From 779291d9060dca6be2dcd438adb8578d140de681 Mon Sep 17 00:00:00 2001
From: "Anna.Kozlova" <anna.kozlova@jetbrains.com>
Date: Mon, 6 Aug 2018 19:32:06 +0200
Subject: [PATCH] ensure fresh variables for the same context don't conflict by
 names (IDEA-196642)

---
 .../resolve/graphInference/InferenceSession.java   |  6 +++---
 .../NameConflictBetweenFreshVariables.java         | 14 ++++++++++++++
 .../lambda/GraphInferenceHighlightingTest.java     |  1 +
 3 files changed, 18 insertions(+), 3 deletions(-)
 create mode 100644 java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/graphInference/NameConflictBetweenFreshVariables.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 df45da42c4f4..9f5d34a94984 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
@@ -1027,6 +1027,7 @@ public class InferenceSession {
 
   protected void resolveBounds(final Collection<InferenceVariable> inferenceVariables,
                              @NotNull PsiSubstitutor substitutor) {
+    final UniqueNameGenerator uniqueNameGenerator = new UniqueNameGenerator();
     final Collection<InferenceVariable> allVars = new ArrayList<>(inferenceVariables);
     while (!allVars.isEmpty()) {
       final List<InferenceVariable> vars = InferenceVariablesOrder.resolveOrder(allVars, this);
@@ -1054,7 +1055,7 @@ public class InferenceSession {
         }
       }
 
-      if (!initFreshVariables(substitutor, unresolved)) {
+      if (!initFreshVariables(substitutor, unresolved, uniqueNameGenerator)) {
         return;
       }
 
@@ -1091,11 +1092,10 @@ public class InferenceSession {
     }
   }
 
-  private boolean initFreshVariables(PsiSubstitutor substitutor, List<InferenceVariable> vars) {
+  private boolean initFreshVariables(PsiSubstitutor substitutor, List<InferenceVariable> vars, UniqueNameGenerator nameGenerator) {
     final PsiElementFactory elementFactory = JavaPsiFacade.getElementFactory(getManager().getProject());
     PsiSubstitutor ySubstitutor = PsiSubstitutor.EMPTY;
     final PsiTypeParameter[] yVars = new PsiTypeParameter[vars.size()];
-    UniqueNameGenerator nameGenerator = new UniqueNameGenerator();
     for (int i = 0; i < vars.size(); i++) {
       InferenceVariable var = vars.get(i);
       final PsiTypeParameter parameter = var.getParameter();
diff --git a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/graphInference/NameConflictBetweenFreshVariables.java b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/graphInference/NameConflictBetweenFreshVariables.java
new file mode 100644
index 000000000000..e56a1542c774
--- /dev/null
+++ b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/graphInference/NameConflictBetweenFreshVariables.java
@@ -0,0 +1,14 @@
+class MyTest {
+
+    static class Foo<A> {}
+
+    static <B> void bar(Foo<? super B> f1, Foo<? super B> f2) { }
+
+    {
+        bar<error descr="'bar(MyTest.Foo<? super B>, MyTest.Foo<? super B>)' in 'MyTest' cannot be applied to '(MyTest.Foo<T>, MyTest.Foo<T>)'">(m(), m())</error>;
+    }
+
+    static <T extends Comparable<T>> Foo<T> m() {
+        return null;
+    }
+}
\ No newline at end of file
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/lambda/GraphInferenceHighlightingTest.java b/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/lambda/GraphInferenceHighlightingTest.java
index 0da9c12569a7..86f5322af0c3 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/lambda/GraphInferenceHighlightingTest.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInsight/daemon/lambda/GraphInferenceHighlightingTest.java
@@ -166,6 +166,7 @@ public class GraphInferenceHighlightingTest extends LightDaemonAnalyzerTestCase
     }
   }
 
+  public void testNameConflictBetweenFreshVariables() { doTest(); }
   public void testCreateFreshVariablesOnlyForWildcardPlacesDuringReturnTypeProcessing() { doTest(); }
   public void testCapturedConversionDuringDirectSuperCheck() { doTest(); }
   //public void _testResolutionOrderForVariableCycles() { doTest(); }