[flang] [llvm] [mlir] [flang][MLIR][OpenMP] make reduction by-ref toggled per variable (PR #92244)

[Tom Eccles via llvm-commits]

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@@ -1488,6 +1520,13 @@ LogicalResult ParallelOp::verify() {
   if (failed(verifyPrivateVarList(*this)))
     return failure();
 
+  auto reductionVarsByRef = getReductionVarsByref();
+  if (reductionVarsByRef &&
+      reductionVarsByRef->size() != getReductionVars().size())
+    return emitOpError()
+           << "expected as many reduction variable by reference attributes "
+              "as reduction variables";
+
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tblah wrote:

I couldn't think of a way to test for this error because we can't write text-form IR like this. I would have to create the operation with C++ like in a unit test, but I didn't know how to catch an error from a unit test.

https://github.com/llvm/llvm-project/pull/92244