record ambiguous label references

compiler/frontend/src/org/jetbrains/jet/lang/resolve/BindingContext.java

@@ -233,6 +233,8 @@ public interface BindingContext {
     WritableSlice<ClassDescriptor, Boolean> IS_ENUM_MOVED_TO_CLASS_OBJECT = Slices.createSimpleSlice();
 
     WritableSlice<JetReferenceExpression, PsiElement> LABEL_TARGET = Slices.<JetReferenceExpression, PsiElement>sliceBuilder().build();
+    WritableSlice<JetReferenceExpression, Collection<? extends PsiElement>> AMBIGUOUS_LABEL_TARGET =
+            Slices.<JetReferenceExpression, Collection<? extends PsiElement>>sliceBuilder().build();
     WritableSlice<ValueParameterDescriptor, PropertyDescriptor> VALUE_PARAMETER_AS_PROPERTY =
             Slices.<ValueParameterDescriptor, PropertyDescriptor>sliceBuilder().build();
 

compiler/frontend/src/org/jetbrains/jet/lang/resolve/BindingContextUtils.java

@@ -26,11 +26,10 @@ import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.util.slicedmap.ReadOnlySlice;
 import org.jetbrains.jet.util.slicedmap.Slices;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.Set;
+import java.util.*;
 
+import static org.jetbrains.jet.lang.diagnostics.Errors.AMBIGUOUS_LABEL;
+import static org.jetbrains.jet.lang.resolve.BindingContext.AMBIGUOUS_LABEL_TARGET;
 import static org.jetbrains.jet.lang.resolve.BindingContext.DECLARATION_TO_DESCRIPTOR;
 
 /**
@@ -253,4 +252,22 @@ public class BindingContextUtils {
         assert descriptor != null : "No descriptor for named declaration: " + declaration.getText() + "\n(of type " + declaration.getClass() + ")";
         return descriptor;
     }
+
+    public static void reportAmbiguousLabel(
+            @NotNull BindingTrace trace,
+            @NotNull JetSimpleNameExpression targetLabel,
+            @NotNull Collection<DeclarationDescriptor> declarationsByLabel
+    ) {
+        Collection<PsiElement> targets = Lists.newArrayList();
+        for (DeclarationDescriptor descriptor : declarationsByLabel) {
+            PsiElement element = descriptorToDeclaration(trace.getBindingContext(), descriptor);
+            if (element != null) {
+                targets.add(element);
+            }
+        }
+        if (!targets.isEmpty()) {
+            trace.record(AMBIGUOUS_LABEL_TARGET, targetLabel, targets);
+        }
+        trace.report(AMBIGUOUS_LABEL.on(targetLabel));
+    }
 }

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

@@ -90,7 +90,7 @@ public class LabelResolver {
         else if (size == 0) {
             return resolveNamedLabel(labelName, labelExpression, reportUnresolved, context);
         }
-        context.trace.report(AMBIGUOUS_LABEL.on(labelExpression));
+        BindingContextUtils.reportAmbiguousLabel(context.trace, labelExpression, declarationsByLabel);
         return null;
     }
 
@@ -117,7 +117,7 @@ public class LabelResolver {
         }
 
         JetElement result = stack.peek();
-        context.trace.record(BindingContext.LABEL_TARGET, labelExpression, result);
+        context.trace.record(LABEL_TARGET, labelExpression, result);
         return result;
     }
 
@@ -172,7 +172,7 @@ public class LabelResolver {
             }
         }
         else {
-            context.trace.report(AMBIGUOUS_LABEL.on(targetLabel));
+            BindingContextUtils.reportAmbiguousLabel(context.trace, targetLabel, declarationsByLabel);
         }
         return LabeledReceiverResolutionResult.labelResolutionFailed();
     }

idea/src/org/jetbrains/jet/plugin/references/JetPsiReference.java

@@ -35,6 +35,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
+import static org.jetbrains.jet.lang.resolve.BindingContext.AMBIGUOUS_LABEL_TARGET;
 import static org.jetbrains.jet.lang.resolve.BindingContext.AMBIGUOUS_REFERENCE_TARGET;
 
 public abstract class JetPsiReference implements PsiPolyVariantReference {
@@ -126,6 +127,10 @@ public abstract class JetPsiReference implements PsiPolyVariantReference {
             if (psiElements.size() > 1) {
                 return PsiElementResolveResult.createResults(psiElements);
             }
+            Collection<? extends PsiElement> labelTargets = bindingContext.get(AMBIGUOUS_LABEL_TARGET, myExpression);
+            if (labelTargets != null && !labelTargets.isEmpty()) {
+                return PsiElementResolveResult.createResults(labelTargets);
+            }
             Collection<PsiElement> standardLibraryElements = resolveStandardLibrarySymbol(bindingContext);
             if (standardLibraryElements.size() > 1) {
                 return PsiElementResolveResult.createResults(standardLibraryElements);