Method reverences language level highlighting

java/java-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightUtil.java

@@ -2538,7 +2538,8 @@ public class HighlightUtil {
     TRY_WITH_RESOURCES(LanguageLevel.JDK_1_7, "feature.try.with.resources"),
     BIN_LITERALS(LanguageLevel.JDK_1_7, "feature.binary.literals"),
     UNDERSCORES(LanguageLevel.JDK_1_7, "feature.underscores.in.literals"),
-    EXTENSION_METHODS(LanguageLevel.JDK_1_8, "feature.extension.methods");
+    EXTENSION_METHODS(LanguageLevel.JDK_1_8, "feature.extension.methods"),
+    METHOD_REFERENCES(LanguageLevel.JDK_1_8, "feature.method.references");
 
     private final LanguageLevel level;
     private final String key;
@@ -2606,4 +2607,9 @@ public class HighlightUtil {
   public static HighlightInfo checkExtensionMethodsFeature(final PsiMethod method) {
     return checkFeature(method, Feature.EXTENSION_METHODS);
   }
+
+  @Nullable
+  public static HighlightInfo checkMethodReferencesFeature(final PsiMethodReferenceExpression expression) {
+    return checkFeature(expression, Feature.METHOD_REFERENCES);
+  }
 }

java/java-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightVisitorImpl.java

@@ -892,7 +892,13 @@ public class HighlightVisitorImpl extends JavaElementVisitor implements Highligh
     if (!myHolder.hasErrorResults()) myHolder.add(HighlightUtil.checkClassReferenceAfterQualifier(expression, resolved));
   }
 
-  @Override public void visitReferenceList(PsiReferenceList list) {
+  @Override
+  public void visitMethodReferenceExpression(PsiMethodReferenceExpression expression) {
+    myHolder.add(HighlightUtil.checkMethodReferencesFeature(expression));
+  }
+
+  @Override
+  public void visitReferenceList(PsiReferenceList list) {
     if (list.getFirstChild() == null) return;
     PsiElement parent = list.getParent();
     if (!(parent instanceof PsiTypeParameter)) {

java/java-psi-api/src/com/intellij/psi/JavaElementVisitor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2009 JetBrains s.r.o.
+ * Copyright 2000-2012 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -244,6 +244,10 @@ public abstract class JavaElementVisitor extends PsiElementVisitor {
    */
   public void visitReferenceExpression(PsiReferenceExpression expression) {}
 
+  public void visitMethodReferenceExpression(PsiMethodReferenceExpression expression) {
+    visitReferenceExpression(expression);
+  }
+
   public void visitReferenceList(PsiReferenceList list) {
     visitElement(list);
   }

java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/PsiMethodReferenceExpressionImpl.java

@@ -104,6 +104,16 @@ public class PsiMethodReferenceExpressionImpl extends PsiReferenceExpressionBase
     return element.getManager().areElementsEquivalent(element, resolve());
   }
 
+  @Override
+  public void accept(@NotNull final PsiElementVisitor visitor) {
+    if (visitor instanceof JavaElementVisitor) {
+      ((JavaElementVisitor)visitor).visitMethodReferenceExpression(this);
+    }
+    else {
+      visitor.visitElement(this);
+    }
+  }
+
   @Override
   public String toString() {
     return "PsiMethodReferenceExpression:" + getText();

java/java-psi-impl/src/messages/JavaErrorMessages.properties

@@ -353,4 +353,5 @@ feature.try.with.resources=Try-with-resources
 feature.binary.literals=Binary literals
 feature.underscores.in.literals=Underscores in literals
 feature.extension.methods=Extension methods
+feature.method.references=Method references
 insufficient.language.level={0} are not supported at this language level

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting/UnsupportedFeatures.java

@@ -37,6 +37,8 @@ class UnsupportedFeatures {
     catch (<error descr="Multi-catches are not supported at this language level">FileNotFoundException | IOException e</error>) { e.printStackTrace(); }
 
     try <error descr="Try-with-resources are not supported at this language level">(Reader r = new FileReader("/dev/null"))</error> { }
+
+    I i = <error descr="Method references are not supported at this language level">UnsupportedFeatures::m</error>;
   }
 
   interface I {