Merge topic 'target_compile_features'

9eaf3755 Export: Populate INTERFACE_COMPILE_FEATURES property.
8ed59fc2 Add target_compile_features command.
4e6ca504 cmTargetPropCommandBase: Change the interface to return bool.
5412dede cmTarget: Transitively evaluate compiler features.
baff4434 cmTarget: Allow populating COMPILE_FEATURES using generator expressions.
f97bf437 Features: Add cxx_auto_type.
03355d6b cmTarget: Add COMPILE_FEATURES target property.
faeddf64 project: Add infrastructure for recording CXX compiler features
913394af cmTarget: Add CXX_STANDARD and CXX_EXTENSION target properties.
8238a6cd Add some COMPILE_OPTIONS for specifying C++ dialect.
892243fc Tests: Require CMake 3.0 for the SystemInformation test.
59b5fdd3 Don't load Clang-CXX from AppleClang-CXX.

Help/command/target_compile_features.rst

@@ -0,0 +1,30 @@
+target_compile_features
+-----------------------
+
+Add expected compiler features to a target.
+
+::
+
+  target_compile_features(<target> <PRIVATE|PUBLIC|INTERFACE> <feature> [...])
+
+Specify compiler features required when compiling a given target.  If the
+feature is not listed in the :variable:`CMAKE_CXX_COMPILE_FEATURES` variable,
+then an error will be reported by CMake.  If the use of the feature requires
+an additional compiler flag, such as ``-std=c++11``, the flag will be added
+automatically.
+
+The ``INTERFACE``, ``PUBLIC`` and ``PRIVATE`` keywords are required to
+specify the scope of the features.  ``PRIVATE`` and ``PUBLIC`` items will
+populate the :prop_tgt:`COMPILE_FEATURES` property of ``<target>``.
+``PUBLIC`` and ``INTERFACE`` items will populate the
+:prop_tgt:`INTERFACE_COMPILE_FEATURES` property of ``<target>``.  Repeated
+calls for the same ``<target>`` append items.
+
+The named ``<target>`` must have been created by a command such as
+:command:`add_executable` or :command:`add_library` and must not be
+an ``IMPORTED`` target.
+
+Arguments to ``target_compile_features`` may use "generator expressions"
+with the syntax ``$<...>``.
+See the :manual:`cmake-generator-expressions(7)` manual for available
+expressions.

Help/manual/cmake-commands.7.rst

@@ -91,6 +91,7 @@ These commands may be used freely in CMake projects.
    /command/source_group
    /command/string
    /command/target_compile_definitions
+   /command/target_compile_features
    /command/target_compile_options
    /command/target_include_directories
    /command/target_link_libraries

Help/manual/cmake-properties.7.rst

@@ -98,6 +98,7 @@ Properties on Targets
    /prop_tgt/COMPATIBLE_INTERFACE_STRING
    /prop_tgt/COMPILE_DEFINITIONS_CONFIG
    /prop_tgt/COMPILE_DEFINITIONS
+   /prop_tgt/COMPILE_FEATURES
    /prop_tgt/COMPILE_FLAGS
    /prop_tgt/COMPILE_OPTIONS
    /prop_tgt/COMPILE_PDB_NAME
@@ -106,6 +107,8 @@ Properties on Targets
    /prop_tgt/COMPILE_PDB_OUTPUT_DIRECTORY_CONFIG
    /prop_tgt/CONFIG_OUTPUT_NAME
    /prop_tgt/CONFIG_POSTFIX
+   /prop_tgt/CXX_STANDARD
+   /prop_tgt/CXX_EXTENSIONS
    /prop_tgt/DEBUG_POSTFIX
    /prop_tgt/DEFINE_SYMBOL
    /prop_tgt/EchoString
@@ -148,6 +151,7 @@ Properties on Targets
    /prop_tgt/INSTALL_RPATH_USE_LINK_PATH
    /prop_tgt/INTERFACE_AUTOUIC_OPTIONS
    /prop_tgt/INTERFACE_COMPILE_DEFINITIONS
+   /prop_tgt/INTERFACE_COMPILE_FEATURES
    /prop_tgt/INTERFACE_COMPILE_OPTIONS
    /prop_tgt/INTERFACE_INCLUDE_DIRECTORIES
    /prop_tgt/INTERFACE_LINK_LIBRARIES

Help/manual/cmake-variables.7.rst

@@ -257,6 +257,10 @@ Variables for Languages
    :maxdepth: 1
 
    /variable/CMAKE_COMPILER_IS_GNULANG
+   /variable/CMAKE_CXX_COMPILE_FEATURES
+   /variable/CMAKE_CXX_KNOWN_FEATURES
+   /variable/CMAKE_CXX_STANDARD
+   /variable/CMAKE_CXX_EXTENSIONS
    /variable/CMAKE_Fortran_MODDIR_DEFAULT
    /variable/CMAKE_Fortran_MODDIR_FLAG
    /variable/CMAKE_Fortran_MODOUT_FLAG

Help/prop_tgt/COMPILE_FEATURES.rst

@@ -0,0 +1,11 @@
+COMPILE_FEATURES
+----------------
+
+Compiler features enabled for this target.
+
+The list of features in this property are a subset of the features listed
+in the :variable:`CMAKE_CXX_COMPILE_FEATURES` variable.
+
+Contents of ``COMPILE_FEATURES`` may use "generator expressions" with the
+syntax ``$<...>``.  See the :manual:`cmake-generator-expressions(7)` manual for
+available expressions.

Help/prop_tgt/CXX_EXTENSIONS.rst

@@ -0,0 +1,8 @@
+CXX_EXTENSIONS
+--------------
+
+Boolean specifying whether compiler specific extensions are requested.
+
+This property specifies whether compiler specific extensions should be
+used.  For some compilers, this results in adding a flag such
+as ``-std=gnu++11`` instead of ``-std=c++11`` to the compile line.

Help/prop_tgt/CXX_STANDARD.rst

@@ -0,0 +1,14 @@
+CXX_STANDARD
+------------
+
+The C++ standard whose features are required to build this target.
+
+This property specifies the C++ standard whose features are required
+to build this target.  For some compilers, this results in adding a
+flag such as ``-std=c++11`` to the compile line.
+
+Supported values are ``98`` and ``11``.
+
+This property is initialized by the value of
+the :variable:`CMAKE_CXX_STANDARD` variable if it is set when a target
+is created.

Help/prop_tgt/INTERFACE_COMPILE_FEATURES.rst

@@ -0,0 +1,14 @@
+INTERFACE_COMPILE_FEATURES
+--------------------------
+
+List of public compile requirements for a library.
+
+Targets may populate this property to publish the compiler features
+required to compile against the headers for the target.  Consuming
+targets can add entries to their own :prop_tgt:`COMPILE_FEATURES`
+property such as ``$<TARGET_PROPERTY:foo,INTERFACE_COMPILE_FEATURES>``
+to require the features specified in the interface of ``foo``.
+
+Contents of ``INTERFACE_COMPILE_FEATURES`` may use "generator expressions"
+with the syntax ``$<...>``.  See the :manual:`cmake-generator-expressions(7)`
+manual for available expressions.

Help/release/dev/compile-language-features.rst

@@ -0,0 +1,18 @@
+target-language-features
+------------------------
+
+* New :prop_tgt:`CXX_STANDARD` and :prop_tgt:`CXX_EXTENSIONS` target
+  properties may specify values which CMake uses to compute required
+  compile options such as ``-std=c++11`` or ``-std=gnu++11``. The
+  :variable:`CMAKE_CXX_STANDARD` and :variable:`CMAKE_CXX_EXTENSIONS`
+  variables may be set to initialize the target properties.
+
+* New :prop_tgt:`COMPILE_FEATURES` target property may contain a list
+  of features required to compile a target.  CMake uses this
+  information to ensure that the compiler in use is capable of building
+  the target, and to add any necessary compile flags to support language
+  features.
+
+* New :command:`target_compile_features` command allows populating the
+  :prop_tgt:`COMPILE_FEATURES` target property, just like any other
+  build variable.

Help/variable/CMAKE_CXX_COMPILE_FEATURES.rst

@@ -0,0 +1,8 @@
+CMAKE_CXX_COMPILE_FEATURES
+--------------------------
+
+List of features known to the C++ compiler
+
+These features are known to be available for use with the C++ compiler. This
+list is a subset of the features listed in the :variable:`CMAKE_CXX_KNOWN_FEATURES`
+variable.

Help/variable/CMAKE_CXX_EXTENSIONS.rst

@@ -0,0 +1,8 @@
+CMAKE_CXX_EXTENSIONS
+--------------------
+
+Default value for ``CXX_EXTENSIONS`` property of targets.
+
+This variable is used to initialize the :prop_tgt:`CXX_EXTENSIONS`
+property on all targets.  See that target property for additional
+information.

Help/variable/CMAKE_CXX_KNOWN_FEATURES.rst

@@ -0,0 +1,18 @@
+CMAKE_CXX_KNOWN_FEATURES
+------------------------
+
+List of C++ features known to this version of CMake.
+
+The features listed in this variable may be known to be available to the
+C++ compiler.  If the feature is available with the C++ compiler, it will
+be listed in the :variable:`CMAKE_CXX_COMPILE_FEATURES` variable.
+
+The features listed here may be used with the :command:`target_compile_features`
+command.
+
+The features known to this version of CMake are:
+
+``cxx_auto_type``
+  Automatic type deduction, as defined in N1984_.
+
+  .. _N1984: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1984.pdf

Help/variable/CMAKE_CXX_STANDARD.rst

@@ -0,0 +1,8 @@
+CMAKE_CXX_STANDARD
+------------------
+
+Default value for ``CXX_STANDARD`` property of targets.
+
+This variable is used to initialize the :prop_tgt:`CXX_STANDARD`
+property on all targets.  See that target property for additional
+information.

Help/variable/CMAKE_DEBUG_TARGET_PROPERTIES.rst

@@ -7,7 +7,7 @@ This variable can be populated with a list of properties to generate
 debug output for when evaluating target properties.  Currently it can
 only be used when evaluating the :prop_tgt:`INCLUDE_DIRECTORIES`,
 :prop_tgt:`COMPILE_DEFINITIONS`, :prop_tgt:`COMPILE_OPTIONS`,
-:prop_tgt:`AUTOUIC_OPTIONS`, :prop_tgt:`SOURCES`,
+:prop_tgt:`AUTOUIC_OPTIONS`, :prop_tgt:`SOURCES`, :prop_tgt:`COMPILE_FEATURES`,
 :prop_tgt:`POSITION_INDEPENDENT_CODE` target properties and any other property
 listed in :prop_tgt:`COMPATIBLE_INTERFACE_STRING` and other ``COMPATIBLE_INTERFACE_``
 properties.  It outputs an origin for each entry in the target property.