Merge topic 'COMPILE_FEATURES-genex'

0dfe395e Features: Add COMPILE_FEATURES generator expression.
aa8a6fce cmMakefile: Add methods for checking availability of a feature.
b6dedf03 cmMakefile: Extract CheckNeeded{C,Cxx}Language methods.
8dd129df cmMakefile: Extract CompileFeaturesAvailable method.
6b9b2fff cmMakefile: Extract CompileFeatureKnown method.

2 files changed, 10 insertions, 0 deletions

diff --git a/Help/manual/cmake-generator-expressions.7.rst b/Help/manual/cmake-generator-expressions.7.rst
index dfda8dc..9184580 100644
--- a/Help/manual/cmake-generator-expressions.7.rst
+++ b/Help/manual/cmake-generator-expressions.7.rst
@@ -83,6 +83,12 @@ otherwise expands to nothing.
   else ``0``.  If the policy was not set, the warning message for the policy
   will be emitted. This generator expression only works for a subset of
   policies.
+``$<COMPILE_FEATURES:feature[,feature]...>``
+  ``1`` if all of the ``feature`` features are available for the 'head'
+  target, and ``0`` otherwise. If this expression is used while evaluating
+  the link implementation of a target and if any dependency transitively
+  increases the required :prop_tgt:`C_STANDARD` or :prop_tgt:`CXX_STANDARD`
+  for the 'head' target, an error is reported.
 
 Informational Expressions
 =========================
diff --git a/Help/release/dev/compile-language-features.rst b/Help/release/dev/compile-language-features.rst
index fe72e39..d10e22b 100644
--- a/Help/release/dev/compile-language-features.rst
+++ b/Help/release/dev/compile-language-features.rst
@@ -22,3 +22,7 @@ target-language-features
 * New :command:`target_compile_features` command allows populating the
   :prop_tgt:`COMPILE_FEATURES` target property, just like any other
   build variable.
+
+* New ``COMPILE_FEATURES``
+  :manual:`generator expression <cmake-generator-expressions(7)>` allows
+  setting build properties based on available compiler features.