Report arity errors on user definable operators.

sdk/lib/_internal/compiler/implementation/resolution/members.dart

Index: sdk/lib/_internal/compiler/implementation/resolution/members.dart
diff --git a/sdk/lib/_internal/compiler/implementation/resolution/members.dart b/sdk/lib/_internal/compiler/implementation/resolution/members.dart
index 278e8009aefd1f5e80cbc64889ec83823f4221ee..9b2ee8849df68ed5de221cd93e85c6f00acc6d04 100644
--- a/sdk/lib/_internal/compiler/implementation/resolution/members.dart
+++ b/sdk/lib/_internal/compiler/implementation/resolution/members.dart
@@ -521,6 +521,7 @@ class ResolverTask extends CompilerTask {
       }
       checkAbstractField(member);
       checkValidOverride(member, cls.lookupSuperMember(member.name));
+      checkUserDefinableOperator(member);
     });
   }
 
@@ -589,6 +590,65 @@ class ResolverTask extends CompilerTask {
     }
   }
 
+  void checkUserDefinableOperator(Element member) {
+    FunctionElement function = member.asFunctionElement();
+    if (function == null) return;
+    String value = member.name.stringValue;
+    if (value == null) return;
+    if (!(isUserDefinableOperator(value) || identical(value, 'unary-'))) return;
+
+    FunctionSignature signature = function.computeSignature(compiler);
+    if (identical(value, 'unary-')) {

[ahe, 2013/01/09 10:17:52]

Consider this approach:

int requiredParameterCount;
if (identical(value, 'unary-')) {
  requiredParameterCount = 0;
} else if (isMinusOperator(value) {
  requiredParameterCount = 1;
} ... {
  internalErrorOnElement(function);
}
checkArity(function, requiredParameterCount, 0, 0);

We should be able to reuse the checkArity method with other code and generate
really nice messages, such as:

Error: extra parameter "y". "+" must have exactly 1 parameter.
operator+(x, y) { ... }
             ^

Error: missing parameter. "+" must have exactly 1 parameter.
operator+() { ... }
         ^^

[Johnni Winther, 2013/01/09 13:00:47]

Done.

+      if (signature.requiredParameterCount != 0) {

[ahe, 2013/01/09 10:17:52]

You should be able to assert this.

+        compiler.reportMessage(
+            compiler.spanFromElement(function),
+            MessageKind.MINUS_OPERATOR_BAD_ARITY.error(),
+            Diagnostic.ERROR);
+      }
+    } else if (isMinusOperator(value)) {
+      if (signature.requiredParameterCount != 1) {
+        compiler.reportMessage(
+            compiler.spanFromElement(function),
+            MessageKind.MINUS_OPERATOR_BAD_ARITY.error(),
+            Diagnostic.ERROR);
+      }
+    } else if (isUnaryOperator(value)) {
+      if (signature.requiredParameterCount != 0) {
+        compiler.reportMessage(
+            compiler.spanFromElement(function),
+            MessageKind.UNARY_OPERATOR_BAD_ARITY.error([function.name]),
+            Diagnostic.ERROR);
+      }
+    } else if (isBinaryOperator(value)) {
+      if (signature.requiredParameterCount != 1) {
+        compiler.reportMessage(
+            compiler.spanFromElement(function),
+            MessageKind.BINARY_OPERATOR_BAD_ARITY.error([function.name]),
+            Diagnostic.ERROR);
+      }
+    } else if (isTernaryOperator(value)) {
+      if (signature.requiredParameterCount != 2) {
+        compiler.reportMessage(
+            compiler.spanFromElement(function),
+            MessageKind.TERNARY_OPERATOR_BAD_ARITY.error([function.name]),
+            Diagnostic.ERROR);
+      }
+    }

[ahe, 2013/01/09 10:17:52]

else {
  // Internal error.
}

[Johnni Winther, 2013/01/09 13:00:47]

Done.

+    if (signature.optionalParameterCount != 0) {
+      if (signature.optionalParametersAreNamed) {
+        compiler.reportMessage(
+            compiler.spanFromElement(function),

[ahe, 2013/01/09 10:17:52]

There is a more accurate position for the optional parameters.

[Johnni Winther, 2013/01/09 13:00:47]

Done.

+            MessageKind.OPERATOR_NAMED_ARGUMENTS.error([function.name]),
+            Diagnostic.ERROR);
+      } else {
+        compiler.reportMessage(
+            compiler.spanFromElement(function),

[ahe, 2013/01/09 10:17:52]

Ditto.

[Johnni Winther, 2013/01/09 13:00:47]

Done.

+            MessageKind.OPERATOR_OPTIONAL_ARGUMENTS.error([function.name]),
+            Diagnostic.ERROR);
+      }
+    }
+  }
+
   reportErrorWithContext(Element errorneousElement,
                          MessageKind errorMessage,
                          Element contextElement,