[clang] [clang-tools-extra] [llvm] [clang] Introduce diagnostics suppression mappings (PR #112517)

[kadir çetinkaya via cfe-commits]

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@@ -1315,6 +1319,29 @@ with its corresponding `Wno-` option.
 Note that when combined with :option:`-w` (which disables all warnings),
 disabling all warnings wins.
 
+.. _warning_suppression_mappings:
+
+Controlling Diagnostics via Suppression Mappings
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Warning suppression mappings enables users to suppress clang's diagnostics in a
+per-file granular manner. Enabling enforcement of diagnostics in specific parts
+of the project, even if there are violations in dependencies or other parts of
+the codebase.
+
+.. code-block:: console
+
+  $ cat mappings.txt
+  [unused]
+  src:foo/*
+
+  $ clang --warning-suppression-mappings=mapping.txt -Wunused foo/bar.cc
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kadircet wrote:

I think this feature isn't about the root of the translation unit, but rather about headers included (hence I was using "dependencies") in a translation unit. hence we should keep the example usage focused there as well. Added some more meat to example, PTAL.

https://github.com/llvm/llvm-project/pull/112517