Return error status when number of operands don't match while parsing.

Previously an error would be emitted but parsing would continue as false was being returned.

PiperOrigin-RevId: 212192167

mlir/lib/Parser/Parser.cpp

@@ -1832,8 +1832,8 @@ public:
     }
 
     if (requiredOperandCount != -1 && result.size() != requiredOperandCount)
-      emitError(startLoc,
-                "expected " + Twine(requiredOperandCount) + " operands");
+      return emitError(startLoc,
+                       "expected " + Twine(requiredOperandCount) + " operands");
     return false;
   }
 

mlir/test/IR/invalid-ops.mlir

@@ -121,3 +121,10 @@ mlfunc @calls(%arg0 : i32) {
   %x = call @calls() : () -> i32  // expected-error {{reference to function with mismatched type}}
   return
 }
+
+// -----
+
+cfgfunc @cfgfunc_with_ops(f32) {
+bb0(%a : f32):
+  %sf = addf(%a, %a) : f32  // expected-error {{custom op 'addf' expected 2 operands}}
+}