From 30b2f19fc1edabbcf929d400f289220875440ffe Mon Sep 17 00:00:00 2001
From: Pierre Langlois <pierre.langlois@gmx.com>
Date: Tue, 1 Sep 2020 00:46:47 +0100
Subject: [PATCH 1/2] mrustc: Use lld.

---
 gnu/packages/patches/mrustc-use-lld.patch | 12 ++++++++++++
 gnu/packages/rust.scm                     |  9 +++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 gnu/packages/patches/mrustc-use-lld.patch

diff --git a/gnu/packages/patches/mrustc-use-lld.patch b/gnu/packages/patches/mrustc-use-lld.patch
new file mode 100644
index 0000000000..2df1f6f8f2
--- /dev/null
+++ b/gnu/packages/patches/mrustc-use-lld.patch
@@ -0,0 +1,12 @@
+diff --git a/src/trans/codegen_c.cpp b/src/trans/codegen_c.cpp
+index df0abf6f..7ab8d183 100644
+--- a/src/trans/codegen_c.cpp
++++ b/src/trans/codegen_c.cpp
+@@ -953,6 +953,7 @@ namespace {
+                     break;
+                 }
+                 args.push_back(m_outfile_path_c.c_str());
++                args.push_back("-fuse-ld=lld");
+                 switch(out_ty)
+                 {
+                 case CodegenOutput::DynamicLibrary:
diff --git a/gnu/packages/rust.scm b/gnu/packages/rust.scm
index 89d0ffee31..97952e8ebe 100644
--- a/gnu/packages/rust.scm
+++ b/gnu/packages/rust.scm
@@ -128,14 +128,17 @@
                 (file-name (git-file-name name version))
                 (sha256
                  (base32
-                  "194ny7vsks5ygiw7d8yxjmp1qwigd71ilchis6xjl6bb2sj97rd2"))))
+                  "194ny7vsks5ygiw7d8yxjmp1qwigd71ilchis6xjl6bb2sj97rd2"))
+                (patches (search-patches "mrustc-use-lld.patch"))))
       (outputs '("out" "cargo"))
       (build-system gnu-build-system)
       (inputs
-       `(("zlib" ,zlib)))
+       `(("lld" ,lld)
+         ("zlib" ,zlib)))
       (native-inputs
        `(("bison" ,bison)
          ("flex" ,flex)
+         ("gcc" ,gcc-10)
          ;; Required for the libstd sources.
          ("rustc" ,(package-source rust-1.29))))
       (arguments
@@ -418,6 +421,8 @@ safety and thread safety guarantees.")
        ("cmake" ,cmake-minimal)
        ("flex" ,flex) ; For the tests
        ("gdb" ,gdb)   ; For the tests
+       ("gcc" ,gcc-10)
+       ("lld" ,lld)
        ("procps" ,procps) ; For the tests
        ("python-2" ,python-2)
        ("rustc-bootstrap" ,mrustc)
--
2.28.0