Request std=c++11 dialect again, and add warning (#900)

* Put back stdc++11 and add compile-time check

* Soften it and update changelog

CHANGELOG.md

@@ -46,6 +46,7 @@
 - `ASDisplayNode, ASLayoutSpec, and ASLayoutElementStyle` now conform to `NSLocking`. They act as recursive locks. Useful locking macros have been added as `ASThread.h`. Subclasses / client code can lock these objects but should be careful as usual when dealing with locks. [Adlai Holler](https://github.com/Adlai-Holler)
 - Introduces `ASRecursiveUnfairLock` as an experiment to improve locking performance. [Adlai Holler](https://github.com/Adlai-Holler)
 - Adds an experiment to shorten init time. [Adlai Holler](https://github.com/Adlai-Holler)
+- Adds a check that Texture is compiled with stdc++11 as specified by the podfile. gnu++11 can cause subtle issues that are currently being investigated. [Adlai Holler](https://github.com/Adlai-Holler)
 
 ## 2.6
 - [Xcode 9] Updated to require Xcode 9 (to fix warnings) [Garrett Moon](https://github.com/garrettmoon)

Source/Base/ASBaseDefines.h

@@ -23,6 +23,9 @@
 // wrap constants, only C functions. See StackOverflow for more details:
 // http://stackoverflow.com/questions/1041866/in-c-source-what-is-the-effect-of-extern-c
 #ifdef __cplusplus
+# ifndef __STRICT_ANSI__
+  #warning "Texture must be compiled with std=c++11. gnu++ is not supported and may cause issues."
+# endif
 # define ASDISPLAYNODE_EXTERN_C_BEGIN extern "C" {
 # define ASDISPLAYNODE_EXTERN_C_END   }
 #else

Texture.podspec

@@ -63,4 +63,9 @@ Pod::Spec.new do |spec|
 
   spec.social_media_url = 'https://twitter.com/TextureiOS'
   spec.library = 'c++'
+  spec.pod_target_xcconfig = {
+    'CLANG_CXX_LANGUAGE_STANDARD' => 'c++11',
+    'CLANG_CXX_LIBRARY' => 'libc++'
+   }
+
 end