbag.AddLocation ($$, GetLocation ($4));
 	  }
-	| null_coalescing_expression INTERR expression COLON CLOSE_BRACE
+	| null_coalescing_expression INTERR conditional_oper_expr COLON CLOSE_BRACE
 	  {
 		Error_SyntaxError (Token.CLOSE_BRACE);
 
@@ -5308,7 +5363,7 @@ lambda_expression
 	  }
 	| OPEN_PARENS_LAMBDA
 	  {
-	  	valid_param_mod = ParameterModifierType.Ref | ParameterModifierType.Out;
+		valid_param_mod = ParameterModifierType.Ref | ParameterModifierType.Out | ParameterModifierType.ReadOnly;
 	  }
 	  opt_lambda_parameter_list CLOSE_PARENS ARROW 
 	  {
@@ -5322,7 +5377,7 @@ lambda_expression
 	  }
 	| ASYNC OPEN_PARENS_LAMBDA
 	  {
-	  	valid_param_mod = ParameterModifierType.Ref | ParameterModifierType.Out;	  
+		valid_param_mod = ParameterModifierType.Ref | ParameterModifierType.Out | ParameterModifierType.ReadOnly;
 	  }
 	  opt_lambda_parameter_list CLOSE_PARENS ARROW 
 	  {
@@ -5522,10 +5577,17 @@ modifiers
 		if ((m1 & m2) != 0) {
 			report.Error (1004, lexer.Location - ModifiersExtensions.Name (m2).Length,
 				"Duplicate `{0}' modifier", ModifiersExtensions.Name (m2));
-		} else if ((m2 & Modifiers.AccessibilityMask) != 0 && (m1 & Modifiers.AccessibilityMask) != 0 &&
-			((m2 | m1 & Modifiers.AccessibilityMask) != (Modifiers.PROTECTED | Modifiers.INTERNAL))) {
-			report.Error (107, lexer.Location - ModifiersExtensions.Name (m2).Length,
-				"More than one protection modifier specified");
+		} else if ((m2 & Modifiers.AccessibilityMask) != 0 && (m1 & Modifiers.AccessibilityMask) != 0) {
+			var accessibility = (m2 | m1 & Modifiers.AccessibilityMask);
+
+			if (accessibility == (Modifiers.PRIVATE | Modifiers.PROTECTED)) {
+				if (lang_version < LanguageVersion.V_7_2) {
+					FeatureIsNotAvailable (lexer.Location, "private protected");
+				}
+			} else if (accessibility != (Modifiers.PROTECTED | Modifiers.INTERNAL)) {
+				report.Error (107, lexer.Location - ModifiersExtensions.Name (m2).Length,
+					"More than one protection modifier specified");
+			}
 		}
 		
 		$$ = m1 | m2;
@@ -6223,11 +6285,28 @@ block_variable_initializer
 	| STACKALLOC simple_type
 	  {
 		report.Error (1575, GetLocation ($1), "A stackalloc expression requires [] after type");
-		$$ = new StackAlloc ((Expression) $2, null, GetLocation ($1));		
+		$$ = new StackAlloc ((Expression) $2, null, GetLocation ($1));
 	  }
 	| reference_expression
 	;
 
+stackalloc_expression
+	: STACKALLOC simple_type OPEN_BRACKET_EXPR expression CLOSE_BRACKET
+	  {
+		if (lang_version < LanguageVersion.V_7_2) {
+			FeatureIsNotAvailable (GetLocation ($1), "ref structs");
+		}
+
+		$$ = new SpanStackAlloc ((Expression) $2, (Expression) $4, GetLocation ($1));
+		lbag.AddLocation ($$, GetLocation ($3), GetLocation ($5));
+	  }
+	| STACKALLOC simple_type
+	  {
+		report.Error (1575, GetLocation ($1), "A stackalloc expression requires [] after type");
+		$$ = new StackAlloc ((Expression) $2, null, GetLocation ($1));
+	  }
+	;
+
 reference_expression
 	: REF expression
 	  {
@@ -7699,7 +7778,7 @@ doc_cref
 	  }
 	| doc_type_declaration_name DOT THIS OPEN_BRACKET
 	  {
-		valid_param_mod = ParameterModifierType.Ref | ParameterModifierType.Out;
+		valid_param_mod = ParameterModifierType.Ref | ParameterModifierType.Out | ParameterModifierType.ReadOnly;
 	  }
 	  opt_doc_parameters CLOSE_BRACKET
 	  {
@@ -7743,7 +7822,7 @@ opt_doc_method_sig
 	: /* empty */
 	| OPEN_PARENS
 	  {
-		valid_param_mod = ParameterModifierType.Ref | ParameterModifierType.Out;
+		valid_param_mod = ParameterModifierType.Ref | ParameterModifierType.Out | ParameterModifierType.ReadOnly;
 	  }
 	  opt_doc_parameters CLOSE_PARENS
 	  {
@@ -7951,6 +8030,14 @@ static bool IsUnaryOperator (Operator.OpType op)
 	return false;
 }
 
+static Statement CreateExpressionBodiedStatement (Expression expr)
+{
+	if (expr is ThrowExpression te)
+		return new StatementExpression (te);
+
+	return new ContextualReturn (expr);
+}
+
 void syntax_error (Location l, string msg)
 {
 	report.Error (1003, l, "Syntax error, " + msg);
@@ -8430,6 +8517,8 @@ static string GetTokenName (int token)
 	case Token.READONLY:
 		return "readonly";
 	case Token.REF:
+	case Token.REF_STRUCT:
+	case Token.REF_PARTIAL:
 		return "ref";
 	case Token.RETURN:
 		return "return";
@@ -8444,7 +8533,6 @@ static string GetTokenName (int token)
 	case Token.STATIC:
 		return "static";
 	case Token.STRUCT:
-	case Token.REF_STRUCT:
 		return "struct";
 	case Token.SWITCH:
 		return "switch";
diff --git a/mcs/mcs/cs-tokenizer.cs b/mcs/mcs/cs-tokenizer.cs
index 37edb5c1224..db5ba1f1f1b 100644
--- a/mcs/mcs/cs-tokenizer.cs
+++ b/mcs/mcs/cs-tokenizer.cs
@@ -825,8 +825,7 @@ namespace Mono.CSharp
 					next_token == Token.CLASS ||
 					next_token == Token.STRUCT ||
 					next_token == Token.INTERFACE ||
-					next_token == Token.VOID ||
-					next_token == Token.REF_STRUCT;
+					next_token == Token.VOID;
 
 				PopPosition ();
 
@@ -916,14 +915,20 @@ namespace Mono.CSharp
 
 				break;
 			case Token.REF:
-				if (peek_token () == Token.STRUCT) {
+				var pp = peek_token ();
+				switch (pp) {
+				case Token.STRUCT:
 					token ();
 					res = Token.REF_STRUCT;
+					break;
+				case Token.PARTIAL:
+					token ();
+					res = Token.REF_PARTIAL;
+					break;
 				}
 				break;
 			}
 
-
 			return res;
 		}
 
@@ -1212,6 +1217,7 @@ namespace Mono.CSharp
 
 				case Token.REF:
 				case Token.OUT:
+				case Token.IN:
 					can_be_type = is_type = false;
 					continue;
 
@@ -1406,6 +1412,8 @@ namespace Mono.CSharp
 			case Token.INTERPOLATED_STRING:
 			case Token.THROW:
 			case Token.DEFAULT_COLON:
+			case Token.REF:
+			case Token.STACKALLOC:
 				next_token = Token.INTERR;
 				break;
 				
@@ -1567,28 +1575,53 @@ namespace Mono.CSharp
 		{
 			int d;
 			bool seen_digits = false;
-			
-			if (c != -1){
+			bool digit_separator = false;
+			int prev = c;
+			var loc = Location;
+
+			if (prev != -1){
 				if (number_pos == MaxNumberLength)
 					Error_NumericConstantTooLong ();
-				number_builder [number_pos++] = (char) c;
+				number_builder [number_pos++] = (char) prev;
 			}
-			
+
 			//
 			// We use peek_char2, because decimal_digits needs to do a 
 			// 2-character look-ahead (5.ToString for example).
 			//
 			while ((d = peek_char2 ()) != -1){
-				if (d >= '0' && d <= '9'){
+				if (d >= '0' && d <= '9') {
 					if (number_pos == MaxNumberLength)
 						Error_NumericConstantTooLong ();
-					number_builder [number_pos++] = (char) d;
-					get_char ();
+					number_builder [number_pos++] = (char)d;
+					prev = get_char ();
 					seen_digits = true;
-				} else
-					break;
+					continue;
+				} else if (d == '_') {
+					if (!digit_separator) {
+						if (context.Settings.Version < LanguageVersion.V_7)
+							Report.FeatureIsNotAvailable (context, Location, "digit separators");
+
+						digit_separator = true;
+					}
+
+					if (prev == '.')
+						break;
+
+					if (prev == 'e' || prev == 'E')
+						Error_InvalidNumber ();
+
+					prev = get_char();
+					continue;
+				}
+
+				break;
 			}
 			
+			if (prev == '_') {
+				Error_InvalidNumber ();
+			}
+
 			return seen_digits;
 		}
 
@@ -1716,9 +1749,8 @@ namespace Mono.CSharp
 			} catch (OverflowException) {
 				Error_NumericConstantTooLong ();
 				return new IntLiteral (context.BuiltinTypes, 0, loc);
-			}
-			catch (FormatException) {
-				Report.Error (1013, Location, "Invalid number");
+			} catch (FormatException) {
+				Error_InvalidNumber ();
 				return new IntLiteral (context.BuiltinTypes, 0, loc);
 			}
 		}
@@ -1757,14 +1789,41 @@ namespace Mono.CSharp
 		{
 			int d;
 			ulong ul;
-			
-			get_char ();
+			bool digit_separator = false;
+			int prev = get_char ();
+
 			while ((d = peek_char ()) != -1){
 				if (is_hex (d)){
 					number_builder [number_pos++] = (char) d;
 					get_char ();
-				} else
-					break;
+
+					prev = d;
+					continue;
+				}
+
+				if (d == '_') {
+					if (prev == 'x' || prev == 'X')
+						Error_InvalidNumber ();
+
+					get_char ();
+
+					if (!digit_separator) {
+						if (context.Settings.Version < LanguageVersion.V_7)
+							Report.FeatureIsNotAvailable (context, Location, "digit separators");
+
+						digit_separator = true;
+					}
+
+					prev = d;
+					continue;
+				}
+
+				break;
+			}
+
+			if (number_pos == 0 || prev == '_') {
+				Error_InvalidNumber ();
+				return new IntLiteral (context.BuiltinTypes, 0, loc);
 			}
 			
 			string s = new String (number_builder, 0, number_pos);
@@ -1779,13 +1838,65 @@ namespace Mono.CSharp
 			} catch (OverflowException){
 				Error_NumericConstantTooLong ();
 				return new IntLiteral (context.BuiltinTypes, 0, loc);
-			}
-			catch (FormatException) {
-				Report.Error (1013, Location, "Invalid number");
+			} catch (FormatException) {
+				Error_InvalidNumber ();
 				return new IntLiteral (context.BuiltinTypes, 0, loc);
 			}
 		}
 
+		ILiteralConstant handle_binary (Location loc)
+		{
+			int d;
+			ulong ul = 0;
+			bool digit_separator = false;
+			int digits = 0;
+			int prev = get_char ();
+
+			while ((d = peek_char ()) != -1){
+
+				if (d == '0' || d == '1') {
+					ul = (ul << 1);
+					digits++;
+					if (d == '1')
+						ul |= 1;
+					get_char ();
+					if (digits > 64) {
+						Error_NumericConstantTooLong ();
+						return new IntLiteral (context.BuiltinTypes, 0, loc);
+					}
+
+					prev = d;
+					continue;
+				}
+
+				if (d == '_') {
+					if (prev == 'b' || prev == 'B')
+						Error_InvalidNumber ();
+
+					get_char ();
+
+					if (!digit_separator) {
+						if (context.Settings.Version < LanguageVersion.V_7)
+							Report.FeatureIsNotAvailable (context, Location, "digit separators");
+						
+						digit_separator = true;
+					}
+
+					prev = d;
+					continue;
+				}
+				 
+				break;
+			}
+
+			if (digits == 0 || prev == '_') {
+				Error_InvalidNumber ();
+				return new IntLiteral (context.BuiltinTypes, 0, loc);
+			}
+
+			return integer_type_suffix (ul, peek_char (), loc);
+		}
+		
 		//
 		// Invoked if we know we have .digits or digits
 		//
@@ -1817,7 +1928,20 @@ namespace Mono.CSharp
 
 						return Token.LITERAL;
 					}
+
+					if (peek == 'b' || peek == 'B'){
+						if (context.Settings.Version < LanguageVersion.V_7)
+							Report.FeatureIsNotAvailable (context, Location, "binary literals");
+
+						val = res = handle_binary (loc);
+#if FULL_AST
+						res.ParsedValue = reader.ReadChars (read_start, reader.Position - 1);
+#endif
+
+						return Token.LITERAL;
+					}
 				}
+
 				decimal_digits (c);
 				c = peek_char ();
 			}
@@ -1869,7 +1993,7 @@ namespace Mono.CSharp
 						Error_NumericConstantTooLong ();
 					number_builder [number_pos++] = '+';
 				}
-					
+
 				decimal_digits (c);
 				c = peek_char ();
 			}
@@ -2944,6 +3068,11 @@ namespace Mono.CSharp
 		{
 			Report.Error (1021, Location, "Integral constant is too large");			
 		}
+
+		void Error_InvalidNumber ()
+		{
+			Report.Error (1013, Location, "Invalid number");
+		}
 		
 		void Error_InvalidDirective ()
 		{
diff --git a/mcs/mcs/ecore.cs b/mcs/mcs/ecore.cs
index 20ee9e73b19..d5926bf4d1f 100644
--- a/mcs/mcs/ecore.cs
+++ b/mcs/mcs/ecore.cs
@@ -241,7 +241,7 @@ namespace Mono.CSharp {
 
 		protected void CheckExpressionVariable (ResolveContext rc)
 		{
-			if (rc.HasAny (ResolveContext.Options.BaseInitializer | ResolveContext.Options.FieldInitializerScope)) {
+			if (rc.HasAny (ResolveContext.Options.BaseInitializer | ResolveContext.Options.FieldInitializerScope) && rc.CurrentAnonymousMethod == null) {
 				rc.Report.Error (8200, loc, "Out variable and pattern variable declarations are not allowed within constructor initializers, field initializers, or property initializers");
 			} else if (rc.HasSet (ResolveContext.Options.QueryClauseScope)) {
 				rc.Report.Error (8201, loc, "Out variable and pattern variable declarations are not allowed within a query clause");
diff --git a/mcs/mcs/expression.cs b/mcs/mcs/expression.cs
index 518ccc8ef43..87db14a0ce7 100644
--- a/mcs/mcs/expression.cs
+++ b/mcs/mcs/expression.cs
@@ -920,7 +920,7 @@ namespace Mono.CSharp
 
 		public override bool ContainsEmitWithAwait ()
 		{
-			throw new NotImplementedException ();
+			return false;
 		}
 
 		public override Expression CreateExpressionTree (ResolveContext ec)
@@ -2051,7 +2051,11 @@ namespace Mono.CSharp
 
 						if (d.BuiltinType == BuiltinTypeSpec.Type.Dynamic)
 							return this;
-						
+
+						// TODO: Requires custom optimized version with variable store
+						if (Variable != null)
+							return this;
+
 						//
 						// Turn is check into simple null check for implicitly convertible reference types
 						//
@@ -2757,6 +2761,12 @@ namespace Mono.CSharp
 			}
 		}
 
+		public override bool IsNull {
+			get {
+				return TypeSpec.IsReferenceType (type);
+			}
+		}
+
 		public override bool ContainsEmitWithAwait ()
 		{
 			return false;
@@ -5669,6 +5679,12 @@ namespace Mono.CSharp
 				ConvCast.Emit (ec, enum_conversion);
 		}
 
+		public override void EmitPrepare (EmitContext ec)
+		{
+			Left.EmitPrepare (ec);
+			Right.EmitPrepare (ec);
+		}
+
 		public override void EmitSideEffect (EmitContext ec)
 		{
 			if ((oper & Operator.LogicalMask) != 0 ||
@@ -6385,7 +6401,7 @@ namespace Mono.CSharp
 							}
 						}
 
-						if (conv_false_expr != null) {
+						if (conv_false_expr != null && false_type != InternalType.ErrorType && true_type != InternalType.ErrorType) {
 							ec.Report.Error (172, true_expr.Location,
 								"Type of conditional expression cannot be determined as `{0}' and `{1}' convert implicitly to each other",
 									true_type.GetSignatureForError (), false_type.GetSignatureForError ());
@@ -6398,7 +6414,7 @@ namespace Mono.CSharp
 				} else if ((conv = Convert.ImplicitConversion (ec, false_expr, true_type, loc)) != null) {
 					false_expr = conv;
 				} else {
-					if (false_type != InternalType.ErrorType) {
+					if (false_type != InternalType.ErrorType && true_type != InternalType.ErrorType) {
 						ec.Report.Error (173, true_expr.Location,
 							"Type of conditional expression cannot be determined because there is no implicit conversion between `{0}' and `{1}'",
 							true_type.GetSignatureForError (), false_type.GetSignatureForError ());
@@ -6427,6 +6443,30 @@ namespace Mono.CSharp
 			return this;
 		}
 
+		public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
+		{
+			expr = expr.Resolve (rc);
+			true_expr = true_expr.Resolve (rc);
+			false_expr = false_expr.Resolve (rc);
+
+			if (true_expr == null || false_expr == null || expr == null)
+				return null;
+			
+			if (!(true_expr is ReferenceExpression && false_expr is ReferenceExpression)) {
+				rc.Report.Error (8326, expr.Location, "Both ref conditional operators must be ref values");
+				return null;
+			}
+
+			if (!TypeSpecComparer.IsEqual (true_expr.Type, false_expr.Type)) {
+				rc.Report.Error (8327, true_expr.Location, "The ref conditional expression types `{0}' and `{1}' have to match",
+				                 true_expr.Type.GetSignatureForError (), false_expr.Type.GetSignatureForError ()); 
+			}
+
+			eclass = ExprClass.Value;
+			type = true_expr.Type;
+			return this;
+		}
+
 		public override void Emit (EmitContext ec)
 		{
 			Label false_target = ec.DefineLabel ();
@@ -6774,7 +6814,7 @@ namespace Mono.CSharp
 						"Cannot use fixed variable `{0}' inside an anonymous method, lambda expression or query expression",
 						GetSignatureForError ());
 				} else if (local_info.IsByRef || local_info.Type.IsByRefLike) {
-					if (ec.CurrentAnonymousMethod is StateMachineInitializer) {
+					if (local_info.Type.IsSpecialRuntimeType || ec.CurrentAnonymousMethod is StateMachineInitializer) {
 						// It's reported later as 4012/4013
 					} else {
 						ec.Report.Error (8175, loc,
@@ -11877,12 +11917,17 @@ namespace Mono.CSharp
 			if (!TypeManager.VerifyUnmanaged (ec.Module, otype, loc))
 				return null;
 
-			type = PointerContainer.MakeType (ec.Module, otype);
+			ResolveExpressionType (ec, otype);
 			eclass = ExprClass.Value;
 
 			return this;
 		}
 
+		protected virtual void ResolveExpressionType (ResolveContext rc, TypeSpec elementType)
+		{
+			type = PointerContainer.MakeType (rc.Module, elementType);
+		}
+
 		public override void Emit (EmitContext ec)
 		{
 			int size = BuiltinTypeSpec.GetSize (otype);
@@ -11931,14 +11976,36 @@ namespace Mono.CSharp
 		public bool ResolveSpanConversion (ResolveContext rc, TypeSpec spanType)
 		{
 			ctor = MemberCache.FindMember (spanType, MemberFilter.Constructor (ParametersCompiled.CreateFullyResolved (PointerContainer.MakeType (rc.Module, rc.Module.Compiler.BuiltinTypes.Void), rc.Module.Compiler.BuiltinTypes.Int)), BindingRestriction.DeclaredOnly) as MethodSpec;
-			if (ctor == null)
+			if (ctor == null) {
+				this.type = InternalType.ErrorType;
 				return false;
+			}
 			
 			this.type = spanType;
 			return true;
 		}
 	}
 
+	class SpanStackAlloc : StackAlloc
+	{
+		public SpanStackAlloc (Expression type, Expression count, Location l)
+			: base (type, count, l)
+		{
+		}
+
+		protected override void ResolveExpressionType (ResolveContext rc, TypeSpec elementType)
+		{
+			var span = rc.Module.PredefinedTypes.SpanGeneric.Resolve ();
+			if (span == null) {
+				type = InternalType.ErrorType;
+				return;
+			}
+
+			type = span.MakeGenericType (rc, new [] { elementType });
+			ResolveSpanConversion (rc, type);
+		}
+	}
+
 	//
 	// An object initializer expression
 	//
@@ -13085,6 +13152,9 @@ namespace Mono.CSharp
 			if (expr is IAssignMethod)
 				return true;
 
+			if (expr is Conditional)
+				return true;
+
 			var invocation = expr as Invocation;
 			if (invocation?.Type.Kind == MemberKind.ByRef)
 				return true;
@@ -13232,6 +13302,10 @@ namespace Mono.CSharp
 			this.loc = loc;
 		}
 
+		protected override void CloneTo (CloneContext clonectx, Expression t)
+		{
+		}
+
 		public override Expression CreateExpressionTree (ResolveContext ec)
 		{
 			throw new NotImplementedException ();
diff --git a/mcs/mcs/field.cs b/mcs/mcs/field.cs
index 86bb028defc..8c667328143 100644
--- a/mcs/mcs/field.cs
+++ b/mcs/mcs/field.cs
@@ -542,7 +542,7 @@ namespace Mono.CSharp
 				}
 			);
 
-			fixed_buffer_type.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray ());
+			fixed_buffer_type.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray (out _));
 #endif
 			//
 			// Don't emit FixedBufferAttribute attribute for private types
@@ -559,7 +559,8 @@ namespace Mono.CSharp
 			encoder.Encode (buffer_size);
 			encoder.EncodeEmptyNamedArguments ();
 
-			FieldBuilder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray ());
+			FieldBuilder.SetCustomAttribute ((ConstructorInfo) ctor.GetMetaInfo (), encoder.ToArray (out var references));
+			Module.AddAssemblyReferences (references);
 		}
 	}
 
diff --git a/mcs/mcs/generic.cs b/mcs/mcs/generic.cs
index ec2965df63b..0c7032b2088 100644
--- a/mcs/mcs/generic.cs
+++ b/mcs/mcs/generic.cs
@@ -3381,7 +3381,7 @@ namespace Mono.CSharp {
 					continue;
 
 				var bound = candidates [ci];
-				if (bound.Type == best_candidate)
+				if (TypeSpecComparer.IsEqual (bound.Type, best_candidate))
 					continue;
 
 				int cii = 0;
diff --git a/mcs/mcs/modifiers.cs b/mcs/mcs/modifiers.cs
index 926ab5d1848..21dd52b3b14 100644
--- a/mcs/mcs/modifiers.cs
+++ b/mcs/mcs/modifiers.cs
@@ -74,6 +74,8 @@ namespace Mono.CSharp
 				return "internal";
 			case Modifiers.PRIVATE:
 				return "private";
+			case Modifiers.PRIVATE | Modifiers.PROTECTED:
+				return "private protected";
 			default:
 				throw new NotImplementedException (mod.ToString ());
 			}
@@ -129,12 +131,16 @@ namespace Mono.CSharp
 			if ((modB & Modifiers.PUBLIC) != 0) {
 				flags = Modifiers.PROTECTED | Modifiers.INTERNAL | Modifiers.PRIVATE;
 			} else if ((modB & Modifiers.PROTECTED) != 0) {
-				if ((modB & Modifiers.INTERNAL) != 0)
-					flags = Modifiers.PROTECTED | Modifiers.INTERNAL;
-
-				flags |= Modifiers.PRIVATE;
-			} else if ((modB & Modifiers.INTERNAL) != 0)
+				if ((modB & Modifiers.INTERNAL) != 0) {
+					flags = Modifiers.PROTECTED | Modifiers.INTERNAL | Modifiers.PRIVATE;
+				} else {
+					modA &= ~Modifiers.PROTECTED;
+					flags = Modifiers.PRIVATE;
+				}
+			} else if ((modB & Modifiers.INTERNAL) != 0) {
+				modA &= ~Modifiers.PROTECTED;
 				flags = Modifiers.PRIVATE;
+			}
 
 			return modB != modA && (modA & (~flags)) == 0;
 		}
@@ -151,6 +157,8 @@ namespace Mono.CSharp
 			} else {
 				if ((mod_flags & Modifiers.PUBLIC) != 0)
 					t = TypeAttributes.NestedPublic;
+				else if ((mod_flags & (Modifiers.PROTECTED | Modifiers.PRIVATE)) == (Modifiers.PROTECTED | Modifiers.PRIVATE))
+					t = TypeAttributes.NestedFamANDAssem;
 				else if ((mod_flags & Modifiers.PRIVATE) != 0)
 					t = TypeAttributes.NestedPrivate;
 				else if ((mod_flags & (Modifiers.PROTECTED | Modifiers.INTERNAL)) == (Modifiers.PROTECTED | Modifiers.INTERNAL))
@@ -173,18 +181,27 @@ namespace Mono.CSharp
 		{
 			FieldAttributes fa = 0;
 
-			if ((mod_flags & Modifiers.PUBLIC) != 0)
+			switch (mod_flags & Modifiers.AccessibilityMask) {
+			case Modifiers.PUBLIC:
 				fa |= FieldAttributes.Public;
-			if ((mod_flags & Modifiers.PRIVATE) != 0)
+				break;
+			case Modifiers.PRIVATE:
 				fa |= FieldAttributes.Private;
-			if ((mod_flags & Modifiers.PROTECTED) != 0) {
-				if ((mod_flags & Modifiers.INTERNAL) != 0)
-					fa |= FieldAttributes.FamORAssem;
-				else 
-					fa |= FieldAttributes.Family;
-			} else {
-				if ((mod_flags & Modifiers.INTERNAL) != 0)
-					fa |= FieldAttributes.Assembly;
+				break;
+			case Modifiers.PROTECTED | Modifiers.INTERNAL:
+				fa |= FieldAttributes.FamORAssem;
+				break;
+			case Modifiers.PROTECTED:
+				fa |= FieldAttributes.Family;
+				break;
+			case Modifiers.INTERNAL:
+				fa |= FieldAttributes.Assembly;
+				break;
+			case Modifiers.PRIVATE | Modifiers.PROTECTED:
+				fa |= FieldAttributes.FamANDAssem;
+				break;
+			default:
+				throw new NotImplementedException (mod_flags.ToString ());
 			}
 
 			if ((mod_flags & Modifiers.STATIC) != 0)
@@ -215,6 +232,9 @@ namespace Mono.CSharp
 			case Modifiers.INTERNAL:
 				ma |= MethodAttributes.Assembly;
 				break;
+			case Modifiers.PRIVATE | Modifiers.PROTECTED:
+				ma |= MethodAttributes.FamANDAssem;
+				break;
 			default:
 				throw new NotImplementedException (mod_flags.ToString ());
 			}
diff --git a/mcs/mcs/module.cs b/mcs/mcs/module.cs
index 2293d825b36..4680433bb01 100644
--- a/mcs/mcs/module.cs
+++ b/mcs/mcs/module.cs
@@ -480,6 +480,18 @@ namespace Mono.CSharp
 			attributes.AddAttribute (attr);
 		}
 
+		public void AddAssemblyReferences (List<Assembly> names)
+		{
+			if (names == null)
+				return;
+
+#if STATIC
+			foreach (var name in names) {
+				Builder.__GetAssemblyToken (name);
+			}
+#endif
+		}
+
 		public override void AddTypeContainer (TypeContainer tc)
 		{
 			AddTypeContainerMember (tc);
diff --git a/mcs/mcs/parameter.cs b/mcs/mcs/parameter.cs
index cc10eee162b..95851478010 100644
--- a/mcs/mcs/parameter.cs
+++ b/mcs/mcs/parameter.cs
@@ -221,12 +221,13 @@ namespace Mono.CSharp {
 			REF = 1 << 1,
 			OUT = 1 << 2,
 			This = 1 << 3,
-			CallerMemberName = 1 << 4,
-			CallerLineNumber = 1 << 5,
-			CallerFilePath = 1 << 6,
+			ReadOnly = 1 << 4,
+			CallerMemberName = 1 << 5,
+			CallerLineNumber = 1 << 6,
+			CallerFilePath = 1 << 7,
 
 			RefOutMask = REF | OUT,
-			ModifierMask = PARAMS | REF | OUT | This,
+			ModifierMask = PARAMS | REF | OUT | This | ReadOnly,
 			CallerMask = CallerMemberName | CallerLineNumber | CallerFilePath
 		}
 
@@ -1474,9 +1475,9 @@ namespace Mono.CSharp {
 					}
 				}
 
-				if (!expr.IsNull && TypeSpec.IsReferenceType (parameter_type) && parameter_type.BuiltinType != BuiltinTypeSpec.Type.String) {
+				if (!res.IsNull && TypeSpec.IsReferenceType (parameter_type) && parameter_type.BuiltinType != BuiltinTypeSpec.Type.String) {
 					rc.Report.Error (1763, Location,
-						"Optional parameter `{0}' of type `{1}' can only be initialized with `null'",
+						"Optional parameter `{0}' of type `{1}' can only be initialized with default value",
 						p.Name, parameter_type.GetSignatureForError ());
 
 					return;
diff --git a/mcs/mcs/report.cs b/mcs/mcs/report.cs
index cc3d82b26e0..5d64c8e766e 100644
--- a/mcs/mcs/report.cs
+++ b/mcs/mcs/report.cs
@@ -42,7 +42,7 @@ namespace Mono.CSharp {
 		public static readonly int[] AllWarnings = new int[] {
 			28, 67, 78,
 			105, 108, 109, 114, 162, 164, 168, 169, 183, 184, 197,
-			219, 251, 252, 253, 278, 282,
+			219, 251, 252, 253, 278, 280, 282,
 			402, 414, 419, 420, 429, 436, 437, 440, 458, 464, 465, 467, 469, 472, 473,
 			612, 618, 626, 628, 642, 649, 652, 657, 658, 659, 660, 661, 665, 672, 675, 693,
 			728,
@@ -107,6 +107,15 @@ namespace Mono.CSharp {
 			case LanguageVersion.V_7:
 				version = "7.0";
 				break;
+			case LanguageVersion.V_7_1:
+				version = "7.1";
+				break;
+			case LanguageVersion.V_7_2:
+				version = "7.2";
+				break;
+			case LanguageVersion.V_7_3:
+				version = "7.3";
+				break;
 			default:
 				throw new InternalErrorException ("Invalid feature version", compiler.Settings.Version);
 			}
diff --git a/mcs/mcs/settings.cs b/mcs/mcs/settings.cs
index 37664187c71..976c9b68128 100644
--- a/mcs/mcs/settings.cs
+++ b/mcs/mcs/settings.cs
@@ -32,10 +32,11 @@ namespace Mono.CSharp {
 		V_7 = 7,
 		V_7_1 = 71,
 		V_7_2 = 72,
+		V_7_3 = 73,
 		Experimental = 100,
 
 		Default = V_7,
-		Latest = V_7_2
+		Latest = V_7_3
 	}
 
 	public enum RuntimeVersion
@@ -1270,6 +1271,7 @@ namespace Mono.CSharp {
 			case "/highentropyva+":
 			case "/highentropyva-":
 			case "/link":
+			case "/sourcelink":
 			case "/moduleassemblyname":
 			case "/nowin32manifest":
 			case "/pdb":
diff --git a/mcs/mcs/statement.cs b/mcs/mcs/statement.cs
index 9c51128548f..c8b77c1adc1 100644
--- a/mcs/mcs/statement.cs
+++ b/mcs/mcs/statement.cs
@@ -928,8 +928,7 @@ namespace Mono.CSharp {
 		public override Reachability MarkReachable (Reachability rc)
 		{
 			base.MarkReachable (rc);
-			expr.MarkReachable (rc);
-			return rc;
+			return expr.MarkReachable (rc);
 		}
 
 		public override bool Resolve (BlockContext ec)
@@ -2419,6 +2418,7 @@ namespace Mono.CSharp {
 			IsLocked = 1 << 8,
 			SymbolFileHidden = 1 << 9,
 			ByRef = 1 << 10,
+			PointerByRef = 1 << 11,
 
 			ReadonlyMask = 1 << 20
 		}
@@ -2609,20 +2609,22 @@ namespace Mono.CSharp {
 
 			if (IsByRef) {
 				builder = ec.DeclareLocal (ReferenceContainer.MakeType (ec.Module, Type), IsFixed);
+			} else if ((flags & Flags.PointerByRef) != 0) {
+				builder = ec.DeclareLocal (ReferenceContainer.MakeType (ec.Module, ((PointerContainer) Type).Element), IsFixed);
 			} else {
 				//
 				// All fixed variabled are pinned, a slot has to be alocated
 				//
-				builder = ec.DeclareLocal(Type, IsFixed);
+				builder = ec.DeclareLocal (Type, IsFixed);
 			}
 
 			if ((flags & Flags.SymbolFileHidden) == 0)
 				ec.DefineLocalVariable (name, builder);
 		}
 
-		public static LocalVariable CreateCompilerGenerated (TypeSpec type, Block block, Location loc, bool writeToSymbolFile = false)
+		public static LocalVariable CreateCompilerGenerated (TypeSpec type, Block block, Location loc, bool writeToSymbolFile = false, Flags additionalFlags = 0)
 		{
-			LocalVariable li = new LocalVariable (block, GetCompilerGeneratedName (block), Flags.CompilerGenerated | Flags.Used, loc);
+			LocalVariable li = new LocalVariable (block, GetCompilerGeneratedName (block), Flags.CompilerGenerated | Flags.Used | additionalFlags, loc);
 			if (!writeToSymbolFile)
 				li.flags |= Flags.SymbolFileHidden;
 			
@@ -2725,6 +2727,11 @@ namespace Mono.CSharp {
 			flags |= Flags.Used;
 		}
 
+		public void SetIsPointerByRef ()
+		{
+			flags |= Flags.PointerByRef;
+		}
+
 		public void SetHasAddressTaken ()
 		{
 			flags |= (Flags.AddressTaken | Flags.Used);
@@ -6562,18 +6569,26 @@ namespace Mono.CSharp {
 
 				// TODO: Should use Binary::Add
 				pinned_string.Emit (ec);
-				ec.Emit (OpCodes.Conv_I);
+				ec.Emit (OpCodes.Conv_U);
 
 				var m = ec.Module.PredefinedMembers.RuntimeHelpersOffsetToStringData.Resolve (loc);
 				if (m == null)
 					return;
 
+				var null_value = ec.DefineLabel ();
+				vi.EmitAssign (ec);
+				vi.Emit (ec);
+				ec.Emit (OpCodes.Brfalse_S, null_value);
+
+				vi.Emit (ec);
 				PropertyExpr pe = new PropertyExpr (m, pinned_string.Location);
 				//pe.InstanceExpression = pinned_string;
 				pe.Resolve (new ResolveContext (ec.MemberContext)).Emit (ec);
 
 				ec.Emit (OpCodes.Add);
 				vi.EmitAssign (ec);
+
+				ec.MarkLabel (null_value);
 			}
 
 			public override void EmitExit (EmitContext ec)
@@ -6660,31 +6675,94 @@ namespace Mono.CSharp {
 					return new ExpressionEmitter (res, li);
 				}
 
-				bool already_fixed = true;
-
 				//
 				// Case 4: & object.
 				//
 				Unary u = res as Unary;
 				if (u != null) {
+					bool already_fixed = true;
+
 					if (u.Oper == Unary.Operator.AddressOf) {
 						IVariableReference vr = u.Expr as IVariableReference;
 						if (vr == null || !vr.IsFixed) {
 							already_fixed = false;
 						}
 					}
-				} else if (initializer is Cast) {
+
+					if (already_fixed) {
+						bc.Report.Error (213, loc, "You cannot use the fixed statement to take the address of an already fixed expression");
+						return null;
+					}
+
+					res = Convert.ImplicitConversionRequired (bc, res, li.Type, loc);
+					return new ExpressionEmitter (res, li);
+				}
+
+				if (initializer is Cast) {
 					bc.Report.Error (254, initializer.Location, "The right hand side of a fixed statement assignment may not be a cast expression");
 					return null;
 				}
 
-				if (already_fixed) {
-					bc.Report.Error (213, loc, "You cannot use the fixed statement to take the address of an already fixed expression");
+				//
+				// Case 5: by-ref GetPinnableReference method on the rhs expression
+				//
+				var method = GetPinnableReference (bc, res);
+				if (method == null) {
+					bc.Report.Error (8385, initializer.Location, "The given expression cannot be used in a fixed statement");
+					return null;
+				}
+
+				var compiler = bc.Module.Compiler;
+				if (compiler.Settings.Version < LanguageVersion.V_7_3) {
+					bc.Report.FeatureIsNotAvailable (compiler, initializer.Location, "extensible fixed statement");
+				}
+
+				method.InstanceExpression = res;
+				res = new Invocation.Predefined (method, null).ResolveLValue (bc, EmptyExpression.OutAccess);
+				if (res == null)
+					return null;
+
+				ReferenceContainer rType = (ReferenceContainer)method.BestCandidateReturnType;
+				PointerContainer lType = li.Type as PointerContainer;
+				if (rType.Element != lType?.Element) {
+					// CSC: Should be better error code
+					res.Error_ValueCannotBeConverted (bc, lType, false);
+					return null;
 				}
 
-				res = Convert.ImplicitConversionRequired (bc, res, li.Type, loc);
+				li.SetIsPointerByRef ();
 				return new ExpressionEmitter (res, li);
 			}
+
+			MethodGroupExpr GetPinnableReference (BlockContext bc, Expression expr)
+			{
+				TypeSpec type = expr.Type;
+				var mexpr = Expression.MemberLookup (bc, false, type,
+					"GetPinnableReference", 0, Expression.MemberLookupRestrictions.ExactArity, loc);
+
+				if (mexpr == null)
+					return null;
+
+				var mg = mexpr as MethodGroupExpr;
+				if (mg == null)
+					return null;
+
+				mg.InstanceExpression = expr;
+
+				// TODO: handle extension methods
+				Arguments args = new Arguments (0);
+				mg = mg.OverloadResolve (bc, ref args, null, OverloadResolver.Restrictions.None);
+
+				if (mg == null || mg.BestCandidate.IsStatic || !mg.BestCandidate.IsPublic || mg.BestCandidateReturnType.Kind != MemberKind.ByRef || !mg.BestCandidate.Parameters.IsEmpty) {
+					if (bc.Module.Compiler.Settings.Version > LanguageVersion.V_7_2) {
+						bc.Report.Warning (280, 2, expr.Location, "`{0}' has the wrong signature to be used in extensible fixed statement", mg.GetSignatureForError ());
+					}
+
+					return null;
+				}
+
+				return mg;
+			}
 		}
 
 
diff --git a/mcs/mcs/tuples.cs b/mcs/mcs/tuples.cs
index 901efdc9541..0b56859615f 100644
--- a/mcs/mcs/tuples.cs
+++ b/mcs/mcs/tuples.cs
@@ -267,6 +267,11 @@ namespace Mono.CSharp
 			this.Location = expr.Location;
 		}
 
+		public TupleLiteralElement Clone (CloneContext clonectx)
+		{
+			return new TupleLiteralElement (Name, Expr.Clone (clonectx), Location);
+		}
+
 		public string Name { get; private set; }
 		public Expression Expr { get; set; }
 		public Location Location { get; private set; }
@@ -288,6 +293,16 @@ namespace Mono.CSharp
 			}
 		}
 
+		protected override void CloneTo (CloneContext clonectx, Expression t)
+		{
+			var clone = new List<TupleLiteralElement> (elements.Count);
+			foreach (var te in elements)
+				clone.Add (te.Clone (clonectx));
+
+			TupleLiteral target = (TupleLiteral)t;
+			target.elements = clone;
+		}
+
 		public static bool ContainsNoTypeElement (TypeSpec type)
 		{
 			var ta = type.TypeArguments;
@@ -432,6 +447,7 @@ namespace Mono.CSharp
 	{
 		Expression source;
 		List<Expression> targetExprs;
+		List<Expression> tempExprs;
 		List<BlockVariable> variables;
 		Expression instance;
 
@@ -440,6 +456,8 @@ namespace Mono.CSharp
 			this.source = source;
 			this.targetExprs = targetExprs;
 			this.loc = loc;
+
+			tempExprs = new List<Expression> ();
 		}
 
 		public TupleDeconstruct (List<BlockVariable> variables, Expression source, Location loc)
@@ -447,6 +465,8 @@ namespace Mono.CSharp
 			this.source = source;
 			this.variables = variables;
 			this.loc = loc;
+
+			tempExprs = new List<Expression> ();
 		}
 
 		public override Expression CreateExpressionTree (ResolveContext ec)
@@ -492,6 +512,15 @@ namespace Mono.CSharp
 					instance = expr_variable.CreateReferenceExpression (rc, loc);
 				}
 
+				var element_srcs = new List<Expression> ();
+				var src_names = new List<string> ();
+				for (int i = 0; i < target_count; ++i) {
+					var element_src = tupleLiteral == null ? new MemberAccess (instance, NamedTupleSpec.GetElementPropertyName (i)) : tupleLiteral.Elements [i].Expr;
+					element_srcs.Add (element_src);
+					if (element_src is VariableReference)
+						src_names.Add ((element_src as VariableReference)?.Name);
+				}
+
 				for (int i = 0; i < target_count; ++i) {
 					var tle = src_type.TypeArguments [i];
 
@@ -522,8 +551,17 @@ namespace Mono.CSharp
 						variable.PrepareAssignmentAnalysis ((BlockContext)rc);
 					}
 
-					var element_src = tupleLiteral == null ? new MemberAccess (instance, NamedTupleSpec.GetElementPropertyName (i)) : tupleLiteral.Elements [i].Expr;
-					targetExprs [i] = new SimpleAssign (targetExprs [i], element_src).Resolve (rc);
+					var element_target = (targetExprs [i] as SimpleName)?.LookupNameExpression (rc, MemberLookupRestrictions.None);
+
+					if (element_target != null && src_names.Contains ((element_target as VariableReference)?.Name)) {
+						var tempType = element_target.Resolve (rc).Type;
+
+						var temp = new LocalTemporary (tempType);
+						tempExprs.Add (new SimpleAssign (temp, element_srcs [i]).Resolve (rc));
+						targetExprs [i] = new SimpleAssign (targetExprs [i], temp).Resolve (rc);
+					} else {
+						targetExprs [i] = new SimpleAssign (targetExprs [i], element_srcs [i]).Resolve (rc);
+					}
 				}
 
 				eclass = ExprClass.Value;
@@ -557,9 +595,24 @@ namespace Mono.CSharp
 			if (instance != null)
 				((ExpressionStatement)source).EmitStatement (ec);
 
-			foreach (ExpressionStatement expr in targetExprs)
+			foreach (ExpressionStatement expr in tempExprs) {
+				var temp = (expr as Assign)?.Target as LocalTemporary;
+				if (temp == null)
+					continue;
+
+				temp.AddressOf (ec, AddressOp.LoadStore);
+				ec.Emit (OpCodes.Initobj, temp.Type);
+				expr.Emit (ec);
+			}
+
+			foreach (ExpressionStatement expr in targetExprs) {
 				expr.Emit (ec);
 
+				var temp = (expr as Assign)?.Source as LocalTemporary;
+				if (temp != null)
+					temp.Release (ec);
+			}
+
 			var ctor = MemberCache.FindMember (type, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly | BindingRestriction.InstanceOnly) as MethodSpec;
 			ec.Emit (OpCodes.Newobj, ctor);
 		}
@@ -574,9 +627,24 @@ namespace Mono.CSharp
 			
 			if (instance != null)
 				((ExpressionStatement) source).EmitStatement (ec);
-			
-			foreach (ExpressionStatement expr in targetExprs)
+
+			foreach (ExpressionStatement expr in tempExprs) {
+				var temp = (expr as Assign)?.Target as LocalTemporary;
+				if (temp == null)
+					continue;
+
+				temp.AddressOf (ec, AddressOp.LoadStore);
+				ec.Emit (OpCodes.Initobj, temp.Type);
+				expr.EmitStatement (ec);
+			}
+
+			foreach (ExpressionStatement expr in targetExprs) {
 				expr.EmitStatement (ec);
+
+				var temp = (expr as Assign)?.Source as LocalTemporary;
+				if (temp != null)
+					temp.Release (ec);
+			}
 		}
 
 		public void Emit (EmitContext ec, bool leave_copy)
@@ -594,6 +662,7 @@ namespace Mono.CSharp
 
 		public override void FlowAnalysis (FlowAnalysisContext fc)
 		{
+			source.FlowAnalysis (fc);
 			foreach (var expr in targetExprs)
 				expr.FlowAnalysis (fc);
 		}
diff --git a/mcs/nunit24/ClientUtilities/util/AssemblyInfo.cs b/mcs/nunit24/ClientUtilities/util/AssemblyInfo.cs
index 919ca07ace3..6489c1b2a58 100644
--- a/mcs/nunit24/ClientUtilities/util/AssemblyInfo.cs
+++ b/mcs/nunit24/ClientUtilities/util/AssemblyInfo.cs
@@ -5,7 +5,3 @@
 // ****************************************************************
 
 using System.Reflection;
-
-[assembly: AssemblyDelaySign(false)]
-[assembly: AssemblyKeyFile("../../nunit.snk")]
-[assembly: AssemblyKeyName("")]
diff --git a/mcs/nunit24/ConsoleRunner/nunit-console/AssemblyInfo.cs b/mcs/nunit24/ConsoleRunner/nunit-console/AssemblyInfo.cs
index 919ca07ace3..6489c1b2a58 100644
--- a/mcs/nunit24/ConsoleRunner/nunit-console/AssemblyInfo.cs
+++ b/mcs/nunit24/ConsoleRunner/nunit-console/AssemblyInfo.cs
@@ -5,7 +5,3 @@
 // ****************************************************************
 
 using System.Reflection;
-
-[assembly: AssemblyDelaySign(false)]
-[assembly: AssemblyKeyFile("../../nunit.snk")]
-[assembly: AssemblyKeyName("")]
diff --git a/mcs/nunit24/NUnitCore/core/AssemblyInfo.cs b/mcs/nunit24/NUnitCore/core/AssemblyInfo.cs
index 747032c7e63..2f66d80222c 100644
--- a/mcs/nunit24/NUnitCore/core/AssemblyInfo.cs
+++ b/mcs/nunit24/NUnitCore/core/AssemblyInfo.cs
@@ -7,7 +7,3 @@ using System;
 using System.Reflection;
 
 [assembly: CLSCompliant(true)]
-
-[assembly: AssemblyDelaySign(false)]
-[assembly: AssemblyKeyFile("../../nunit.snk")]
-[assembly: AssemblyKeyName("")]
diff --git a/mcs/nunit24/NUnitCore/interfaces/AssemblyInfo.cs b/mcs/nunit24/NUnitCore/interfaces/AssemblyInfo.cs
index fa86732b3d3..efeaecf1986 100644
--- a/mcs/nunit24/NUnitCore/interfaces/AssemblyInfo.cs
+++ b/mcs/nunit24/NUnitCore/interfaces/AssemblyInfo.cs
@@ -8,7 +8,3 @@ using System;
 using System.Reflection;
 
 [assembly: CLSCompliant(true)]
-
-[assembly: AssemblyDelaySign(false)]
-[assembly: AssemblyKeyFile("../../nunit.snk")]
-[assembly: AssemblyKeyName("")]
diff --git a/mcs/nunit24/NUnitExtensions/core/AssemblyInfo.cs b/mcs/nunit24/NUnitExtensions/core/AssemblyInfo.cs
index fa86732b3d3..efeaecf1986 100644
--- a/mcs/nunit24/NUnitExtensions/core/AssemblyInfo.cs
+++ b/mcs/nunit24/NUnitExtensions/core/AssemblyInfo.cs
@@ -8,7 +8,3 @@ using System;
 using System.Reflection;
 
 [assembly: CLSCompliant(true)]
-
-[assembly: AssemblyDelaySign(false)]
-[assembly: AssemblyKeyFile("../../nunit.snk")]
-[assembly: AssemblyKeyName("")]
diff --git a/mcs/nunit24/NUnitExtensions/framework/AssemblyInfo.cs b/mcs/nunit24/NUnitExtensions/framework/AssemblyInfo.cs
index a9553f691cd..2b4b5bfb340 100644
--- a/mcs/nunit24/NUnitExtensions/framework/AssemblyInfo.cs
+++ b/mcs/nunit24/NUnitExtensions/framework/AssemblyInfo.cs
@@ -8,7 +8,3 @@ using System;
 using System.Reflection;
 
 [assembly: CLSCompliant(true)]
-
-[assembly: AssemblyDelaySign(false)]
-[assembly: AssemblyKeyFile("../../nunit.snk")]
-[assembly: AssemblyKeyName("")]
diff --git a/mcs/nunit24/NUnitFramework/framework/AssemblyInfo.cs b/mcs/nunit24/NUnitFramework/framework/AssemblyInfo.cs
index fa86732b3d3..efeaecf1986 100644
--- a/mcs/nunit24/NUnitFramework/framework/AssemblyInfo.cs
+++ b/mcs/nunit24/NUnitFramework/framework/AssemblyInfo.cs
@@ -8,7 +8,3 @@ using System;
 using System.Reflection;
 
 [assembly: CLSCompliant(true)]
-
-[assembly: AssemblyDelaySign(false)]
-[assembly: AssemblyKeyFile("../../nunit.snk")]
-[assembly: AssemblyKeyName("")]
diff --git a/mcs/nunit24/NUnitMocks/mocks/AssemblyInfo.cs b/mcs/nunit24/NUnitMocks/mocks/AssemblyInfo.cs
index 599b04ce453..f87ae602810 100644
--- a/mcs/nunit24/NUnitMocks/mocks/AssemblyInfo.cs
+++ b/mcs/nunit24/NUnitMocks/mocks/AssemblyInfo.cs
@@ -6,7 +6,3 @@
 
 using System;
 using System.Reflection;
-
-[assembly: AssemblyDelaySign(false)]
-[assembly: AssemblyKeyFile("../../nunit.snk")]
-[assembly: AssemblyKeyName("")]
diff --git a/mcs/tests/dtest-066.cs b/mcs/tests/dtest-066.cs
new file mode 100644
index 00000000000..893fb40dffa
--- /dev/null
+++ b/mcs/tests/dtest-066.cs
@@ -0,0 +1,13 @@
+class C
+{
+	static void Main()
+	{
+		object o = 1;
+		dynamic d = 1;
+		
+		var a = new[] {
+			new { X = o },
+			new { X = d }
+		};
+	}
+}
diff --git a/mcs/tests/gtest-647.cs b/mcs/tests/gtest-647.cs
new file mode 100644
index 00000000000..4aae641f85f
--- /dev/null
+++ b/mcs/tests/gtest-647.cs
@@ -0,0 +1,34 @@
+using System;
+
+public class Program
+{
+	public static int Main ()
+	{
+		int B = default (MyStruct?); 
+		if (MyStruct.counter != 1)
+			return 1;
+
+		switch (default (MyStruct?)) {
+			case 0:
+				break;
+			default:
+				return 2;
+		}
+
+		if (MyStruct.counter != 2)
+			return 4;
+
+		return 0;
+	}
+
+	public struct MyStruct
+	{
+		public static int counter;
+
+		public static implicit operator int (MyStruct? s)
+		{
+			++counter;
+			return 0;
+		}
+	}
+}
\ No newline at end of file
diff --git a/mcs/tests/test-928.cs b/mcs/tests/test-928.cs
index 90180137957..290ee4d1fb3 100644
--- a/mcs/tests/test-928.cs
+++ b/mcs/tests/test-928.cs
@@ -15,6 +15,24 @@ unsafe class Program
 		}
 	}
 
+	public static bool StringNull (string s)
+	{
+		unsafe {
+			fixed (char *a = s) {
+				return a == null;
+			}
+		}
+	}
+
+	public static bool ArrayNull (int[] a)
+	{
+		unsafe {
+			fixed (int *e = a) {
+				return e == null;
+			}
+		}
+	}
+
 	public static int Main ()
 	{
 		Test ();
@@ -24,6 +42,12 @@ unsafe class Program
 		if (lv.IsPinned)
 			return 1;
 
+		if (!StringNull (null))
+			return 1;
+
+		if (!ArrayNull (null))
+			return 2;
+
 		return 0;
 	}
 }
diff --git a/mcs/tests/test-948.cs b/mcs/tests/test-948.cs
index 34b3ab9a0c4..563e37dc7d5 100644
--- a/mcs/tests/test-948.cs
+++ b/mcs/tests/test-948.cs
@@ -1,4 +1,4 @@
-// Compiler options: -langversion:7.2 -unsafe
+// Compiler options: -langversion:7.2 /unsafe
 
 using System;
 
@@ -7,10 +7,16 @@ class X
 	public static void Main ()
 	{
 		Span<int> stackSpan = stackalloc int[100];
+
+		bool b = false;
+
+		var r1 = !b ? stackalloc char[1] : throw null;
+		var r2 = b ? throw null : stackalloc char[1];
+		var r3 = b ? stackalloc char[1] : stackalloc char[2];
 	}
 
+	// Disables verifier
 	unsafe void Foo ()
 	{
-
 	}
-}
\ No newline at end of file
+}
diff --git a/mcs/tests/test-950.cs b/mcs/tests/test-950.cs
new file mode 100644
index 00000000000..fef764c85cc
--- /dev/null
+++ b/mcs/tests/test-950.cs
@@ -0,0 +1,12 @@
+using System;
+
+public class B
+{
+	public static void Main ()
+	{
+		int a = 1_0_3;
+		double b = 0__0e+1_1;
+		int c = 0b0__1_0;
+		int d = 0x0__F_0;
+	}
+}
\ No newline at end of file
diff --git a/mcs/tests/test-960.cs b/mcs/tests/test-960.cs
new file mode 100644
index 00000000000..ac2a1ca7435
--- /dev/null
+++ b/mcs/tests/test-960.cs
@@ -0,0 +1,20 @@
+// Compiler options: -langversion:7.2
+
+public class B
+{
+	private protected enum E
+	{
+	}
+
+	public int Index { get; protected private set; }
+
+	internal string S1 { get; private protected set; }
+
+	protected string S2 { get; private protected set; }
+
+	private protected int field;
+
+	public static void Main ()
+	{
+	}
+}
\ No newline at end of file
diff --git a/mcs/tests/test-961.cs b/mcs/tests/test-961.cs
new file mode 100644
index 00000000000..efe19673875
--- /dev/null
+++ b/mcs/tests/test-961.cs
@@ -0,0 +1,34 @@
+// Compiler options: -langversion:latest
+
+using System;
+
+public static class B {
+	public static void Main ()
+	{
+		int lo = 1;
+		Bar (in lo);		
+	}
+
+	public static void Bar (in int arg)
+	{
+	}
+
+	static void Foo (this in int src)
+	{
+		D p = (in int a) => {};
+	}
+
+}
+
+delegate void D (in int arg);
+
+class M
+{
+	int this[in int a] { set { } }
+	public static implicit operator string (in M m) => null;
+	public M (in int arg) { }
+
+	public void Test2 (in int arg)
+	{
+	}
+}
\ No newline at end of file
diff --git a/mcs/tests/test-anon-123.cs b/mcs/tests/test-anon-123.cs
index 91c72b45afe..45aab27c0a5 100644
--- a/mcs/tests/test-anon-123.cs
+++ b/mcs/tests/test-anon-123.cs
@@ -1,3 +1,4 @@
+// Compiler options: -langversion:latest
 // Cloning tests
 
 using System;
@@ -103,7 +104,11 @@ public class C : B
 			default:
 				break;
 			}
-		});		
+		});
+
+		Test (() => {
+			char ch = default;
+		});
 		
 		var c = new C ();
 		c.InstanceTests ();
diff --git a/mcs/tests/test-binaryliteral.cs b/mcs/tests/test-binaryliteral.cs
new file mode 100644
index 00000000000..3d9cc89bcbd
--- /dev/null
+++ b/mcs/tests/test-binaryliteral.cs
@@ -0,0 +1,57 @@
+
+class Demo {
+	static int Main ()
+	{
+		if (0b1 != 1)
+			return 1;
+		var hex1 = 0x123ul;
+		var bin1  = 0b100100011ul;
+		var bin11 = 0b100100011lu;
+		if (hex1 != bin1)
+			return 2;
+		if (hex1 != bin11)
+			return 3;
+		if (hex1.GetType () != bin1.GetType ())
+			return 4;
+		if (hex1.GetType () != bin11.GetType ())
+			return 5;
+
+		var hex2 = 0x7FFFFFFF;
+		var bin2 = 0b1111111111111111111111111111111;
+
+		if (hex2 != bin2)
+			return 6;
+		if (hex2.GetType () != bin2.GetType ())
+			return 7;
+
+		var hex3 = 0xFFFFFFFF;
+		var bin3 = 0b11111111111111111111111111111111;
+		if (hex3 != bin3)
+			return 8;
+		if (hex3.GetType () != bin3.GetType ())
+			return 9;
+
+		var hex4 = 0xFFFFFFFFu;
+		var bin4 = 0b11111111111111111111111111111111u;
+		if (hex4 != bin4)
+			return 10;
+		if (hex4.GetType () != bin4.GetType ())
+			return 11;
+
+		var hex5 = 0x7FFFFFFFFFFFFFFF;
+		var bin5 = 0b111111111111111111111111111111111111111111111111111111111111111;
+		if (hex5 != bin5)
+			return 12;
+		if (hex5.GetType () != bin5.GetType ())
+			return 13;
+
+		var hex6 = 0xFFFFFFFFFFFFFFFF;
+		var bin6 = 0b1111111111111111111111111111111111111111111111111111111111111111;
+		if (hex6 != bin6)
+			return 14;
+		if (hex6.GetType () != bin6.GetType ())
+			return 15;
+
+		return 0;
+	}
+}
\ No newline at end of file
diff --git a/mcs/tests/test-decl-expr-05.cs b/mcs/tests/test-decl-expr-05.cs
index 730fd4278ca..907cde0b8d7 100644
--- a/mcs/tests/test-decl-expr-05.cs
+++ b/mcs/tests/test-decl-expr-05.cs
@@ -6,6 +6,11 @@ class X
 		{
 			arg = s.ToString ();
 		}
+
+		while (true && Call (out string s2))
+		{
+			arg = s2.ToString ();
+		}
 	}
 
 	static bool Call (out string s)
diff --git a/mcs/tests/test-decl-expr-06.cs b/mcs/tests/test-decl-expr-06.cs
new file mode 100644
index 00000000000..9734f2ec2a7
--- /dev/null
+++ b/mcs/tests/test-decl-expr-06.cs
@@ -0,0 +1,17 @@
+using System;
+
+public class C
+{
+	Func<bool> f = () => Foo (out int arg);
+
+	static bool Foo (out int arg)
+	{
+		arg = 2;
+		return false;
+	}
+
+	public static void Main ()
+	{
+		new C ();
+	}
+}
\ No newline at end of file
diff --git a/mcs/tests/test-default-01.cs b/mcs/tests/test-default-01.cs
index 823e33c451b..28aff830cd9 100644
--- a/mcs/tests/test-default-01.cs
+++ b/mcs/tests/test-default-01.cs
@@ -41,7 +41,11 @@ static class X
 	static System.Func<int> M4 ()
 	{
 		return () => default;
-	} 
+	}
+
+	static void Foo (II a = default (II), II b = default, II c = (II) null)
+	{
+	}
 }
 /*
 enum E
@@ -49,4 +53,10 @@ enum E
 	A = default,
 	B = default + 1
 }
-*/
\ No newline at end of file
+*/
+
+
+interface II
+{
+
+}
\ No newline at end of file
diff --git a/mcs/tests/test-fixed-01.cs b/mcs/tests/test-fixed-01.cs
new file mode 100644
index 00000000000..4684b0c5a06
--- /dev/null
+++ b/mcs/tests/test-fixed-01.cs
@@ -0,0 +1,20 @@
+// Compiler options: -unsafe -langversion:latest
+
+unsafe class C
+{
+	public static void Main ()
+	{
+		fixed (int* p = new Fixable ()) {
+			System.Console.WriteLine (*p);
+			System.Console.WriteLine (p [2]);
+		}
+	}
+
+	struct Fixable
+	{
+		public ref int GetPinnableReference ()
+		{
+			return ref (new int[] { 1, 2, 3 })[0];
+		}
+	}
+}
\ No newline at end of file
diff --git a/mcs/tests/test-pattern-13.cs b/mcs/tests/test-pattern-13.cs
new file mode 100644
index 00000000000..315c7a9e4be
--- /dev/null
+++ b/mcs/tests/test-pattern-13.cs
@@ -0,0 +1,19 @@
+using System;
+
+class C : B
+{
+
+}
+
+public class B
+{
+	public static void Main ()
+	{
+		C c = new C ();
+
+		if (c is B b)
+		{
+			Console.WriteLine (b == null);
+		}
+	}
+}
\ No newline at end of file
diff --git a/mcs/tests/test-ref-07.cs b/mcs/tests/test-ref-07.cs
index 4aa16579752..f17cfb443b5 100644
--- a/mcs/tests/test-ref-07.cs
+++ b/mcs/tests/test-ref-07.cs
@@ -1,6 +1,6 @@
 // Compiler options: -langversion:latest
 
-public readonly partial ref struct Test
+public readonly ref partial struct Test
 {
 	public static void Main ()
 	{
@@ -14,6 +14,11 @@ public readonly partial ref struct Test
 	}
 }
 
+ref partial struct Test
+{
+
+}
+
 ref struct Second
 {
 	Test field;
diff --git a/mcs/tests/test-ref-11.cs b/mcs/tests/test-ref-11.cs
new file mode 100644
index 00000000000..8d392a77d07
--- /dev/null
+++ b/mcs/tests/test-ref-11.cs
@@ -0,0 +1,13 @@
+class Program
+{
+	static int x;
+	static int y;
+
+    public static int Main ()
+    {
+    	bool b = false;
+        ref int targetBucket = ref b ? ref x : ref y;
+
+        return 0;
+    }
+}
\ No newline at end of file
diff --git a/mcs/tests/test-ref-12.cs b/mcs/tests/test-ref-12.cs
new file mode 100644
index 00000000000..786a4162f4f
--- /dev/null
+++ b/mcs/tests/test-ref-12.cs
@@ -0,0 +1,22 @@
+// Compiler options: -unsafe
+
+unsafe class X
+{
+	public static void Main ()
+	{
+		void* pointer = null;
+ 		Bar (ref Foo (ref *(byte*)pointer));
+	}
+
+	static int field;
+
+	static ref int Foo (ref byte b)
+	{
+		return ref field;
+	}
+
+	static void Bar (ref int i)
+	{
+
+	}
+}
\ No newline at end of file
diff --git a/mcs/tests/test-tuple-02.cs b/mcs/tests/test-tuple-02.cs
index c0492759452..ab722642aeb 100644
--- a/mcs/tests/test-tuple-02.cs
+++ b/mcs/tests/test-tuple-02.cs
@@ -26,6 +26,11 @@ class TupleConversions
 		(string v1, object v2) b = ("a", "b");
 
 		(int v1, long v2)? x = null;
+
+        var array = new [] {
+            (name: "A", offset: 0),
+            (name: "B", size: 4)
+        };		
 	}
 
 	static void Foo<T> (T arg)
diff --git a/mcs/tests/test-tuple-08.cs b/mcs/tests/test-tuple-08.cs
new file mode 100644
index 00000000000..fd3375b4df6
--- /dev/null
+++ b/mcs/tests/test-tuple-08.cs
@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+
+class X
+{
+	public static void Main ()
+	{
+		var x = new X ();
+		x.Test ().Wait ();
+	}
+
+	int a, b;
+
+	async Task Test ()
+	{
+		(a, b) = await Waiting ();
+	}
+
+	Task<(int, int)> Waiting ()
+	{
+		return Task.FromResult ((1, 3));
+	}
+}
\ No newline at end of file
diff --git a/mcs/tests/test-tuple-10.cs b/mcs/tests/test-tuple-10.cs
new file mode 100644
index 00000000000..82f4e01ec1f
--- /dev/null
+++ b/mcs/tests/test-tuple-10.cs
@@ -0,0 +1,9 @@
+using System.Linq;
+
+class Program {
+    public static int Main ()
+    {
+        var l = (from f in (typeof (Program)).GetFields() select (name: f.Name, offset: 0)).ToList();
+        return 0;
+    }
+}
\ No newline at end of file
diff --git a/mcs/tests/test-tuple-11.cs b/mcs/tests/test-tuple-11.cs
new file mode 100644
index 00000000000..b2aeb24026c
--- /dev/null
+++ b/mcs/tests/test-tuple-11.cs
@@ -0,0 +1,20 @@
+using System;
+
+class Program
+{
+	public static int Main ()
+	{
+		int x = 1;
+		int y = 2;
+
+		(x, y) = (y, x);
+
+		if (x != 2)
+			return 1;
+
+		if (y != 1)
+			return 2;
+
+		return 0;
+	}
+}
diff --git a/mcs/tests/ver-il-net_4_x.xml b/mcs/tests/ver-il-net_4_x.xml
index 4dbc7042a8a..2bde8270338 100644
--- a/mcs/tests/ver-il-net_4_x.xml
+++ b/mcs/tests/ver-il-net_4_x.xml
@@ -3168,6 +3168,33 @@
       </method>
     </type>
   </test>
+  <test name="dtest-066.cs">
+    <type name="C">
+      <method name="Void Main()" attrs="145">
+        <size>41</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+    <type name="&lt;&gt;__AnonType0`1[&lt;X&gt;__T]">
+      <method name="&lt;X&gt;__T get_X()" attrs="2182">
+        <size>7</size>
+      </method>
+      <method name="Boolean Equals(System.Object)" attrs="198">
+        <size>39</size>
+      </method>
+      <method name="Int32 GetHashCode()" attrs="198">
+        <size>63</size>
+      </method>
+      <method name="System.String ToString()" attrs="198">
+        <size>67</size>
+      </method>
+      <method name="Void .ctor(&lt;X&gt;__T)" attrs="6278">
+        <size>14</size>
+      </method>
+    </type>
+  </test>
   <test name="dtest-anontype-01.cs">
     <type name="C">
       <method name="Void Main()" attrs="150">
@@ -11064,7 +11091,7 @@
     </type>
     <type name="X">
       <method name="Int32 Beer(System.Nullable`1[IrishPub])" attrs="145">
-        <size>72</size>
+        <size>60</size>
       </method>
       <method name="Int32 Test(System.Nullable`1[System.Int32])" attrs="145">
         <size>62</size>
@@ -19508,7 +19535,7 @@
     </type>
     <type name="C">
       <method name="Int32 Main()" attrs="150">
-        <size>267</size>
+        <size>255</size>
       </method>
       <method name="Void .ctor()" attrs="6278">
         <size>7</size>
@@ -19742,7 +19769,7 @@
   <test name="gtest-629.cs">
     <type name="Program">
       <method name="Void Main()" attrs="150">
-        <size>116</size>
+        <size>121</size>
       </method>
       <method name="Void .ctor()" attrs="6278">
         <size>7</size>
@@ -20147,6 +20174,21 @@
       </method>
     </type>
   </test>
+  <test name="gtest-647.cs">
+    <type name="Program">
+      <method name="Int32 Main()" attrs="150">
+        <size>99</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+    <type name="Program+MyStruct">
+      <method name="Int32 op_Implicit(System.Nullable`1[Program+MyStruct])" attrs="2198">
+        <size>22</size>
+      </method>
+    </type>
+  </test>
   <test name="gtest-anontype-01.cs">
     <type name="Test">
       <method name="Int32 Main()" attrs="150">
@@ -47609,7 +47651,7 @@
         <size>7</size>
       </method>
       <method name="Void CopyTo(Int32, Char[], Int32, Int32)" attrs="145">
-        <size>73</size>
+        <size>78</size>
       </method>
     </type>
   </test>
@@ -51468,10 +51510,10 @@
   <test name="test-88.cs">
     <type name="X">
       <method name="Void f(System.String)" attrs="145">
-        <size>20</size>
+        <size>12</size>
       </method>
       <method name="Int32 Main()" attrs="150">
-        <size>70</size>
+        <size>62</size>
       </method>
       <method name="Void .ctor()" attrs="6278">
         <size>7</size>
@@ -52148,7 +52190,7 @@
         <size>14</size>
       </method>
       <method name="Void Outer(System.String)" attrs="145">
-        <size>29</size>
+        <size>34</size>
       </method>
       <method name="Void Inner(Char* ByRef, Char*)" attrs="145">
         <size>10</size>
@@ -52359,10 +52401,10 @@
   <test name="test-928.cs">
     <type name="Program">
       <method name="Void Test()" attrs="150">
-        <size>25</size>
+        <size>30</size>
       </method>
       <method name="Int32 Main()" attrs="150">
-        <size>105</size>
+        <size>141</size>
       </method>
       <method name="Boolean &lt;Main&gt;m__0(System.Reflection.LocalVariableInfo)" attrs="145">
         <size>29</size>
@@ -52370,6 +52412,12 @@
       <method name="Void .ctor()" attrs="6278">
         <size>7</size>
       </method>
+      <method name="Boolean StringNull(System.String)" attrs="150">
+        <size>32</size>
+      </method>
+      <method name="Boolean ArrayNull(Int32[])" attrs="150">
+        <size>45</size>
+      </method>
     </type>
   </test>
   <test name="test-929.cs">
@@ -52814,7 +52862,7 @@
   <test name="test-948.cs">
     <type name="X">
       <method name="Void Main()" attrs="150">
-        <size>16</size>
+        <size>103</size>
       </method>
       <method name="Void Foo()" attrs="129">
         <size>2</size>
@@ -52834,6 +52882,16 @@
       </method>
     </type>
   </test>
+  <test name="test-950.cs">
+    <type name="B">
+      <method name="Void Main()" attrs="150">
+        <size>23</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+  </test>
   <test name="test-96.cs">
     <type name="N1.A">
       <method name="Int32 Main()" attrs="150">
@@ -52858,6 +52916,80 @@
       </method>
     </type>
   </test>
+  <test name="test-960.cs">
+    <type name="B">
+      <method name="Int32 get_Index()" attrs="2182">
+        <size>14</size>
+      </method>
+      <method name="Void set_Index(Int32)" attrs="2178">
+        <size>8</size>
+      </method>
+      <method name="System.String get_S1()" attrs="2179">
+        <size>14</size>
+      </method>
+      <method name="Void set_S1(System.String)" attrs="2178">
+        <size>8</size>
+      </method>
+      <method name="System.String get_S2()" attrs="2180">
+        <size>14</size>
+      </method>
+      <method name="Void set_S2(System.String)" attrs="2178">
+        <size>8</size>
+      </method>
+      <method name="Void Main()" attrs="150">
+        <size>2</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+  </test>
+  <test name="test-961.cs">
+    <type name="B">
+      <method name="Void Main()" attrs="150">
+        <size>10</size>
+      </method>
+      <method name="Void Foo(Int32)" attrs="145">
+        <size>32</size>
+      </method>
+      <method name="Void &lt;Foo&gt;m__0(Int32)" attrs="145">
+        <size>2</size>
+      </method>
+    </type>
+    <type name="D">
+      <method name="Void Invoke(Int32)" attrs="454">
+        <size>0</size>
+      </method>
+      <method name="System.IAsyncResult BeginInvoke(Int32, System.AsyncCallback, System.Object)" attrs="454">
+        <size>0</size>
+      </method>
+      <method name="Void EndInvoke(System.IAsyncResult)" attrs="454">
+        <size>0</size>
+      </method>
+      <method name="Void .ctor(Object, IntPtr)" attrs="6278">
+        <size>0</size>
+      </method>
+    </type>
+    <type name="M">
+      <method name="Void set_Item(Int32, Int32)" attrs="2177">
+        <size>2</size>
+      </method>
+      <method name="System.String op_Implicit(M)" attrs="2198">
+        <size>9</size>
+      </method>
+      <method name="Void Test2(Int32)" attrs="134">
+        <size>2</size>
+      </method>
+      <method name="Void .ctor(Int32)" attrs="6278">
+        <size>8</size>
+      </method>
+    </type>
+    <type name="B">
+      <method name="Void Bar(Int32)" attrs="150">
+        <size>2</size>
+      </method>
+    </type>
+  </test>
   <test name="test-97.cs">
     <type name="X">
       <method name="Int32 Main()" attrs="150">
@@ -54448,7 +54580,7 @@
         <size>19</size>
       </method>
       <method name="Void Main()" attrs="150">
-        <size>247</size>
+        <size>281</size>
       </method>
       <method name="Void &lt;BaseM&gt;__BaseCallProxy0()" attrs="129">
         <size>7</size>
@@ -54518,6 +54650,9 @@
       <method name="Void &lt;Main&gt;m__5(E)" attrs="145">
         <size>35</size>
       </method>
+      <method name="Void &lt;Main&gt;m__6()" attrs="145">
+        <size>4</size>
+      </method>
     </type>
   </test>
   <test name="test-anon-124.cs">
@@ -67020,6 +67155,16 @@
       </method>
     </type>
   </test>
+  <test name="test-binaryliteral.cs">
+    <type name="Demo">
+      <method name="Int32 Main()" attrs="145">
+        <size>503</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+  </test>
   <test name="test-cls-00.cs">
     <type name="CLSCLass_6">
       <method name="Void add_Disposed(Delegate)" attrs="2182">
@@ -68641,7 +68786,7 @@
   <test name="test-decl-expr-05.cs">
     <type name="X">
       <method name="Void Test(System.String)" attrs="129">
-        <size>29</size>
+        <size>62</size>
       </method>
       <method name="Boolean Call(System.String ByRef)" attrs="145">
         <size>17</size>
@@ -68654,6 +68799,22 @@
       </method>
     </type>
   </test>
+  <test name="test-decl-expr-06.cs">
+    <type name="C">
+      <method name="Boolean Foo(Int32 ByRef)" attrs="145">
+        <size>13</size>
+      </method>
+      <method name="Void Main()" attrs="150">
+        <size>8</size>
+      </method>
+      <method name="Boolean &lt;f&gt;m__0()" attrs="145">
+        <size>15</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>42</size>
+      </method>
+    </type>
+  </test>
   <test name="test-default-01.cs">
     <type name="X">
       <method name="Void Main()" attrs="150">
@@ -68674,6 +68835,9 @@
       <method name="Int32 &lt;M4&gt;m__0()" attrs="145">
         <size>9</size>
       </method>
+      <method name="Void Foo(II, II, II)" attrs="145">
+        <size>2</size>
+      </method>
     </type>
   </test>
   <test name="test-default-02.cs">
@@ -69158,6 +69322,21 @@
       </method>
     </type>
   </test>
+  <test name="test-fixed-01.cs">
+    <type name="C">
+      <method name="Void Main()" attrs="150">
+        <size>39</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+    <type name="C+Fixable">
+      <method name="Int32&amp; GetPinnableReference()" attrs="134">
+        <size>32</size>
+      </method>
+    </type>
+  </test>
   <test name="test-interpolation-01.cs">
     <type name="Test">
       <method name="Int32 Main()" attrs="150">
@@ -72564,7 +72743,7 @@
     </type>
     <type name="X+&lt;Test&gt;c__Iterator0">
       <method name="Boolean MoveNext()" attrs="486">
-        <size>184</size>
+        <size>206</size>
       </method>
       <method name="Int32 System.Collections.Generic.IEnumerator&lt;int&gt;.get_Current()" attrs="2529">
         <size>14</size>
@@ -72750,6 +72929,21 @@
       </method>
     </type>
   </test>
+  <test name="test-pattern-13.cs">
+    <type name="C">
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+    <type name="B">
+      <method name="Void Main()" attrs="150">
+        <size>35</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+  </test>
   <test name="test-pragma-unrecognized.cs">
     <type name="C">
       <method name="Void Main()" attrs="150">
@@ -73155,6 +73349,11 @@
     </type>
   </test>
   <test name="test-ref-07.cs">
+    <type name="TestMain">
+      <method name="Void Main()" attrs="150">
+        <size>6</size>
+      </method>
+    </type>
     <type name="Test">
       <method name="Void Main()" attrs="150">
         <size>18</size>
@@ -73243,6 +73442,32 @@
       </method>
     </type>
   </test>
+  <test name="test-ref-11.cs">
+    <type name="Program">
+      <method name="Int32 Main()" attrs="150">
+        <size>34</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+  </test>
+  <test name="test-ref-12.cs">
+    <type name="X">
+      <method name="Void Main()" attrs="150">
+        <size>16</size>
+      </method>
+      <method name="Int32&amp; Foo(Byte ByRef)" attrs="145">
+        <size>14</size>
+      </method>
+      <method name="Void Bar(Int32 ByRef)" attrs="145">
+        <size>2</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+  </test>
   <test name="test-static-using-01.cs">
     <type name="A.B.X">
       <method name="Int32 Test()" attrs="150">
@@ -73482,7 +73707,7 @@
         <size>32</size>
       </method>
       <method name="Int32 Test()" attrs="134">
-        <size>10</size>
+        <size>2</size>
       </method>
       <method name="System.Object Foo()" attrs="129">
         <size>10</size>
@@ -73491,16 +73716,16 @@
         <size>23</size>
       </method>
       <method name="Void Test3(Int32 ByRef)" attrs="145">
-        <size>3</size>
+        <size>2</size>
       </method>
       <method name="Int32 get_Item(Int32)" attrs="2177">
-        <size>10</size>
+        <size>2</size>
       </method>
       <method name="Void add_Event(System.Action)" attrs="2182">
-        <size>3</size>
+        <size>2</size>
       </method>
       <method name="Void remove_Event(System.Action)" attrs="2182">
-        <size>3</size>
+        <size>2</size>
       </method>
       <method name="Void TestExpr_1(Boolean)" attrs="129">
         <size>21</size>
@@ -73527,7 +73752,7 @@
         <size>7</size>
       </method>
       <method name="Int32 TestExpr_6(Int32 ByRef)" attrs="145">
-        <size>10</size>
+        <size>2</size>
       </method>
       <method name="Int32 TestExpr_7(Int32 ByRef)" attrs="129">
         <size>15</size>
@@ -73569,7 +73794,7 @@
   <test name="test-tuple-02.cs">
     <type name="TupleConversions">
       <method name="Void Main()" attrs="150">
-        <size>314</size>
+        <size>368</size>
       </method>
       <method name="Void Foo[T](T)" attrs="145">
         <size>2</size>
@@ -73761,6 +73986,29 @@
       </method>
     </type>
   </test>
+  <test name="test-tuple-10.cs">
+    <type name="Program">
+      <method name="Int32 Main()" attrs="150">
+        <size>65</size>
+      </method>
+      <method name="System.ValueTuple`2[System.String,System.Int32] &lt;Main&gt;m__0(System.Reflection.FieldInfo)" attrs="145">
+        <size>21</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+  </test>
+  <test name="test-tuple-11.cs">
+    <type name="Program">
+      <method name="Int32 Main()" attrs="150">
+        <size>70</size>
+      </method>
+      <method name="Void .ctor()" attrs="6278">
+        <size>7</size>
+      </method>
+    </type>
+  </test>
   <test name="test-var-01.cs">
     <type name="Test">
       <method name="Int32 Main()" attrs="150">
@@ -73896,4 +74144,4 @@
       </method>
     </type>
   </test>
-</tests>
\ No newline at end of file
+</tests>
diff --git a/msvc/scripts/System.Web.pre b/msvc/scripts/System.Web.pre
index c071bf45bfd..8f8d262597f 100644
--- a/msvc/scripts/System.Web.pre
+++ b/msvc/scripts/System.Web.pre
@@ -1 +1 @@
-@MONO@ $(ProjectDir)\..\lib\net_4_x\culevel.exe -o $(ProjectDir)\System.Web\UplevelHelper.cs $(ProjectDir)\UplevelHelperDefinitions.xml
+@MONO@ $([MSBuild]::GetDirectoryNameOfFileAbove($(TargetDir), culevel.exe))\culevel.exe -o $(ProjectDir)\System.Web\UplevelHelper.cs $(ProjectDir)\UplevelHelperDefinitions.xml
diff --git a/msvc/scripts/csproj.tmpl b/msvc/scripts/csproj.tmpl
index 642c9537321..c18b51d334e 100644
--- a/msvc/scripts/csproj.tmpl
+++ b/msvc/scripts/csproj.tmpl
@@ -17,6 +17,7 @@
     <IntermediateOutputPath>obj-@OUTPUTSUFFIX@</IntermediateOutputPath>
     <GenerateTargetFrameworkAttribute>false</GenerateTargetFrameworkAttribute>
     @NOSTDLIB@
+    @METADATAVERSION@
     @STARTUPOBJECT@
     @NOCONFIG@
     @ALLOWUNSAFE@
diff --git a/msvc/scripts/genproj.cs b/msvc/scripts/genproj.cs
index 3987abb212b..1440800b2b3 100644
--- a/msvc/scripts/genproj.cs
+++ b/msvc/scripts/genproj.cs
@@ -27,27 +27,43 @@ public enum Target {
 
 class SlnGenerator {
 	public static readonly string NewLine = "\r\n"; //Environment.NewLine; // "\n"; 
-	public SlnGenerator (string formatVersion = "2012")
+	public SlnGenerator (string slnVersion)
 	{
-		switch (formatVersion) {
-		case "2008":
-			this.header = MakeHeader ("10.00", "2008");
-			break;
-		default:
-			this.header = MakeHeader ("12.00", "2012");
-			break;
-		}
+		Console.WriteLine("Requested sln version is {0}", slnVersion);
+		this.header = MakeHeader ("12.00", "15", "15.0.0.0");
 	}
 
-	const string project_start = "Project(\"{{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}}\") = \"{0}\", \"{1}\", \"{2}\""; // Note: No need to double up on {} around {2}
+	const string project_start = "Project(\"{0}\") = \"{1}\", \"{2}\", \"{3}\""; // Note: No need to double up on {} around {2}
 	const string project_end = "EndProject";
 
+	public List<string> profiles = new List<string> {
+		"net_4_x",
+		"monodroid",
+		"monotouch",
+		"monotouch_tv",
+		"monotouch_watch",
+		"orbis",
+		"unreal",
+		"wasm",
+		"winaot",
+		"xammac",
+	};
+
+	const string jay_vcxproj_guid = "{5D485D32-3B9F-4287-AB24-C8DA5B89F537}";
+	const string jay_sln_guid = "{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}";
+
 	public List<MsbuildGenerator.VsCsproj> libraries = new List<MsbuildGenerator.VsCsproj> ();
 	string header;
 
-	string MakeHeader (string formatVersion, string yearTag)
+	string MakeHeader (string formatVersion, string yearTag, string minimumVersion)
 	{
-		return string.Format ("Microsoft Visual Studio Solution File, Format Version {0}" + NewLine + "# Visual Studio {1}", formatVersion, yearTag);
+		return string.Format (
+			"Microsoft Visual Studio Solution File, Format Version {0}" + NewLine + 
+			"# Visual Studio {1}" + NewLine + 
+			"MinimumVisualStudioVersion = {2}", 
+			formatVersion, yearTag,
+			minimumVersion
+		);
 	}
 
 	public void Add (MsbuildGenerator.VsCsproj vsproj)
@@ -59,6 +75,40 @@ class SlnGenerator {
 		}
 	}
 
+	private void WriteProjectReference (StreamWriter sln, string prefixGuid, string library, string relativePath, string projectGuid, params string[] dependencyGuids)
+	{
+		sln.WriteLine (project_start, prefixGuid, library, relativePath, projectGuid);
+
+		foreach (var guid in dependencyGuids) {
+    		sln.WriteLine ("    ProjectSection(ProjectDependencies) = postProject");
+    		sln.WriteLine ("        {0} = {0}", guid);
+    		sln.WriteLine ("    EndProjectSection");
+		}
+
+		sln.WriteLine (project_end);
+	}
+
+	private void WriteProjectReference (StreamWriter sln, string slnFullPath, MsbuildGenerator.VsCsproj proj)
+	{
+		var unixProjFile = proj.csProjFilename.Replace ("\\", "/");
+		var fullProjPath = Path.GetFullPath (unixProjFile);
+		var relativePath = MsbuildGenerator.GetRelativePath (slnFullPath, fullProjPath);
+		var dependencyGuids = new string[0];
+		if (proj.preBuildEvent.Contains ("jay"))
+			dependencyGuids = new [] { jay_vcxproj_guid };
+		WriteProjectReference(sln, "{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}", proj.library, relativePath, proj.projectGuid, dependencyGuids);
+	}
+
+	private void WriteProjectConfigurationPlatforms (StreamWriter sln, string guid, string platformToBuild)
+	{
+		foreach (var profile in profiles) {
+			sln.WriteLine ("\t\t{0}.Debug|{1}.ActiveCfg = Debug|{2}", guid, profile, platformToBuild);
+			sln.WriteLine ("\t\t{0}.Debug|{1}.Build.0 = Debug|{2}", guid, profile, platformToBuild);
+			sln.WriteLine ("\t\t{0}.Release|{1}.ActiveCfg = Release|{2}", guid, profile, platformToBuild);
+			sln.WriteLine ("\t\t{0}.Release|{1}.Build.0 = Release|{2}", guid, profile, platformToBuild);
+		}
+	}
+
 	public void Write (string filename)
 	{
 		var fullPath = Path.GetDirectoryName (filename) + "/";
@@ -66,27 +116,32 @@ class SlnGenerator {
 		using (var sln = new StreamWriter (filename)) {
 			sln.WriteLine ();
 			sln.WriteLine (header);
+
+			// Manually insert jay's vcxproj. We depend on jay.exe to perform build steps later.
+			WriteProjectReference (sln, jay_sln_guid, "jay", "mcs\\jay\\jay.vcxproj", jay_vcxproj_guid);
+
 			foreach (var proj in libraries) {
-				var unixProjFile = proj.csProjFilename.Replace ("\\", "/");
-				var fullProjPath = Path.GetFullPath (unixProjFile);
-				sln.WriteLine (project_start, proj.library, MsbuildGenerator.GetRelativePath (fullPath, fullProjPath), proj.projectGuid);
-				sln.WriteLine (project_end);
+				WriteProjectReference (sln, fullPath, proj);
 			}
+
 			sln.WriteLine ("Global");
 
 			sln.WriteLine ("\tGlobalSection(SolutionConfigurationPlatforms) = preSolution");
-			sln.WriteLine ("\t\tDebug|Any CPU = Debug|Any CPU");
-			sln.WriteLine ("\t\tRelease|Any CPU = Release|Any CPU");
+			foreach (var profile in profiles) {
+				sln.WriteLine ("\t\tDebug|{0} = Debug|{0}", profile);
+				sln.WriteLine ("\t\tRelease|{0} = Release|{0}", profile);
+			}
 			sln.WriteLine ("\tEndGlobalSection");
 
 			sln.WriteLine ("\tGlobalSection(ProjectConfigurationPlatforms) = postSolution");
+
+			// Manually insert jay's configurations because they are different
+			WriteProjectConfigurationPlatforms (sln, jay_vcxproj_guid, "Win32");
+
 			foreach (var proj in libraries) {
-				var guid = proj.projectGuid;
-				sln.WriteLine ("\t\t{0}.Debug|Any CPU.ActiveCfg = Debug|Any CPU", guid);
-				sln.WriteLine ("\t\t{0}.Debug|Any CPU.Build.0 = Debug|Any CPU", guid);
-				sln.WriteLine ("\t\t{0}.Release|Any CPU.ActiveCfg = Release|Any CPU", guid);
-				sln.WriteLine ("\t\t{0}.Release|Any CPU.Build.0 = Release|Any CPU", guid);
+				WriteProjectConfigurationPlatforms (sln, proj.projectGuid, "Any CPU");
 			}
+
 			sln.WriteLine ("\tEndGlobalSection");
 
 			sln.WriteLine ("\tGlobalSection(SolutionProperties) = preSolution");
@@ -634,6 +689,7 @@ class MsbuildGenerator {
 		public List<VsCsproj> projReferences = new List<VsCsproj> ();
 		public string library;
 		public MsbuildGenerator MsbuildGenerator;
+		public string preBuildEvent, postBuildEvent;
 	}
 
 	public VsCsproj Csproj;
@@ -682,7 +738,7 @@ class MsbuildGenerator {
 				fx_version = "4.0";
 				profile = "net_4_0";
 			} else if (response.Contains (profile_4_x)) {
-				fx_version = "4.5";
+				fx_version = "4.6.2";
 				profile = "net_4_x";
 			}
 		}
@@ -882,6 +938,26 @@ class MsbuildGenerator {
 
 		bool basic_or_build = (library.Contains ("-basic") || library.Contains ("-build"));
 
+		// If an EXE is built with nostdlib, it won't work unless run with mono.exe. This stops our build steps
+		//  from working in visual studio (because we already replace @MONO@ with '' on Windows.)
+
+		if (Target != Target.Library)
+			StdLib = true;
+
+		// We have our target framework set to 4.5 in many places because broken scripts check for files with 4.5
+		//  in the path, even though we compile code that uses 4.6 features. So we need to manually fix that here.
+
+		if (fx_version == "4.5")
+			fx_version = "4.6.2";
+
+		// The VS2017 signing system fails to sign using this key for some reason, so for now,
+		//  just disable code signing for the nunit assemblies. It's not important.
+		// I'd rather fix this by updating the makefiles but it seems to be impossible to disable
+		//  code signing in our make system...
+
+		if (StrongNameKeyFile?.Contains("nunit.snk") ?? false)
+			StrongNameKeyFile = null;
+
 		//
 		// Replace the template values
 		//
@@ -894,6 +970,9 @@ class MsbuildGenerator {
 				"    <AssemblyOriginatorKeyFile>{0}</AssemblyOriginatorKeyFile>",
 				StrongNameKeyFile, StrongNameDelaySign ? "    <DelaySign>true</DelaySign>" + NewLine : "");
 		}
+
+		string assemblyName = Path.GetFileNameWithoutExtension (output_name);
+
 		Csproj.output = template.
 			Replace ("@OUTPUTTYPE@", Target == Target.Library ? "Library" : "Exe").
 			Replace ("@SIGNATURE@", strongNameSection).
@@ -906,7 +985,7 @@ class MsbuildGenerator {
 			Replace ("@NOCONFIG@", "<NoConfig>" + (!load_default_config).ToString () + "</NoConfig>").
 			Replace ("@ALLOWUNSAFE@", Unsafe ? "<AllowUnsafeBlocks>true</AllowUnsafeBlocks>" : "").
 			Replace ("@FX_VERSION", fx_version).
-			Replace ("@ASSEMBLYNAME@", Path.GetFileNameWithoutExtension (output_name)).
+			Replace ("@ASSEMBLYNAME@", assemblyName).
 			Replace ("@OUTPUTDIR@", build_output_dir).
 			Replace ("@OUTPUTSUFFIX@", Path.GetFileName (build_output_dir)).
 			Replace ("@DEFINECONSTANTS@", defines.ToString ()).
@@ -920,7 +999,11 @@ class MsbuildGenerator {
 			Replace ("@ADDITIONALLIBPATHS@", String.Empty).
 			Replace ("@RESOURCES@", resources.ToString ()).
 			Replace ("@OPTIMIZE@", Optimize ? "true" : "false").
-			Replace ("@SOURCES@", sources.ToString ());
+			Replace ("@SOURCES@", sources.ToString ()).
+			Replace ("@METADATAVERSION@", assemblyName == "mscorlib" ? "<RuntimeMetadataVersion>Mono</RuntimeMetadataVersion>" : "");
+
+		Csproj.preBuildEvent = prebuild;
+		Csproj.postBuildEvent = postbuild;
 
 		//Console.WriteLine ("Generated {0}", ofile.Replace ("\\", "/"));
 		using (var o = new StreamWriter (generatedProjFile)) {
@@ -939,15 +1022,13 @@ class MsbuildGenerator {
 		if (q != -1)
 			target = target + Load (library.Substring (0, q) + suffix);
 
-		if (target.IndexOf ("@MONO@") != -1){
-			target_unix = target.Replace ("@MONO@", "mono").Replace ("@CAT@", "cat");
-			target_windows = target.Replace ("@MONO@", "").Replace ("@CAT@", "type");
-		} else {
-			target_unix = target.Replace ("jay.exe", "jay");
-			target_windows = target;
-		}
+		target_unix = target.Replace ("@MONO@", "mono").Replace ("@CAT@", "cat");
+		target_windows = target.Replace ("@MONO@", "").Replace ("@CAT@", "type");
+
+		target_unix = target_unix.Replace ("\\jay\\jay.exe", "\\jay\\jay\\jay");
+
 		target_unix = target_unix.Replace ("@COPY@", "cp");
-		target_windows = target_unix.Replace ("@COPY@", "copy");
+		target_windows = target_windows.Replace ("@COPY@", "copy");
 
 		target_unix = target_unix.Replace ("\r", "");
 		const string condition_unix    = "Condition=\" '$(OS)' != 'Windows_NT' \"";