From d9e2ba4fcce0a405e2d103e43c19f01fa1a5401d Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <iant@golang.org>
Date: Wed, 19 Dec 2018 07:03:04 -0800
Subject: [PATCH] cmd/cgo: ensure the command passed to run retains a trailing
 dash

This was accidentally broken by CL 127755.

Fixes #29333

Change-Id: I5e92048c64a55c1699d6c38eb4dbbd51c817b820
Reviewed-on: https://go-review.googlesource.com/c/155037
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
---
 misc/cgo/test/issue4339.go | 3 ++-
 src/cmd/cgo/gcc.go         | 4 +++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/misc/cgo/test/issue4339.go b/misc/cgo/test/issue4339.go
index 4fa4b2bbd7..3715fde575 100644
--- a/misc/cgo/test/issue4339.go
+++ b/misc/cgo/test/issue4339.go
@@ -5,7 +5,8 @@
 package cgotest
 
 /*
-#include "issue4339.h"
+// We've historically permitted #include <>, so test it here.  Issue 29333.
+#include <issue4339.h>
 */
 import "C"
 
diff --git a/src/cmd/cgo/gcc.go b/src/cmd/cgo/gcc.go
index 27bd59b54e..11c3ff3a9c 100644
--- a/src/cmd/cgo/gcc.go
+++ b/src/cmd/cgo/gcc.go
@@ -1992,8 +1992,10 @@ func (p *Package) gccErrors(stdin []byte) string {
 		}
 	}
 
-	// Force -O0 optimization
+	// Force -O0 optimization but keep the trailing "-" at the end.
 	nargs = append(nargs, "-O0")
+	nl := len(nargs)
+	nargs[nl-2], nargs[nl-1] = nargs[nl-1], nargs[nl-2]
 
 	if *debugGcc {
 		fmt.Fprintf(os.Stderr, "$ %s <<EOF\n", strings.Join(nargs, " "))