release/20.x: [clang] Stop parsing warning suppression mappings in driver (#125722)

[llvmbot]

Backport df22bbe

Requested by: @kadircet

[llvmbot]

@jyknight What do you think about merging this PR to the release branch?

[llvmbot]

@llvm/pr-subscribers-clang-driver

@llvm/pr-subscribers-clang

Author: None (llvmbot)

Changes

Backport df22bbe

Requested by: @kadircet

---

Full diff: https://github.com/llvm/llvm-project/pull/126027.diff

2 Files Affected:

• (added) clang/test/Driver/warning-suppression-mappings-not-parsed.cpp (+5)
• (modified) clang/tools/driver/driver.cpp (+4)

diff --git a/clang/test/Driver/warning-suppression-mappings-not-parsed.cpp b/clang/test/Driver/warning-suppression-mappings-not-parsed.cpp
new file mode 100644
index 000000000000000..8f52fb1c6cc7d6c
--- /dev/null
+++ b/clang/test/Driver/warning-suppression-mappings-not-parsed.cpp
@@ -0,0 +1,5 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: echo '[unknown-warning]' > %t/foo.txt
+// RUN: %clang -fdriver-only --warning-suppression-mappings=%t/foo.txt %s | FileCheck -allow-empty %s
+// CHECK-NOT: unknown warning option 'unknown-warning'
diff --git a/clang/tools/driver/driver.cpp b/clang/tools/driver/driver.cpp
index 74923247b7ee169..00c00cea16f470f 100644
--- a/clang/tools/driver/driver.cpp
+++ b/clang/tools/driver/driver.cpp
@@ -318,6 +318,10 @@ int clang_main(int Argc, char **Argv, const llvm::ToolContext &ToolContext) {
 
   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts =
       CreateAndPopulateDiagOpts(Args);
+  // Driver's diagnostics don't use suppression mappings, so don't bother
+  // parsing them. CC1 still receives full args, so this doesn't impact other
+  // actions.
+  DiagOpts->DiagnosticSuppressionMappingsFile.clear();
 
   TextDiagnosticPrinter *DiagClient
     = new TextDiagnosticPrinter(llvm::errs(), &*DiagOpts);

[github-actions]

@kadircet (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR.