From 81a13b0fc04b7605874cf8aa70d8190263da4f54 Mon Sep 17 00:00:00 2001
From: Anna Kozlova <anna.kozlova@jetbrains.com>
Date: Wed, 5 Jun 2019 09:16:08 +0200
Subject: [PATCH] inference: register nested sessions for void compatible
 lambdas (IDEA-207070)

GitOrigin-RevId: 77f740e2754917b0053fcb79fb56e2b0c62436f4
---
 .../graphInference/InferenceSession.java      |  2 +-
 ...xpressionInVoidCompatibleLambdaReturn.java | 20 +++++++++++++++++++
 .../lambda/NewLambdaHighlightingTest.java     |  1 +
 3 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newLambda/PolyExpressionInVoidCompatibleLambdaReturn.java

diff --git a/java/java-psi-impl/src/com/intellij/psi/impl/source/resolve/graphInference/InferenceSession.java b/java/java-psi-impl/src/com/intellij/psi/impl/source/resolve/graphInference/InferenceSession.java
index fc8d1a17b08e..0e0bfd096c7f 100644
--- a/java/java-psi-impl/src/com/intellij/psi/impl/source/resolve/graphInference/InferenceSession.java
+++ b/java/java-psi-impl/src/com/intellij/psi/impl/source/resolve/graphInference/InferenceSession.java
@@ -456,7 +456,7 @@ public class InferenceSession {
                                              boolean addConstraint,
                                              PsiSubstitutor initialSubstitutor) {
     final PsiType interfaceReturnType = LambdaUtil.getFunctionalInterfaceReturnType(parameterType);
-    if (interfaceReturnType != null && !PsiType.VOID.equals(interfaceReturnType)) {
+    if (interfaceReturnType != null && (!PsiType.VOID.equals(interfaceReturnType) || !addConstraint)) {
       final List<PsiExpression> returnExpressions = LambdaUtil.getReturnExpressions(lambdaExpression);
       for (PsiExpression returnExpression : returnExpressions) {
         processReturnExpression(additionalConstraints, ignoredConstraints, returnExpression, interfaceReturnType, addConstraint, initialSubstitutor);
diff --git a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newLambda/PolyExpressionInVoidCompatibleLambdaReturn.java b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newLambda/PolyExpressionInVoidCompatibleLambdaReturn.java
new file mode 100644
index 000000000000..70f9a77ec662
--- /dev/null
+++ b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newLambda/PolyExpressionInVoidCompatibleLambdaReturn.java
@@ -0,0 +1,20 @@
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Function;
+
+class MyTest {
+
+    {
+        foo(() -> build(id(x -> x)));
+    }
+
+    static <I> I id(I i) {
+      return i;
+    }
+    static <K> void foo(Runnable e) {}
+    
+    static <TT> List<TT> build(Function<String, TT> transformers) {
+        return null;
+    }
+}
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/lambda/NewLambdaHighlightingTest.java b/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/lambda/NewLambdaHighlightingTest.java
index 3a28270d98df..3b9787052a68 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/lambda/NewLambdaHighlightingTest.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/lambda/NewLambdaHighlightingTest.java
@@ -168,6 +168,7 @@ public class NewLambdaHighlightingTest extends LightDaemonAnalyzerTestCase {
   public void testUnhandledExceptionInLambdaChain() { doTest(); }
   public void testFunctionalBound() { doTest(); }
   public void testValidFixesOnUnresolvedMethod() { doTest(); }
+  public void testPolyExpressionInVoidCompatibleLambdaReturn() { doTest(); }
 
   private void doTest() {
     IdeaTestUtil.setTestVersion(JavaSdkVersion.JDK_1_8, getModule(), getTestRootDisposable());