From 0e9ef0a07d9723c8e6b4f0cdbd81cbcf3407046a Mon Sep 17 00:00:00 2001
From: Adam Joseph <adam@westernsemico.com>
Date: Sun, 7 May 2023 01:27:01 -0700
Subject: [PATCH 1/3] cc-wrapper: when merging gcc32 and gcc64, merge libgcc as
 well

Our gcc_multi and glibc_multi expressions merge together a
32-bit-targeted and 64-bit-targeted gcc.  However they do not thread
through the passthru.libgcc from these merged gccs.

This commit corrects that.

It also extends passthru.libgcc to allow a *list* rather than just a
single outpath.

Resolves part of #221891 (at least getting it back to the error
message it gave before).
---
 pkgs/build-support/cc-wrapper/default.nix  |  6 +++---
 pkgs/development/compilers/llvm/multi.nix  |  2 +-
 pkgs/development/libraries/glibc/multi.nix | 13 +++++++++++--
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/pkgs/build-support/cc-wrapper/default.nix b/pkgs/build-support/cc-wrapper/default.nix
index bc9c199f778d..77ecaf098eac 100644
--- a/pkgs/build-support/cc-wrapper/default.nix
+++ b/pkgs/build-support/cc-wrapper/default.nix
@@ -364,9 +364,9 @@ stdenv.mkDerivation {
     ''
     # this ensures that when clang passes -lgcc_s to lld (as it does
     # when building e.g. firefox), lld is able to find libgcc_s.so
-    + lib.optionalString (gccForLibs?libgcc) ''
-      echo "-L${gccForLibs.libgcc}/lib" >> $out/nix-support/cc-ldflags
-    '')
+    + concatMapStrings (libgcc: ''
+      echo "-L${libgcc}/lib" >> $out/nix-support/cc-ldflags
+    '') (lib.toList (gccForLibs.libgcc or [])))
 
     ##
     ## General libc support
diff --git a/pkgs/development/compilers/llvm/multi.nix b/pkgs/development/compilers/llvm/multi.nix
index ecea5d440378..7906f2b2bd6c 100644
--- a/pkgs/development/compilers/llvm/multi.nix
+++ b/pkgs/development/compilers/llvm/multi.nix
@@ -46,7 +46,7 @@ let
       libc = gcc_multi_sysroot;
     };
 
-    gccForLibs = gcc_multi_sysroot;
+    gccForLibs = gcc_multi_sysroot // { inherit (glibc_multi) libgcc; };
   };
 
 in clangMulti
diff --git a/pkgs/development/libraries/glibc/multi.nix b/pkgs/development/libraries/glibc/multi.nix
index be190d77c736..5cd48958ec2c 100644
--- a/pkgs/development/libraries/glibc/multi.nix
+++ b/pkgs/development/libraries/glibc/multi.nix
@@ -1,4 +1,5 @@
-{ runCommand, glibc, glibc32
+{ lib
+, runCommand, glibc, glibc32
 }:
 
 let
@@ -7,7 +8,15 @@ let
 in
 runCommand "${nameVersion.name}-multi-${nameVersion.version}"
   # out as the first output is an exception exclusive to glibc
-  { outputs = [ "out" "bin" "dev" ]; } # TODO: no static version here (yet)
+  {
+    outputs = [ "out" "bin" "dev" ];  # TODO: no static version here (yet)
+    passthru = {
+      libgcc = lib.lists.filter (x: x!=null) [
+        (glibc64.libgcc or null)
+        (glibc32.libgcc or null)
+      ];
+    };
+  }
   ''
     mkdir -p "$out/lib"
     ln -s '${glibc64.out}'/lib/* "$out/lib"

From c02c5f0860ee5ea791a1a839fbbb872ef7072b73 Mon Sep 17 00:00:00 2001
From: Adam Joseph <adam@westernsemico.com>
Date: Tue, 9 May 2023 00:10:04 -0700
Subject: [PATCH 2/3] wrapClangMulti: set gcc_multi_sysroot.langCC

The phoney gcc that we construct for multilib was missing the
`langCC` attribute, which `cc-wrapper` needs in order to decide
whether or not to add gcc's `libstdc++` headers as an `-isystem` for
`clang`.
---
 pkgs/development/compilers/llvm/multi.nix | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/pkgs/development/compilers/llvm/multi.nix b/pkgs/development/compilers/llvm/multi.nix
index 7906f2b2bd6c..d579e001563a 100644
--- a/pkgs/development/compilers/llvm/multi.nix
+++ b/pkgs/development/compilers/llvm/multi.nix
@@ -46,7 +46,13 @@ let
       libc = gcc_multi_sysroot;
     };
 
-    gccForLibs = gcc_multi_sysroot // { inherit (glibc_multi) libgcc; };
+    gccForLibs = gcc_multi_sysroot // {
+      inherit (glibc_multi) libgcc;
+      langCC =
+        assert (gcc64.cc.langCC != gcc32.cc.langCC)
+               -> throw "(gcc64.cc.langCC=${gcc64.cc.langCC}) != (gcc32.cc.langCC=${gcc32.cc.langCC})";
+        gcc64.cc.langCC;
+    };
   };
 
 in clangMulti

From 62794bf2bbab395dc841db4227079e7bba86dcc8 Mon Sep 17 00:00:00 2001
From: Adam Joseph <adam@westernsemico.com>
Date: Tue, 9 May 2023 00:11:37 -0700
Subject: [PATCH 3/3] wrapClangMulti: link include/c++ into gcc_multi_sysroot

The phoney gcc that we construct for multilib was missing the
`$out/include/c++` directory which `cc-wrapper` needs to pass as an
`-isystem` to `clang`.

Closes #221891
---
 pkgs/development/compilers/llvm/multi.nix | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/pkgs/development/compilers/llvm/multi.nix b/pkgs/development/compilers/llvm/multi.nix
index d579e001563a..136e13ba21f5 100644
--- a/pkgs/development/compilers/llvm/multi.nix
+++ b/pkgs/development/compilers/llvm/multi.nix
@@ -28,7 +28,9 @@ let
 
 
     # includes
-    ln -s ${glibc_multi.dev}/include $out/
+    mkdir -p $out/include
+    ln -s ${glibc_multi.dev}/include/* $out/include
+    ln -s ${gcc64.cc}/include/c++ $out/include/c++
 
     # dynamic linkers
     mkdir -p $out/lib/32