inference: ensure foreign variables do not participate in inference process, e.g. variables from method reference overload resolution (IDEA-154622)

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

@@ -625,8 +625,10 @@ public class InferenceSession {
     return mySiteSubstitutor;
   }
 
-  public InitialInferenceState createInitialState(InferenceSessionContainer container, PsiSubstitutor topInferenceSubstitutor) {
-    return new InitialInferenceState(myInferenceVariables,
+  public InitialInferenceState createInitialState(InferenceSessionContainer container,
+                                                  Collection<InferenceVariable> variables,
+                                                  PsiSubstitutor topInferenceSubstitutor) {
+    return new InitialInferenceState(variables,
                                      topInferenceSubstitutor,
                                      myContext, 
                                      myInferenceSubstitution, 
@@ -652,6 +654,7 @@ public class InferenceSession {
       final PsiElementFactory elementFactory = JavaPsiFacade.getElementFactory(parameter.getProject());
       myInferenceSubstitution = myInferenceSubstitution.put(parameter, elementFactory.createType(variable));
       myRestoreNameSubstitution = myRestoreNameSubstitution.put(variable, elementFactory.createType(parameter));
+      myInferenceVariables.add(variable);
     }
     for (InferenceVariable variable : result) {
       PsiTypeParameter parameter = variable.getParameter();
@@ -669,7 +672,6 @@ public class InferenceSession {
                           InferenceBound.UPPER, null);
       }
     }
-    myInferenceVariables.addAll(result);
     return result.toArray(new InferenceVariable[result.size()]);
   }
 
@@ -893,10 +895,7 @@ public class InferenceSession {
 
   public InferenceVariable getInferenceVariable(PsiType psiType) {
     final PsiClass psiClass = PsiUtil.resolveClassInClassTypeOnly(psiType);
-    if (psiClass instanceof InferenceVariable) {
-      return (InferenceVariable)psiClass;
-    }
-    return null;
+    return psiClass instanceof InferenceVariable ? getInferenceVariable((PsiTypeParameter)psiClass) : null;
   }
 
   public boolean isProperType(@Nullable PsiType type) {
@@ -1875,9 +1874,9 @@ public class InferenceSession {
     return myContext;
   }
 
-  public void propagateVariables(Collection<InferenceVariable> variables, PsiSubstitutor substitution) {
+  public void propagateVariables(Collection<InferenceVariable> variables, PsiSubstitutor restoreNamesSubstitution) {
     myInferenceVariables.addAll(variables);
-    myRestoreNameSubstitution = myRestoreNameSubstitution.putAll(substitution);
+    myRestoreNameSubstitution = myRestoreNameSubstitution.putAll(restoreNamesSubstitution);
   }
 
   public PsiType substituteWithInferenceVariables(PsiType type) {

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

@@ -54,6 +54,7 @@ public class InferenceSessionContainer {
         ExpressionCompatibilityConstraint.reduceExpressionCompatibilityConstraint(session, returnExpression, returnType);
       if (inferenceSession != null && inferenceSession != session) {
         registerNestedSession(inferenceSession);
+        session.propagateVariables(inferenceSession.getInferenceVariables(), inferenceSession.getRestoreNameSubstitution());
       }
     }
   }
@@ -159,7 +160,7 @@ public class InferenceSessionContainer {
     };
     final Map<PsiElement, InferenceSession> nestedSessions = topLevelSession.getInferenceSessionContainer().myNestedSessions;
     for (Map.Entry<PsiElement, InferenceSession> entry : nestedSessions.entrySet()) {
-      nestedStates.put(entry.getKey(), entry.getValue().createInitialState(copy, topInferenceSubstitutor));
+      nestedStates.put(entry.getKey(), entry.getValue().createInitialState(copy, topLevelSession.getInferenceVariables(), topInferenceSubstitutor));
     }
 
     PsiSubstitutor substitutor = PsiSubstitutor.EMPTY;

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

@@ -19,10 +19,7 @@ import com.intellij.openapi.util.Pair;
 import com.intellij.psi.*;
 import com.intellij.psi.util.PsiUtil;
 
-import java.util.ArrayList;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Set;
+import java.util.*;
 
 class InitialInferenceState {
   private final Set<InferenceVariable> myInferenceVariables;
@@ -34,7 +31,7 @@ class InitialInferenceState {
   private final InferenceSessionContainer myInferenceSessionContainer;
   private final boolean myErased;
 
-  InitialInferenceState(Set<InferenceVariable> inferenceVariables,
+  InitialInferenceState(Collection<InferenceVariable> inferenceVariables,
                         PsiSubstitutor topInferenceSubstitutor,
                         PsiElement context,
                         PsiSubstitutor inferenceSubstitutor,

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

@@ -0,0 +1,27 @@
+
+import java.util.function.Function;
+
+class SomeClass<K, V> {
+
+  SomeClass(Function<K, V> transformer) {}
+
+  static <M, N> SomeClass<M, N> create(Function<M, N> t) {
+    return null;
+  }
+
+  static void someMethod() {
+    final SomeClass<MyBean, String> instance = create(MyBean::overloadedMethod);
+    final SomeClass<MyBean, String> instance1 = new SomeClass<>(MyBean::overloadedMethod);
+  }
+}
+class MyBean {
+
+  private String overloadedMethod(String param) {
+    return param;
+  }
+
+  public String overloadedMethod() {
+    return overloadedMethod(null);
+  }
+
+}

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

@@ -510,6 +510,10 @@ public class NewMethodRefHighlightingTest extends LightDaemonAnalyzerTestCase {
     doTest();
   }
 
+  public void testIgnoreForeignVariables() throws Exception {
+    doTest();
+  }
+
   private void doTest() {
     doTest(false);
   }