Add infrastructure to detect secondary compiler version information

Create a `CMAKE_<LANG>_COMPILER_VERSION_INTERNAL` variable to hold
a secondary/internal compiler version number detected at the same
time as the primary compiler version.  This will be useful for some
compilers where we need such a number to determine correct usage.
Inspired-by: Stefan Andersson <tfosm@hotmail.com>
Suggested-by: Norbert Lange <norbert.lange@andritz.com>
Issue: #17264

Help/manual/cmake-variables.7.rst

@@ -400,6 +400,7 @@ Variables for Languages
    /variable/CMAKE_LANG_COMPILER_PREDEFINES_COMMAND
    /variable/CMAKE_LANG_COMPILER_TARGET
    /variable/CMAKE_LANG_COMPILER_VERSION
+   /variable/CMAKE_LANG_COMPILER_VERSION_INTERNAL
    /variable/CMAKE_LANG_COMPILE_OBJECT
    /variable/CMAKE_LANG_CREATE_SHARED_LIBRARY
    /variable/CMAKE_LANG_CREATE_SHARED_MODULE

Help/variable/CMAKE_LANG_COMPILER_VERSION_INTERNAL.rst

+CMAKE_<LANG>_COMPILER_VERSION_INTERNAL
+--------------------------------------
+
+An internal variable subject to change.
+
+This is used to identify the variant of a compiler based on an internal
+version number.  For some compilers this is needed to determine the
+correct usage.

Modules/CMakeCCompiler.cmake.in

@@ -2,6 +2,7 @@ set(CMAKE_C_COMPILER "@CMAKE_C_COMPILER@")
 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_COMPILER_VERSION_INTERNAL "@CMAKE_C_COMPILER_VERSION_INTERNAL@")
 set(CMAKE_C_COMPILER_WRAPPER "@CMAKE_C_COMPILER_WRAPPER@")
 set(CMAKE_C_STANDARD_COMPUTED_DEFAULT "@CMAKE_C_STANDARD_COMPUTED_DEFAULT@")
 set(CMAKE_C_COMPILE_FEATURES "@CMAKE_C_COMPILE_FEATURES@")

Modules/CMakeCCompilerId.c.in

@@ -67,6 +67,9 @@ int main(int argc, char* argv[])
 #ifdef COMPILER_VERSION_MAJOR
   require += info_version[argc];
 #endif
+#ifdef COMPILER_VERSION_INTERNAL
+  require += info_version_internal[argc];
+#endif
 #ifdef SIMULATE_ID
   require += info_simulate[argc];
 #endif

Modules/CMakeCXXCompiler.cmake.in

@@ -2,6 +2,7 @@ set(CMAKE_CXX_COMPILER "@CMAKE_CXX_COMPILER@")
 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_COMPILER_VERSION_INTERNAL "@CMAKE_CXX_COMPILER_VERSION_INTERNAL@")
 set(CMAKE_CXX_COMPILER_WRAPPER "@CMAKE_CXX_COMPILER_WRAPPER@")
 set(CMAKE_CXX_STANDARD_COMPUTED_DEFAULT "@CMAKE_CXX_STANDARD_COMPUTED_DEFAULT@")
 set(CMAKE_CXX_COMPILE_FEATURES "@CMAKE_CXX_COMPILE_FEATURES@")

Modules/CMakeCXXCompilerId.cpp.in

@@ -55,6 +55,9 @@ int main(int argc, char* argv[])
 #ifdef COMPILER_VERSION_MAJOR
   require += info_version[argc];
 #endif
+#ifdef COMPILER_VERSION_INTERNAL
+  require += info_version_internal[argc];
+#endif
 #ifdef SIMULATE_ID
   require += info_simulate[argc];
 #endif

Modules/CMakeDetermineCompilerId.cmake

@@ -108,6 +108,7 @@ function(CMAKE_DETERMINE_COMPILER_ID lang flagvar src)
   set(CMAKE_${lang}_XCODE_CURRENT_ARCH "${CMAKE_${lang}_XCODE_CURRENT_ARCH}" PARENT_SCOPE)
   set(CMAKE_${lang}_CL_SHOWINCLUDES_PREFIX "${CMAKE_${lang}_CL_SHOWINCLUDES_PREFIX}" PARENT_SCOPE)
   set(CMAKE_${lang}_COMPILER_VERSION "${CMAKE_${lang}_COMPILER_VERSION}" PARENT_SCOPE)
+  set(CMAKE_${lang}_COMPILER_VERSION_INTERNAL "${CMAKE_${lang}_COMPILER_VERSION_INTERNAL}" PARENT_SCOPE)
   set(CMAKE_${lang}_COMPILER_WRAPPER "${CMAKE_${lang}_COMPILER_WRAPPER}" PARENT_SCOPE)
   set(CMAKE_${lang}_SIMULATE_ID "${CMAKE_${lang}_SIMULATE_ID}" PARENT_SCOPE)
   set(CMAKE_${lang}_SIMULATE_VERSION "${CMAKE_${lang}_SIMULATE_VERSION}" PARENT_SCOPE)
@@ -473,6 +474,7 @@ function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
     set(COMPILER_VERSION_MINOR 0)
     set(COMPILER_VERSION_PATCH 0)
     set(COMPILER_VERSION_TWEAK 0)
+    set(COMPILER_VERSION_INTERNAL "")
     set(HAVE_COMPILER_VERSION_MAJOR 0)
     set(HAVE_COMPILER_VERSION_MINOR 0)
     set(HAVE_COMPILER_VERSION_PATCH 0)
@@ -514,6 +516,10 @@ function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
         string(REGEX REPLACE "^0+([0-9])" "\\1" COMPILER_VERSION "${CMAKE_MATCH_1}")
         string(REGEX REPLACE "\\.0+([0-9])" ".\\1" COMPILER_VERSION "${COMPILER_VERSION}")
       endif()
+      if("${info}" MATCHES "INFO:compiler_version_internal\\[([^]\"]*)\\]")
+        string(REGEX REPLACE "^0+([0-9])" "\\1" COMPILER_VERSION_INTERNAL "${CMAKE_MATCH_1}")
+        string(REGEX REPLACE "\\.0+([0-9])" ".\\1" COMPILER_VERSION_INTERNAL "${COMPILER_VERSION_INTERNAL}")
+      endif()
       foreach(comp MAJOR MINOR PATCH TWEAK)
         foreach(digit 1 2 3 4 5 6 7 8 9)
           if("${info}" MATCHES "INFO:compiler_version_${comp}_digit_${digit}\\[([0-9])\\]")
@@ -589,6 +595,7 @@ function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
       set(CMAKE_${lang}_COMPILER_ARCHITECTURE_ID "${ARCHITECTURE_ID}")
       set(MSVC_${lang}_ARCHITECTURE_ID "${ARCHITECTURE_ID}")
       set(CMAKE_${lang}_COMPILER_VERSION "${COMPILER_VERSION}")
+      set(CMAKE_${lang}_COMPILER_VERSION_INTERNAL "${COMPILER_VERSION_INTERNAL}")
       set(CMAKE_${lang}_SIMULATE_ID "${SIMULATE_ID}")
       set(CMAKE_${lang}_SIMULATE_VERSION "${SIMULATE_VERSION}")
     endif()
@@ -640,6 +647,7 @@ function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
   set(MSVC_${lang}_ARCHITECTURE_ID "${MSVC_${lang}_ARCHITECTURE_ID}"
     PARENT_SCOPE)
   set(CMAKE_${lang}_COMPILER_VERSION "${CMAKE_${lang}_COMPILER_VERSION}" PARENT_SCOPE)
+  set(CMAKE_${lang}_COMPILER_VERSION_INTERNAL "${CMAKE_${lang}_COMPILER_VERSION_INTERNAL}" PARENT_SCOPE)
   set(CMAKE_${lang}_COMPILER_WRAPPER "${COMPILER_WRAPPER}" PARENT_SCOPE)
   set(CMAKE_${lang}_SIMULATE_ID "${CMAKE_${lang}_SIMULATE_ID}" PARENT_SCOPE)
   set(CMAKE_${lang}_SIMULATE_VERSION "${CMAKE_${lang}_SIMULATE_VERSION}" PARENT_SCOPE)

Modules/CMakePlatformId.h.in

@@ -201,6 +201,15 @@ char const info_version[] = {
   ']','\0'};
 #endif
 
+/* Construct a string literal encoding the internal version number. */
+#ifdef COMPILER_VERSION_INTERNAL
+char const info_version_internal[] = {
+  'I', 'N', 'F', 'O', ':',
+  'c','o','m','p','i','l','e','r','_','v','e','r','s','i','o','n','_',
+  'i','n','t','e','r','n','a','l','[',
+  COMPILER_VERSION_INTERNAL,']','\0'};
+#endif
+
 /* Construct a string literal encoding the version number components. */
 #ifdef SIMULATE_VERSION_MAJOR
 char const info_simulate_version[] = {