Add a CMAKE_<LANG>_COMPILER_ARCHITECTURE_ID variable

Compilers such as MSVC and IAR may have variants that target different
architectures.  We have been using a `MSVC_<LANG>_ARCHITECTURE_ID`
variable to hold this information for MSVC.  Add an alternative with a
more general name (later we can port MSVC to it too).

This additional information may be needed to generate proper invocations
of the compiler based on its architecture variant.

Help/manual/cmake-variables.7.rst

@@ -386,6 +386,7 @@ Variables for Languages
    /variable/CMAKE_LANG_ARCHIVE_FINISH
    /variable/CMAKE_LANG_COMPILER
    /variable/CMAKE_LANG_COMPILER_ABI
+   /variable/CMAKE_LANG_COMPILER_ARCHITECTURE_ID
    /variable/CMAKE_LANG_COMPILER_EXTERNAL_TOOLCHAIN
    /variable/CMAKE_LANG_COMPILER_ID
    /variable/CMAKE_LANG_COMPILER_LOADED

Help/variable/CMAKE_LANG_COMPILER_ARCHITECTURE_ID.rst

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

Modules/CMakeASMCompiler.cmake.in

@@ -9,6 +9,7 @@ set(CMAKE_ASM@ASM_DIALECT@_COMPILER_LOADED 1)
 set(CMAKE_ASM@ASM_DIALECT@_COMPILER_ID "@_CMAKE_ASM_COMPILER_ID@")
 set(CMAKE_ASM@ASM_DIALECT@_COMPILER_VERSION "@_CMAKE_ASM_COMPILER_VERSION@")
 set(CMAKE_ASM@ASM_DIALECT@_COMPILER_ENV_VAR "@_CMAKE_ASM_COMPILER_ENV_VAR@")
+@_SET_CMAKE_ASM_COMPILER_ARCHITECTURE_ID@
 
 set(CMAKE_ASM@ASM_DIALECT@_IGNORE_EXTENSIONS h;H;o;O;obj;OBJ;def;DEF;rc;RC)
 set(CMAKE_ASM@ASM_DIALECT@_LINKER_PREFERENCE 0)

Modules/CMakeCCompiler.cmake.in

@@ -12,6 +12,7 @@ set(CMAKE_C11_COMPILE_FEATURES "@CMAKE_C11_COMPILE_FEATURES@")
 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_CMAKE_C_COMPILER_ARCHITECTURE_ID@
 @SET_MSVC_C_ARCHITECTURE_ID@
 @SET_CMAKE_XCODE_CURRENT_ARCH@
 set(CMAKE_AR "@CMAKE_AR@")

Modules/CMakeCXXCompiler.cmake.in

@@ -13,6 +13,7 @@ set(CMAKE_CXX17_COMPILE_FEATURES "@CMAKE_CXX17_COMPILE_FEATURES@")
 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_CMAKE_CXX_COMPILER_ARCHITECTURE_ID@
 @SET_MSVC_CXX_ARCHITECTURE_ID@
 @SET_CMAKE_XCODE_CURRENT_ARCH@
 set(CMAKE_AR "@CMAKE_AR@")

Modules/CMakeDetermineASMCompiler.cmake

@@ -170,6 +170,13 @@ foreach(_var
   set(_CMAKE_ASM_${_var} "${CMAKE_ASM${ASM_DIALECT}_${_var}}")
 endforeach()
 
+if(CMAKE_ASM${ASM_DIALECT}_COMPILER_ARCHITECTURE_ID)
+  set(_SET_CMAKE_ASM_COMPILER_ARCHITECTURE_ID
+    "set(CMAKE_ASM${ASM_DIALECT}_COMPILER_ARCHITECTURE_ID ${CMAKE_ASM${ASM_DIALECT}_COMPILER_ARCHITECTURE_ID})")
+else()
+  set(_SET_CMAKE_ASM_COMPILER_ARCHITECTURE_ID "")
+endif()
+
 # configure variables set in this file for fast reload later on
 configure_file(${CMAKE_ROOT}/Modules/CMakeASMCompiler.cmake.in
   ${CMAKE_PLATFORM_INFO_DIR}/CMakeASM${ASM_DIALECT}Compiler.cmake @ONLY)

Modules/CMakeDetermineCCompiler.cmake

@@ -170,6 +170,13 @@ set(_CMAKE_PROCESSING_LANGUAGE "C")
 include(Compiler/${CMAKE_C_COMPILER_ID}-FindBinUtils OPTIONAL)
 unset(_CMAKE_PROCESSING_LANGUAGE)
 
+if(CMAKE_C_COMPILER_ARCHITECTURE_ID)
+  set(_SET_CMAKE_C_COMPILER_ARCHITECTURE_ID
+    "set(CMAKE_C_COMPILER_ARCHITECTURE_ID ${CMAKE_C_COMPILER_ARCHITECTURE_ID})")
+else()
+  set(_SET_CMAKE_C_COMPILER_ARCHITECTURE_ID "")
+endif()
+
 if(MSVC_C_ARCHITECTURE_ID)
   set(SET_MSVC_C_ARCHITECTURE_ID
     "set(MSVC_C_ARCHITECTURE_ID ${MSVC_C_ARCHITECTURE_ID})")

Modules/CMakeDetermineCXXCompiler.cmake

@@ -165,6 +165,13 @@ set(_CMAKE_PROCESSING_LANGUAGE "CXX")
 include(Compiler/${CMAKE_CXX_COMPILER_ID}-FindBinUtils OPTIONAL)
 unset(_CMAKE_PROCESSING_LANGUAGE)
 
+if(CMAKE_CXX_COMPILER_ARCHITECTURE_ID)
+  set(_SET_CMAKE_CXX_COMPILER_ARCHITECTURE_ID
+    "set(CMAKE_CXX_COMPILER_ARCHITECTURE_ID ${CMAKE_CXX_COMPILER_ARCHITECTURE_ID})")
+else()
+  set(_SET_CMAKE_CXX_COMPILER_ARCHITECTURE_ID "")
+endif()
+
 if(MSVC_CXX_ARCHITECTURE_ID)
   set(SET_MSVC_CXX_ARCHITECTURE_ID
     "set(MSVC_CXX_ARCHITECTURE_ID ${MSVC_CXX_ARCHITECTURE_ID})")

Modules/CMakeDetermineCompilerId.cmake

@@ -102,6 +102,7 @@ function(CMAKE_DETERMINE_COMPILER_ID lang flagvar src)
 
   set(CMAKE_${lang}_COMPILER_ID "${CMAKE_${lang}_COMPILER_ID}" PARENT_SCOPE)
   set(CMAKE_${lang}_PLATFORM_ID "${CMAKE_${lang}_PLATFORM_ID}" PARENT_SCOPE)
+  set(CMAKE_${lang}_COMPILER_ARCHITECTURE_ID "${CMAKE_${lang}_COMPILER_ARCHITECTURE_ID}" PARENT_SCOPE)
   set(MSVC_${lang}_ARCHITECTURE_ID "${MSVC_${lang}_ARCHITECTURE_ID}"
     PARENT_SCOPE)
   set(CMAKE_${lang}_XCODE_CURRENT_ARCH "${CMAKE_${lang}_XCODE_CURRENT_ARCH}" PARENT_SCOPE)
@@ -576,6 +577,7 @@ function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
     if(COMPILER_ID AND NOT COMPILER_ID_TWICE)
       set(CMAKE_${lang}_COMPILER_ID "${COMPILER_ID}")
       set(CMAKE_${lang}_PLATFORM_ID "${PLATFORM_ID}")
+      set(CMAKE_${lang}_COMPILER_ARCHITECTURE_ID "${ARCHITECTURE_ID}")
       set(MSVC_${lang}_ARCHITECTURE_ID "${ARCHITECTURE_ID}")
       set(CMAKE_${lang}_COMPILER_VERSION "${COMPILER_VERSION}")
       set(CMAKE_${lang}_SIMULATE_ID "${SIMULATE_ID}")
@@ -625,6 +627,7 @@ function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
   # Return the information extracted.
   set(CMAKE_${lang}_COMPILER_ID "${CMAKE_${lang}_COMPILER_ID}" PARENT_SCOPE)
   set(CMAKE_${lang}_PLATFORM_ID "${CMAKE_${lang}_PLATFORM_ID}" PARENT_SCOPE)
+  set(CMAKE_${lang}_COMPILER_ARCHITECTURE_ID "${CMAKE_${lang}_COMPILER_ARCHITECTURE_ID}" PARENT_SCOPE)
   set(MSVC_${lang}_ARCHITECTURE_ID "${MSVC_${lang}_ARCHITECTURE_ID}"
     PARENT_SCOPE)
   set(CMAKE_${lang}_COMPILER_VERSION "${CMAKE_${lang}_COMPILER_VERSION}" PARENT_SCOPE)

Modules/CMakeDetermineFortranCompiler.cmake

@@ -261,6 +261,13 @@ set(_CMAKE_PROCESSING_LANGUAGE "Fortran")
 include(Compiler/${CMAKE_Fortran_COMPILER_ID}-FindBinUtils OPTIONAL)
 unset(_CMAKE_PROCESSING_LANGUAGE)
 
+if(CMAKE_Fortran_COMPILER_ARCHITECTURE_ID)
+  set(_SET_CMAKE_Fortran_COMPILER_ARCHITECTURE_ID
+    "set(CMAKE_Fortran_COMPILER_ARCHITECTURE_ID ${CMAKE_Fortran_COMPILER_ARCHITECTURE_ID})")
+else()
+  set(_SET_CMAKE_Fortran_COMPILER_ARCHITECTURE_ID "")
+endif()
+
 if(MSVC_Fortran_ARCHITECTURE_ID)
   set(SET_MSVC_Fortran_ARCHITECTURE_ID
     "set(MSVC_Fortran_ARCHITECTURE_ID ${MSVC_Fortran_ARCHITECTURE_ID})")

Modules/CMakeFortranCompiler.cmake.in

@@ -6,6 +6,7 @@ set(CMAKE_Fortran_COMPILER_WRAPPER "@CMAKE_Fortran_COMPILER_WRAPPER@")
 set(CMAKE_Fortran_PLATFORM_ID "@CMAKE_Fortran_PLATFORM_ID@")
 set(CMAKE_Fortran_SIMULATE_ID "@CMAKE_Fortran_SIMULATE_ID@")
 set(CMAKE_Fortran_SIMULATE_VERSION "@CMAKE_Fortran_SIMULATE_VERSION@")
+@_SET_CMAKE_Fortran_COMPILER_ARCHITECTURE_ID@
 @SET_MSVC_Fortran_ARCHITECTURE_ID@
 set(CMAKE_AR "@CMAKE_AR@")
 set(CMAKE_Fortran_COMPILER_AR "@CMAKE_Fortran_COMPILER_AR@")