disjunction type equals/hashCode, essential for new inference (IDEA-140150)

java/java-psi-api/src/com/intellij/psi/PsiDisjunctionType.java

@@ -148,4 +148,24 @@ public class PsiDisjunctionType extends PsiType.Stub {
       return new PsiType[]{lub};
     }
   }
+
+  @Override
+  public int hashCode() {
+    return myTypes.get(0).hashCode();
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (o == null || getClass() != o.getClass()) return false;
+
+    final PsiDisjunctionType that = (PsiDisjunctionType)o;
+    if (that.myTypes.size() != myTypes.size()) return false;
+
+    for (int i = 0; i < myTypes.size(); i++) {
+      if (!myTypes.get(i).equals(that.myTypes.get(i))) return false;
+    }
+
+    return true;
+  }
 }

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

@@ -0,0 +1,28 @@
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.Optional;
+
+class Main {
+  public static class Either<A, B> {
+    final public Optional<A> _1;
+    final public Optional<B> _2;
+
+    private Either(Optional<A> _1, Optional<B> _2) {
+      this._1 = _1;
+      this._2 = _2;
+    }
+
+    public static <A, B> Either<A, B> _2(B value) {
+      return null;
+    }
+  }
+
+  public Either<String, Exception> test1() {
+    try {
+      new FileOutputStream("").write(1);
+      return null;
+    } catch (NullPointerException | IOException e) {
+      return Either._2(e);
+    }
+  }
+}

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

@@ -275,6 +275,10 @@ public class GraphInferenceHighlightingTest extends LightDaemonAnalyzerTestCase
     doTest();
   }
 
+  public void testDisjunctionTypeEquality() throws Exception {
+    doTest();
+  }
+
   private void doTest() throws Exception {
     doTest(false);
   }