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

[Boaz Brickner via cfe-commits]

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@@ -167,4 +176,159 @@ TEST(DiagnosticTest, storedDiagEmptyWarning) {
   // Make sure an empty warning can round-trip with \c StoredDiagnostic.
   Diags.Report(CaptureConsumer.StoredDiags.front());
 }
+
+class SuppressionMappingTest : public testing::Test {
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bricknerb wrote:

Do you also test pragmas here?

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