Added 'variable expected' error on assignments

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

@@ -143,17 +143,18 @@ public interface Errors {
     PsiElementOnlyDiagnosticFactory3<JetModifierListOwner, CallableMemberDescriptor, CallableMemberDescriptor, DeclarationDescriptor> VIRTUAL_MEMBER_HIDDEN = PsiElementOnlyDiagnosticFactory3.create(ERROR, "''{0}'' hides ''{1}'' in class {2} and needs 'override' modifier", DescriptorRenderer.TEXT);
 
     PsiElementOnlyDiagnosticFactory1<JetSimpleNameExpression, DeclarationDescriptor> UNINITIALIZED_VARIABLE = PsiElementOnlyDiagnosticFactory1.create(ERROR, "Variable ''{0}'' must be initialized", NAME);
-    PsiElementOnlyDiagnosticFactory2<JetSimpleNameExpression, DeclarationDescriptor, JetProperty[]> VAL_REASSIGNMENT = new PsiElementOnlyDiagnosticFactory2<JetSimpleNameExpression, DeclarationDescriptor, JetProperty[]>(ERROR, "Val can not be reassigned", NAME) {
+    PsiElementOnlyDiagnosticFactory2<JetExpression, DeclarationDescriptor, JetProperty[]> VAL_REASSIGNMENT = new PsiElementOnlyDiagnosticFactory2<JetExpression, DeclarationDescriptor, JetProperty[]>(ERROR, "Val can not be reassigned", NAME) {
         @NotNull
         @Override
-        public DiagnosticWithPsiElement<JetSimpleNameExpression> on(@NotNull JetSimpleNameExpression elementToBlame, @NotNull ASTNode nodeToMark, @NotNull DeclarationDescriptor declarationDescriptor, @NotNull JetProperty[] property) {
-            DiagnosticWithPsiElement<JetSimpleNameExpression> diagnostic = super.on(elementToBlame, nodeToMark, declarationDescriptor, property);
+        public DiagnosticWithPsiElement<JetExpression> on(@NotNull JetExpression elementToBlame, @NotNull ASTNode nodeToMark, @NotNull DeclarationDescriptor declarationDescriptor, @NotNull JetProperty[] property) {
+            DiagnosticWithPsiElement<JetExpression> diagnostic = super.on(elementToBlame, nodeToMark, declarationDescriptor, property);
             if (property.length == 1) {
                 return diagnostic.add(DiagnosticParameters.PROPERTY, property[0]);
             }
             return diagnostic;
         }
     };
+    SimplePsiElementOnlyDiagnosticFactory<JetExpression> VARIABLE_EXPECTED = new SimplePsiElementOnlyDiagnosticFactory<JetExpression>(ERROR, "Variable expected");
 
     PsiElementOnlyDiagnosticFactory1<JetSimpleNameExpression, DeclarationDescriptor> INITIALIZATION_USING_BACKING_FIELD = PsiElementOnlyDiagnosticFactory1.create(ERROR, "Initialization using backing field required", NAME);
 

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

@@ -6,6 +6,7 @@ import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.descriptors.*;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.BindingContext;
+import org.jetbrains.jet.lang.resolve.BindingContextUtils;
 import org.jetbrains.jet.lang.resolve.TemporaryBindingTrace;
 import org.jetbrains.jet.lang.resolve.TopDownAnalyzer;
 import org.jetbrains.jet.lang.resolve.calls.CallMaker;
@@ -150,6 +151,10 @@ public class ExpressionTypingVisitorForStatements extends BasicExpressionTypingV
         if (right != null) {
             JetType rightType = facade.getType(right, context.replaceExpectedType(leftType).replaceScope(scope));
         }
+        VariableDescriptor variable = BindingContextUtils.extractVariableDescriptorIfAny(context.trace.getBindingContext(), left, true);
+        if (variable == null && leftType != null) { //if leftType == null, some another error has been generated
+            context.trace.report(VARIABLE_EXPECTED.on(left != null ? left : expression.getLeft()));
+        }
         if (left instanceof JetSimpleNameExpression) {
             JetSimpleNameExpression simpleName = (JetSimpleNameExpression) left;
             String referencedName = simpleName.getReferencedName();

compiler/testData/checkerWithErrorTypes/quick/LValueAssignment.jet

@@ -0,0 +1,38 @@
+namespace lvalue_assignment
+
+open class B() {
+    var b: Int = 2
+    val c: Int = 34
+}
+
+class C() : B() {
+    var x = 4
+    fun foo(c: C) {
+        this.x = 34
+        this.b = 123
+        super.b = 23
+        <!VAL_REASSIGNMENT!>this.c<!> = 34
+        <!VAL_REASSIGNMENT!>super.c<!> = 3535
+
+        <!VARIABLE_EXPECTED!>getInt()<!> = 12
+    }
+
+    fun foo(c: C) {
+        <!VARIABLE_EXPECTED!>this<!> = c  //should be an error
+    }
+}
+
+fun getInt() = 0
+
+class D() {
+    class B() {
+        fun foo() {
+            <!VARIABLE_EXPECTED!>this@D<!> = D()
+        }
+    }
+}
+
+fun cannotBe() {
+    <!UNRESOLVED_REFERENCE!>z<!> = 30;
+    <!VARIABLE_EXPECTED!>()<!> = ();
+}