nixpkgs/pkgs/development/tools/build-managers/bazel/trim-last-argument-to-gcc-if-empty.patch

From 177b4720d6fbaa7fdd17e5e11b2c79ac8f246786 Mon Sep 17 00:00:00 2001
From: "Wael M. Nasreddine" <wael.nasreddine@gmail.com>
Date: Thu, 27 Jun 2019 21:08:51 -0700
Subject: [PATCH] Trim last argument to gcc if empty, on Darwin

On Darwin, the last argument to GCC is coming up as an empty string.
This is breaking the build of proto_library targets. However, I was not
able to reproduce with the example cpp project[0].

This commit removes the last argument if it's an empty string. This is
not a problem on Linux.

[0]: https://github.com/bazelbuild/examples/tree/master/cpp-tutorial/stage3
---
 tools/cpp/osx_cc_wrapper.sh.tpl | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/cpp/osx_cc_wrapper.sh.tpl b/tools/cpp/osx_cc_wrapper.sh.tpl
index 4c85cd9b6b..6c611e3d25 100644
--- a/tools/cpp/osx_cc_wrapper.sh.tpl
+++ b/tools/cpp/osx_cc_wrapper.sh.tpl
@@ -53,7 +53,11 @@ done
 %{env}
 
 # Call the C++ compiler
-%{cc} "$@"
+if [[ ${*: -1} = "" ]]; then
+    %{cc} "${@:0:$#}"
+else
+    %{cc} "$@"
+fi
 
 function get_library_path() {
     for libdir in ${LIB_DIRS}; do
-- 
2.19.2