Apple: Use CMAKE_EFFECTIVE_SYSTEM_NAME to share compiler info

Apple platforms macOS, iOS, tvOS, and watchOS can all share the same
compiler information.  Rename `Darwin-*` modules to `Apple-*` and load
them all through `CMAKE_EFFECTIVE_SYSTEM_NAME`.  This saves duplication
of 4 * 21 compiler information modules.

Issue: #17870

Modules/CMakeSystemSpecificInitialize.cmake

@@ -11,6 +11,11 @@
 #
 # It is useful to share the same aforementioned configuration files and
 # avoids duplicating them in case of tightly related platforms.
+#
+# An example are the platforms supported by Xcode (macOS, iOS, tvOS,
+# and watchOS). For all of those the CMAKE_EFFECTIVE_SYSTEM_NAME is
+# set to Apple which results in using
+# Platfom/Apple-AppleClang-CXX.cmake for the Apple C++ compiler.
 set(CMAKE_EFFECTIVE_SYSTEM_NAME "${CMAKE_SYSTEM_NAME}")
 
 include(Platform/${CMAKE_SYSTEM_NAME}-Initialize OPTIONAL)

Modules/Platform/Apple-AppleClang-C.cmake

@@ -1,4 +1,4 @@
-include(Platform/Darwin-Clang-C)
+include(Platform/Apple-Clang-C)
 if(NOT CMAKE_C_COMPILER_VERSION VERSION_LESS 4.2)
   set(CMAKE_C_SYSTEM_FRAMEWORK_SEARCH_FLAG "-iframework ")
 else()

Modules/Platform/Apple-AppleClang-CXX.cmake

@@ -1,4 +1,4 @@
-include(Platform/Darwin-Clang-CXX)
+include(Platform/Apple-Clang-CXX)
 if(NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.2)
   set(CMAKE_CXX_SYSTEM_FRAMEWORK_SEARCH_FLAG "-iframework ")
 else()

Modules/Platform/Apple-Clang-C.cmake

@@ -0,0 +1,2 @@
+include(Platform/Apple-Clang)
+__apple_compiler_clang(C)

Modules/Platform/Apple-Clang-CXX.cmake

@@ -0,0 +1,2 @@
+include(Platform/Apple-Clang)
+__apple_compiler_clang(CXX)

Modules/Platform/Apple-Clang.cmake

@@ -3,12 +3,12 @@
 
 
 # This module is shared by multiple languages; use include blocker.
-if(__DARWIN_COMPILER_CLANG)
+if(__APPLE_COMPILER_CLANG)
   return()
 endif()
-set(__DARWIN_COMPILER_CLANG 1)
+set(__APPLE_COMPILER_CLANG 1)
 
-macro(__darwin_compiler_clang lang)
+macro(__apple_compiler_clang lang)
   set(CMAKE_${lang}_VERBOSE_FLAG "-v -Wl,-v") # also tell linker to print verbose output
   set(CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS "-dynamiclib -Wl,-headerpad_max_install_names")
   set(CMAKE_SHARED_MODULE_CREATE_${lang}_FLAGS "-bundle -Wl,-headerpad_max_install_names")

Modules/Platform/Apple-GNU-C.cmake

@@ -1,4 +1,4 @@
-include(Platform/Darwin-GNU)
-__darwin_compiler_gnu(C)
+include(Platform/Apple-GNU)
+__apple_compiler_gnu(C)
 cmake_gnu_set_sysroot_flag(C)
 cmake_gnu_set_osx_deployment_target_flag(C)

Modules/Platform/Apple-GNU-CXX.cmake

@@ -1,4 +1,4 @@
-include(Platform/Darwin-GNU)
-__darwin_compiler_gnu(CXX)
+include(Platform/Apple-GNU)
+__apple_compiler_gnu(CXX)
 cmake_gnu_set_sysroot_flag(CXX)
 cmake_gnu_set_osx_deployment_target_flag(CXX)

Modules/Platform/Apple-GNU-Fortran.cmake

@@ -1,8 +1,8 @@
 # Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
 # file Copyright.txt or https://cmake.org/licensing for details.
 
-include(Platform/Darwin-GNU)
-__darwin_compiler_gnu(Fortran)
+include(Platform/Apple-GNU)
+__apple_compiler_gnu(Fortran)
 cmake_gnu_set_sysroot_flag(Fortran)
 cmake_gnu_set_osx_deployment_target_flag(Fortran)
 

Modules/Platform/Apple-GNU.cmake

@@ -3,12 +3,12 @@
 
 
 # This module is shared by multiple languages; use include blocker.
-if(__DARWIN_COMPILER_GNU)
+if(__APPLE_COMPILER_GNU)
   return()
 endif()
-set(__DARWIN_COMPILER_GNU 1)
+set(__APPLE_COMPILER_GNU 1)
 
-macro(__darwin_compiler_gnu lang)
+macro(__apple_compiler_gnu lang)
   set(CMAKE_${lang}_VERBOSE_FLAG "-v -Wl,-v") # also tell linker to print verbose output
   # GNU does not have -shared on OS X
   set(CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS "-dynamiclib -Wl,-headerpad_max_install_names")

Modules/Platform/Apple-Intel-C.cmake

@@ -0,0 +1,2 @@
+include(Platform/Apple-Intel)
+__apple_compiler_intel(C)

Modules/Platform/Apple-Intel-CXX.cmake

@@ -0,0 +1,2 @@
+include(Platform/Apple-Intel)
+__apple_compiler_intel(CXX)

Modules/Platform/Apple-Intel-Fortran.cmake

@@ -1,8 +1,8 @@
 # Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
 # file Copyright.txt or https://cmake.org/licensing for details.
 
-include(Platform/Darwin-Intel)
-__darwin_compiler_intel(Fortran)
+include(Platform/Apple-Intel)
+__apple_compiler_intel(Fortran)
 
 set(CMAKE_Fortran_OSX_COMPATIBILITY_VERSION_FLAG "-compatibility_version ")
 set(CMAKE_Fortran_OSX_CURRENT_VERSION_FLAG "-current_version ")

Modules/Platform/Apple-Intel.cmake

@@ -3,12 +3,12 @@
 
 
 # This module is shared by multiple languages; use include blocker.
-if(__DARWIN_COMPILER_INTEL)
+if(__APPLE_COMPILER_INTEL)
   return()
 endif()
-set(__DARWIN_COMPILER_INTEL 1)
+set(__APPLE_COMPILER_INTEL 1)
 
-macro(__darwin_compiler_intel lang)
+macro(__apple_compiler_intel lang)
   set(CMAKE_${lang}_VERBOSE_FLAG "-v -Wl,-v") # also tell linker to print verbose output
   set(CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS "-dynamiclib -Wl,-headerpad_max_install_names")
   set(CMAKE_SHARED_MODULE_CREATE_${lang}_FLAGS "-bundle -Wl,-headerpad_max_install_names")

Modules/Platform/Apple-PGI-C.cmake

@@ -0,0 +1,2 @@
+include(Platform/Apple-PGI)
+__apple_compiler_pgi(C)

Modules/Platform/Apple-PGI-CXX.cmake

@@ -0,0 +1,2 @@
+include(Platform/Apple-PGI)
+__apple_compiler_pgi(CXX)

Modules/Platform/Apple-PGI-Fortran.cmake

@@ -0,0 +1,2 @@
+include(Platform/Apple-PGI)
+__apple_compiler_pgi(Fortran)

Modules/Platform/Apple-PGI.cmake

@@ -2,12 +2,12 @@
 # file Copyright.txt or https://cmake.org/licensing for details.
 
 # This module is shared by multiple languages; use include blocker.
-if(__DARWIN_COMPILER_PGI)
+if(__APPLE_COMPILER_PGI)
   return()
 endif()
-set(__DARWIN_COMPILER_PGI 1)
+set(__APPLE_COMPILER_PGI 1)
 
-macro(__darwin_compiler_pgi lang)
+macro(__apple_compiler_pgi lang)
   set(CMAKE_${lang}_OSX_COMPATIBILITY_VERSION_FLAG "-Wl,-compatibility_version,")
   set(CMAKE_${lang}_OSX_CURRENT_VERSION_FLAG "-Wl,-current_version,")
   set(CMAKE_SHARED_LIBRARY_SONAME_${lang}_FLAG "-Wl,-install_name")

Modules/Platform/Apple-VisualAge-C.cmake

@@ -0,0 +1 @@
+include(Platform/Apple-XL-C)

Modules/Platform/Apple-VisualAge-CXX.cmake

@@ -0,0 +1 @@
+include(Platform/Apple-XL-CXX)

Modules/Platform/Darwin-Clang-C.cmake

@@ -1,2 +0,0 @@
-include(Platform/Darwin-Clang)
-__darwin_compiler_clang(C)

Modules/Platform/Darwin-Clang-CXX.cmake

@@ -1,2 +0,0 @@
-include(Platform/Darwin-Clang)
-__darwin_compiler_clang(CXX)

Modules/Platform/Darwin-Initialize.cmake

@@ -20,6 +20,10 @@ execute_process(COMMAND sw_vers -productVersion
 set(CMAKE_OSX_ARCHITECTURES "$ENV{CMAKE_OSX_ARCHITECTURES}" CACHE STRING
   "Build architectures for OSX")
 
+# macOS, iOS, tvOS, and watchOS should lookup compilers from
+# Platform/Apple-${CMAKE_CXX_COMPILER_ID}-<LANG>
+set(CMAKE_EFFECTIVE_SYSTEM_NAME "Apple")
+
 #----------------------------------------------------------------------------
 # _CURRENT_OSX_VERSION - as a two-component string: 10.5, 10.6, ...
 #

Modules/Platform/Darwin-Intel-C.cmake

@@ -1,2 +0,0 @@
-include(Platform/Darwin-Intel)
-__darwin_compiler_intel(C)

Modules/Platform/Darwin-Intel-CXX.cmake

@@ -1,2 +0,0 @@
-include(Platform/Darwin-Intel)
-__darwin_compiler_intel(CXX)

Modules/Platform/Darwin-PGI-C.cmake

@@ -1,2 +0,0 @@
-include(Platform/Darwin-PGI)
-__darwin_compiler_pgi(C)

Modules/Platform/Darwin-PGI-CXX.cmake

@@ -1,2 +0,0 @@
-include(Platform/Darwin-PGI)
-__darwin_compiler_pgi(CXX)

Modules/Platform/Darwin-PGI-Fortran.cmake

@@ -1,2 +0,0 @@
-include(Platform/Darwin-PGI)
-__darwin_compiler_pgi(Fortran)

Modules/Platform/Darwin-VisualAge-C.cmake

@@ -1 +0,0 @@
-include(Platform/Darwin-XL-C)

Modules/Platform/Darwin-VisualAge-CXX.cmake

@@ -1 +0,0 @@
-include(Platform/Darwin-XL-CXX)