"field": control of accessor parameter name shadowing, test

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -379,6 +379,7 @@ public interface Errors {
     // General
 
     DiagnosticFactory1<PsiElement, String> NAME_SHADOWING = DiagnosticFactory1.create(WARNING, PositioningStrategies.FOR_REDECLARATION);
+    DiagnosticFactory0<PsiElement> ACCESSOR_PARAMETER_NAME_SHADOWING = DiagnosticFactory0.create(WARNING);
 
     DiagnosticFactory0<JetExpression> TYPECHECKER_HAS_RUN_INTO_RECURSIVE_PROBLEM = DiagnosticFactory0.create(ERROR);
 

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -114,6 +114,7 @@ public class DefaultErrorMessages {
 
         MAP.put(REDECLARATION, "Redeclaration: {0}", STRING);
         MAP.put(NAME_SHADOWING, "Name shadowed: {0}", STRING);
+        MAP.put(ACCESSOR_PARAMETER_NAME_SHADOWING, "Accessor parameter name 'field' is shadowed by backing field variable");
 
         MAP.put(TYPE_MISMATCH, "Type mismatch: inferred type is {1} but {0} was expected", RENDER_TYPE, RENDER_TYPE);
         MAP.put(INCOMPATIBLE_MODIFIERS, "Modifier ''{0}'' is incompatible with ''{1}''", TO_STRING, TO_STRING);

compiler/frontend/src/org/jetbrains/kotlin/resolve/BodyResolver.java

@@ -779,6 +779,11 @@ public class BodyResolver {
             SyntheticFieldDescriptor fieldDescriptor = new SyntheticFieldDescriptor(accessorDescriptor, property);
             WritableScopeStorage innerScopeStorage = (WritableScopeStorage) innerScope;
             innerScopeStorage.addVariableOrClassDescriptor(fieldDescriptor);
+            for (JetParameter parameter : function.getValueParameters()) {
+                if (SyntheticFieldDescriptor.NAME.equals(parameter.getNameAsName())) {
+                    trace.report(Errors.ACCESSOR_PARAMETER_NAME_SHADOWING.on(parameter));
+                }
+            }
         }
 
         DataFlowInfo dataFlowInfo = null;

compiler/testData/diagnostics/tests/backingField/FieldAsParam.kt

@@ -0,0 +1,8 @@
+var y: Int = 1
+
+// No backing field!
+<!MUST_BE_INITIALIZED!>var x: Int<!>
+    get() = y
+    set(<!ACCESSOR_PARAMETER_NAME_SHADOWING!>field<!>) {
+        y = field
+    }

compiler/testData/diagnostics/tests/backingField/FieldAsParam.txt

@@ -0,0 +1,4 @@
+package
+
+public var x: kotlin.Int
+public var y: kotlin.Int

compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java

@@ -1326,6 +1326,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("FieldAsParam.kt")
+            public void testFieldAsParam() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/backingField/FieldAsParam.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("FieldAsProperty.kt")
             public void testFieldAsProperty() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/backingField/FieldAsProperty.kt");