From 72c1a73caceb08ca748071af6d96fbf32bef00d3 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sat, 12 Jan 2019 00:33:43 +0900
Subject: [PATCH] graphicsdriver/metal: Avoid using @available syntax for old
 Xcode (#781)

---
 internal/graphicsdriver/metal/ca/ca.go |  5 +++-
 internal/graphicsdriver/metal/ca/ca.m  | 36 ++++++++++++++++----------
 2 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/internal/graphicsdriver/metal/ca/ca.go b/internal/graphicsdriver/metal/ca/ca.go
index 4aedd5653..30f44aae5 100644
--- a/internal/graphicsdriver/metal/ca/ca.go
+++ b/internal/graphicsdriver/metal/ca/ca.go
@@ -28,7 +28,10 @@ import (
 	"github.com/hajimehoshi/ebiten/internal/graphicsdriver/metal/mtl"
 )
 
-// #cgo CFLAGS: -mmacosx-version-min=10.11
+// Suppress the warnings about availability guard with -Wno-unguarded-availability-new.
+// It is because old Xcode (8 or older?) does not accept @available syntax.
+
+// #cgo CFLAGS: -mmacosx-version-min=10.11 -Wno-unguarded-availability-new
 // #cgo LDFLAGS: -framework QuartzCore -framework Foundation -framework CoreGraphics
 //
 // #include "ca.h"
diff --git a/internal/graphicsdriver/metal/ca/ca.m b/internal/graphicsdriver/metal/ca/ca.m
index 4b04a06b4..b168c8d18 100644
--- a/internal/graphicsdriver/metal/ca/ca.m
+++ b/internal/graphicsdriver/metal/ca/ca.m
@@ -46,27 +46,35 @@ const char *MetalLayer_SetPixelFormat(void *metalLayer, uint16_t pixelFormat) {
 
 const char *MetalLayer_SetMaximumDrawableCount(void *metalLayer,
                                                uint_t maximumDrawableCount) {
-  if (@available(macOS 10.13.2, *)) {
-    @try {
-      if ([(CAMetalLayer *)metalLayer
-              respondsToSelector:@selector(setMaximumDrawableCount:)]) {
-        [((CAMetalLayer *)metalLayer)
-            setMaximumDrawableCount:(NSUInteger)maximumDrawableCount];
-      }
-    } @catch (NSException *exception) {
-      return exception.reason.UTF8String;
+  // @available syntax is not available for old Xcode (#781)
+  //
+  // If possible, we'd want to write the guard like:
+  //
+  //     if (@available(macOS 10.13.2, *)) { ...
+
+  @try {
+    if ([(CAMetalLayer *)metalLayer
+            respondsToSelector:@selector(setMaximumDrawableCount:)]) {
+      [((CAMetalLayer *)metalLayer)
+          setMaximumDrawableCount:(NSUInteger)maximumDrawableCount];
     }
+  } @catch (NSException *exception) {
+    return exception.reason.UTF8String;
   }
   return NULL;
 }
 
 void MetalLayer_SetDisplaySyncEnabled(void *metalLayer,
                                       BOOL displaySyncEnabled) {
-  if (@available(macOS 10.13, *)) {
-    if ([(CAMetalLayer *)metalLayer
-            respondsToSelector:@selector(setDisplaySyncEnabled:)]) {
-      [((CAMetalLayer *)metalLayer) setDisplaySyncEnabled:displaySyncEnabled];
-    }
+  // @available syntax is not available for old Xcode (#781)
+  //
+  // If possible, we'd want to write the guard like:
+  //
+  //     if (@available(macOS 10.13, *)) { ...
+
+  if ([(CAMetalLayer *)metalLayer
+          respondsToSelector:@selector(setDisplaySyncEnabled:)]) {
+    [((CAMetalLayer *)metalLayer) setDisplaySyncEnabled:displaySyncEnabled];
   }
 }