lambda: check lambda return type compatibility before more specific checks (IDEA-97870)

java/java-psi-impl/src/com/intellij/psi/scope/conflictResolvers/JavaMethodsConflictResolver.java

@@ -81,15 +81,15 @@ public class JavaMethodsConflictResolver implements PsiConflictResolver{
     // then noone can be more specific
     if (!atLeastOneMatch) return null;
 
+    checkLambdaApplicable(conflicts);
+    if (conflicts.size() == 1) return conflicts.get(0);
+
     checkSpecifics(conflicts, applicabilityLevel);
     if (conflicts.size() == 1) return conflicts.get(0);
 
     checkPrimitiveVarargs(conflicts, myActualParameterTypes.length);
     if (conflicts.size() == 1) return conflicts.get(0);
 
-    checkLambdaApplicable(conflicts);
-    if (conflicts.size() == 1) return conflicts.get(0);
-
     THashSet<CandidateInfo> uniques = new THashSet<CandidateInfo>(conflicts);
     if (uniques.size() == 1) return uniques.iterator().next();
     return null;

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/highlighting/ReturnTypeCompatibilityBeforeSpecificsCheck.java

@@ -0,0 +1,25 @@
+class X {
+    public static void main(final Stream<String> stream) throws Throwable {
+        stream.map(s -> s.substring("http://".length())).forEach(System.out::println);
+    }
+}
+
+interface Stream<T> {
+    <R> Stream<R> map(Function<? super T, ? extends R> mapper);
+    IntStream map(IntFunction<? super T> mapper);
+    void forEach(Block<? super T> block);
+}
+
+interface IntFunction<T> extends Function<T, Integer> {
+    public int applyAsInt(T t);
+}
+
+interface Function<T, R> {
+    public R apply(T t);
+}
+
+interface IntStream extends BaseStream<Integer> {}
+interface BaseStream<T> {}
+interface Block<T> {
+    public void accept(T t);
+}

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

@@ -173,6 +173,10 @@ public class LambdaHighlightingTest extends LightDaemonAnalyzerTestCase {
     doTest();
   }
 
+  public void testReturnTypeCompatibilityBeforeSpecificsCheck() throws Exception {
+    doTest();
+  }
+
   private void doTest() throws Exception {
     doTest(BASE_PATH + "/" + getTestName(false) + ".java", false, false);
   }