[clang] Document runtime config directory options (PR #66593)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

<details>
<summary>Changes</summary>

In the clang user manual the build options `CLANG_CONFIG_FILE_USER_DIR` and `CLANG_CONFIG_FILE_SYSTEM_DIR` are documented, but the run time overrides `--config-user-dir` and `--config-system-dir` are not.

I have updated the manual to add these run time arguments.
---
Full diff: https://github.com/llvm/llvm-project/pull/66593.diff


1 Files Affected:

- (modified) clang/docs/UsersManual.rst (+7-4) 


``````````diff
diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
index 25bbd72c81f7a3b..e180f77793e80b7 100644
--- a/clang/docs/UsersManual.rst
+++ b/clang/docs/UsersManual.rst
@@ -944,10 +944,13 @@ treated as a file name and is searched for sequentially in the directories:
     - system directory,
     - the directory where Clang executable resides.
 
-Both user and system directories for configuration files are specified during
-clang build using CMake parameters, ``CLANG_CONFIG_FILE_USER_DIR`` and
-``CLANG_CONFIG_FILE_SYSTEM_DIR`` respectively. The first file found is used.
-It is an error if the required file cannot be found.
+Both user and system directories for configuration files can be specified
+either during build or during runtime. At build time, use
+``CLANG_CONFIG_FILE_USER_DIR`` and ``CLANG_CONFIG_FILE_SYSTEM_DIR``. At run
+time use the ``--config-user-dir=`` and ``--config-system-dir=`` command line
+options. Specifying config directories at runtime overrides the config
+directories set at build time The first file found is used. It is an error if
+the required file cannot be found.
 
 The default configuration files are searched for in the same directories
 following the rules described in the next paragraphs. Loading default

``````````

</details>


https://github.com/llvm/llvm-project/pull/66593