// of the Go command.
const KnownEnv = `
	AR
	CC
	CGO_CFLAGS
	CGO_CFLAGS_ALLOW
	CGO_CFLAGS_DISALLOW
	CGO_CPPFLAGS
	CGO_CPPFLAGS_ALLOW
	CGO_CPPFLAGS_DISALLOW
	CGO_CXXFLAGS
	CGO_CXXFLAGS_ALLOW
	CGO_CXXFLAGS_DISALLOW
	CGO_ENABLED
	CGO_FFLAGS
	CGO_FFLAGS_ALLOW
	CGO_FFLAGS_DISALLOW
	CGO_LDFLAGS
	CGO_LDFLAGS_ALLOW
	CGO_LDFLAGS_DISALLOW
	CXX
	FC

env GOSUMDB=nodefault
env GOPROXY=nodefault
env GO111MODULE=auto
env CGO_CFLAGS=nodefault
env CGO_CPPFLAGS=nodefault

go env -changed
# linux output like GOTOOLCHAIN='local'
# windows output like GOTOOLCHAIN=local
stdout 'GOTOOLCHAIN=''?local''?'
stdout 'GOSUMDB=''?nodefault''?'
stdout 'GOPROXY=''?nodefault''?'
stdout 'GO111MODULE=''?auto''?'
stdout 'CGO_CFLAGS=''?nodefault''?'
stdout 'CGO_CPPFLAGS=''?nodefault''?'

# Explicitly rebuild it to ensure that it is cached.
# (See https://go.dev/issue/50892.)
#
# If running in non-short mode, explicitly vary CGO_CFLAGS
# as a control case (to ensure that our regexps do catch rebuilds).

[!short] env GOCACHE=$WORK/cache
[!short] env CGO_CFLAGS=-DTestScript_cgo_stale_precompiled=true
go build -x runtime/cgo
[!short] stderr '[/\\]cgo'$GOEXE'["]? .* -importpath runtime/cgo'

 */
struct cgoTracebackArg {
	uintptr_t  Context;
	uintptr_t  SigContext;
	uintptr_t* Buf;
	uintptr_t  Max;
};

/*
 * TSAN support.  This is only useful when building with
 *   CGO_CFLAGS="-fsanitize=thread" CGO_LDFLAGS="-fsanitize=thread" go install
 */
#undef CGO_TSAN
#if defined(__has_feature)
# if __has_feature(thread_sanitizer)
#  define CGO_TSAN
# endif
#elif defined(__SANITIZE_THREAD__)

		t.Run(cflags, func(t *testing.T) {
			testenv.MustHaveGoBuild(t)
			testenv.MustHaveCGO(t)
			t.Parallel()

			cmd := exec.Command("go", "build", path("issue14669.go"))
			cmd.Env = append(os.Environ(), "CGO_CFLAGS="+cflags)
			out, err := cmd.CombinedOutput()
			if err != nil {
				t.Errorf("%#q: %v:\n%s", strings.Join(cmd.Args, " "), err, out)
			}
		})
	}
}

func TestMallocCrashesOnNil(t *testing.T) {

		if strings.Contains(testenv.Builder(), "clang") {
			extraLDFlags += " -fuse-ld=lld"
		}
		const cflags = "-flto -Wno-lto-type-mismatch -Wno-unknown-warning-option"
		cmd.Env = append(cmd.Environ(),
			"CGO_CFLAGS="+cflags,
			"CGO_CXXFLAGS="+cflags,
			"CGO_LDFLAGS="+cflags+extraLDFlags)
	}
	out, err := cmd.CombinedOutput()
	if string(out) != "OK\n" {
		t.Errorf("%s", string(out))
	}
	if err != nil {