[Mlir-commits] [mlir] [mlir] Fix crash in diagnostic verifier for unmatched @unknown expectations (PR #186148)

[llvmlistbot at llvm.org]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-mlir

@llvm/pr-subscribers-mlir-core

Author: Mehdi Amini (joker-eph)

<details>
<summary>Changes</summary>

When an expected-* directive uses the @<!-- -->unknown location specifier, the associated ExpectedDiag record has an invalid (null) SMLoc as its fileLoc. If the expected diagnostic is never produced, emitError() is called to report the unmatched expectation, but it unconditionally constructs an SMRange from fileLoc, triggering a null-pointer dereference (UBSan) and an assertion failure in SMRange's constructor which requires both endpoints to have equal validity.

Fix by guarding the SMRange construction with a fileLoc.isValid() check. When fileLoc is invalid, call PrintMessage without a source range.

Fixes #<!-- -->163343

Assisted-by: Claude Code

---
Full diff: https://github.com/llvm/llvm-project/pull/186148.diff


2 Files Affected:

- (modified) mlir/lib/IR/Diagnostics.cpp (+11-3) 
- (added) mlir/test/mlir-opt/expected-unknown-loc-unmatched.mlir (+9) 


``````````diff
diff --git a/mlir/lib/IR/Diagnostics.cpp b/mlir/lib/IR/Diagnostics.cpp
index f4c9242ed3479..5caf826c84bdd 100644
--- a/mlir/lib/IR/Diagnostics.cpp
+++ b/mlir/lib/IR/Diagnostics.cpp
@@ -600,9 +600,17 @@ struct ExpectedDiag {
   /// Emit an error at the location referenced by this diagnostic.
   LogicalResult emitError(raw_ostream &os, llvm::SourceMgr &mgr,
                           const Twine &msg) {
-    SMRange range(fileLoc, SMLoc::getFromPointer(fileLoc.getPointer() +
-                                                 substring.size()));
-    mgr.PrintMessage(os, fileLoc, llvm::SourceMgr::DK_Error, msg, range);
+    // fileLoc may be invalid when the expected diagnostic used an unknown
+    // location specifier (e.g. `// expected-error @unknown {{...}}`). In that
+    // case, skip the source range to avoid a null-pointer dereference and an
+    // assertion in SMRange that both endpoints must have the same validity.
+    if (fileLoc.isValid()) {
+      SMRange range(fileLoc, SMLoc::getFromPointer(fileLoc.getPointer() +
+                                                   substring.size()));
+      mgr.PrintMessage(os, fileLoc, llvm::SourceMgr::DK_Error, msg, range);
+    } else {
+      mgr.PrintMessage(os, fileLoc, llvm::SourceMgr::DK_Error, msg);
+    }
     return failure();
   }
 
diff --git a/mlir/test/mlir-opt/expected-unknown-loc-unmatched.mlir b/mlir/test/mlir-opt/expected-unknown-loc-unmatched.mlir
new file mode 100644
index 0000000000000..5a06d386dabf8
--- /dev/null
+++ b/mlir/test/mlir-opt/expected-unknown-loc-unmatched.mlir
@@ -0,0 +1,9 @@
+// Test that an unmatched `expected-*` directive using the `@unknown` location
+// specifier emits a diagnostic instead of crashing.
+// See https://github.com/llvm/llvm-project/issues/163343
+
+// RUN: not mlir-opt --verify-diagnostics %s 2>&1 | FileCheck %s
+
+// CHECK: expected warning "some warning that is never produced" was not produced
+
+// expected-warning @unknown {{some warning that is never produced}}

``````````

</details>


https://github.com/llvm/llvm-project/pull/186148