don't open capture if reference expression is returned from lambda expression (IDEA-139089)

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

@@ -424,6 +424,12 @@ public class LambdaUtil {
     return typeByExpression instanceof PsiMethodReferenceType || typeByExpression instanceof PsiLambdaExpressionType || typeByExpression instanceof PsiLambdaParameterType;
   }
 
+  public static boolean isLambdaReturnExpression(PsiElement element) {
+    final PsiElement parent = element.getParent();
+    return parent instanceof PsiLambdaExpression ||
+           parent instanceof PsiReturnStatement && PsiTreeUtil.getParentOfType(parent, PsiLambdaExpression.class, true, PsiMethod.class) != null;
+  }
+  
   public static PsiReturnStatement[] getReturnStatements(PsiLambdaExpression lambdaExpression) {
     final PsiElement body = lambdaExpression.getBody();
     return body instanceof PsiCodeBlock ? PsiUtil.findReturnStatements((PsiCodeBlock)body) : PsiReturnStatement.EMPTY_ARRAY;

java/java-psi-impl/src/com/intellij/psi/impl/PsiImplUtil.java

@@ -415,6 +415,9 @@ public class PsiImplUtil {
   private static PsiType doNormalizeWildcardByPosition(final PsiType type, @NotNull PsiExpression expression, final PsiExpression toplevel) {
     if (type instanceof PsiCapturedWildcardType) {
       final PsiWildcardType wildcardType = ((PsiCapturedWildcardType)type).getWildcard();
+      if (expression instanceof PsiReferenceExpression && LambdaUtil.isLambdaReturnExpression(expression)) {
+        return type;
+      }
 
       if (PsiUtil.isAccessedForWriting(toplevel)) {
         return wildcardType.isSuper() ? wildcardType.getBound() : PsiCapturedWildcardType.create(wildcardType, expression);

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newLambda/CaptureInReturnStatementOfLambdaExpression.java

@@ -0,0 +1,14 @@
+import java.util.function.Function;
+
+interface I<T>{
+  void foo(Function<T, T> f);
+}
+
+class C {
+  void bar(I<?> x) {
+    x.foo(a -> {
+      x.foo(y -> <error descr="Bad return type in lambda expression: capture of ? cannot be converted to capture of ?">a</error>);
+      return a;
+    });
+  }
+}

java/java-tests/testSrc/com/intellij/codeInsight/daemon/lambda/NewLambdaHighlightingTest.java

@@ -195,6 +195,10 @@ public class NewLambdaHighlightingTest extends LightDaemonAnalyzerTestCase {
     doTest();
   }
 
+  public void testCaptureInReturnStatementOfLambdaExpression() throws Exception {
+    doTest();
+  }
+
   private void doTest() {
     doTest(false);
   }