From 7b0c37aacd5a5e104c189680c0f7191e8015cf81 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Motiejus=20Jak=C5=A1tys?= <motiejus@uber.com>
Date: Thu, 5 Aug 2021 15:21:38 +0300
Subject: [PATCH] add DEFAULT_COPTS

---
 toolchain/defs.bzl | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/toolchain/defs.bzl b/toolchain/defs.bzl
index 08fd935..5a2b71e 100644
--- a/toolchain/defs.bzl
+++ b/toolchain/defs.bzl
@@ -18,6 +18,10 @@ DEFAULT_INCLUDE_DIRECTORIES = [
     "libcxxabi/include",
 ]
 
+# -Os, -O2 or -O3 must be set, because some dependencies use C's undefined
+# behavior. See https://github.com/ziglang/zig/issues/4830
+DEFAULT_COPTS = ["-O3"]
+
 _fcntl_map = """
 GLIBC_2.2.5 {
    fcntl;
@@ -64,7 +68,7 @@ def _target_darwin(gocpu, zigcpu):
             "libc/include/{}-macos-gnu".format(zigcpu),
         ],
         linkopts = [],
-        copts = [],
+        copts = DEFAULT_COPTS,
         bazel_target_cpu = "darwin",
         constraint_values = [
             "@platforms//os:macos",
@@ -109,7 +113,7 @@ def _target_linux_gnu(gocpu, zigcpu, glibc_version = ""):
         compiler_extra_includes = ["glibchack-fcntl.h"] if fcntl_hack else [],
         linker_version_scripts = ["glibc-hacks/fcntl.map"] if fcntl_hack else [],
         linkopts = ["-lc++", "-lc++abi"],
-        copts = [],
+        copts = DEFAULT_COPTS,
         bazel_target_cpu = "k8",
         constraint_values = [
             "@platforms//os:linux",
@@ -129,7 +133,7 @@ def _target_linux_musl(gocpu, zigcpu):
             "libc/include/{}-linux-any".format(zigcpu),
         ],
         linkopts = ["-s", "-w"],
-        copts = ["-D_LIBCPP_HAS_MUSL_LIBC", "-D_LIBCPP_HAS_THREAD_API_PTHREAD"],
+        copts = DEFAULT_COPTS + ["-D_LIBCPP_HAS_MUSL_LIBC", "-D_LIBCPP_HAS_THREAD_API_PTHREAD"],
         bazel_target_cpu = "k8",
         constraint_values = [
             "@platforms//os:linux",