[clang] [Clang][Driver] Emit warning when -fsanitize-trap=undefined is passed without -fsanitize=undefined (PR #147997)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Anthony Tran (anthonyhatran)

<details>
<summary>Changes</summary>

Part of a GSoC 2025 Project


---
Full diff: https://github.com/llvm/llvm-project/pull/147997.diff


2 Files Affected:

- (modified) clang/include/clang/Basic/DiagnosticDriverKinds.td (+5) 
- (modified) clang/include/clang/Basic/DiagnosticGroups.td (+3) 


``````````diff
diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 34b6c0d7a8acd..49a8bdf06bda4 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -874,4 +874,9 @@ def warn_drv_openacc_without_cir
     : Warning<"OpenACC directives will result in no runtime behavior; use "
               "-fclangir to enable runtime effect">,
       InGroup<SourceUsesOpenACC>;
+
+def warn_drv_sanitize_trap_mismatch : Warning<
+  "-fsanitize-trap=%0 has no effect because the matching sanitizer is not enabled; "
+  "did you mean to pass \"-fsanitize=%0\" as well?">,
+  InGroup<SanitizeTrapMismatch>;
 }
diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
index f54a830b0103e..a79562cd9c2e0 100644
--- a/clang/include/clang/Basic/DiagnosticGroups.td
+++ b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -1752,3 +1752,6 @@ def ExplicitSpecializationStorageClass : DiagGroup<"explicit-specialization-stor
 
 // A warning for options that enable a feature that is not yet complete
 def ExperimentalOption : DiagGroup<"experimental-option">;
+
+// Warnings for sanitizer arguments
+def SanitizeTrapMismatch : DiagGroup<"sanitize-trap-mismatch">;

``````````

</details>


https://github.com/llvm/llvm-project/pull/147997