Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

cmd/cgo: use --no-gc-sections if available #53028

Closed
wants to merge 1 commit into from
Closed

cmd/cgo: use --no-gc-sections if available #53028

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
42 changes: 33 additions & 9 deletions src/cmd/go/internal/work/exec.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2528,6 +2528,13 @@ func (b *Builder) compilerCmd(compiler []string, incdir, workdir string) []strin
a = append(a, "-Qunused-arguments")
}

// zig cc passes --gc-sections to the underlying linker, which then causes
// undefined symbol errors when compiling with cgo but without C code.
// https://github.com/golang/go/issues/52690
if b.gccSupportsFlag(compiler, "-Wl,--no-gc-sections") {
a = append(a, "-Wl,--no-gc-sections")
}

// disable word wrapping in error messages
a = append(a, "-fmessage-length=0")

Expand Down Expand Up @@ -2584,7 +2591,12 @@ func (b *Builder) gccSupportsFlag(compiler []string, flag string) bool {
}

tmp := os.DevNull
if runtime.GOOS == "windows" {

// On the iOS builder the command
// $CC -Wl,--no-gc-sections -x c - -o /dev/null < /dev/null
// is failing with:
// Unable to remove existing file: Invalid argument
if runtime.GOOS == "windows" || runtime.GOOS == "ios" {
f, err := os.CreateTemp(b.WorkDir, "")
if err != nil {
return false
Expand All @@ -2594,13 +2606,21 @@ func (b *Builder) gccSupportsFlag(compiler []string, flag string) bool {
defer os.Remove(tmp)
}

// We used to write an empty C file, but that gets complicated with
// go build -n. We tried using a file that does not exist, but that
// fails on systems with GCC version 4.2.1; that is the last GPLv2
// version of GCC, so some systems have frozen on it.
// Now we pass an empty file on stdin, which should work at least for
// GCC and clang.
cmdArgs := str.StringList(compiler, flag, "-c", "-x", "c", "-", "-o", tmp)
// We used to write an empty C file, but that gets complicated with go
// build -n. We tried using a file that does not exist, but that fails on
// systems with GCC version 4.2.1; that is the last GPLv2 version of GCC,
// so some systems have frozen on it. Now we pass an empty file on stdin,
// which should work at least for GCC and clang.
//
// If the argument is "-Wl,", then it's testing the linker. In that case,
// skip "-c". If it's not "-Wl,", then we are testing the compiler and
// can emit the linking step with "-c".
cmdArgs := str.StringList(compiler, flag)
if !strings.HasPrefix(flag, "-Wl,") /* linker flag */ {
cmdArgs = append(cmdArgs, "-c")
}
cmdArgs = append(cmdArgs, "-x", "c", "-", "-o", tmp)

if cfg.BuildN || cfg.BuildX {
b.Showcmd(b.WorkDir, "%s || true", joinUnambiguously(cmdArgs))
if cfg.BuildN {
Expand All @@ -2613,12 +2633,16 @@ func (b *Builder) gccSupportsFlag(compiler []string, flag string) bool {
out, _ := cmd.CombinedOutput()
// GCC says "unrecognized command line option".
// clang says "unknown argument".
// tcc says "unsupported"
// AIX says "not recognized"
// Older versions of GCC say "unrecognised debug output level".
// For -fsplit-stack GCC says "'-fsplit-stack' is not supported".
supported := !bytes.Contains(out, []byte("unrecognized")) &&
!bytes.Contains(out, []byte("unknown")) &&
!bytes.Contains(out, []byte("unrecognised")) &&
!bytes.Contains(out, []byte("is not supported"))
!bytes.Contains(out, []byte("is not supported")) &&
!bytes.Contains(out, []byte("not recognized")) &&
!bytes.Contains(out, []byte("unsupported"))
b.flagCache[key] = supported
return supported
}
Expand Down