>From dd73f985107937ee1c593f0878bdd5b01178af1c Mon Sep 17 00:00:00 2001
From: Alan Third <address@hidden>
Date: Thu, 6 Jul 2017 23:10:49 +0100
Subject: [PATCH] Use a run-time check for macOS Sierra tabbing support

* src/nsterm.m (initFrameFromEmacs) [NS_IMPL_COCOA]: Switch from
compile-time check to run-time.
* src/nsterm.h (NSWindowTabbingMode): Define in pre-Sierra macOS.
(NS_SILENCE_MISSING_METHOD_WARNING_BEGIN,
NS_SILENCE_MISSING_METHOD_WARNING_BEGIN_END): Add #defines for
silencing known missing method warnings.
---
 src/nsterm.h | 33 +++++++++++++++++++++++++++++++++
 src/nsterm.m |  8 +++++---
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/src/nsterm.h b/src/nsterm.h
index 0f1b36db7b..c5b4b17eed 100644
--- a/src/nsterm.h
+++ b/src/nsterm.h
@@ -1317,6 +1317,39 @@ extern char gnustep_base_version[];  /* version tracking */
 #ifdef __OBJC__
 typedef NSUInteger NSWindowStyleMask;
 #endif
+
+/* Window tabbing mode enums are new too. */
+enum NSWindowTabbingMode
+  {
+    NSWindowTabbingModeAutomatic,
+    NSWindowTabbingModePreferred,
+    NSWindowTabbingModeDisallowed
+  };
+#endif
+
+/* Surround code with the following macros to silence a missing method
+ * warning from the compiler.  This is useful when testing whether a
+ * method is available on an object, and then calling it if so.
+ *
+ *       if ([obj respondsToSelector: @selector(methodName)])
+ *         [obj methodName];
+ *
+ * Where obj doesn't have a selector methodName, the compiler will
+ * issue a warning.  Sometimes we want to build against libraries
+ * where we don't know if the method exists, for example when a new
+ * version of Cocoa adds or removes a method.
+ */
+#if defined (__GNUC__) && !defined (__clang__)
+/* gcc doesn't seem to have any way to silence this warning. */
+#define NS_SILENCE_MISSING_METHOD_WARNING_BEGIN
+#define NS_SILENCE_MISSING_METHOD_WARNING_BEGIN_END
+
+#elif defined (__clang__)
+#define NS_SILENCE_MISSING_METHOD_WARNING_BEGIN                   \
+  _Pragma ("clang diagnostic push")                               \
+  _Pragma ("clang diagnostic ignored \"-Wobjc-method-access\"")
+#define NS_SILENCE_MISSING_METHOD_WARNING_BEGIN_END     \
+  _Pragma ("clang diagnostic pop")
 #endif
 
 #endif	/* HAVE_NS */
diff --git a/src/nsterm.m b/src/nsterm.m
index a3c7031331..e1ce05b978 100644
--- a/src/nsterm.m
+++ b/src/nsterm.m
@@ -7091,9 +7091,11 @@ - (instancetype) initFrameFromEmacs: (struct frame *)f
   /* macOS Sierra automatically enables tabbed windows.  We can't
      allow this to be enabled until it's available on a Free system.
      Currently it only happens by accident and is buggy anyway. */
-#if defined (NS_IMPL_COCOA) && \
-  MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_12
-  [win setTabbingMode: NSWindowTabbingModeDisallowed];
+#ifdef NS_IMPL_COCOA
+  NS_SILENCE_MISSING_METHOD_WARNING_BEGIN
+  if ([win respondsToSelector: @selector(setTabbingMode:)])
+    [win setTabbingMode: NSWindowTabbingModeDisallowed];
+  NS_SILENCE_MISSING_METHOD_WARNING_BEGIN_END
 #endif
 
   ns_window_num++;
-- 
2.12.0