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

[Aaron Ballman via cfe-commits]

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@@ -0,0 +1,97 @@
+============================
+Warning suppression mappings
+============================
+
+.. contents::
+   :local:
+
+Introduction
+============
+
+Warning suppression mappings enable 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 some headers.
+
+Goal and usage
+==============
+
+Clang allows diagnostics to be configured at a translation-unit granularity.
+If a ``foo.cpp`` is compiled with ``-Wfoo``, all transitively included headers
+also need to be clean. Hence turning on new warnings in large codebases requires
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AaronBallman wrote:

Add comma: Hence, turning on

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