[clang] [CIR] Upstream Exception Attr in CallOp (PR #164964)

[Andy Kaylor via cfe-commits]

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@@ -729,9 +735,15 @@ static mlir::ParseResult parseCallCommon(mlir::OpAsmParser &parser,
   if (parser.parseRParen())
     return mlir::failure();
 
-  if (parser.parseOptionalKeyword("nothrow").succeeded())
+  llvm::SMLoc optionalNothrowLoc = parser.getCurrentLocation();
+  if (parser.parseOptionalKeyword("nothrow").succeeded()) {
+    if (hasExceptions)
+      return parser.emitError(
+          optionalNothrowLoc,
+          "should have either `exception` or `nothrow`, but not both");
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andykaylor wrote:

It's not clear to me why we need both of these. Can we not just assume that the absence of 'nothrow' means 'maythrow'?

https://github.com/llvm/llvm-project/pull/164964