Document the new options

Author: sharadhr

clang/docs/StandardCPlusPlusModules.rst

@@ -398,6 +398,13 @@ BMIs cannot be shipped in an archive to create a module library. Instead, the
 BMIs(``*.pcm``) are compiled into object files(``*.o``) and those object files
 are added to the archive instead.
 
+clang-cl
+~~~~~~~~
+
+``clang-cl`` supports the same options as ``clang++`` for modules as detailed above;
+there is no need to prefix these options with ``/clang:``. Note that ``cl.exe``
+options to emit `IFC files <https://devblogs.microsoft.com/cppblog/using-cpp-modules-in-msvc-from-the-command-line-part-1/>` are *not* supported. The precompiled modules are also not compatible for use with ``cl.exe``.
+
 Consistency Requirements
 ~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -1176,12 +1183,12 @@ have ``.cppm`` (or ``.ccm``, ``.cxxm``, ``.c++m``) as the file extension.
 However, the behavior is inconsistent with other compilers. This is tracked by
 `#57416 <https://github.com/llvm/llvm-project/issues/57416>`_.
 
-clang-cl is not compatible with standard C++ modules
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.. clang-cl is not compatible with standard C++ modules
+.. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-``/clang:-fmodule-file`` and ``/clang:-fprebuilt-module-path`` cannot be used
-to specify the BMI with ``clang-cl.exe``. This is tracked by
-`#64118 <https://github.com/llvm/llvm-project/issues/64118>`_.
+.. ``/clang:-fmodule-file`` and ``/clang:-fprebuilt-module-path`` cannot be used
+.. to specify the BMI with ``clang-cl.exe``. This is tracked by
+.. `#64118 <https://github.com/llvm/llvm-project/issues/64118>`_.
 
 Incorrect ODR violation diagnostics
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

clang/docs/UsersManual.rst

@@ -4732,6 +4732,12 @@ Execute ``clang-cl /?`` to see a list of supported options:
       -flto=<value>           Set LTO mode to either 'full' or 'thin'
       -flto                   Enable LTO in 'full' mode
       -fmerge-all-constants   Allow merging of constants
+      -fmodule-file=<module_name>=<module-file>
+                              Use the specified module file that provides the module <module_name>
+      -fmodule-header=<header>
+                              Build <header> as a C++20 header unit
+      -fmodule-output=<path>
+                              Save intermediate module file results when compiling a standard C++ module unit.
       -fms-compatibility-version=<value>
                               Dot-separated value representing the Microsoft compiler version
                               number to report in _MSC_VER (0 = don't define it; default is same value as installed cl.exe, or 1933)