method ref: ensure top substitutor is not overridden with raw replacement from second method ref search (IDEA-158636)

java/java-psi-impl/src/com/intellij/psi/impl/source/resolve/graphInference/InferenceSession.java

@@ -1599,7 +1599,7 @@ public class InferenceSession {
               return receiverSubstitutor;
             }
           }
-          mySiteSubstitutor = receiverSubstitutor;
+          mySiteSubstitutor = mySiteSubstitutor.putAll(receiverSubstitutor);
 
           if (methodContainingClass != null) {
             final PsiSubstitutor superSubstitutor = TypeConversionUtil.getClassSubstitutor(methodContainingClass, containingClass, receiverSubstitutor);

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newMethodRef/MethodReferenceSecondSearchDontInfluenceTopSiteSubstitutor.java

@@ -0,0 +1,13 @@
+package pi;
+
+import java.util.stream.Stream;
+
+abstract class Foo<T> {
+  public abstract <X> Foo<X> getAssociatedFoo();
+
+  public abstract static class Bar<Z> {
+    public Stream<Foo<Object>> getAssociatedFoos(Stream<Foo<Z>> stream) {
+      return stream.map(Foo::getAssociatedFoo);
+    }
+  }
+}

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

@@ -518,6 +518,10 @@ public class NewMethodRefHighlightingTest extends LightDaemonAnalyzerTestCase {
     doTest();
   }
 
+  public void testMethodReferenceSecondSearchDontInfluenceTopSiteSubstitutor() throws Exception {
+    doTest();
+  }
+
   private void doTest() {
     doTest(false);
   }