Help: Document CMAKE_<LANG>_COMPILER_ARCHITECTURE_ID

Issue: #17702

Help/manual/cmake-variables.7.rst

@@ -73,6 +73,7 @@ Variables that Provide Information
    /variable/CMAKE_JOB_POOL_PRECOMPILE_HEADER
    /variable/CMAKE_JOB_POOLS
    /variable/CMAKE_LANG_COMPILER_AR
+   /variable/CMAKE_LANG_COMPILER_ARCHITECTURE_ID
    /variable/CMAKE_LANG_COMPILER_FRONTEND_VARIANT
    /variable/CMAKE_LANG_COMPILER_LINKER
    /variable/CMAKE_LANG_COMPILER_LINKER_FRONTEND_VARIANT
@@ -815,7 +816,6 @@ are subject to change, and not recommended for use in project code.
    /variable/CMAKE_HOME_DIRECTORY
    /variable/CMAKE_INTERNAL_PLATFORM_ABI
    /variable/CMAKE_LANG_COMPILER_ABI
-   /variable/CMAKE_LANG_COMPILER_ARCHITECTURE_ID
    /variable/CMAKE_LANG_COMPILER_VERSION_INTERNAL
    /variable/CMAKE_LANG_LINKER_PREFERENCE
    /variable/CMAKE_LANG_LINKER_PREFERENCE_PROPAGATES

Help/variable/CMAKE_LANG_COMPILER_ARCHITECTURE_ID.rst

@@ -3,8 +3,166 @@ CMAKE_<LANG>_COMPILER_ARCHITECTURE_ID
 
 .. versionadded:: 3.10
 
-An internal variable subject to change.
+Identifier indicating the
+target architecture of the compiler for language ``<LANG>``.
 
-This is used to identify the variant of a compiler based on its target
+Possible values for each platform are documented in the following sections.
-architecture.  For some compilers this is needed to determine the correct
+
-usage.
+Windows Platforms with MSVC ABI
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. versionadded:: 3.10
+
+These identifiers are used when the :variable:`CMAKE_<LANG>_COMPILER`
+targets Windows with a MSVC ABI (``_WIN32`` and ``_MSC_VER`` are defined).
+
+``ARM64``
+  ARM 64-bit
+
+``ARM64EC``
+  ARM 64-bit Emulation-Compatible
+
+``ARMV4I``, ``ARMV5I``, ``ARMV7``
+  ARM 32-bit
+
+``IA64``
+  Itanium 64-bit
+
+``MIPS``
+  MIPS
+
+``SHx``, ``SH3``, ``SH3DSP``, ``SH4``, ``SH5``
+  SuperH
+
+``x64``
+  Intel 64-bit
+
+``X86``
+  Intel 32-bit
+
+Windows Platforms with Watcom ABI
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. versionadded:: 3.10
+
+These identifiers are used when :variable:`CMAKE_<LANG>_COMPILER_ID` is
+``OpenWatcom`` or ``Watcom``.
+
+``I86``
+  Intel 16-bit
+
+``X86``
+  Intel 32-bit
+
+Green Hills MULTI Platforms
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. versionadded:: 3.14
+
+These identifiers are used when :variable:`CMAKE_<LANG>_COMPILER_ID` is
+``GHS``.
+
+``ARM``
+  ARM 32-bit
+
+``PPC``
+  PowerPC 32-bit
+
+``PPC64``
+  PowerPC 64-bit
+
+``x64``
+  Intel 64-bit
+
+``X86``
+  Intel 32-bit
+
+IAR Platforms
+^^^^^^^^^^^^^
+
+.. versionadded:: 3.10
+
+These identifiers are used when :variable:`CMAKE_<LANG>_COMPILER_ID` is
+``IAR``.
+
+``8051``
+  ..
+
+``ARM``
+  ..
+
+``AVR``
+  ..
+
+``MSP430``
+  ..
+
+``RH850``
+  ..
+
+``RISCV``
+  ..
+
+``RL78``
+  ..
+
+``RX``
+  ..
+
+``STM8``
+  ..
+
+``V850``
+  ..
+
+TASKING Platforms
+^^^^^^^^^^^^^^^^^
+
+.. versionadded:: 3.25
+
+These identifiers are used when :variable:`CMAKE_<LANG>_COMPILER_ID` is
+``Tasking``.
+
+``8051``
+  ..
+
+``ARC``
+  ..
+
+``ARM``
+  ..
+
+``MCS``
+  ..
+
+``PCP``
+  ..
+
+``TriCore``
+  ..
+
+Texas Instruments Platforms
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. versionadded:: 3.19
+
+These identifiers are used when :variable:`CMAKE_<LANG>_COMPILER_ID` is
+``TI``.
+
+``ARM``
+  ..
+
+``Blackfin``
+  ..
+
+``MSP430``
+  ..
+
+``SHARC``
+  ..
+
+``TMS320C28x``
+  ..
+
+``TMS320C6x``
+  ..