OSX: Use the oldest SDK, but always set our target to 10.8

Build binaries usable on older machines even if older SDKs are not
installed. Older SDKs can no longer be installed on newer Xcode
versions.

Port of https://android-review.googlesource.com/207242

Change-Id: If66f2eef7593bce9fb858fc7b71369f55dd362e4

1 files changed, 7 insertions, 9 deletions

diff --git a/cc/x86_darwin_host.go b/cc/x86_darwin_host.go
index 9a7b68a9..bff9a03f 100644
--- a/cc/x86_darwin_host.go
+++ b/cc/x86_darwin_host.go
@@ -79,10 +79,10 @@ var (
 	darwinX8664ClangLdflags = clangFilterUnknownCflags(darwinX8664Ldflags)
 
 	darwinSupportedSdkVersions = []string{
-		"macosx10.8",
-		"macosx10.9",
-		"macosx10.10",
-		"macosx10.11",
+		"10.8",
+		"10.9",
+		"10.10",
+		"10.11",
 	}
 )
 
@@ -99,9 +99,7 @@ func init() {
 	pctx.VariableFunc("macSdkRoot", func(config interface{}) (string, error) {
 		return xcrunSdk(config.(common.Config), "--show-sdk-path")
 	})
-	pctx.VariableFunc("macSdkVersion", func(config interface{}) (string, error) {
-		return xcrunSdk(config.(common.Config), "--show-sdk-version")
-	})
+	pctx.StaticVariable("macSdkVersion", darwinSupportedSdkVersions[0])
 	pctx.VariableFunc("macArPath", func(config interface{}) (string, error) {
 		bytes, err := exec.Command("xcrun", "--find", "ar").Output()
 		return strings.TrimSpace(string(bytes)), err
@@ -138,7 +136,7 @@ func init() {
 
 func xcrunSdk(config common.Config, arg string) (string, error) {
 	if selected := config.Getenv("MAC_SDK_VERSION"); selected != "" {
-		if !inList("macosx"+selected, darwinSupportedSdkVersions) {
+		if !inList(selected, darwinSupportedSdkVersions) {
 			return "", fmt.Errorf("MAC_SDK_VERSION %s isn't supported: %q", selected, darwinSupportedSdkVersions)
 		}
 
@@ -150,7 +148,7 @@ func xcrunSdk(config common.Config, arg string) (string, error) {
 	}
 
 	for _, sdk := range darwinSupportedSdkVersions {
-		bytes, err := exec.Command("xcrun", "--sdk", sdk, arg).Output()
+		bytes, err := exec.Command("xcrun", "--sdk", "macosx"+sdk, arg).Output()
 		if err == nil {
 			return strings.TrimSpace(string(bytes)), err
 		}