[java] raw string literals: language level check (IDEA-189075)

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

@@ -2897,7 +2897,8 @@ public class HighlightUtil extends HighlightUtilBase {
     INTERSECTION_CASTS(LanguageLevel.JDK_1_8, "feature.intersections.in.casts"),
     STATIC_INTERFACE_CALLS(LanguageLevel.JDK_1_8, "feature.static.interface.calls"),
     REFS_AS_RESOURCE(LanguageLevel.JDK_1_9, "feature.try.with.resources.refs"),
-    MODULES(LanguageLevel.JDK_1_9, "feature.modules");
+    MODULES(LanguageLevel.JDK_1_9, "feature.modules"),
+    RAW_LITERALS(LanguageLevel.JDK_11_PREVIEW, "feature.raw.literals");
 
     private final LanguageLevel level;
     private final String key;

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

@@ -459,6 +459,9 @@ public class HighlightVisitorImpl extends JavaElementVisitor implements Highligh
   @Override
   public void visitJavaToken(PsiJavaToken token) {
     super.visitJavaToken(token);
+    if (!myHolder.hasErrorResults() && token.getTokenType() == JavaTokenType.RAW_STRING_LITERAL) {
+      myHolder.add(checkFeature(token, Feature.RAW_LITERALS));
+    }
     if (!myHolder.hasErrorResults() && token.getTokenType() == JavaTokenType.RBRACE && token.getParent() instanceof PsiCodeBlock) {
       PsiElement gParent = token.getParent().getParent();
       PsiCodeBlock codeBlock;

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

@@ -463,4 +463,5 @@ feature.intersections.in.casts=Intersection types in casts
 feature.static.interface.calls=Static interface method calls
 feature.try.with.resources.refs=Resource references
 feature.modules=Modules
+feature.raw.literals=Raw string literals
 insufficient.language.level={0} are not supported at language level ''{1}''

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

@@ -20,5 +20,7 @@ class UnsupportedFeatures {
 
     java.lang.annotation.ElementType t = null;
     switch (<error descr="Incompatible types. Found: 'java.lang.annotation.ElementType', required: 'byte, char, short or int'">t</error>) { }
+
+    String raw = <error descr="Raw string literals are not supported at language level '1.4'">`hi there`</error>;
   }
 }