From 3e5acdacdd54b1c8d9c254d6cc722cef7b01aef8 Mon Sep 17 00:00:00 2001
From: Randy Eckenrode <randy@largeandhighquality.com>
Date: Mon, 23 Sep 2024 21:19:20 -0400
Subject: [PATCH] llvmPackages.compiler-rt: fix cross-compilation on Darwin

When compiler-rt targets Darwin, it is built with `-target`, which
causes clang to try to invoke `ld` without a target prefix (e.g., it
will try to exec `ld` instead of `x86_64-apple-darwin-ld` on a
cross-build to x86_64-darwin). Specifying `--ld-path` overrides that
behavior, allowing it to find the appropriate cross-linker.
---
 .../llvm/common/compiler-rt/default.nix       | 25 +++++++++++--------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/pkgs/development/compilers/llvm/common/compiler-rt/default.nix b/pkgs/development/compilers/llvm/common/compiler-rt/default.nix
index 8a2cec518033..ad8d837b77ac 100644
--- a/pkgs/development/compilers/llvm/common/compiler-rt/default.nix
+++ b/pkgs/development/compilers/llvm/common/compiler-rt/default.nix
@@ -84,16 +84,21 @@ stdenv.mkDerivation ({
     # This can be removed once the minimum SDK >10.12 on x86_64-darwin.
     ++ lib.optionals (stdenv.hostPlatform.isDarwin && !stdenv.hostPlatform.isStatic) [ apple-sdk' ];
 
-  env.NIX_CFLAGS_COMPILE = toString ([
-    "-DSCUDO_DEFAULT_OPTIONS=DeleteSizeMismatch=0:DeallocationTypeMismatch=0"
-  ] ++ lib.optionals (!haveLibc) [
-    # The compiler got stricter about this, and there is a usellvm patch below
-    # which patches out the assert include causing an implicit definition of
-    # assert. It would be nicer to understand why compiler-rt thinks it should
-    # be able to #include <assert.h> in the first place; perhaps it's in the
-    # wrong, or perhaps there is a way to provide an assert.h.
-    "-Wno-error=implicit-function-declaration"
-  ]);
+  env = {
+    NIX_CFLAGS_COMPILE = toString ([
+      "-DSCUDO_DEFAULT_OPTIONS=DeleteSizeMismatch=0:DeallocationTypeMismatch=0"
+    ] ++ lib.optionals (!haveLibc) [
+      # The compiler got stricter about this, and there is a usellvm patch below
+      # which patches out the assert include causing an implicit definition of
+      # assert. It would be nicer to understand why compiler-rt thinks it should
+      # be able to #include <assert.h> in the first place; perhaps it's in the
+      # wrong, or perhaps there is a way to provide an assert.h.
+      "-Wno-error=implicit-function-declaration"
+    ]);
+  } // lib.optionalAttrs (stdenv.hostPlatform.isDarwin) {
+    # Work around clang’s trying to invoke unprefixed-ld on Darwin when `-target` is passed.
+    NIX_CFLAGS_LINK = "--ld-path=${stdenv.cc.bintools}/bin/${stdenv.cc.targetPrefix}ld";
+  };
 
   cmakeFlags = [
     "-DCOMPILER_RT_DEFAULT_TARGET_ONLY=ON"