Highlighting "as Foo" for useless casts in gray.

#KT-6070 fixed

compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/Errors.java

@@ -530,8 +530,8 @@ public interface Errors {
     DiagnosticFactory1<JetElement, JetType> CANNOT_CHECK_FOR_ERASED = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory2<JetBinaryExpressionWithTypeRHS, JetType, JetType> UNCHECKED_CAST = DiagnosticFactory2.create(WARNING);
 
-    DiagnosticFactory0<JetSimpleNameExpression> USELESS_CAST_STATIC_ASSERT_IS_FINE = DiagnosticFactory0.create(WARNING);
-    DiagnosticFactory0<JetSimpleNameExpression> USELESS_CAST = DiagnosticFactory0.create(WARNING);
+    DiagnosticFactory0<JetBinaryExpressionWithTypeRHS> USELESS_CAST_STATIC_ASSERT_IS_FINE = DiagnosticFactory0.create(WARNING, AS_TYPE);
+    DiagnosticFactory0<JetBinaryExpressionWithTypeRHS> USELESS_CAST = DiagnosticFactory0.create(WARNING, AS_TYPE);
     DiagnosticFactory0<JetSimpleNameExpression> CAST_NEVER_SUCCEEDS = DiagnosticFactory0.create(WARNING);
     DiagnosticFactory0<JetTypeReference> DYNAMIC_NOT_ALLOWED = DiagnosticFactory0.create(ERROR);
 
@@ -631,7 +631,7 @@ public interface Errors {
             INVISIBLE_MEMBER, INVISIBLE_MEMBER_FROM_INLINE, INVISIBLE_REFERENCE, INVISIBLE_SETTER);
     ImmutableSet<? extends DiagnosticFactory<?>> UNUSED_ELEMENT_DIAGNOSTICS = ImmutableSet.of(
             UNUSED_VARIABLE, UNUSED_PARAMETER, ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE, VARIABLE_WITH_REDUNDANT_INITIALIZER,
-            UNUSED_FUNCTION_LITERAL);
+            UNUSED_FUNCTION_LITERAL, USELESS_CAST, USELESS_CAST_STATIC_ASSERT_IS_FINE);
     ImmutableSet<? extends DiagnosticFactory<?>> TYPE_INFERENCE_ERRORS = ImmutableSet.of(
             TYPE_INFERENCE_NO_INFORMATION_FOR_PARAMETER, TYPE_INFERENCE_CONFLICTING_SUBSTITUTIONS, TYPE_INFERENCE_TYPE_CONSTRUCTOR_MISMATCH,
             TYPE_INFERENCE_UPPER_BOUND_VIOLATED, TYPE_INFERENCE_EXPECTED_TYPE_MISMATCH);

compiler/frontend/src/org/jetbrains/jet/lang/diagnostics/PositioningStrategies.kt

@@ -365,4 +365,10 @@ public object PositioningStrategies {
             return Errors.UNREACHABLE_CODE.cast(diagnostic).getA()
         }
     }
+
+    public val AS_TYPE: PositioningStrategy<JetBinaryExpressionWithTypeRHS> = object : PositioningStrategy<JetBinaryExpressionWithTypeRHS>() {
+        override fun mark(element: JetBinaryExpressionWithTypeRHS): List<TextRange> {
+            return markRange(element.getOperationReference(), element)
+        }
+    }
 }

compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/BasicExpressionTypingVisitor.java

@@ -223,14 +223,14 @@ public class BasicExpressionTypingVisitor extends ExpressionTypingVisitor {
         JetTypeChecker typeChecker = JetTypeChecker.DEFAULT;
         if (actualType.equals(targetType)) {
             // cast to itself: String as String
-            context.trace.report(USELESS_CAST.on(expression.getOperationReference()));
+            context.trace.report(USELESS_CAST.on(expression));
             return;
         }
         Collection<JetType> possibleTypes = DataFlowUtils.getAllPossibleTypes(
                 expression.getLeft(), context.dataFlowInfo, actualType, context.trace.getBindingContext());
         for (JetType possibleType : possibleTypes) {
             if (typeChecker.isSubtypeOf(possibleType, targetType)) {
-                context.trace.report(USELESS_CAST_STATIC_ASSERT_IS_FINE.on(expression.getOperationReference()));
+                context.trace.report(USELESS_CAST_STATIC_ASSERT_IS_FINE.on(expression));
                 return;
             }
         }