CMakeDetermineCompilerId: Add notion of "simulated" id/version

Some compilers try to simulate other compilers as a drop-in replacement
supporting all the same command-line options and predefined preprocessor
macros.  In such cases it will be useful to have CMake load the compiler
information files for the simulated compiler instead of duplicating the
information.  Teach CMakeDetermineCompilerId to extract the simulated
compiler id and version when the compiler id detection provides it.

Modules/CMakeCCompiler.cmake.in

@@ -3,6 +3,8 @@ set(CMAKE_C_COMPILER_ARG1 "@CMAKE_C_COMPILER_ARG1@")
 set(CMAKE_C_COMPILER_ID "@CMAKE_C_COMPILER_ID@")
 set(CMAKE_C_COMPILER_VERSION "@CMAKE_C_COMPILER_VERSION@")
 set(CMAKE_C_PLATFORM_ID "@CMAKE_C_PLATFORM_ID@")
+set(CMAKE_C_SIMULATE_ID "@CMAKE_C_SIMULATE_ID@")
+set(CMAKE_C_SIMULATE_VERSION "@CMAKE_C_SIMULATE_VERSION@")
 @SET_MSVC_C_ARCHITECTURE_ID@
 set(CMAKE_AR "@CMAKE_AR@")
 set(CMAKE_RANLIB "@CMAKE_RANLIB@")

Modules/CMakeCCompilerId.c.in

@@ -206,6 +206,9 @@
    because some compilers will just produce instructions to fill the
    array rather than assigning a pointer to a static array.  */
 char const* info_compiler = "INFO" ":" "compiler[" COMPILER_ID "]";
+#ifdef SIMULATE_ID
+char const* info_simulate = "INFO" ":" "simulate[" SIMULATE_ID "]";
+#endif
 
 @CMAKE_C_COMPILER_ID_PLATFORM_CONTENT@
 
@@ -222,6 +225,12 @@ int main(int argc, char* argv[])
   require += info_arch[argc];
 #ifdef COMPILER_VERSION_MAJOR
   require += info_version[argc];
+#endif
+#ifdef SIMULATE_ID
+  require += info_simulate[argc];
+#endif
+#ifdef SIMULATE_VERSION_MAJOR
+  require += info_simulate_version[argc];
 #endif
   (void)argv;
   return require;

Modules/CMakeCXXCompiler.cmake.in

@@ -3,6 +3,8 @@ set(CMAKE_CXX_COMPILER_ARG1 "@CMAKE_CXX_COMPILER_ARG1@")
 set(CMAKE_CXX_COMPILER_ID "@CMAKE_CXX_COMPILER_ID@")
 set(CMAKE_CXX_COMPILER_VERSION "@CMAKE_CXX_COMPILER_VERSION@")
 set(CMAKE_CXX_PLATFORM_ID "@CMAKE_CXX_PLATFORM_ID@")
+set(CMAKE_CXX_SIMULATE_ID "@CMAKE_CXX_SIMULATE_ID@")
+set(CMAKE_CXX_SIMULATE_VERSION "@CMAKE_CXX_SIMULATE_VERSION@")
 @SET_MSVC_CXX_ARCHITECTURE_ID@
 set(CMAKE_AR "@CMAKE_AR@")
 set(CMAKE_RANLIB "@CMAKE_RANLIB@")

Modules/CMakeCXXCompilerId.cpp.in

@@ -199,6 +199,9 @@
    because some compilers will just produce instructions to fill the
    array rather than assigning a pointer to a static array.  */
 char const* info_compiler = "INFO" ":" "compiler[" COMPILER_ID "]";
+#ifdef SIMULATE_ID
+char const* info_simulate = "INFO" ":" "simulate[" SIMULATE_ID "]";
+#endif
 
 @CMAKE_CXX_COMPILER_ID_PLATFORM_CONTENT@
 
@@ -211,6 +214,12 @@ int main(int argc, char* argv[])
   require += info_platform[argc];
 #ifdef COMPILER_VERSION_MAJOR
   require += info_version[argc];
+#endif
+#ifdef SIMULATE_ID
+  require += info_simulate[argc];
+#endif
+#ifdef SIMULATE_VERSION_MAJOR
+  require += info_simulate_version[argc];
 #endif
   (void)argv;
   return require;

Modules/CMakeDetermineCompilerId.cmake

@@ -80,6 +80,8 @@ function(CMAKE_DETERMINE_COMPILER_ID lang flagvar src)
   set(MSVC_${lang}_ARCHITECTURE_ID "${MSVC_${lang}_ARCHITECTURE_ID}"
     PARENT_SCOPE)
   set(CMAKE_${lang}_COMPILER_VERSION "${CMAKE_${lang}_COMPILER_VERSION}" PARENT_SCOPE)
+  set(CMAKE_${lang}_SIMULATE_ID "${CMAKE_${lang}_SIMULATE_ID}" PARENT_SCOPE)
+  set(CMAKE_${lang}_SIMULATE_VERSION "${CMAKE_${lang}_SIMULATE_VERSION}" PARENT_SCOPE)
 endfunction()
 
 #-----------------------------------------------------------------------------
@@ -309,8 +311,10 @@ function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
     set(COMPILER_VERSION)
     set(PLATFORM_ID)
     set(ARCHITECTURE_ID)
+    set(SIMULATE_ID)
+    set(SIMULATE_VERSION)
     file(STRINGS ${file}
-      CMAKE_${lang}_COMPILER_ID_STRINGS LIMIT_COUNT 4 REGEX "INFO:")
+      CMAKE_${lang}_COMPILER_ID_STRINGS LIMIT_COUNT 6 REGEX "INFO:")
     set(COMPILER_ID_TWICE)
     foreach(info ${CMAKE_${lang}_COMPILER_ID_STRINGS})
       if("${info}" MATCHES ".*INFO:compiler\\[([^]\"]*)\\].*")
@@ -333,6 +337,14 @@ function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
         string(REGEX REPLACE "^0+([0-9])" "\\1" COMPILER_VERSION "${COMPILER_VERSION}")
         string(REGEX REPLACE "\\.0+([0-9])" ".\\1" COMPILER_VERSION "${COMPILER_VERSION}")
       endif()
+      if("${info}" MATCHES ".*INFO:simulate\\[([^]\"]*)\\].*")
+        set(SIMULATE_ID "${CMAKE_MATCH_1}")
+      endif()
+      if("${info}" MATCHES ".*INFO:simulate_version\\[([^]\"]*)\\].*")
+        set(SIMULATE_VERSION "${CMAKE_MATCH_1}")
+        string(REGEX REPLACE "^0+([0-9])" "\\1" SIMULATE_VERSION "${SIMULATE_VERSION}")
+        string(REGEX REPLACE "\\.0+([0-9])" ".\\1" SIMULATE_VERSION "${SIMULATE_VERSION}")
+      endif()
     endforeach()
 
     # Detect the exact architecture from the PE header.
@@ -370,6 +382,8 @@ function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
       set(CMAKE_${lang}_PLATFORM_ID "${PLATFORM_ID}")
       set(MSVC_${lang}_ARCHITECTURE_ID "${ARCHITECTURE_ID}")
       set(CMAKE_${lang}_COMPILER_VERSION "${COMPILER_VERSION}")
+      set(CMAKE_${lang}_SIMULATE_ID "${SIMULATE_ID}")
+      set(CMAKE_${lang}_SIMULATE_VERSION "${SIMULATE_VERSION}")
     endif()
 
     # Check the compiler identification string.
@@ -418,6 +432,8 @@ function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
   set(MSVC_${lang}_ARCHITECTURE_ID "${MSVC_${lang}_ARCHITECTURE_ID}"
     PARENT_SCOPE)
   set(CMAKE_${lang}_COMPILER_VERSION "${CMAKE_${lang}_COMPILER_VERSION}" PARENT_SCOPE)
+  set(CMAKE_${lang}_SIMULATE_ID "${CMAKE_${lang}_SIMULATE_ID}" PARENT_SCOPE)
+  set(CMAKE_${lang}_SIMULATE_VERSION "${CMAKE_${lang}_SIMULATE_VERSION}" PARENT_SCOPE)
   set(CMAKE_EXECUTABLE_FORMAT "${CMAKE_EXECUTABLE_FORMAT}" PARENT_SCOPE)
 endfunction()
 

Modules/CMakePlatformId.h.in

@@ -151,6 +151,24 @@ char const info_version[] = {
   ']','\0'};
 #endif
 
+/* Construct a string literal encoding the version number components. */
+#ifdef SIMULATE_VERSION_MAJOR
+char const info_simulate_version[] = {
+  'I', 'N', 'F', 'O', ':',
+  's','i','m','u','l','a','t','e','_','v','e','r','s','i','o','n','[',
+  SIMULATE_VERSION_MAJOR,
+# ifdef SIMULATE_VERSION_MINOR
+  '.', SIMULATE_VERSION_MINOR,
+#  ifdef SIMULATE_VERSION_PATCH
+   '.', SIMULATE_VERSION_PATCH,
+#   ifdef SIMULATE_VERSION_TWEAK
+    '.', SIMULATE_VERSION_TWEAK,
+#   endif
+#  endif
+# endif
+  ']','\0'};
+#endif
+
 /* Construct the string literal in pieces to prevent the source from
    getting matched.  Store it in a pointer rather than an array
    because some compilers will just produce instructions to fill the

Source/cmDocumentVariables.cxx

@@ -1658,6 +1658,28 @@ void cmDocumentVariables::DefineVariables(cmake* cm)
      false,
      "Variables for Languages");
 
+  cm->DefineProperty
+    ("CMAKE_<LANG>_SIMULATE_ID", cmProperty::VARIABLE,
+     "Identification string of \"simulated\" compiler.",
+     "Some compilers simulate other compilers to serve as drop-in "
+     "replacements.  "
+     "When CMake detects such a compiler it sets this variable to what "
+     "would have been the CMAKE_<LANG>_COMPILER_ID for the simulated "
+     "compiler.",
+     false,
+     "Variables for Languages");
+
+  cm->DefineProperty
+    ("CMAKE_<LANG>_SIMULATE_VERSION", cmProperty::VARIABLE,
+     "Version string of \"simulated\" compiler.",
+     "Some compilers simulate other compilers to serve as drop-in "
+     "replacements.  "
+     "When CMake detects such a compiler it sets this variable to what "
+     "would have been the CMAKE_<LANG>_COMPILER_VERSION for the simulated "
+     "compiler.",
+     false,
+     "Variables for Languages");
+
   cm->DefineProperty
     ("CMAKE_<LANG>_SIZEOF_DATA_PTR", cmProperty::VARIABLE,
      "Size of pointer-to-data types for language <LANG>.",