From c99904e11307cbade607ad855a29f07694762f37 Mon Sep 17 00:00:00 2001
From: Andrew Childs <lorne@cons.org.nz>
Date: Thu, 4 Feb 2021 18:29:29 +0900
Subject: [PATCH] clang_11: revert -fno-common default

---
 .../compilers/llvm/11/clang/default.nix            | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/pkgs/development/compilers/llvm/11/clang/default.nix b/pkgs/development/compilers/llvm/11/clang/default.nix
index 67b5e0c17fea..f23394a8b754 100644
--- a/pkgs/development/compilers/llvm/11/clang/default.nix
+++ b/pkgs/development/compilers/llvm/11/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, fetchpatch, cmake, libxml2, libllvm, version, clang-tools-extra_src, python3
 , buildLlvmTools
 , fixDarwinDylibNames
 , enableManpages ? false
@@ -45,6 +45,18 @@ let
       ./purity.patch
       # https://reviews.llvm.org/D51899
       ./gnu-install-dirs.patch
+      # Revert: [Driver] Default to -fno-common for all targets
+      # https://reviews.llvm.org/D75056
+      #
+      # Maintains compatibility with packages that haven't been fixed yet, and
+      # matches gcc10's configuration in nixpkgs.
+      (fetchpatch {
+        revert = true;
+        url = "https://github.com/llvm/llvm-project/commit/0a9fc9233e172601e26381810d093e02ef410f65.diff";
+        stripLen = 1;
+        excludes = [ "docs/*" "test/*" ];
+        sha256 = "0gxgmi0qbm89mq911dahallhi8m6wa9vpklklqmxafx4rplrr8ph";
+      })
     ];
 
     postPatch = ''