[mlir][gpu] NFC - Fail gracefully when type conversion fails instead of crashing

Author: nicolasvasilache

mlir/lib/Conversion/GPUCommon/GPUOpsLowering.cpp

@@ -51,9 +51,16 @@ GPUFuncOpLowering::matchAndRewrite(gpu::GPUFuncOp gpuFuncOp, OpAdaptor adaptor,
   // Remap proper input types.
   TypeConverter::SignatureConversion signatureConversion(
       gpuFuncOp.front().getNumArguments());
+
   Type funcType = getTypeConverter()->convertFunctionSignature(
       gpuFuncOp.getFunctionType(), /*isVariadic=*/false,
       getTypeConverter()->getOptions().useBarePtrCallConv, signatureConversion);
+  if (!funcType) {
+    return rewriter.notifyMatchFailure(gpuFuncOp, [&](Diagnostic &diag) {
+      diag << "failed to convert function signature type for: "
+           << gpuFuncOp.getFunctionType();
+    });
+  }
 
   // Create the new function operation. Only copy those attributes that are
   // not specific to function modeling.