Merge topic 'features-from-default-standard'

c7213ca870 Features: Do not use a lower-than-default standard for requested features

Acked-by: Kitware Robot <[email protected]>
Merge-request: !3023

Source/cmMakefile.cxx

@@ -4725,6 +4725,13 @@ bool cmMakefile::AddRequiredTargetCxxFeature(cmTarget* target,
                                needCxx17, needCxx20);
 
   const char* existingCxxStandard = target->GetProperty("CXX_STANDARD");
+  if (existingCxxStandard == nullptr) {
+    const char* defaultCxxStandard =
+      this->GetDefinition("CMAKE_CXX_STANDARD_DEFAULT");
+    if (defaultCxxStandard && *defaultCxxStandard) {
+      existingCxxStandard = defaultCxxStandard;
+    }
+  }
   const char* const* existingCxxLevel = nullptr;
   if (existingCxxStandard) {
     existingCxxLevel =
@@ -4827,6 +4834,13 @@ bool cmMakefile::AddRequiredTargetCFeature(cmTarget* target,
   this->CheckNeededCLanguage(feature, needC90, needC99, needC11);
 
   const char* existingCStandard = target->GetProperty("C_STANDARD");
+  if (existingCStandard == nullptr) {
+    const char* defaultCStandard =
+      this->GetDefinition("CMAKE_C_STANDARD_DEFAULT");
+    if (defaultCStandard && *defaultCStandard) {
+      existingCStandard = defaultCStandard;
+    }
+  }
   if (existingCStandard) {
     if (std::find_if(cm::cbegin(C_STANDARDS), cm::cend(C_STANDARDS),
                      cmStrCmp(existingCStandard)) == cm::cend(C_STANDARDS)) {

Tests/CompileFeatures/CMakeLists.txt

@@ -338,11 +338,11 @@ else()
 
   add_executable(CompileFeaturesGenex2 genex_test.cpp)
   target_compile_features(CompileFeaturesGenex2 PRIVATE cxx_std_11)
-  target_compile_definitions(CompileFeaturesGenex2 PRIVATE ${genex_test_defs})
+  target_compile_definitions(CompileFeaturesGenex2 PRIVATE ${genex_test_defs} ALLOW_LATER_STANDARDS=1)
 
   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 std_11_iface)
-  target_compile_definitions(CompileFeaturesGenex3 PRIVATE ${genex_test_defs})
+  target_compile_definitions(CompileFeaturesGenex3 PRIVATE ${genex_test_defs} ALLOW_LATER_STANDARDS=1)
 endif()

Tests/CompileFeatures/genex_test.cpp

@@ -15,10 +15,10 @@
 #  if !HAVE_CXX_STD_11
 #    error HAVE_CXX_STD_11 is false with CXX_STANDARD == 11
 #  endif
-#  if HAVE_CXX_STD_14
+#  if HAVE_CXX_STD_14 && !defined(ALLOW_LATER_STANDARDS)
 #    error HAVE_CXX_STD_14 is true with CXX_STANDARD == 11
 #  endif
-#  if HAVE_CXX_STD_17
+#  if HAVE_CXX_STD_17 && !defined(ALLOW_LATER_STANDARDS)
 #    error HAVE_CXX_STD_17 is true with CXX_STANDARD == 11
 #  endif
 #endif