Merge topic 'revert-explicit-LANGUAGE-flag' into release-3.19

30aa715fac Revert "specify language flag when source LANGUAGE property is set"

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !5519

Help/release/3.19.rst

@@ -330,3 +330,19 @@ Other Changes
 * If ``CUDA`` compiler detection fails with user-specified
   :variable:`CMAKE_CUDA_ARCHITECTURES` or
   :variable:`CMAKE_CUDA_HOST_COMPILER`, an error is raised.
+
+Updates
+=======
+
+Changes made since CMake 3.19.0 include the following.
+
+3.19.1
+------
+
+* CMake 3.19.0 compiles source files with the :prop_sf:`LANGUAGE`
+  property by passing an explicit language flag such as ``-x c``.
+  This is consistent with the property's documented meaning that
+  the source file is written in the specified language.  However,
+  it can break projects that were using the property only to
+  cause the specified language's compiler to be used.  This has
+  been reverted to restore behavior from CMake 3.18 and below.

Modules/Compiler/AppleClang-C.cmake

@@ -1,8 +1,6 @@
 include(Compiler/Clang)
 __compiler_clang(C)
 
-set(CMAKE_C_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -x c)
-
 if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.0)
   set(CMAKE_C90_STANDARD_COMPILE_OPTION "-std=c90")
   set(CMAKE_C90_EXTENSION_COMPILE_OPTION "-std=gnu90")

Modules/Compiler/AppleClang-CXX.cmake

@@ -1,8 +1,6 @@
 include(Compiler/Clang)
 __compiler_clang(CXX)
 
-set(CMAKE_CXX_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -x c++)
-
 if(NOT "x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC")
   set(CMAKE_CXX_COMPILE_OPTIONS_VISIBILITY_INLINES_HIDDEN "-fvisibility-inlines-hidden")
 endif()

Modules/Compiler/Clang-C.cmake

@@ -8,8 +8,6 @@ endif()
 
 if("x${CMAKE_C_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC")
   set(CMAKE_C_CLANG_TIDY_DRIVER_MODE "cl")
-elseif("x${CMAKE_CXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU")
-  set(CMAKE_C_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -x c)
 endif()
 
 if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 3.4)

Modules/Compiler/Clang-CXX.cmake

@@ -2,9 +2,7 @@ include(Compiler/Clang)
 __compiler_clang(CXX)
 __compiler_clang_cxx_standards(CXX)
 
-
 if("x${CMAKE_CXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU")
-  set(CMAKE_CXX_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -x c++)
   set(CMAKE_CXX_COMPILE_OPTIONS_VISIBILITY_INLINES_HIDDEN "-fvisibility-inlines-hidden")
 endif()
 

Modules/Compiler/GNU-C.cmake

@@ -1,8 +1,6 @@
 include(Compiler/GNU)
 __compiler_gnu(C)
 
-set(CMAKE_C_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -x c)
-
 if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.5)
   set(CMAKE_C90_STANDARD_COMPILE_OPTION "-std=c90")
   set(CMAKE_C90_EXTENSION_COMPILE_OPTION "-std=gnu90")

Modules/Compiler/GNU-CXX.cmake

@@ -1,8 +1,6 @@
 include(Compiler/GNU)
 __compiler_gnu(CXX)
 
-set(CMAKE_CXX_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -x c++)
-
 if (WIN32)
   if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.6)
     set(CMAKE_CXX_COMPILE_OPTIONS_VISIBILITY_INLINES_HIDDEN "-fno-keep-inline-dllexport")

Modules/Compiler/Intel-C.cmake

@@ -28,8 +28,6 @@ if("x${CMAKE_C_SIMULATE_ID}" STREQUAL "xMSVC")
 
 else()
 
-  set(CMAKE_C_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -x c)
-
   if (NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 15.0.0)
     set(CMAKE_C11_STANDARD_COMPILE_OPTION "-std=c11")
     set(CMAKE_C11_EXTENSION_COMPILE_OPTION "-std=gnu11")

Modules/Compiler/Intel-CXX.cmake

@@ -42,8 +42,6 @@ if("x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC")
 
 else()
 
-  set(CMAKE_CXX_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -x c++)
-
   if (NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 19.0.0)
     set(CMAKE_CXX20_STANDARD_COMPILE_OPTION "-std=c++20")
     set(CMAKE_CXX20_EXTENSION_COMPILE_OPTION "-std=gnu++20")

Modules/Compiler/XL-C.cmake

@@ -6,8 +6,6 @@ string(APPEND CMAKE_C_FLAGS_MINSIZEREL_INIT " -DNDEBUG")
 # -qthreaded = Ensures that all optimizations will be thread-safe
 string(APPEND CMAKE_C_FLAGS_INIT " -qthreaded")
 
-set(CMAKE_C_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -qsourcetype=c)
-
 if (CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL 10.1)
   set(CMAKE_C90_STANDARD_COMPILE_OPTION "-qlanglvl=stdc89")
   set(CMAKE_C90_EXTENSION_COMPILE_OPTION "-qlanglvl=extc89")

Modules/Compiler/XL-CXX.cmake

@@ -6,8 +6,6 @@ string(APPEND CMAKE_CXX_FLAGS_MINSIZEREL_INIT " -DNDEBUG")
 # -qthreaded = Ensures that all optimizations will be thread-safe
 string(APPEND CMAKE_CXX_FLAGS_INIT " -qthreaded")
 
-set(CMAKE_CXX_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -+)
-
 if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 10.1)
   if(CMAKE_SYSTEM MATCHES "Linux")
     set(CMAKE_CXX98_STANDARD_COMPILE_OPTION "")
@@ -34,3 +32,6 @@ if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 10.1)
 endif ()
 
 __compiler_check_default_language_standard(CXX 10.1 98)
+
+set(CMAKE_CXX_COMPILE_OBJECT
+  "<CMAKE_CXX_COMPILER> -+ <DEFINES> <INCLUDES> <FLAGS> -o <OBJECT> -c <SOURCE>")

Modules/Compiler/XLClang-C.cmake

@@ -1,8 +1,6 @@
 include(Compiler/XLClang)
 __compiler_xlclang(C)
 
-set(CMAKE_C_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -x c)
-
 if (CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL 13.1.1)
   set(CMAKE_C90_STANDARD_COMPILE_OPTION  "-std=c89")
   set(CMAKE_C90_EXTENSION_COMPILE_OPTION "-std=gnu89")

Modules/Compiler/XLClang-CXX.cmake

@@ -1,8 +1,6 @@
 include(Compiler/XLClang)
 __compiler_xlclang(CXX)
 
-set(CMAKE_CXX_COMPILE_OPTIONS_EXPLICIT_LANGUAGE -x c++)
-
 if (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 13.1.1)
   set(CMAKE_CXX98_STANDARD_COMPILE_OPTION  "")
   set(CMAKE_CXX98_EXTENSION_COMPILE_OPTION "")

Source/cmExtraSublimeTextGenerator.cxx

@@ -349,13 +349,6 @@ std::string cmExtraSublimeTextGenerator::ComputeFlagsForObject(
   if (language.empty()) {
     language = "C";
   }
-
-  // explicitly add the explicit language flag before any other flag
-  // this way backwards compatibility with user flags is maintained
-  if (source->GetProperty("LANGUAGE")) {
-    lg->AppendFeatureOptions(flags, language, "EXPLICIT_LANGUAGE");
-  }
-
   std::string const& config =
     lg->GetMakefile()->GetSafeDefinition("CMAKE_BUILD_TYPE");
 

Source/cmGlobalXCodeGenerator.cxx

@@ -937,14 +937,6 @@ cmXCodeObject* cmGlobalXCodeGenerator::CreateXCodeSourceFile(
     default:
       break;
   }
-
-  // explicitly add the explicit language flag before any other flag
-  // this way backwards compatibility with user flags is maintained
-  if (sf->GetProperty("LANGUAGE")) {
-    this->CurrentLocalGenerator->AppendFeatureOptions(flags, lang,
-                                                      "EXPLICIT_LANGUAGE");
-  }
-
   const std::string COMPILE_FLAGS("COMPILE_FLAGS");
   if (cmProp cflags = sf->GetProperty(COMPILE_FLAGS)) {
     lg->AppendFlags(flags, genexInterpreter.Evaluate(*cflags, COMPILE_FLAGS));

Source/cmMakefileTargetGenerator.cxx

@@ -573,13 +573,6 @@ void cmMakefileTargetGenerator::WriteObjectRuleFiles(
   // Build the set of compiler flags.
   std::string flags;
 
-  // explicitly add the explicit language flag before any other flag
-  // this way backwards compatibility with user flags is maintained
-  if (source.GetProperty("LANGUAGE")) {
-    this->LocalGenerator->AppendFeatureOptions(flags, lang,
-                                               "EXPLICIT_LANGUAGE");
-  }
-
   // Add language-specific flags.
   std::string langFlags = cmStrCat("$(", lang, "_FLAGS", filterArch, ")");
   this->LocalGenerator->AppendFlags(flags, langFlags);

Source/cmNinjaTargetGenerator.cxx

@@ -190,16 +190,7 @@ std::string cmNinjaTargetGenerator::ComputeFlagsForObject(
     }
   }
 
-  std::string flags;
-  // explicitly add the explicit language flag before any other flag
-  // this way backwards compatibility with user flags is maintained
-  if (source->GetProperty("LANGUAGE")) {
-    this->LocalGenerator->AppendFeatureOptions(flags, language,
-                                               "EXPLICIT_LANGUAGE");
-    flags += " ";
-  }
-
-  flags += this->GetFlags(language, config, filterArch);
+  std::string flags = this->GetFlags(language, config, filterArch);
 
   // Add Fortran format flags.
   if (language == "Fortran") {

Tests/SetLang/CMakeLists.txt

@@ -15,10 +15,3 @@ if(CMAKE_GENERATOR MATCHES "^Visual Studio" AND "x${CMAKE_C_COMPILER_ID}" STREQU
   add_library(stay stay_c.c stay_cxx.cxx)
   set_property(TARGET stay PROPERTY COMPILE_OPTIONS "-TP")
 endif()
-
-if((CMAKE_C_COMPILER_ID MATCHES "(GNU|Clang|MSVC|Borland|Embarcadero|Intel|TI|XL)"))
-  add_library(zoom zoom.zzz)
-  set_source_files_properties(zoom.zzz PROPERTIES LANGUAGE CXX)
-  target_link_libraries(SetLang zoom)
-  target_compile_definitions(SetLang PRIVATE WITH_ZOOM)
-endif()

Tests/SetLang/bar.c

@@ -1,22 +1,10 @@
 #include <stdio.h>
 
 int foo();
-
-#ifdef WITH_ZOOM
-int zoom();
-#endif
-
 class A
 {
 public:
-  A()
-  {
-    this->i = foo();
-#ifdef WITH_ZOOM
-    i += zoom();
-    i -= zoom();
-#endif
-  }
+  A() { this->i = foo(); }
   int i;
 };
 

Tests/SetLang/zoom.zzz

@@ -1,7 +0,0 @@
-int zoom()
-{
-  int r = 10;
-  r++;
-  int ret = r + 10;
-  return ret;
-}