Merge topic 'default_extensions'

4a0485be7f cmStandardLevelResolver: Avoid unnecessary flags, fix unset level logic
29e2b85171 Tests: Simplify RunCMake.CompileFeatures introspection
fc3a1cbdd8 CompilerID: Compiler extensions default detection
2adfd95d79 CompilerID: Rename language_dialect to language_standard
00055d7779 Help: Document CMAKE_<LANG>_STANDARD_DEFAULT
a65bee4cfc Help: Document HIP standard/extensions properties and variables
a40ff1bb5a Help: Make language standard/extensions variable pages less wordy
3feff8379b Help: Generic language standard and extension variables documentation

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !6177

13 files changed, 225 insertions, 61 deletions

diff --git a/Tests/RunCMake/CMakeLists.txt b/Tests/RunCMake/CMakeLists.txt
index eb2c2d9..af6cbb5 100644
--- a/Tests/RunCMake/CMakeLists.txt
+++ b/Tests/RunCMake/CMakeLists.txt
@@ -310,7 +310,7 @@ add_RunCMake_test(TargetProperties)
 add_RunCMake_test(ToolchainFile)
 add_RunCMake_test(find_dependency)
 add_RunCMake_test(CompileDefinitions)
-add_RunCMake_test(CompileFeatures)
+add_RunCMake_test(CompileFeatures -DCMake_NO_C_STANDARD=${CMake_NO_C_STANDARD} -DCMake_NO_CXX_STANDARD=${CMake_NO_CXX_STANDARD})
 add_RunCMake_test(Policy)
 add_RunCMake_test(PolicyScope)
 add_RunCMake_test(WriteBasicConfigVersionFile)
diff --git a/Tests/RunCMake/CompileFeatures/CMP0128WarnMatch-stderr.txt b/Tests/RunCMake/CompileFeatures/CMP0128WarnMatch-stderr.txt
new file mode 100644
index 0000000..320c2ba
--- /dev/null
+++ b/Tests/RunCMake/CompileFeatures/CMP0128WarnMatch-stderr.txt
@@ -0,0 +1,8 @@
+CMake Warning \(dev\) in CMakeLists\.txt:
+  Policy CMP0128 is not set: Selection of language standard and extension
+  flags improved\.  Run "cmake --help-policy CMP0128" for policy details\.  Use
+  the cmake_policy command to set the policy and suppress this warning\.
+
+  For compatibility with older versions of CMake, unnecessary flags for
+  language standard or compiler extensions may be added.
+This warning is for project developers\.  Use -Wno-dev to suppress it\.
diff --git a/Tests/RunCMake/CompileFeatures/CMP0128WarnMatch.cmake b/Tests/RunCMake/CompileFeatures/CMP0128WarnMatch.cmake
new file mode 100644
index 0000000..0a5606a
--- /dev/null
+++ b/Tests/RunCMake/CompileFeatures/CMP0128WarnMatch.cmake
@@ -0,0 +1,7 @@
+enable_language(@lang@)
+cmake_policy(SET CMP0128 OLD)
+set(CMAKE_POLICY_WARNING_CMP0128 ON)
+
+set(CMAKE_@lang@_EXTENSIONS @extensions_default@)
+set(CMAKE_@lang@_STANDARD @standard_default@)
+add_library(foo "@RunCMake_SOURCE_DIR@/empty.@ext@")
diff --git a/Tests/RunCMake/CompileFeatures/CMP0128WarnUnset-stderr.txt b/Tests/RunCMake/CompileFeatures/CMP0128WarnUnset-stderr.txt
new file mode 100644
index 0000000..068cba9
--- /dev/null
+++ b/Tests/RunCMake/CompileFeatures/CMP0128WarnUnset-stderr.txt
@@ -0,0 +1,8 @@
+CMake Warning \(dev\) in CMakeLists\.txt:
+  Policy CMP0128 is not set: Selection of language standard and extension
+  flags improved\.  Run "cmake --help-policy CMP0128" for policy details\.  Use
+  the cmake_policy command to set the policy and suppress this warning\.
+
+  For compatibility with older versions of CMake, compiler extensions won't
+  be @opposite@\.
+This warning is for project developers\.  Use -Wno-dev to suppress it\.
diff --git a/Tests/RunCMake/CompileFeatures/CMP0128WarnUnset.cmake b/Tests/RunCMake/CompileFeatures/CMP0128WarnUnset.cmake
new file mode 100644
index 0000000..cd7af2c
--- /dev/null
+++ b/Tests/RunCMake/CompileFeatures/CMP0128WarnUnset.cmake
@@ -0,0 +1,6 @@
+enable_language(@lang@)
+cmake_policy(SET CMP0128 OLD)
+set(CMAKE_POLICY_WARNING_CMP0128 ON)
+
+set(CMAKE_@lang@_EXTENSIONS @extensions_opposite@)
+add_library(foo "@RunCMake_SOURCE_DIR@/empty.@ext@")
diff --git a/Tests/RunCMake/CompileFeatures/NoUnnecessaryFlag-build-check.cmake b/Tests/RunCMake/CompileFeatures/NoUnnecessaryFlag-build-check.cmake
new file mode 100644
index 0000000..4f767fa
--- /dev/null
+++ b/Tests/RunCMake/CompileFeatures/NoUnnecessaryFlag-build-check.cmake
@@ -0,0 +1,8 @@
+foreach(flag @flags@)
+  string(FIND "${actual_stdout}" "${flag}" position)
+
+  if(NOT position EQUAL -1)
+    set(RunCMake_TEST_FAILED "\"${flag}\" compile flag found.")
+    break()
+  endif()
+endforeach()
diff --git a/Tests/RunCMake/CompileFeatures/NoUnnecessaryFlag.cmake b/Tests/RunCMake/CompileFeatures/NoUnnecessaryFlag.cmake
new file mode 100644
index 0000000..8ef3a72
--- /dev/null
+++ b/Tests/RunCMake/CompileFeatures/NoUnnecessaryFlag.cmake
@@ -0,0 +1,9 @@
+enable_language(@lang@)
+
+# Make sure the compile command is not hidden.
+string(REPLACE "${CMAKE_START_TEMP_FILE}" "" CMAKE_@lang@_COMPILE_OBJECT "${CMAKE_@lang@_COMPILE_OBJECT}")
+string(REPLACE "${CMAKE_END_TEMP_FILE}" "" CMAKE_@lang@_COMPILE_OBJECT "${CMAKE_@lang@_COMPILE_OBJECT}")
+
+set(CMAKE_@lang@_EXTENSIONS @extensions_default@)
+set(CMAKE_@lang@_STANDARD @standard_default@)
+add_library(foo "@RunCMake_SOURCE_DIR@/empty.@ext@")
diff --git a/Tests/RunCMake/CompileFeatures/RunCMakeTest.cmake b/Tests/RunCMake/CompileFeatures/RunCMakeTest.cmake
index 5a70da2..3bfd211 100644
--- a/Tests/RunCMake/CompileFeatures/RunCMakeTest.cmake
+++ b/Tests/RunCMake/CompileFeatures/RunCMakeTest.cmake
@@ -9,17 +9,8 @@ run_cmake(NotAFeature_OriginDebugGenex)
 run_cmake(NotAFeature_OriginDebugTransitive)
 run_cmake(NotAFeature_OriginDebugCommand)
 
-run_cmake(generate_feature_list)
-file(READ
-  "${RunCMake_BINARY_DIR}/generate_feature_list-build/c_features.txt"
-  C_FEATURES
-)
-file(READ
-  "${RunCMake_BINARY_DIR}/generate_feature_list-build/cxx_features.txt"
-  CXX_FEATURES
-)
-include("${RunCMake_BINARY_DIR}/generate_feature_list-build/c_standard_default.cmake")
-include("${RunCMake_BINARY_DIR}/generate_feature_list-build/cxx_standard_default.cmake")
+run_cmake(compiler_introspection)
+include("${RunCMake_BINARY_DIR}/compiler_introspection-build/info.cmake")
 
 if (NOT C_FEATURES)
   run_cmake(NoSupportedCFeatures)
@@ -43,21 +34,133 @@ elseif (cxx_std_98 IN_LIST CXX_FEATURES AND cxx_std_11 IN_LIST CXX_FEATURES)
   unset(RunCMake_TEST_OPTIONS)
 endif()
 
+configure_file("${RunCMake_SOURCE_DIR}/CMakeLists.txt" "${RunCMake_BINARY_DIR}/CMakeLists.txt" COPYONLY)
+
+macro(test_build)
+  set(test ${name}-${lang})
+
+  configure_file("${RunCMake_SOURCE_DIR}/${name}.cmake" "${RunCMake_BINARY_DIR}/${test}.cmake" @ONLY)
+  if(EXISTS "${RunCMake_SOURCE_DIR}/${name}-build-check.cmake")
+    configure_file("${RunCMake_SOURCE_DIR}/${name}-build-check.cmake" "${RunCMake_BINARY_DIR}/${test}-build-check.cmake" @ONLY)
+  endif()
+  if(EXISTS "${RunCMake_SOURCE_DIR}/${name}-stderr.txt")
+    configure_file("${RunCMake_SOURCE_DIR}/${name}-stderr.txt" "${RunCMake_BINARY_DIR}/${test}-stderr.txt" @ONLY)
+  endif()
+
+  set(RunCMake_SOURCE_DIR "${RunCMake_BINARY_DIR}")
+  set(RunCMake_TEST_BINARY_DIR "${RunCMake_BINARY_DIR}/${test}-build")
+  run_cmake(${test})
+  set(RunCMake_TEST_NO_CLEAN 1)
+  run_cmake_command(${test}-build ${CMAKE_COMMAND} --build . ${ARGN})
+endmacro()
+
+# Mangle flags such as they're in verbose build output.
+macro(mangle_flags variable)
+  set(result "${${variable}}")
+
+  if(RunCMake_GENERATOR MATCHES "Visual Studio" AND MSVC_TOOLSET_VERSION GREATER_EQUAL 141)
+    string(REPLACE "-" "/" result "${result}")
+  elseif(RunCMake_GENERATOR STREQUAL "Xcode" AND CMAKE_XCODE_BUILD_SYSTEM GREATER_EQUAL 12)
+    string(REPLACE "=" [[\\=]] result "${result}")
+  endif()
+
+  string(REPLACE ";" " " result "${result}")
+  list(APPEND flags "${result}")
+endmacro()
+
+function(test_unset_standard)
+  if(extensions_opposite)
+    set(flag_ext "_EXT")
+  endif()
+
+  set(flag "${${lang}${${lang}_STANDARD_DEFAULT}${flag_ext}_FLAG}")
+
+  if(NOT flag)
+    return()
+  endif()
+
+  mangle_flags(flag)
+
+  set(name UnsetStandard)
+  set(RunCMake_TEST_OPTIONS -DCMAKE_POLICY_DEFAULT_CMP0128=NEW)
+  test_build(--verbose)
+endfunction()
+
+function(test_no_unnecessary_flag)
+  set(standard_flag "${${lang}${${lang}_STANDARD_DEFAULT}_FLAG}")
+  set(extension_flag "${${lang}${${lang}_STANDARD_DEFAULT}_EXT_FLAG}")
+
+  if(NOT standard_flag AND NOT extension_flag)
+    return()
+  endif()
+
+  mangle_flags(standard_flag)
+  mangle_flags(extension_flag)
+
+  set(name NoUnnecessaryFlag)
+  set(RunCMake_TEST_OPTIONS -DCMAKE_POLICY_DEFAULT_CMP0128=NEW)
+  test_build(--verbose)
+endfunction()
+
+function(test_cmp0128_warn_match)
+  set(name CMP0128WarnMatch)
+  test_build()
+endfunction()
+
+function(test_cmp0128_warn_unset)
+  # For compilers that had CMAKE_<LANG>_EXTENSION_COMPILE_OPTION (only IAR)
+  # there is no behavioural change and thus no warning.
+  if(NOT "${${lang}_EXT_FLAG}" STREQUAL "")
+    return()
+  endif()
+
+  if(extensions_opposite)
+    set(opposite "enabled")
+  else()
+    set(opposite "disabled")
+  endif()
+
+  set(name CMP0128WarnUnset)
+  test_build()
+endfunction()
+
+function(test_lang lang ext)
+  if(CMake_NO_${lang}_STANDARD)
+    return()
+  endif()
+
+  set(extensions_default "${${lang}_EXTENSIONS_DEFAULT}")
+  set(standard_default "${${lang}_STANDARD_DEFAULT}")
+
+  if(extensions_default)
+    set(extensions_opposite OFF)
+  else()
+    set(extensions_opposite ON)
+  endif()
+
+  test_unset_standard()
+  test_no_unnecessary_flag()
+  test_cmp0128_warn_match()
+  test_cmp0128_warn_unset()
+endfunction()
+
+if(C_STANDARD_DEFAULT)
+  test_lang(C c)
+endif()
+
 if(CXX_STANDARD_DEFAULT)
   run_cmake(NotAStandard)
 
   foreach(standard 98 11)
-    file(READ
-      "${RunCMake_BINARY_DIR}/generate_feature_list-build/cxx${standard}_flag.txt"
-      CXX${standard}_FLAG
-    )
     if (CXX${standard}_FLAG STREQUAL NOTFOUND)
       run_cmake(RequireCXX${standard})
       run_cmake(RequireCXX${standard}Variable)
     endif()
-    if (CXX${standard}EXT_FLAG STREQUAL NOTFOUND)
+    if (CXX${standard}_EXT_FLAG STREQUAL NOTFOUND)
       run_cmake(RequireCXX${standard}Ext)
       run_cmake(RequireCXX${standard}ExtVariable)
     endif()
   endforeach()
+
+  test_lang(CXX cpp)
 endif()
diff --git a/Tests/RunCMake/CompileFeatures/UnsetStandard-build-check.cmake b/Tests/RunCMake/CompileFeatures/UnsetStandard-build-check.cmake
new file mode 100644
index 0000000..abe293c
--- /dev/null
+++ b/Tests/RunCMake/CompileFeatures/UnsetStandard-build-check.cmake
@@ -0,0 +1,12 @@
+foreach(flag @flags@)
+  string(FIND "${actual_stdout}" "${flag}" position)
+
+  if(NOT position EQUAL -1)
+    set(found TRUE)
+    break()
+  endif()
+endforeach()
+
+if(NOT found)
+  set(RunCMake_TEST_FAILED "No compile flags from \"@flags@\" found for CMAKE_@lang@_EXTENSIONS=@extensions_opposite@.")
+endif()
diff --git a/Tests/RunCMake/CompileFeatures/UnsetStandard.cmake b/Tests/RunCMake/CompileFeatures/UnsetStandard.cmake
new file mode 100644
index 0000000..99bb3f0
--- /dev/null
+++ b/Tests/RunCMake/CompileFeatures/UnsetStandard.cmake
@@ -0,0 +1,8 @@
+enable_language(@lang@)
+
+# Make sure the compile command is not hidden.
+string(REPLACE "${CMAKE_START_TEMP_FILE}" "" CMAKE_@lang@_COMPILE_OBJECT "${CMAKE_@lang@_COMPILE_OBJECT}")
+string(REPLACE "${CMAKE_END_TEMP_FILE}" "" CMAKE_@lang@_COMPILE_OBJECT "${CMAKE_@lang@_COMPILE_OBJECT}")
+
+set(CMAKE_@lang@_EXTENSIONS @extensions_opposite@)
+add_library(foo "@RunCMake_SOURCE_DIR@/empty.@ext@")
diff --git a/Tests/RunCMake/CompileFeatures/compiler_introspection.cmake b/Tests/RunCMake/CompileFeatures/compiler_introspection.cmake
new file mode 100644
index 0000000..5691344
--- /dev/null
+++ b/Tests/RunCMake/CompileFeatures/compiler_introspection.cmake
@@ -0,0 +1,38 @@
+enable_language(C CXX)
+
+set(info "")
+
+if(MSVC_TOOLSET_VERSION)
+  string(APPEND info "
+set(MSVC_TOOLSET_VERSION ${MSVC_TOOLSET_VERSION})
+
+")
+endif()
+
+if(CMAKE_XCODE_BUILD_SYSTEM)
+  string(APPEND info "
+set(CMAKE_XCODE_BUILD_SYSTEM ${CMAKE_XCODE_BUILD_SYSTEM})
+
+")
+endif()
+
+macro(info lang)
+  string(APPEND info "\
+set(${lang}_STANDARD_DEFAULT ${CMAKE_${lang}_STANDARD_DEFAULT})
+set(${lang}_EXTENSIONS_DEFAULT ${CMAKE_${lang}_EXTENSIONS_DEFAULT})
+set(${lang}_FEATURES ${CMAKE_${lang}_COMPILE_FEATURES})
+
+set(${lang}_EXT_FLAG ${CMAKE_${lang}_EXTENSION_COMPILE_OPTION})
+")
+
+  foreach(standard ${ARGN})
+    string(APPEND info "\
+set(${lang}${standard}_FLAG ${CMAKE_${lang}${standard}_STANDARD_COMPILE_OPTION})
+set(${lang}${standard}_EXT_FLAG ${CMAKE_${lang}${standard}_EXTENSION_COMPILE_OPTION})
+")
+  endforeach()
+endmacro()
+
+info(C 90 99 11 17 23)
+info(CXX 98 11 14 17 20 23)
+file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/info.cmake" "${info}")
diff --git a/Tests/RunCMake/CompileFeatures/empty.c b/Tests/RunCMake/CompileFeatures/empty.c
index 11ec041..8d91e77 100644
--- a/Tests/RunCMake/CompileFeatures/empty.c
+++ b/Tests/RunCMake/CompileFeatures/empty.c
@@ -1,7 +1,7 @@
 #ifdef _WIN32
 __declspec(dllexport)
 #endif
-  int empty()
+  int empty(void)
 {
   return 0;
 }
diff --git a/Tests/RunCMake/CompileFeatures/generate_feature_list.cmake b/Tests/RunCMake/CompileFeatures/generate_feature_list.cmake
deleted file mode 100644
index 5c58052..0000000
--- a/Tests/RunCMake/CompileFeatures/generate_feature_list.cmake
+++ /dev/null
@@ -1,43 +0,0 @@
-
-enable_language(C)
-
-file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/c_features.txt"
-  "${CMAKE_C_COMPILE_FEATURES}"
-)
-
-file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/cxx_features.txt"
-  "${CMAKE_CXX_COMPILE_FEATURES}"
-)
-
-if(DEFINED CMAKE_C_STANDARD_DEFAULT)
-  set(c_standard_default_code "set(C_STANDARD_DEFAULT \"${CMAKE_C_STANDARD_DEFAULT}\")\n")
-else()
-  set(c_standard_default_code "unset(C_STANDARD_DEFAULT)\n")
-endif()
-file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/c_standard_default.cmake" "${c_standard_default_code}")
-
-if(DEFINED CMAKE_CXX_STANDARD_DEFAULT)
-  set(cxx_standard_default_code "set(CXX_STANDARD_DEFAULT \"${CMAKE_CXX_STANDARD_DEFAULT}\")\n")
-else()
-  set(cxx_standard_default_code "unset(CXX_STANDARD_DEFAULT)\n")
-endif()
-file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/cxx_standard_default.cmake" "${cxx_standard_default_code}")
-
-foreach(standard 98 11)
-  set(CXX${standard}_FLAG NOTFOUND)
-  if (DEFINED CMAKE_CXX${standard}_STANDARD_COMPILE_OPTION)
-    set(CXX${standard}_FLAG ${CMAKE_CXX${standard}_STANDARD_COMPILE_OPTION})
-  endif()
-
-  file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/cxx${standard}_flag.txt"
-    "${CXX${standard}_FLAG}"
-  )
-  set(CXX${standard}EXT_FLAG NOTFOUND)
-  if (DEFINED CMAKE_CXX${standard}_EXTENSION_COMPILE_OPTION)
-    set(CXX${standard}EXT_FLAG ${CMAKE_CXX${standard}_EXTENSION_COMPILE_OPTION})
-  endif()
-
-  file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/cxx${standard}ext_flag.txt"
-    "${CXX${standard}EXT_FLAG}"
-  )
-endforeach()