[flang-commits] [flang] [flang] Fix crash on erroneous program (PR #88192)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-flang-semantics

Author: Peter Klausler (klausler)

<details>
<summary>Changes</summary>

Constant folding had a CHECK on array subscript rank that should more gracefully handle a bad program with a subscript that is a matrix or higher rank.

Fixes https://github.com/llvm/llvm-project/issues/88112.

---
Full diff: https://github.com/llvm/llvm-project/pull/88192.diff


1 Files Affected:

- (modified) flang/lib/Evaluate/fold-implementation.h (+2-1) 


``````````diff
diff --git a/flang/lib/Evaluate/fold-implementation.h b/flang/lib/Evaluate/fold-implementation.h
index 470dbe9e740997..543d415209271b 100644
--- a/flang/lib/Evaluate/fold-implementation.h
+++ b/flang/lib/Evaluate/fold-implementation.h
@@ -201,11 +201,12 @@ std::optional<Constant<T>> Folder<T>::ApplySubscripts(const Constant<T> &array,
   ConstantSubscripts resultShape;
   ConstantSubscripts ssLB;
   for (const auto &ss : subscripts) {
-    CHECK(ss.Rank() <= 1);
     if (ss.Rank() == 1) {
       resultShape.push_back(static_cast<ConstantSubscript>(ss.size()));
       elements *= ss.size();
       ssLB.push_back(ss.lbounds().front());
+    } else if (ss.Rank() > 1) {
+      return std::nullopt; // error recovery
     }
   }
   ConstantSubscripts ssAt(rank, 0), at(rank, 0), tmp(1, 0);

``````````

</details>


https://github.com/llvm/llvm-project/pull/88192