From 0deaf6d6a5ad4de770736d598c6805c09e79d756 Mon Sep 17 00:00:00 2001
From: Anna Kozlova <anna.kozlova@jetbrains.com>
Date: Mon, 26 Oct 2015 18:52:08 +0100
Subject: [PATCH] recursive substitutors: additional constraints substitution
 should not repeat already performed substitution with site substitutor
 (IDEA-146841)

---
 .../graphInference/InferenceSession.java      |  7 +++++-
 ...SubstitutorsWithAdditionalConstraints.java | 23 +++++++++++++++++++
 .../lambda/NewLambdaHighlightingTest.java     |  4 ++++
 3 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newLambda/RecursiveAtSiteSubstitutorsWithAdditionalConstraints.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 fe9e2309bf28..a0164ac251a5 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
@@ -1120,7 +1120,12 @@ public class InferenceSession {
   }
 
   private boolean proceedWithAdditionalConstraints(Set<ConstraintFormula> additionalConstraints) {
-    final PsiSubstitutor siteSubstitutor = mySiteSubstitutor;
+    //empty substitutor should be used to resolve input variables:
+    //all types in additional constraints are already substituted during collecting phase, 
+    //recursive site substitutors (T -> List<T>) would make additional constraints work with multiple times substituted types, which is incorrect.
+    //at the same time, recursive substitutions should not appear during inference but appear rather on site,
+    //so the problem should not influence consequence substitution of additional constraints
+    final PsiSubstitutor siteSubstitutor = PsiSubstitutor.EMPTY;
 
     while (!additionalConstraints.isEmpty()) {
       //extract subset of constraints
diff --git a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newLambda/RecursiveAtSiteSubstitutorsWithAdditionalConstraints.java b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newLambda/RecursiveAtSiteSubstitutorsWithAdditionalConstraints.java
new file mode 100644
index 000000000000..d96c7e1b7758
--- /dev/null
+++ b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newLambda/RecursiveAtSiteSubstitutorsWithAdditionalConstraints.java
@@ -0,0 +1,23 @@
+import java.util.concurrent.ExecutorService;
+import java.util.function.*;
+
+abstract class List<A> {
+
+  public abstract int length();
+  public abstract <B> B foldLeft(B identity, Function<B, Function<A, B>> f);
+  public abstract <B> List<B> map(Function<A, B> f);
+  public abstract <B> List<B> flatMap(Function<A, List<B>> f);
+
+  public List<List<A>> splitListAt(int i) {
+    return null;
+  }
+
+  public List<List<A>> divide(List<List<A>> list, int depth) {
+    final List<List<A>> divide = divide(list.flatMap(x -> x.splitListAt(x.length() / 2)), depth / 2);
+    return null;
+  }
+
+  public <C> void parFoldLeft(ExecutorService es, C identity, Function<C, Function<A, C>> f, List<List<A>> dList) {
+    dList.map(x -> es.submit(() -> x.foldLeft(identity, f)));
+  }
+}
diff --git a/java/java-tests/testSrc/com/intellij/codeInsight/daemon/lambda/NewLambdaHighlightingTest.java b/java/java-tests/testSrc/com/intellij/codeInsight/daemon/lambda/NewLambdaHighlightingTest.java
index 33242381ec35..281ca8ba8621 100644
--- a/java/java-tests/testSrc/com/intellij/codeInsight/daemon/lambda/NewLambdaHighlightingTest.java
+++ b/java/java-tests/testSrc/com/intellij/codeInsight/daemon/lambda/NewLambdaHighlightingTest.java
@@ -232,6 +232,10 @@ public class NewLambdaHighlightingTest extends LightDaemonAnalyzerTestCase {
     doTest();
   }
 
+  public void testRecursiveAtSiteSubstitutorsWithAdditionalConstraints() throws Exception {
+    doTest();
+  }
+
   private void doTest() {
     doTest(false);
   }