bug with automatically casting mutable variables (KT-228) fixed

idea/src/org/jetbrains/jet/lang/descriptors/LocalVariableDescriptor.java

@@ -12,6 +12,7 @@ import java.util.List;
  * @author abreslav
  */
 public class LocalVariableDescriptor extends VariableDescriptorImpl {
+    private boolean isVar;
     public LocalVariableDescriptor(
             @NotNull DeclarationDescriptor containingDeclaration,
             @NotNull List<AnnotationDescriptor> annotations,
@@ -19,6 +20,7 @@ public class LocalVariableDescriptor extends VariableDescriptorImpl {
             @Nullable JetType type,
             boolean mutable) {
         super(containingDeclaration, annotations, name, mutable ? type : null, type);
+        isVar = mutable;
     }
 
     @NotNull
@@ -31,4 +33,9 @@ public class LocalVariableDescriptor extends VariableDescriptorImpl {
     public <R, D> R accept(DeclarationDescriptorVisitor<R, D> visitor, D data) {
         return visitor.visitLocalVariableDescriptor(this, data);
     }
+
+    @Override
+    public boolean isVar() {
+        return isVar;
+    }
 }

idea/src/org/jetbrains/jet/lang/descriptors/ValueParameterDescriptorImpl.java

@@ -94,4 +94,9 @@ public class ValueParameterDescriptorImpl extends VariableDescriptorImpl impleme
     public <R, D> R accept(DeclarationDescriptorVisitor<R, D> visitor, D data) {
         return visitor.visitValueParameterDescriptor(this, data);
     }
+    
+    @Override
+    public boolean isVar() {
+        return isVar;
+    }
 }

idea/src/org/jetbrains/jet/lang/descriptors/VariableDescriptor.java

@@ -29,4 +29,6 @@ public interface VariableDescriptor extends DeclarationDescriptor {
     @NotNull
     @Override
     VariableDescriptor substitute(TypeSubstitutor substitutor);
+
+    boolean isVar();
 }

idea/src/org/jetbrains/jet/lang/resolve/BindingTrace.java

@@ -5,6 +5,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.ErrorHandlerWithRegions;
 import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
 import org.jetbrains.jet.lang.descriptors.PropertyDescriptor;
+import org.jetbrains.jet.lang.descriptors.VariableDescriptor;
 import org.jetbrains.jet.lang.descriptors.annotations.AnnotationDescriptor;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.constants.CompileTimeConstant;
@@ -43,7 +44,7 @@ public interface BindingTrace {
 
     void requireBackingField(@NotNull PropertyDescriptor propertyDescriptor);
 
-    void recordAutoCast(@NotNull JetExpression expression, @NotNull JetType type);
+    void recordAutoCast(@NotNull JetExpression expression, @NotNull JetType type, @NotNull VariableDescriptor variableDescriptor);
 
     @NotNull
     ErrorHandlerWithRegions getErrorHandler();

idea/src/org/jetbrains/jet/lang/resolve/BindingTraceAdapter.java

@@ -5,6 +5,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.ErrorHandlerWithRegions;
 import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
 import org.jetbrains.jet.lang.descriptors.PropertyDescriptor;
+import org.jetbrains.jet.lang.descriptors.VariableDescriptor;
 import org.jetbrains.jet.lang.descriptors.annotations.AnnotationDescriptor;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.constants.CompileTimeConstant;
@@ -17,8 +18,8 @@ public class BindingTraceAdapter implements BindingTrace {
     private final BindingTrace originalTrace;
 
     @Override
-    public void recordAutoCast(@NotNull JetExpression expression, @NotNull JetType type) {
-        originalTrace.recordAutoCast(expression, type);
+    public void recordAutoCast(@NotNull JetExpression expression, @NotNull JetType type, @NotNull VariableDescriptor variableDescriptor) {
+        originalTrace.recordAutoCast(expression, type, variableDescriptor);
     }
 
     public BindingTraceAdapter(BindingTrace originalTrace) {

idea/src/org/jetbrains/jet/lang/resolve/BindingTraceContext.java

@@ -167,8 +167,13 @@ public class BindingTraceContext implements BindingContext, BindingTrace {
     }
 
     @Override
-    public void recordAutoCast(@NotNull JetExpression expression, @NotNull JetType type) {
-        safePut(autoCasts, expression, type);
+    public void recordAutoCast(@NotNull JetExpression expression, @NotNull JetType type, @NotNull VariableDescriptor variableDescriptor) {
+        if (variableDescriptor.isVar()) {
+            getErrorHandler().genericError(expression.getNode(), "Automatic cast to " + type + " is impossible, because variable " + variableDescriptor.getName() + " is mutable");
+        }
+        else {
+            safePut(autoCasts, expression, type);
+        }
     }
 
     @Override

idea/src/org/jetbrains/jet/lang/types/JetTypeInferrer.java

@@ -763,29 +763,31 @@ public class JetTypeInferrer {
                 semanticServices.getTypeChecker().isSubtypeOf(expressionType, context.expectedType)) {
                 return expressionType;
             }
-            VariableDescriptor variableDescriptor = getVariableDescriptorFromSimpleName(expression, context);
-            if (variableDescriptor == null) return expressionType;
-
             JetType enrichedType = null;
-            List<JetType> possibleTypes = Lists.newArrayList(context.dataFlowInfo.getPossibleTypes(variableDescriptor));
-            Collections.reverse(possibleTypes);
-            for (JetType possibleType: possibleTypes) {
-                if (semanticServices.getTypeChecker().isSubtypeOf(possibleType, context.expectedType)) {
-                    enrichedType = possibleType;
-                    break;
+
+            VariableDescriptor variableDescriptor = getVariableDescriptorFromSimpleName(expression, context);
+            if (variableDescriptor != null) {
+
+                List<JetType> possibleTypes = Lists.newArrayList(context.dataFlowInfo.getPossibleTypes(variableDescriptor));
+                Collections.reverse(possibleTypes);
+                for (JetType possibleType : possibleTypes) {
+                    if (semanticServices.getTypeChecker().isSubtypeOf(possibleType, context.expectedType)) {
+                        enrichedType = possibleType;
+                        break;
+                    }
+                }
+                if (enrichedType == null) {
+                    enrichedType = context.dataFlowInfo.getOutType(variableDescriptor);
                 }
-            }
-            if (enrichedType == null) {
-                enrichedType = context.dataFlowInfo.getOutType(variableDescriptor);
             }
             if (enrichedType == null) {
                 enrichedType = expressionType;
             }
 
-            if (!semanticServices.getTypeChecker().isSubtypeOf(enrichedType, context.expectedType)) {
+            if (variableDescriptor == null || !semanticServices.getTypeChecker().isSubtypeOf(enrichedType, context.expectedType)) {
                 context.trace.getErrorHandler().typeMismatch(expression, context.expectedType, expressionType);
             } else {
-                context.trace.recordAutoCast(expression, context.expectedType);
+                context.trace.recordAutoCast(expression, context.expectedType, variableDescriptor);
             }
             return enrichedType;
         }
@@ -2120,7 +2122,7 @@ public class JetTypeInferrer {
                         selectorReturnType = getSelectorReturnType(possibleType, selectorExpression, context);
                         if (selectorReturnType != null) {
                             regionToCommit = errorHandler.closeAndReturnCurrentRegion();
-                            context.trace.recordAutoCast(receiverExpression, possibleType);
+                            context.trace.recordAutoCast(receiverExpression, possibleType, variableDescriptor);
                             break;
                         }
                         else {

idea/testData/checker/infos/Autocasts.jet

@@ -229,6 +229,25 @@ fun mergeAutocasts(a: Any?) {
     is String, is Any => a.<error>compareTo</error>("")
   }
   if (a is String && a is Any) {
-    val i: Int = <info descr="Automatically cast to String">a</info>.length
+    val i: Int = <info descr="Automatically cast to String">a</info>.compareTo("")
   }
+}
+
+//mutability
+fun f(): String {
+    var a: Any = 11
+    if (a is String) {
+        val i: String = <error>a</error>
+        <error>a</error>.compareTo("f")
+        val f: Function0<String> = { <error>a</error> }
+        return <error>a</error>
+    }
+    return ""
+}
+
+fun foo(var a: Any): Int {
+    if (a is Int) {
+        return <error>a</error>
+    }
+    return 1
 }

idea/tests/org/jetbrains/jet/JetTestUtils.java

@@ -83,7 +83,7 @@ public class JetTestUtils {
         }
 
         @Override
-        public void recordAutoCast(@NotNull JetExpression expression, @NotNull JetType type) {
+        public void recordAutoCast(@NotNull JetExpression expression, @NotNull JetType type, @NotNull VariableDescriptor variableDescriptor) {
 
         }