llvmPackages*.clang: fix linker invocation with LLVMgold plugin

When using GNU binutils, clang passes the LLVMgold.so plugin to the
linker for certain operations that require special support in the linker
like doing link time optimization (LTO). When passing the plugin to the
linker's command line, clang assumes that llvm and itself are installed
in the same prefix and thus `/path/to/clang/bin/../lib/LLVMgold.so` is
the plugin.

Since we install clang and llvm to separate store paths, this assumption
does not hold. When clang-unwrapped only had a single output, we worked
around this issue by symlinking `$out/lib/LLVMgold.so` to
`${llvm}/lib/LLVMgold.so`. However since we split all llvm packages into
multiple outputs clang's `$out` no longer has a lib directory and clang
can't discover clangs lib output on its own. As a result LTO was broken.

Instead of introducing yet another hack and having a symlink to
LLVMgold.so in `$out/lib` (despite having `$lib/lib` as well), we patch
clang to use a hard coded path to `${libllvm.lib}/lib` for discovering
`LLVMgold.so`.

Resolves #123361.

pkgs/development/compilers/llvm/10/clang/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, llvm_meta, fetch, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
+{ lib, stdenv, llvm_meta, fetch, substituteAll, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
 , buildLlvmTools
 , fixDarwinDylibNames
 , enableManpages ? false
@@ -46,6 +46,10 @@ let
       # https://reviews.llvm.org/D51899
       ./compiler-rt-baremetal.patch
       ./gnu-install-dirs.patch
+      (substituteAll {
+        src = ../../clang-6-10-LLVMgold-path.patch;
+        libllvmLibdir = "${libllvm.lib}/lib";
+      })
     ];
 
     postPatch = ''
@@ -64,12 +68,7 @@ let
 
     outputs = [ "out" "lib" "dev" "python" ];
 
-    # Clang expects to find LLVMgold in its own prefix
     postInstall = ''
-      if [ -e ${libllvm.lib}/lib/LLVMgold.so ]; then
-        ln -sv ${libllvm.lib}/lib/LLVMgold.so $lib/lib
-      fi
-
       ln -sv $out/bin/clang $out/bin/cpp
 
       # Move libclang to 'lib' output

pkgs/development/compilers/llvm/11/clang/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, llvm_meta, fetch, fetchpatch, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
+{ lib, stdenv, llvm_meta, fetch, fetchpatch, substituteAll, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
 , buildLlvmTools
 , fixDarwinDylibNames
 , enableManpages ? false
@@ -57,6 +57,10 @@ let
         excludes = [ "docs/*" "test/*" ];
         sha256 = "0gxgmi0qbm89mq911dahallhi8m6wa9vpklklqmxafx4rplrr8ph";
       })
+      (substituteAll {
+        src = ../../clang-11-12-LLVMgold-path.patch;
+        libllvmLibdir = "${libllvm.lib}/lib";
+      })
     ];
 
     postPatch = ''
@@ -75,12 +79,7 @@ let
 
     outputs = [ "out" "lib" "dev" "python" ];
 
-    # Clang expects to find LLVMgold in its own prefix
     postInstall = ''
-      if [ -e ${libllvm.lib}/lib/LLVMgold.so ]; then
-        ln -sv ${libllvm.lib}/lib/LLVMgold.so $lib/lib
-      fi
-
       ln -sv $out/bin/clang $out/bin/cpp
 
       # Move libclang to 'lib' output

pkgs/development/compilers/llvm/12/clang/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, llvm_meta, fetch, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
+{ lib, stdenv, llvm_meta, fetch, substituteAll, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
 , buildLlvmTools
 , fixDarwinDylibNames
 , enableManpages ? false
@@ -44,6 +44,10 @@ let
       ./purity.patch
       # https://reviews.llvm.org/D51899
       ./gnu-install-dirs.patch
+      (substituteAll {
+        src = ../../clang-11-12-LLVMgold-path.patch;
+        libllvmLibdir = "${libllvm.lib}/lib";
+      })
     ];
 
     postPatch = ''
@@ -59,12 +63,7 @@ let
 
     outputs = [ "out" "lib" "dev" "python" ];
 
-    # Clang expects to find LLVMgold in its own prefix
     postInstall = ''
-      if [ -e ${libllvm.lib}/lib/LLVMgold.so ]; then
-        ln -sv ${libllvm.lib}/lib/LLVMgold.so $lib/lib
-      fi
-
       ln -sv $out/bin/clang $out/bin/cpp
 
       # Move libclang to 'lib' output

pkgs/development/compilers/llvm/5/clang/LLVMgold-path.patch

@@ -0,0 +1,14 @@
+diff --git a/lib/Driver/ToolChains/CommonArgs.cpp b/lib/Driver/ToolChains/CommonArgs.cpp
+index 00bd60bc24bb..17416b0bd3c0 100644
+--- a/lib/Driver/ToolChains/CommonArgs.cpp
++++ b/lib/Driver/ToolChains/CommonArgs.cpp
+@@ -376,8 +376,7 @@ void tools::AddGoldPlugin(const ToolChain &ToolChain, const ArgList &Args,
+   // as gold requires -plugin to come before any -plugin-opt that -Wl might
+   // forward.
+   CmdArgs.push_back("-plugin");
+-  std::string Plugin =
+-      ToolChain.getDriver().Dir + "/../lib" CLANG_LIBDIR_SUFFIX "/LLVMgold.so";
++  std::string Plugin = "@libllvmLibdir@" "/LLVMgold.so";
+   CmdArgs.push_back(Args.MakeArgString(Plugin));
+ 
+   // Try to pass driver level flags relevant to LTO code generation down to

pkgs/development/compilers/llvm/5/clang/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, llvm_meta, fetch, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
+{ lib, stdenv, llvm_meta, fetch, substituteAll, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
 , buildLlvmTools
 , fixDarwinDylibNames
 , enableManpages ? false
@@ -43,6 +43,10 @@ let
     patches = [
       ./purity.patch
       ./gnu-install-dirs.patch
+      (substituteAll {
+        src = ./LLVMgold-path.patch;
+        libllvmLibdir = "${libllvm.lib}/lib";
+      })
     ];
 
     postPatch = ''
@@ -58,12 +62,7 @@ let
 
     outputs = [ "out" "lib" "dev" "python" ];
 
-    # Clang expects to find LLVMgold in its own prefix
     postInstall = ''
-      if [ -e ${libllvm.lib}/lib/LLVMgold.so ]; then
-        ln -sv ${libllvm.lib}/lib/LLVMgold.so $lib/lib
-      fi
-
       ln -sv $out/bin/clang $out/bin/cpp
 
       # Move libclang to 'lib' output

pkgs/development/compilers/llvm/6/clang/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, llvm_meta, fetch, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
+{ lib, stdenv, llvm_meta, fetch, substituteAll, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
 , buildLlvmTools
 , fixDarwinDylibNames
 , enableManpages ? false
@@ -43,6 +43,10 @@ let
     patches = [
       ./purity.patch
       ./gnu-install-dirs.patch
+      (substituteAll {
+        src = ../../clang-6-10-LLVMgold-path.patch;
+        libllvmLibdir = "${libllvm.lib}/lib";
+      })
     ];
 
     postPatch = ''
@@ -58,12 +62,7 @@ let
 
     outputs = [ "out" "lib" "dev" "python" ];
 
-    # Clang expects to find LLVMgold in its own prefix
     postInstall = ''
-      if [ -e ${libllvm.lib}/lib/LLVMgold.so ]; then
-        ln -sv ${libllvm.lib}/lib/LLVMgold.so $lib/lib
-      fi
-
       ln -sv $out/bin/clang $out/bin/cpp
 
       # Move libclang to 'lib' output

pkgs/development/compilers/llvm/7/clang/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, llvm_meta, fetch, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
+{ lib, stdenv, llvm_meta, fetch, substituteAll, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
 , buildLlvmTools
 , fixDarwinDylibNames
 , enableManpages ? false
@@ -52,6 +52,10 @@ let
       # needed for our bootstrapping to not interfere with C.
       ./unwindlib.patch
       ./gnu-install-dirs.patch
+      (substituteAll {
+        src = ../../clang-6-10-LLVMgold-path.patch;
+        libllvmLibdir = "${libllvm.lib}/lib";
+      })
     ];
 
     postPatch = ''
@@ -70,12 +74,7 @@ let
 
     outputs = [ "out" "lib" "dev" "python" ];
 
-    # Clang expects to find LLVMgold in its own prefix
     postInstall = ''
-      if [ -e ${libllvm.lib}/lib/LLVMgold.so ]; then
-        ln -sv ${libllvm.lib}/lib/LLVMgold.so $lib/lib
-      fi
-
       ln -sv $out/bin/clang $out/bin/cpp
 
       # Move libclang to 'lib' output

pkgs/development/compilers/llvm/8/clang/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, llvm_meta, fetch, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
+{ lib, stdenv, llvm_meta, fetch, substituteAll, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
 , buildLlvmTools
 , fixDarwinDylibNames
 , enableManpages ? false
@@ -59,6 +59,10 @@ let
       # make clang -xhip use $PATH to find executables
       ./HIP-use-PATH-8.patch
       ./gnu-install-dirs.patch
+      (substituteAll {
+        src = ../../clang-6-10-LLVMgold-path.patch;
+        libllvmLibdir = "${libllvm.lib}/lib";
+      })
     ];
 
     postPatch = ''
@@ -77,12 +81,7 @@ let
 
     outputs = [ "out" "lib" "dev" "python" ];
 
-    # Clang expects to find LLVMgold in its own prefix
     postInstall = ''
-      if [ -e ${libllvm.lib}/lib/LLVMgold.so ]; then
-        ln -sv ${libllvm.lib}/lib/LLVMgold.so $lib/lib
-      fi
-
       ln -sv $out/bin/clang $out/bin/cpp
 
       # Move libclang to 'lib' output

pkgs/development/compilers/llvm/9/clang/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, llvm_meta, fetch, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
+{ lib, stdenv, llvm_meta, fetch, substituteAll, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
 , buildLlvmTools
 , fixDarwinDylibNames
 , enableManpages ? false
@@ -52,6 +52,10 @@ let
       # make clang -xhip use $PATH to find executables
       ./HIP-use-PATH-9.patch
       ./gnu-install-dirs.patch
+      (substituteAll {
+        src = ../../clang-6-10-LLVMgold-path.patch;
+        libllvmLibdir = "${libllvm.lib}/lib";
+      })
     ];
 
     postPatch = ''
@@ -70,12 +74,7 @@ let
 
     outputs = [ "out" "lib" "dev" "python" ];
 
-    # Clang expects to find LLVMgold in its own prefix
     postInstall = ''
-      if [ -e ${libllvm.lib}/lib/LLVMgold.so ]; then
-        ln -sv ${libllvm.lib}/lib/LLVMgold.so $lib/lib
-      fi
-
       ln -sv $out/bin/clang $out/bin/cpp
 
       # Move libclang to 'lib' output

pkgs/development/compilers/llvm/clang-11-12-LLVMgold-path.patch

@@ -0,0 +1,13 @@
+diff --git a/lib/Driver/ToolChains/CommonArgs.cpp b/lib/Driver/ToolChains/CommonArgs.cpp
+index 6b6e276b8ce7..7896542a1202 100644
+--- a/lib/Driver/ToolChains/CommonArgs.cpp
++++ b/lib/Driver/ToolChains/CommonArgs.cpp
+@@ -409,7 +409,7 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
+ 
+     SmallString<1024> Plugin;
+     llvm::sys::path::native(
+-        Twine(D.Dir) + "/../lib" CLANG_LIBDIR_SUFFIX "/LLVMgold" + Suffix,
++        Twine("@libllvmLibdir@" "/LLVMgold") + Suffix,
+         Plugin);
+     CmdArgs.push_back(Args.MakeArgString(Plugin));
+   }

pkgs/development/compilers/llvm/clang-6-10-LLVMgold-path.patch

@@ -0,0 +1,15 @@
+diff --git a/lib/Driver/ToolChains/CommonArgs.cpp b/lib/Driver/ToolChains/CommonArgs.cpp
+index 37ec73468570..b73e75aa6e59 100644
+--- a/lib/Driver/ToolChains/CommonArgs.cpp
++++ b/lib/Driver/ToolChains/CommonArgs.cpp
+@@ -370,8 +370,8 @@ void tools::AddGoldPlugin(const ToolChain &ToolChain, const ArgList &Args,
+ #endif
+ 
+   SmallString<1024> Plugin;
+-  llvm::sys::path::native(Twine(ToolChain.getDriver().Dir) +
+-                              "/../lib" CLANG_LIBDIR_SUFFIX "/LLVMgold" +
++  llvm::sys::path::native(Twine("@libllvmLibdir@"
++                                "/LLVMgold") +
+                               Suffix,
+                           Plugin);
+   CmdArgs.push_back(Args.MakeArgString(Plugin));