Merge topic 'compile-features-for-language-standards'

9a8d758c Help: Document language standard meta-features
df252db1 Features: Test cycle diagnostic with language standard meta-feature
6d5fb0e0 Features: Test feature propagation with language standard meta-feature
a34b98a8 WCDH: Ignore language standard meta-features
b0996a3f Features: Add meta-features requesting awareness of a particular standard
8b6cc251 Features: Centralize per-compiler recording macros
2d23f7b2 Features: Do not record features on MSVC < 2010

Help/manual/cmake-compile-features.7.rst

@@ -84,6 +84,33 @@ Feature requirements are evaluated transitively by consuming the link
 implementation.  See :manual:`cmake-buildsystem(7)` for more on
 transitive behavior of build properties and usage requirements.
 
+Requiring Language Standards
+----------------------------
+
+In projects that use a large number of commonly available features from
+a particular language standard (e.g. C++ 11) one may specify a
+meta-feature (e.g. ``cxx_std_11``) that requires use of a compiler mode
+aware of that standard.  This is simpler than specifying all the
+features individually, but does not guarantee the existence of any
+particular feature.  Diagnosis of use of unsupported features will be
+delayed until compile time.
+
+For example, if C++ 11 features are used extensively in a project's
+header files, then clients must use a compiler mode aware of C++ 11
+or above.  This can be requested with the code:
+
+.. code-block:: cmake
+
+  target_compile_features(mylib PUBLIC cxx_std_11)
+
+In this example, CMake will ensure the compiler is invoked in a mode
+that is aware of C++ 11 (or above), adding flags such as
+``-std=gnu++11`` if necessary.  This applies to sources within ``mylib``
+as well as any dependents (that may include headers from ``mylib``).
+
+Availability of Compiler Extensions
+-----------------------------------
+
 Because the :prop_tgt:`CXX_EXTENSIONS` target property is ``ON`` by default,
 CMake uses extended variants of language dialects by default, such as
 ``-std=gnu++11`` instead of ``-std=c++11``.  That target property may be

Help/prop_gbl/CMAKE_CXX_KNOWN_FEATURES.rst

@@ -14,6 +14,15 @@ compile features and a list of supported compilers.
 
 The features known to this version of CMake are:
 
+``cxx_std_98``
+  Compiler mode is aware of C++ 98.
+
+``cxx_std_11``
+  Compiler mode is aware of C++ 11.
+
+``cxx_std_14``
+  Compiler mode is aware of C++ 14.
+
 ``cxx_aggregate_default_initializers``
   Aggregate default initializers, as defined in N3605_.
 

Help/prop_gbl/CMAKE_C_KNOWN_FEATURES.rst

@@ -13,6 +13,15 @@ compile features and a list of supported compilers.
 
 The features known to this version of CMake are:
 
+``c_std_90``
+  Compiler mode is aware of C 90.
+
+``c_std_99``
+  Compiler mode is aware of C 99.
+
+``c_std_11``
+  Compiler mode is aware of C 11.
+
 ``c_function_prototypes``
   Function prototypes, as defined in ``ISO/IEC 9899:1990``.
 

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

@@ -0,0 +1,7 @@
+compile-features-for-language-standards
+---------------------------------------
+
+* The :manual:`Compile Features <cmake-compile-features(7)>` functionality
+  now offers meta-features that request compiler modes for specific language
+  standard levels.  See :prop_gbl:`CMAKE_C_KNOWN_FEATURES` and
+  :prop_gbl:`CMAKE_CXX_KNOWN_FEATURES`.

Modules/Compiler/AppleClang-C.cmake

@@ -25,18 +25,14 @@ if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.0)
 endif()
 
 macro(cmake_record_c_compile_features)
-  macro(_get_appleclang_features std_version list)
-    record_compiler_features(C "${std_version}" ${list})
-  endmacro()
-
   set(_result 0)
   if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.0)
-    _get_appleclang_features(${CMAKE_C11_STANDARD_COMPILE_OPTION} CMAKE_C11_COMPILE_FEATURES)
+    _record_compiler_features_c(11)
     if (_result EQUAL 0)
-      _get_appleclang_features(${CMAKE_C99_STANDARD_COMPILE_OPTION} CMAKE_C99_COMPILE_FEATURES)
+      _record_compiler_features_c(99)
     endif()
     if (_result EQUAL 0)
-      _get_appleclang_features(${CMAKE_C90_STANDARD_COMPILE_OPTION} CMAKE_C90_COMPILE_FEATURES)
+      _record_compiler_features_c(90)
     endif()
   endif()
 endmacro()

Modules/Compiler/AppleClang-CXX.cmake

@@ -36,21 +36,17 @@ endif()
 
 
 macro(cmake_record_cxx_compile_features)
-  macro(_get_appleclang_features std_version list)
-    record_compiler_features(CXX "${std_version}" ${list})
-  endmacro()
-
   set(_result 0)
   if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.0)
     set(_result 0)
     if(CMAKE_CXX14_STANDARD_COMPILE_OPTION)
-      _get_appleclang_features(${CMAKE_CXX14_STANDARD_COMPILE_OPTION} CMAKE_CXX14_COMPILE_FEATURES)
+      _record_compiler_features_cxx(14)
     endif()
     if (_result EQUAL 0)
-      _get_appleclang_features(${CMAKE_CXX11_STANDARD_COMPILE_OPTION} CMAKE_CXX11_COMPILE_FEATURES)
+      _record_compiler_features_cxx(11)
     endif()
     if (_result EQUAL 0)
-      _get_appleclang_features(${CMAKE_CXX98_STANDARD_COMPILE_OPTION} CMAKE_CXX98_COMPILE_FEATURES)
+      _record_compiler_features_cxx(98)
     endif()
   endif()
 endmacro()

Modules/Compiler/Clang-C.cmake

@@ -34,18 +34,14 @@ if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 3.4)
 endif()
 
 macro(cmake_record_c_compile_features)
-  macro(_get_clang_features std_version list)
-    record_compiler_features(C "${std_version}" ${list})
-  endmacro()
-
   set(_result 0)
   if (UNIX AND NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 3.4)
-    _get_clang_features(${CMAKE_C11_STANDARD_COMPILE_OPTION} CMAKE_C11_COMPILE_FEATURES)
+    _record_compiler_features_c(11)
     if (_result EQUAL 0)
-      _get_clang_features(${CMAKE_C99_STANDARD_COMPILE_OPTION} CMAKE_C99_COMPILE_FEATURES)
+      _record_compiler_features_c(99)
     endif()
     if (_result EQUAL 0)
-      _get_clang_features(${CMAKE_C90_STANDARD_COMPILE_OPTION} CMAKE_C90_COMPILE_FEATURES)
+      _record_compiler_features_c(90)
     endif()
   endif()
 endmacro()

Modules/Compiler/Clang-CXX.cmake

@@ -44,18 +44,14 @@ if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.4)
 endif()
 
 macro(cmake_record_cxx_compile_features)
-  macro(_get_clang_features std_version list)
-    record_compiler_features(CXX "${std_version}" ${list})
-  endmacro()
-
   set(_result 0)
   if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.4)
-    _get_clang_features(${CMAKE_CXX14_STANDARD_COMPILE_OPTION} CMAKE_CXX14_COMPILE_FEATURES)
+    _record_compiler_features_cxx(14)
     if (_result EQUAL 0)
-      _get_clang_features(${CMAKE_CXX11_STANDARD_COMPILE_OPTION} CMAKE_CXX11_COMPILE_FEATURES)
+      _record_compiler_features_cxx(11)
     endif()
     if (_result EQUAL 0)
-      _get_clang_features(${CMAKE_CXX98_STANDARD_COMPILE_OPTION} CMAKE_CXX98_COMPILE_FEATURES)
+      _record_compiler_features_cxx(98)
     endif()
   endif()
 endmacro()

Modules/Compiler/GNU-C.cmake

@@ -40,20 +40,16 @@ endif()
 
 
 macro(cmake_record_c_compile_features)
-  macro(_get_gcc_features std_version list)
-    record_compiler_features(C "${std_version}" ${list})
-  endmacro()
-
   set(_result 0)
   if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.6)
-    _get_gcc_features(${CMAKE_C11_STANDARD_COMPILE_OPTION} CMAKE_C11_COMPILE_FEATURES)
+    _record_compiler_features_c(11)
   endif()
   if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.4)
     if (_result EQUAL 0)
-      _get_gcc_features(${CMAKE_C99_STANDARD_COMPILE_OPTION} CMAKE_C99_COMPILE_FEATURES)
+      _record_compiler_features_c(99)
     endif()
     if (_result EQUAL 0)
-      _get_gcc_features(${CMAKE_C90_STANDARD_COMPILE_OPTION} CMAKE_C90_COMPILE_FEATURES)
+      _record_compiler_features_c(90)
     endif()
   endif()
 endmacro()

Modules/Compiler/GNU-CXX.cmake

@@ -47,20 +47,16 @@ if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.4)
 endif()
 
 macro(cmake_record_cxx_compile_features)
-  macro(_get_gcc_features std_version list)
-    record_compiler_features(CXX "${std_version}" ${list})
-  endmacro()
-
   set(_result 0)
   if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.8)
-    _get_gcc_features(${CMAKE_CXX14_STANDARD_COMPILE_OPTION} CMAKE_CXX14_COMPILE_FEATURES)
+    _record_compiler_features_cxx(14)
   endif()
   if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.4)
     if (_result EQUAL 0)
-      _get_gcc_features(${CMAKE_CXX11_STANDARD_COMPILE_OPTION} CMAKE_CXX11_COMPILE_FEATURES)
+      _record_compiler_features_cxx(11)
     endif()
     if (_result EQUAL 0)
-      _get_gcc_features(${CMAKE_CXX98_STANDARD_COMPILE_OPTION} CMAKE_CXX98_COMPILE_FEATURES)
+      _record_compiler_features_cxx(98)
     endif()
   endif()
 endmacro()

Modules/Compiler/Intel-C.cmake

@@ -47,20 +47,16 @@ unset(_std)
 unset(_ext)
 
 macro(cmake_record_c_compile_features)
-  macro(_get_intel_c_features std_version list)
-    record_compiler_features(C "${std_version}" ${list})
-  endmacro()
-
   set(_result 0)
   if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 12.1)
     if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 15.0.0)
-      _get_intel_c_features(${CMAKE_C11_STANDARD_COMPILE_OPTION} CMAKE_C11_COMPILE_FEATURES)
+      _record_compiler_features_C(11)
     endif()
     if (_result EQUAL 0)
-      _get_intel_c_features(${CMAKE_C99_STANDARD_COMPILE_OPTION} CMAKE_C99_COMPILE_FEATURES)
+      _record_compiler_features_C(99)
     endif()
     if (_result EQUAL 0)
-      _get_intel_c_features(${CMAKE_C90_STANDARD_COMPILE_OPTION} CMAKE_C90_COMPILE_FEATURES)
+      _record_compiler_features_C(90)
     endif()
   endif()
 endmacro()

Modules/Compiler/Intel-CXX.cmake

@@ -60,20 +60,16 @@ unset(_std)
 unset(_ext)
 
 macro(cmake_record_cxx_compile_features)
-  macro(_get_intel_features std_version list)
-    record_compiler_features(CXX "${std_version}" ${list})
-  endmacro()
-
   set(_result 0)
   if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 12.1)
     if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 15.0)
-      _get_intel_features("${CMAKE_CXX14_STANDARD_COMPILE_OPTION}" CMAKE_CXX14_COMPILE_FEATURES)
+      _record_compiler_features_cxx(14)
     endif()
     if (_result EQUAL 0)
-      _get_intel_features("${CMAKE_CXX11_STANDARD_COMPILE_OPTION}" CMAKE_CXX11_COMPILE_FEATURES)
+      _record_compiler_features_cxx(11)
     endif()
     if (_result EQUAL 0)
-      _get_intel_features("${CMAKE_CXX98_STANDARD_COMPILE_OPTION}" CMAKE_CXX98_COMPILE_FEATURES)
+      _record_compiler_features_cxx(98)
     endif()
   endif()
 endmacro()

Modules/Compiler/MSVC-CXX.cmake

@@ -5,5 +5,12 @@ if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 16.0)
 endif()
 
 macro(cmake_record_cxx_compile_features)
-  record_compiler_features(CXX "" CMAKE_CXX_COMPILE_FEATURES)
+  if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 16.0)
+    list(APPEND CMAKE_CXX_COMPILE_FEATURES
+      cxx_std_98
+      cxx_std_11
+      cxx_std_14
+      )
+    _record_compiler_features(CXX "" CMAKE_CXX_COMPILE_FEATURES)
+  endif()
 endmacro()

Modules/Compiler/SunPro-CXX.cmake

@@ -32,6 +32,8 @@ set(CMAKE_CXX_CREATE_STATIC_LIBRARY
   "<CMAKE_RANLIB> <TARGET> ")
 
 if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.13)
+  set(CMAKE_CXX98_STANDARD_COMPILE_OPTION "")
+  set(CMAKE_CXX98_EXTENSION_COMPILE_OPTION "")
   set(CMAKE_CXX11_STANDARD_COMPILE_OPTION "-std=c++11")
   set(CMAKE_CXX11_EXTENSION_COMPILE_OPTION "-std=c++11")
 endif()
@@ -49,15 +51,11 @@ if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.13)
 endif()
 
 macro(cmake_record_cxx_compile_features)
-  macro(_get_solaris_studio_features std_version list)
-    record_compiler_features(CXX "${std_version}" ${list})
-  endmacro()
-
   set(_result 0)
   if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.13)
-    _get_solaris_studio_features(${CMAKE_CXX11_STANDARD_COMPILE_OPTION} CMAKE_CXX11_COMPILE_FEATURES)
+    _record_compiler_features_cxx(11)
     if (_result EQUAL 0)
-      _get_solaris_studio_features("" CMAKE_CXX98_COMPILE_FEATURES)
+      _record_compiler_features_cxx(98)
     endif()
   endif()
 endmacro()

Modules/Internal/FeatureTesting.cmake

@@ -1,5 +1,5 @@
 
-macro(record_compiler_features lang compile_flags feature_list)
+macro(_record_compiler_features lang compile_flags feature_list)
   include("${CMAKE_ROOT}/Modules/Compiler/${CMAKE_${lang}_COMPILER_ID}-${lang}-FeatureTests.cmake" OPTIONAL)
 
   string(TOLOWER ${lang} lang_lc)
@@ -58,3 +58,13 @@ macro(record_compiler_features lang compile_flags feature_list)
       "Detecting ${lang} [${compile_flags}] compiler features failed to compile with the following output:\n${_output}\n${_copy_error}\n\n")
   endif()
 endmacro()
+
+macro(_record_compiler_features_c std)
+  list(APPEND CMAKE_C${std}_COMPILE_FEATURES c_std_${std})
+  _record_compiler_features(C "${CMAKE_C${std}_STANDARD_COMPILE_OPTION}" CMAKE_C${std}_COMPILE_FEATURES)
+endmacro()
+
+macro(_record_compiler_features_cxx std)
+  list(APPEND CMAKE_CXX${std}_COMPILE_FEATURES cxx_std_${std})
+  _record_compiler_features(CXX "${CMAKE_CXX${std}_STANDARD_COMPILE_OPTION}" CMAKE_CXX${std}_COMPILE_FEATURES)
+endmacro()

Modules/WriteCompilerDetectionHeader.cmake

@@ -76,6 +76,7 @@
 # Available features in this version of CMake are listed in the
 # :prop_gbl:`CMAKE_C_KNOWN_FEATURES` and
 # :prop_gbl:`CMAKE_CXX_KNOWN_FEATURES` global properties.
+# The ``{c,cxx}_std_*`` meta-features are ignored if requested.
 #
 # See the :manual:`cmake-compile-features(7)` manual for information on
 # compile features.
@@ -358,7 +359,11 @@ function(write_compiler_detection_header
   endif()
 
   foreach(feature ${_WCD_FEATURES})
-    if (feature MATCHES "^cxx_")
+    if (feature MATCHES "^c_std_")
+      # ignored
+    elseif (feature MATCHES "^cxx_std_")
+      # ignored
+    elseif (feature MATCHES "^cxx_")
       list(APPEND _langs CXX)
       list(APPEND CXX_features ${feature})
     elseif (feature MATCHES "^c_")

Source/cmake.h

@@ -535,12 +535,18 @@ private:
   }
 
 #define FOR_EACH_C_FEATURE(F)                                                 \
+  F(c_std_90)                                                                 \
+  F(c_std_99)                                                                 \
+  F(c_std_11)                                                                 \
   F(c_function_prototypes)                                                    \
   F(c_restrict)                                                               \
   F(c_static_assert)                                                          \
   F(c_variadic_macros)
 
 #define FOR_EACH_CXX_FEATURE(F)                                               \
+  F(cxx_std_98)                                                               \
+  F(cxx_std_11)                                                               \
+  F(cxx_std_14)                                                               \
   F(cxx_aggregate_default_initializers)                                       \
   F(cxx_alias_templates)                                                      \
   F(cxx_alignas)                                                              \

Tests/CompileFeatures/CMakeLists.txt

@@ -23,10 +23,12 @@ macro(run_test feature lang)
 endmacro()
 
 get_property(c_features GLOBAL PROPERTY CMAKE_C_KNOWN_FEATURES)
+list(REMOVE_ITEM c_features c_std_90 c_std_99 c_std_11)
 foreach(feature ${c_features})
   run_test(${feature} C)
 endforeach()
 get_property(cxx_features GLOBAL PROPERTY CMAKE_CXX_KNOWN_FEATURES)
+list(REMOVE_ITEM cxx_features cxx_std_98 cxx_std_11 cxx_std_14)
 foreach(feature ${cxx_features})
   run_test(${feature} CXX)
 endforeach()
@@ -396,7 +398,7 @@ if (CMAKE_CXX_COMPILE_FEATURES)
   )
 
   add_executable(CompileFeaturesGenex2 genex_test.cpp)
-  target_compile_features(CompileFeaturesGenex2 PRIVATE cxx_static_assert)
+  target_compile_features(CompileFeaturesGenex2 PRIVATE cxx_std_11)
   target_compile_definitions(CompileFeaturesGenex2 PRIVATE
     HAVE_OVERRIDE_CONTROL=$<COMPILE_FEATURES:cxx_final,cxx_override>
     HAVE_AUTO_TYPE=$<COMPILE_FEATURES:cxx_auto_type>
@@ -405,10 +407,10 @@ if (CMAKE_CXX_COMPILE_FEATURES)
     HAVE_INHERITING_CONSTRUCTORS_AND_FINAL=$<COMPILE_FEATURES:cxx_inheriting_constructors,cxx_final>
   )
 
-  add_library(static_assert_iface INTERFACE)
-  target_compile_features(static_assert_iface INTERFACE cxx_static_assert)
+  add_library(std_11_iface INTERFACE)
+  target_compile_features(std_11_iface INTERFACE cxx_std_11)
   add_executable(CompileFeaturesGenex3 genex_test.cpp)
-  target_link_libraries(CompileFeaturesGenex3 PRIVATE static_assert_iface)
+  target_link_libraries(CompileFeaturesGenex3 PRIVATE std_11_iface)
   target_compile_definitions(CompileFeaturesGenex3 PRIVATE
     HAVE_OVERRIDE_CONTROL=$<COMPILE_FEATURES:cxx_final,cxx_override>
     HAVE_AUTO_TYPE=$<COMPILE_FEATURES:cxx_auto_type>

Tests/RunCMake/CompileFeatures/LinkImplementationFeatureCycle.cmake

@@ -3,13 +3,13 @@ add_library(empty1 empty.cpp)
 
 add_library(empty2 INTERFACE)
 add_library(empty3 INTERFACE)
-target_compile_features(empty3 INTERFACE cxx_static_assert)
+target_compile_features(empty3 INTERFACE cxx_std_11)
 
 target_link_libraries(empty1
   # When starting, $<COMPILE_FEATURES:cxx_auto_type> is '0', so 'freeze' the
   # CXX_STANDARD at 98 during computation.
   $<$<COMPILE_FEATURES:cxx_auto_type>:empty2>
-  # This would add cxx_static_assert, but that would require CXX_STANDARD = 11,
+  # This would add cxx_std_11, but that would require CXX_STANDARD = 11,
   # which is not allowed after freeze.  Report an error.
   empty3
 )

Tests/RunCMake/CompileFeatures/LinkImplementationFeatureCycleSolved.cmake

@@ -3,7 +3,7 @@ add_library(empty1 empty.cpp)
 
 add_library(empty2 INTERFACE)
 add_library(empty3 INTERFACE)
-target_compile_features(empty3 INTERFACE cxx_static_assert)
+target_compile_features(empty3 INTERFACE cxx_std_11)
 
 target_link_libraries(empty1
   $<$<COMPILE_FEATURES:cxx_nullptr>:empty2>