[clang] [mlir] [mlir] Diagnose missing call result arrow (PR #206215)

[via cfe-commits]

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@@ -1388,8 +1388,11 @@ static ParseResult parseCallTypeAndResolveOperands(
   }
   SmallVector<Type> argTypes;
   SmallVector<Type> resTypes;
+  SMLoc signatureLoc = parser.getCurrentLocation();
   if (call_interface_impl::parseFunctionSignature(parser, argTypes, argAttrs,
                                                   resTypes, resultAttrs)) {
+    if (parser.getCurrentLocation() != signatureLoc)
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mygitljf wrote:

I added this to keep the existing fallback diagnostic when parsing fails before consuming any of the signature. In the missing `->` case, the parser has already consumed `()` and emitted a more specific error, so without this check we'd also emit the generic `expected direct call...` error.
The nearby `call_missing_ptr_type` test covers the no-progress case. I can add a comment here if that would help.

https://github.com/llvm/llvm-project/pull/206215