From 4dc3227d4c4646bec09e13c11087b5f89682c0fe Mon Sep 17 00:00:00 2001
From: Randy Eckenrode <randy@largeandhighquality.com>
Date: Mon, 23 Sep 2024 22:06:54 -0400
Subject: [PATCH] llvmPackages.clang: use the system libunwind on Darwin
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While the Darwin stdenv bootstrap sets up its own clang wrappers and
doesn’t provide these wrappers in the final stdenv, it does use them
indirectly via the LLVM bootstrap to build LLVM and its libraries.

Note on using the system libunwind: It is possible to build and use the
LLVM libunwind on Darwin, but using the system by default one ensures
everything is using the same unwinder.
---
 .../compilers/llvm/common/default.nix            | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/pkgs/development/compilers/llvm/common/default.nix b/pkgs/development/compilers/llvm/common/default.nix
index 681e563d65a7..c863d0d8a82a 100644
--- a/pkgs/development/compilers/llvm/common/default.nix
+++ b/pkgs/development/compilers/llvm/common/default.nix
@@ -781,16 +781,20 @@ let
           bintools = bintools';
           extraPackages =
             [ targetLlvmLibraries.compiler-rt-no-libc ]
-            ++ lib.optionals (!stdenv.targetPlatform.isWasm && !stdenv.targetPlatform.isFreeBSD) [
-              targetLlvmLibraries.libunwind
-            ];
+            ++ lib.optionals
+              (
+                !stdenv.targetPlatform.isWasm && !stdenv.targetPlatform.isFreeBSD && !stdenv.targetPlatform.isDarwin
+              )
+              [
+                targetLlvmLibraries.libunwind
+              ];
           extraBuildCommands =
             lib.optionalString (lib.versions.major metadata.release_version == "13") (
               ''
                 echo "-rtlib=compiler-rt -Wno-unused-command-line-argument" >> $out/nix-support/cc-cflags
                 echo "-B${targetLlvmLibraries.compiler-rt-no-libc}/lib" >> $out/nix-support/cc-cflags
               ''
-              + lib.optionalString (!stdenv.targetPlatform.isWasm) ''
+              + lib.optionalString (!stdenv.targetPlatform.isWasm && !stdenv.targetPlatform.isDarwin) ''
                 echo "--unwindlib=libunwind" >> $out/nix-support/cc-cflags
                 echo "-L${targetLlvmLibraries.libunwind}/lib" >> $out/nix-support/cc-ldflags
               ''
@@ -811,7 +815,7 @@ let
               "-B${targetLlvmLibraries.compiler-rt-no-libc}/lib"
             ]
             ++ lib.optional (
-              !stdenv.targetPlatform.isWasm && !stdenv.targetPlatform.isFreeBSD
+              !stdenv.targetPlatform.isWasm && !stdenv.targetPlatform.isFreeBSD && !stdenv.targetPlatform.isDarwin
             ) "--unwindlib=libunwind"
             ++ lib.optional (
               !stdenv.targetPlatform.isWasm
@@ -820,7 +824,7 @@ let
             ) "-lunwind"
             ++ lib.optional stdenv.targetPlatform.isWasm "-fno-exceptions";
           nixSupport.cc-ldflags = lib.optionals (
-            !stdenv.targetPlatform.isWasm && !stdenv.targetPlatform.isFreeBSD
+            !stdenv.targetPlatform.isWasm && !stdenv.targetPlatform.isFreeBSD && !stdenv.targetPlatform.isDarwin
           ) [ "-L${targetLlvmLibraries.libunwind}/lib" ];
         }
       );