[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 {
+public:
+  SuppressionMappingTest() {
+    Diags.setClient(&CaptureConsumer, /*ShouldOwnClient=*/false);
+  }
+
+protected:
+  llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> FS =
+      llvm::makeIntrusiveRefCnt<llvm::vfs::InMemoryFileSystem>();
+  DiagnosticsEngine Diags{new DiagnosticIDs(), new DiagnosticOptions};
+
+  std::vector<StoredDiagnostic> takeDiags() {
+    return std::move(CaptureConsumer.StoredDiags);
+  }
+
+private:
+  class CaptureDiagnosticConsumer : public DiagnosticConsumer {
+  public:
+    std::vector<StoredDiagnostic> StoredDiags;
+
+    void HandleDiagnostic(DiagnosticsEngine::Level level,
+                          const Diagnostic &Info) override {
+      StoredDiags.push_back(StoredDiagnostic(level, Info));
+    }
+  };
+  CaptureDiagnosticConsumer CaptureConsumer;
+};
+
+MATCHER_P(WithMessage, Msg, "has diagnostic message") {
+  return arg.getMessage() == Msg;
+}
+
+TEST_F(SuppressionMappingTest, MissingMappingFile) {
+  Diags.getDiagnosticOptions().DiagnosticSuppressionMappingsFile = "foo.txt";
+  clang::ProcessWarningOptions(Diags, Diags.getDiagnosticOptions(), *FS);
+  EXPECT_THAT(takeDiags(), testing::ElementsAre(WithMessage(
+                               "no such file or directory: 'foo.txt'")));
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bricknerb wrote:

Why do we only test the message and not also level and possibly other fields?

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