Project: Split the compiler id detection into a separate function.

This can be extended with parameters to control the output and re-used
in other contexts.

Modules/CMakeCompilerIdDetection.cmake

@@ -0,0 +1,99 @@
+
+#=============================================================================
+# Copyright 2014 Stephen Kelly <steveire@gmail.com>
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file Copyright.txt for details.
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+#=============================================================================
+# (To distribute this file outside of CMake, substitute the full
+#  License text for the above reference.)
+
+function(_readFile file)
+  include(${file})
+  get_filename_component(name ${file} NAME_WE)
+  string(REGEX REPLACE "-.*" "" CompilerId ${name})
+  set(_compiler_id_version_compute_${CompilerId} ${_compiler_id_version_compute} PARENT_SCOPE)
+  set(_compiler_id_pp_test_${CompilerId} ${_compiler_id_pp_test} PARENT_SCOPE)
+endfunction()
+
+function(compiler_id_detection outvar lang)
+
+  file(GLOB lang_files
+    "${CMAKE_ROOT}/Modules/Compiler/*-${lang}-DetermineCompiler.cmake")
+
+  if (NOT lang STREQUAL Fortran)
+    file(GLOB non_lang_files
+      "${CMAKE_ROOT}/Modules/Compiler/*-DetermineCompiler.cmake")
+  endif()
+
+  set(files ${lang_files} ${non_lang_files})
+  if (files)
+    foreach(file ${files})
+      _readFile(${file})
+    endforeach()
+
+    set(ordered_compilers
+      # Order is relevant here. For example, compilers which pretend to be
+      # GCC must appear before the actual GCC.
+      Comeau
+      Intel
+      PathScale
+      AppleClang
+      Clang
+      Embarcadero
+      Borland
+      Watcom
+      OpenWatcom
+      SunPro
+      HP
+      Compaq
+      zOS
+      XL
+      VisualAge
+      PGI
+      Cray
+      TI
+      SCO
+      GNU
+      MSVC
+      ADSP
+      IAR
+      MIPSpro)
+
+    set(pp_if "#if")
+    set(CMAKE_${lang}_COMPILER_ID_CONTENT "/* Version number components: V=Version, R=Revision, P=Patch
+   Version date components:   YYYY=Year, MM=Month,   DD=Day  */\n")
+
+    foreach(Id ${ordered_compilers})
+      if (NOT _compiler_id_pp_test_${Id})
+        message(FATAL_ERROR "No preprocessor test for \"${Id}\"")
+      endif()
+      set(id_content "${pp_if} ${_compiler_id_pp_test_${Id}}\n# define COMPILER_ID \"${Id}\"${_compiler_id_version_compute_${Id}}\n")
+      set(CMAKE_${lang}_COMPILER_ID_CONTENT "${CMAKE_${lang}_COMPILER_ID_CONTENT}\n${id_content}")
+      set(pp_if "#elif")
+    endforeach()
+
+    set(platform_compiler_detection "
+/* These compilers are either not known or too old to define an
+  identification macro.  Try to identify the platform and guess that
+  it is the native compiler.  */
+#elif defined(__sgi)
+# define COMPILER_ID \"MIPSpro\"
+
+#elif defined(__hpux) || defined(__hpua)
+# define COMPILER_ID \"HP\"
+
+#else /* unknown compiler */
+# define COMPILER_ID \"\"
+
+#endif")
+
+    set(CMAKE_${lang}_COMPILER_ID_CONTENT "${CMAKE_${lang}_COMPILER_ID_CONTENT}\n${platform_compiler_detection}")
+  endif()
+
+  set(${outvar} ${CMAKE_${lang}_COMPILER_ID_CONTENT} PARENT_SCOPE)
+endfunction()

Modules/CMakeDetermineCompilerId.cmake

@@ -97,13 +97,7 @@ function(CMAKE_DETERMINE_COMPILER_ID lang flagvar src)
   set(CMAKE_${lang}_SIMULATE_VERSION "${CMAKE_${lang}_SIMULATE_VERSION}" PARENT_SCOPE)
 endfunction()
 
-function(_readFile file)
+include(CMakeCompilerIdDetection)
-  include(${file})
-  get_filename_component(name ${file} NAME_WE)
-  string(REGEX REPLACE "-.*" "" CompilerId ${name})
-  set(_compiler_id_version_compute_${CompilerId} ${_compiler_id_version_compute} PARENT_SCOPE)
-  set(_compiler_id_pp_test_${CompilerId} ${_compiler_id_pp_test} PARENT_SCOPE)
-endfunction()
 
 #-----------------------------------------------------------------------------
 # Function to write the compiler id source file.
@@ -111,73 +105,7 @@ function(CMAKE_DETERMINE_COMPILER_ID_WRITE lang src)
   find_file(src_in ${src}.in PATHS ${CMAKE_ROOT}/Modules ${CMAKE_MODULE_PATH} NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH)
   file(READ ${src_in} ID_CONTENT_IN)
 
-  file(GLOB lang_files
+  compiler_id_detection(CMAKE_${lang}_COMPILER_ID_CONTENT ${lang})
-    "${CMAKE_ROOT}/Modules/Compiler/*-${lang}-DetermineCompiler.cmake")
-
-  if (NOT lang STREQUAL Fortran)
-    file(GLOB non_lang_files
-      "${CMAKE_ROOT}/Modules/Compiler/*-${lang}-DetermineCompiler.cmake")
-  endif()
-
-  set(files ${lang_files} ${non_lang_files})
-  if (files)
-    foreach(file ${files})
-      _readFile(${file})
-    endforeach()
-    set(pp_if "#if")
-    set(CMAKE_CXX_COMPILER_ID_CONTENT "/* Version number components: V=Version, R=Revision, P=Patch
-   Version date components:   YYYY=Year, MM=Month,   DD=Day  */\n")
-
-    foreach(Id
-        Comeau
-        Intel
-        PathScale
-        AppleClang
-        Clang
-        Embarcadero
-        Borland
-        Watcom
-        OpenWatcom
-        SunPro
-        HP
-        Compaq
-        zOS
-        XL
-        VisualAge
-        PGI
-        Cray
-        TI
-        SCO
-        GNU
-        MSVC
-        ADSP
-        IAR
-        MIPSpro)
-      if (NOT _compiler_id_pp_test_${Id})
-        message(FATAL_ERROR "No test for \"${Id}\"")
-      endif()
-      set(id_content "${pp_if} ${_compiler_id_pp_test_${Id}}\n# define COMPILER_ID \"${Id}\"${_compiler_id_version_compute_${Id}}\n")
-      set(CMAKE_CXX_COMPILER_ID_CONTENT "${CMAKE_CXX_COMPILER_ID_CONTENT}\n${id_content}")
-      set(pp_if "#elif")
-    endforeach()
-
-    set(platform_compiler_detection "
-/* These compilers are either not known or too old to define an
-  identification macro.  Try to identify the platform and guess that
-  it is the native compiler.  */
-#elif defined(__sgi)
-# define COMPILER_ID \"MIPSpro\"
-
-#elif defined(__hpux) || defined(__hpua)
-# define COMPILER_ID \"HP\"
-
-#else /* unknown compiler */
-# define COMPILER_ID \"\"
-
-#endif")
-
-    set(CMAKE_CXX_COMPILER_ID_CONTENT "${CMAKE_CXX_COMPILER_ID_CONTENT}\n${platform_compiler_detection}")
-  endif()
 
   unset(src_in CACHE)
   string(CONFIGURE "${ID_CONTENT_IN}" ID_CONTENT_OUT @ONLY)