[bug#51241] [PATCH 1/1] gnu: ragel: Fix build of knot on aarch64-linux.

[Simon South <simon@simonsouth.net>]

Make explicit Ragel's assumption of the "char" type being signed on both its
build and target platforms, allowing the current version of Knot and perhaps
other dependent packages to build successfully on aarch64-linux where "char"
is unsigned by default.

* gnu/packages/patches/ragel-specify-char-signedness.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/ragel.scm (ragel)[source]: Apply it.
---
 gnu/local.mk                                  |  1 +
 .../ragel-specify-char-signedness.patch       | 58 +++++++++++++++++++
 gnu/packages/ragel.scm                        |  4 +-
 3 files changed, 62 insertions(+), 1 deletion(-)
 create mode 100644 gnu/packages/patches/ragel-specify-char-signedness.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index d1803e7f59..a4dd01a40f 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1716,6 +1716,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/quassel-qt-514-compat.patch		\
   %D%/packages/patches/quickswitch-fix-dmenu-check.patch	\
   %D%/packages/patches/qtwebkit-pbutils-include.patch		\
+  %D%/packages/patches/ragel-specify-char-signedness.patch	\
   %D%/packages/patches/randomjungle-disable-static-build.patch	\
   %D%/packages/patches/rapicorn-isnan.patch			\
   %D%/packages/patches/rapidjson-gcc-compat.patch		\
diff --git a/gnu/packages/patches/ragel-specify-char-signedness.patch b/gnu/packages/patches/ragel-specify-char-signedness.patch
new file mode 100644
index 0000000000..fccb79d432
--- /dev/null
+++ b/gnu/packages/patches/ragel-specify-char-signedness.patch
@@ -0,0 +1,58 @@
+Ragel assumes C and C++'s "char" type is signed by default but this is not
+true for every architecture gcc supports.  Prevent build failures of dependent
+packages (on architectures such as AArch64 where "char" is normally unsigned)
+by making explicit Ragel's assumption of character signedness.
+
+This is functionally very similar to upstream commit e2650a7, "common: Fix
+ambiguous CHAR_MIN/MAX definition", which is also meant to address this issue.
+However this patch applies to Ragel version 6 and it removes altogether the
+ambiguous "char" type from generated C code, causing Ragel to instead specify
+"signed char" or "unsigned char" as appropriate.
+
+diff --git a/ragel/common.cpp b/ragel/common.cpp
+index 8e9f8ed0..649f388c 100644
+--- a/ragel/common.cpp
++++ b/ragel/common.cpp
+@@ -27,7 +27,7 @@
+ 
+ HostType hostTypesC[] =
+ {
+-	{ "char",     0,       "char",    true,   true,  false,  CHAR_MIN,  CHAR_MAX,   0, 0,              sizeof(char) },
++	{ "signed",   "char",  "char",    true,   true,  false,  SCHAR_MIN, SCHAR_MAX,  0, 0,              sizeof(signed char) },
+ 	{ "unsigned", "char",  "uchar",   false,  true,  false,  0, 0,                  0,     UCHAR_MAX,  sizeof(unsigned char) },
+ 	{ "short",    0,       "short",   true,   true,  false,  SHRT_MIN,  SHRT_MAX,   0, 0,              sizeof(short) },
+ 	{ "unsigned", "short", "ushort",  false,  true,  false,  0, 0,                  0,     USHRT_MAX,  sizeof(unsigned short) },
+@@ -66,7 +66,7 @@ HostType hostTypesC[] =
+ 
+ HostType hostTypesD[] =
+ {
+-	{ "byte",    0,  "byte",    true,   true,  false,  CHAR_MIN,  CHAR_MAX,    0, 0,                   1 },
++	{ "byte",    0,  "byte",    true,   true,  false,  SCHAR_MIN, SCHAR_MAX,   0, 0,                   1 },
+ 	{ "ubyte",   0,  "ubyte",   false,  true,  false,  0, 0,                   0,         UCHAR_MAX,   1 },
+ 	{ "char",    0,  "char",    false,  true,  false,  0, 0,                   0,         UCHAR_MAX,   1 },
+ 	{ "short",   0,  "short",   true,   true,  false,  SHRT_MIN,  SHRT_MAX,    0, 0,                   2 },
+@@ -93,7 +93,7 @@ HostType hostTypesGo[] =
+ 
+ HostType hostTypesJava[] = 
+ {
+-	{ "byte",    0,  "byte",   true,   true,  false,  CHAR_MIN,  CHAR_MAX,    0, 0,                   1 },
++	{ "byte",    0,  "byte",   true,   true,  false,  SCHAR_MIN, SCHAR_MAX,   0, 0,                   1 },
+ 	{ "short",   0,  "short",  true,   true,  false,  SHRT_MIN,  SHRT_MAX,    0, 0,                   2 },
+ 	{ "char",    0,  "char",   false,  true,  false,  0, 0,                   0,         USHRT_MAX,   2 },
+ 	{ "int",     0,  "int",    true,   true,  false,  INT_MIN,   INT_MAX,     0, 0,                   4 },
+@@ -102,13 +102,13 @@ HostType hostTypesJava[] =
+ /* What are the appropriate types for ruby? */
+ HostType hostTypesRuby[] = 
+ {
+-	{ "char",    0,  "char",   true,   true,  false,  CHAR_MIN,  CHAR_MAX,    0, 0, 1 },
++	{ "char",    0,  "char",   true,   true,  false,  SCHAR_MIN, SCHAR_MAX,   0, 0, 1 },
+ 	{ "int",     0,  "int",    true,   true,  false,  INT_MIN,   INT_MAX,     0, 0, 4 },
+ };
+ 
+ HostType hostTypesCSharp[] =
+ {
+-	{ "sbyte",   0,  "sbyte",   true,   true,  false,  CHAR_MIN,  CHAR_MAX,    0, 0,                   1 },
++	{ "sbyte",   0,  "sbyte",   true,   true,  false,  SCHAR_MIN, SCHAR_MAX,   0, 0,                   1 },
+ 	{ "byte",    0,  "byte",    false,  true,  false,  0, 0,                   0,         UCHAR_MAX,   1 },
+ 	{ "short",   0,  "short",   true,   true,  false,  SHRT_MIN,  SHRT_MAX,    0, 0,                   2 },
+ 	{ "ushort",  0,  "ushort",  false,  true,  false,  0, 0,                   0,         USHRT_MAX,   2 },
diff --git a/gnu/packages/ragel.scm b/gnu/packages/ragel.scm
index 1d9b67a6e0..e3fc980bd7 100644
--- a/gnu/packages/ragel.scm
+++ b/gnu/packages/ragel.scm
@@ -34,7 +34,9 @@ (define-public ragel
                                   version ".tar.gz"))
               (sha256
                (base32
-                "0gvcsl62gh6sg73nwaxav4a5ja23zcnyxncdcdnqa2yjcpdnw5az"))))
+                "0gvcsl62gh6sg73nwaxav4a5ja23zcnyxncdcdnqa2yjcpdnw5az"))
+              (patches
+               (search-patches "ragel-specify-char-signedness.patch"))))
     (build-system gnu-build-system)
     (home-page "https://www.colm.net/open-source/ragel/")
     (synopsis "State machine compiler")
-- 
2.33.0