CMake/Help/release/dev/WCDH-thread_local.rst

WriteCompilerDetectionHeader thread_local portability
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* The :module:`WriteCompilerDetectionHeader` module learned to
  create a define for portability of the cxx_thread_local feature. The define
  expands to either the C++11 ``thread_local`` keyword, or a
  pre-standardization compiler-specific equivalent, as appropriate.
WCDH: Add feature portability for thread_local. AppleClang does not support the cxx_thread_local feature, even though it is based on a Clang version which does support the feature. http://stackoverflow.com/a/23850891/2428389 A possible reason for that is that thread_local might be used as a variable in existing Apple SDK headers. Extend the WriteCompilerDetectionHeader module to generate a define for that feature with portability fallbacks. For the avoidance of making it easy to write code which looks correct but which has odd runtime behavior, don't set the define symbol at all if no equivalent keyword is known. 2015-01-01 17:56:01 +01:00			`WriteCompilerDetectionHeader thread_local portability`
			`-----------------------------------------------------`

			* The :module:`WriteCompilerDetectionHeader` module learned to
			`create a define for portability of the cxx_thread_local feature. The define`
			expands to either the C++11 ``thread_local`` keyword, or a
			`pre-standardization compiler-specific equivalent, as appropriate.`