new inference: use site substitutor during return constraints processing (red code in Collectors)

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

@@ -369,7 +369,7 @@ public class InferenceSession {
           targetType = getTargetType(context);
         }
         if (targetType != null) {
-          registerConstraints(returnType, targetType);
+          registerConstraints(PsiUtil.isRawSubstitutor(method, mySiteSubstitutor) ? returnType : mySiteSubstitutor.substitute(returnType), targetType);
         }
       }
     }
@@ -400,7 +400,7 @@ public class InferenceSession {
           PsiTypeParameter[] copy = new PsiTypeParameter[typeParameters.length];
           for (int i = 0; i < typeParameters.length; i++) {
             PsiTypeParameter typeParameter = typeParameters[i];
-            copy[i] = elementFactory.createTypeParameterFromText(typeParameter.getName(), null);
+            copy[i] = elementFactory.createTypeParameterFromText("rCopy" + typeParameter.getName(), null);
             initBounds(copy[i]);
             subst = subst.put(typeParameter, elementFactory.createType(copy[i]));
           }

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

@@ -21,6 +21,7 @@ import com.intellij.psi.impl.source.resolve.graphInference.InferenceVariable;
 import com.intellij.psi.impl.source.resolve.graphInference.PsiPolyExpressionUtil;
 import com.intellij.psi.impl.source.tree.java.PsiMethodCallExpressionImpl;
 import com.intellij.psi.infos.MethodCandidateInfo;
+import com.intellij.psi.util.PsiUtil;
 import com.intellij.psi.util.TypeConversionUtil;
 import com.intellij.util.containers.HashSet;
 import org.jetbrains.annotations.NotNull;
@@ -134,7 +135,7 @@ public class ExpressionCompatibilityConstraint extends InputOutputConstraintForm
           if (!accepted) {
             //todo return false;
           }
-          callSession.registerConstraints(returnType, substitutor.substitute(returnType));
+          callSession.registerConstraints(method != null && !PsiUtil.isRawSubstitutor(method, siteSubstitutor) ? siteSubstitutor.substitute(returnType) : returnType, substitutor.substitute(returnType));
           if (callSession.repeatInferencePhases(true)) {
             final Collection<InferenceVariable> inferenceVariables = callSession.getInferenceVariables();
             if (sameMethodCall) {

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/graphInference/SiteSubstitutionForReturnConstraint.java

@@ -0,0 +1,21 @@
+import java.util.function.Function;
+import java.util.stream.Collector;
+
+class Collectors {
+
+  public static <A,R,RR> void collectingAndThen(Function<R, RR> finisher, Function<A, R> finisher1) {
+    Function<A, RR> f = finisher1.andThen(finisher);
+  }
+
+}
+
+
+class Collectors1 {
+  public static<T,A,R,RR> Collector<T,A,RR> collectingAndThen(Function<R, RR> finisher, Function<A, R> function) {
+    return factory(function.andThen(finisher));
+  }
+
+  static <Ts, As, Rs> Collector<Ts, As, Rs> factory(Function<As, Rs> f) {
+    return null;
+  }
+}

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

@@ -164,6 +164,10 @@ public class GraphInferenceHighlightingTest extends LightDaemonAnalyzerTestCase
     doTest();
   }
 
+  public void testSiteSubstitutionForReturnConstraint() throws Exception {
+    doTest();
+  }
+
   private void doTest() throws Exception {
     doTest(false);
   }