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''?'

		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 {

		from appearing in #cgo CFLAGS source code directives.
		Does not apply to the CGO_CFLAGS environment variable.
	CGO_CPPFLAGS, CGO_CPPFLAGS_ALLOW, CGO_CPPFLAGS_DISALLOW
		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
		but for the C preprocessor.
	CGO_CXXFLAGS, CGO_CXXFLAGS_ALLOW, CGO_CXXFLAGS_DISALLOW
		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
		but for the C++ compiler.

		q, err := quoted.Join(s)
		if err != nil {
			return strings.Join(s, " ")
		}
		return q
	}

	ret := []cfg.EnvVar{
		// Note: Update the switch in runEnv below when adding to this list.
		{Name: "CGO_CFLAGS", Value: join(cflags)},
		{Name: "CGO_CPPFLAGS", Value: join(cppflags)},
		{Name: "CGO_CXXFLAGS", Value: join(cxxflags)},
		{Name: "CGO_FFLAGS", Value: join(fflags)},
		{Name: "CGO_LDFLAGS", Value: join(ldflags)},

	tg.run("env", "GCCGO")
	tg.grepStdout(".", "GCCGO unexpectedly empty")

	tg.run("env", "CGO_CFLAGS")
	tg.grepStdout(".", "default CGO_CFLAGS unexpectedly empty")

	tg.setenv("CGO_CFLAGS", "-foobar")
	tg.run("env", "CGO_CFLAGS")
	tg.grepStdout("^-foobar$", "CGO_CFLAGS not honored")

	tg.setenv("CC", "gcc -fmust -fgo -ffaster")
	tg.run("env", "CC")
	tg.grepStdout("gcc", "CC not found")

//		from appearing in #cgo CFLAGS source code directives.
//		Does not apply to the CGO_CFLAGS environment variable.
//	CGO_CPPFLAGS, CGO_CPPFLAGS_ALLOW, CGO_CPPFLAGS_DISALLOW
//		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
//		but for the C preprocessor.
//	CGO_CXXFLAGS, CGO_CXXFLAGS_ALLOW, CGO_CXXFLAGS_DISALLOW
//		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
//		but for the C++ compiler.

	cmd := testenv.Command(t, testenv.GoToolPath(t), "build", "-buildmode=c-archive", "-o", ar, lib)
	env := []string{
		"CGO_ENABLED=1",
		"GOOS=ios",
		"GOARCH=arm64",
		"CC=" + strings.Join(CC, " "),
		"CGO_CFLAGS=", // ensure CGO_CFLAGS does not contain any flags. Issue #35459
		"CGO_LDFLAGS=" + strings.Join(CGO_LDFLAGS, " "),
	}
	cmd.Env = append(os.Environ(), env...)
	t.Logf("%q %v", env, cmd)

			}
		}

	case os == "aix", os == "android", os == "dragonfly", os == "freebsd", os == "linux", os == "netbsd", os == "openbsd":
		gt := cgoTest("external-g0", "test", "external", "")
		gt.env = append(gt.env, "CGO_CFLAGS=-g0 -fdiagnostics-color")

		cgoTest("external", "testtls", "external", "")
		switch {
		case os == "aix":
			// no static linking
		case p == "freebsd/arm":

permitted, notably alphanumeric characters and a few symbols, such as
'.', that will not be interpreted in unexpected ways. Attempts to use
forbidden characters will get a "malformed #cgo argument" error.

When building, the CGO_CFLAGS, CGO_CPPFLAGS, CGO_CXXFLAGS, CGO_FFLAGS and
CGO_LDFLAGS environment variables are added to the flags derived from
these directives. Package-specific flags should be set using the