Provide CMAKE_<LANG>_COMPILER_ARCHITECTURE_ID on more compilers

Provide it whenever we can detect a target architecture from the
compiler during compiler inspection.  In order to avoid changing
existing IDs, do this only for compilers where we don't already
detect a target architecture during compiler identification.

Fixes: #17702

Help/variable/CMAKE_LANG_COMPILER_ARCHITECTURE_ID.rst

@@ -3,11 +3,149 @@ CMAKE_<LANG>_COMPILER_ARCHITECTURE_ID
 
 .. versionadded:: 3.10
 
-Identifier indicating the
-target architecture of the compiler for language ``<LANG>``.
+:ref:`List <CMake Language Lists>` of identifiers indicating the
+target architecture(s) of the compiler for language ``<LANG>``.
+
+Typically the list has one entry unless :variable:`CMAKE_OSX_ARCHITECTURES`
+lists multiple architectures.
 
 Possible values for each platform are documented in the following sections.
 
+.. Sync with:
+     Modules/CMakeCompilerABI.h
+     Modules/CMakeFortranCompilerABI.F
+     Modules/CMakeFortranCompilerABI.F90
+     Modules/Internal/CMakeParseCompilerArchitectureId.cmake
+
+Apple Platforms
+^^^^^^^^^^^^^^^
+
+.. versionadded:: 4.1
+
+These identifiers are used when the :variable:`CMAKE_<LANG>_COMPILER`
+targets an Apple platform (``__APPLE__`` is defined).
+
+``arm64``
+  ARM 64-bit
+
+``arm64e``
+  ARM 64-bit with Pointer Authentication (PACs)
+
+``arm64_32``
+  ARM 64-bit with 32-bit pointers (watchOS)
+
+``armv5``, ``armv6``, ``armv7``, ``armv7k``, ``armv7s``
+  ARM 32-bit
+
+``i386``, ``i486``, ``i586``, ``i686``
+  Intel 32-bit
+
+``ppc``
+  PowerPC 32-bit
+
+``x86_64``
+  Intel 64-bit
+
+UNIX Platforms
+^^^^^^^^^^^^^^
+
+.. versionadded:: 4.1
+
+These identifiers are used when the :variable:`CMAKE_<LANG>_COMPILER`
+targets a UNIX platform.
+
+``aarch64``
+  ARM 64-bit
+
+``alpha``
+  DEC Alpha
+
+``armv5``, ``armv6``, ``armv7``
+  ARM 32-bit
+
+``i386``, ``i486``, ``i586``, ``i686``
+  Intel 32-bit
+
+``ia64``
+  Itanium 64-bit
+
+``loongarch32``
+  LoongArch 32-bit
+
+``loongarch64``
+  LoongArch 64-bit
+
+``m68k``
+  Motorola 68000
+
+``mips``
+  MIPS 32-bit big-endian
+
+``mipsel``
+  MIPS 32-bit little-endian
+
+``mips64``
+  MIPS 64-bit big-endian
+
+``mips64el``
+  MIPS 64-bit little-endian
+
+``parisc``
+  PA-RISC 32-bit
+
+``parisc64``
+  PA-RISC 64-bit
+
+``ppc``
+  PowerPC 32-bit big-endian
+
+``ppcle``
+  PowerPC 32-bit little-endian
+
+``ppc64``
+  PowerPC 64-bit big-endian
+
+``ppc64le``
+  PowerPC 64-bit little-endian
+
+``riscv32``
+  RISC-V 32-bit
+
+``riscv64``
+  RISC-V 64-bit
+
+``s390``, ``s390x``
+  IBM Z
+
+``sparc``
+  SPARC 32-bit
+
+``sparcv9``
+  SPARC 64-bit
+
+``x86_64``
+  Intel 64-bit
+
+Windows Platforms with GNU ABI (MinGW)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. versionadded:: 4.1
+
+These identifiers are used when the :variable:`CMAKE_<LANG>_COMPILER`
+targets Windows with a GNU ABI (``_WIN32`` and ``__MINGW32__`` are defined).
+
+``aarch64``
+  ARM 64-bit
+
+``armv7``
+  ARM 32-bit
+
+``i386``, ``i486``, ``i586``, ``i686``
+  Intel 32-bit
+
+``x86_64``
+  Intel 64-bit
+
 Windows Platforms with MSVC ABI
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^