From 0426dbb41166a28e5eac1136116ef55feb8a9544 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Thu, 10 Aug 2017 13:14:43 +0700
Subject: [PATCH] IDEA-177306 False Positive: reporting "useless" Optional map

---
 .../intellij/codeInspection/util/OptionalUtil.java    | 11 ++++++++---
 .../inspection/optionalChains/beforeExplicitType.java |  8 ++++++++
 .../optionalChains/beforeExplicitType2.java           |  8 ++++++++
 3 files changed, 24 insertions(+), 3 deletions(-)
 create mode 100644 java/java-tests/testData/inspection/optionalChains/beforeExplicitType.java
 create mode 100644 java/java-tests/testData/inspection/optionalChains/beforeExplicitType2.java

diff --git a/java/java-impl/src/com/intellij/codeInspection/util/OptionalUtil.java b/java/java-impl/src/com/intellij/codeInspection/util/OptionalUtil.java
index a3ea8061436f..495111574d0a 100644
--- a/java/java-impl/src/com/intellij/codeInspection/util/OptionalUtil.java
+++ b/java/java-impl/src/com/intellij/codeInspection/util/OptionalUtil.java
@@ -30,6 +30,7 @@ import com.siyeh.ig.psiutils.MethodCallUtils;
 import com.siyeh.ig.psiutils.StreamApiUtil;
 import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * @author Tagir Valeev
@@ -108,10 +109,14 @@ public class OptionalUtil {
    * @return an expression text which will unwrap an {@code Optional}.
    */
   public static String generateOptionalUnwrap(String qualifier, PsiVariable var,
-                                               PsiExpression trueExpression, PsiExpression falseExpression,
-                                               PsiType targetType, boolean useOrElseGet) {
+                                              PsiExpression trueExpression, PsiExpression falseExpression,
+                                              @Nullable PsiType targetType, boolean useOrElseGet) {
     PsiExpression stripped = PsiUtil.skipParenthesizedExprDown(trueExpression);
-    if (!ExpressionUtils.isReferenceTo(trueExpression, var)) {
+    boolean trivialMap = ExpressionUtils.isReferenceTo(trueExpression, var) &&
+                         targetType != null &&
+                         trueExpression.getType() != null &&
+                         trueExpression.getType().isAssignableFrom(targetType);
+    if (!trivialMap) {
       if (stripped instanceof PsiTypeCastExpression && ExpressionUtils.isNullLiteral(falseExpression)) {
         PsiTypeCastExpression castExpression = (PsiTypeCastExpression)stripped;
         PsiTypeElement castType = castExpression.getCastType();
diff --git a/java/java-tests/testData/inspection/optionalChains/beforeExplicitType.java b/java/java-tests/testData/inspection/optionalChains/beforeExplicitType.java
new file mode 100644
index 000000000000..86ba9669dfac
--- /dev/null
+++ b/java/java-tests/testData/inspection/optionalChains/beforeExplicitType.java
@@ -0,0 +1,8 @@
+// "Fix all 'Simplify Optional call chains' problems in file" "false"
+import java.util.Optional;
+
+public class Tests {
+  static <T> void test(Optional<? extends T> opt, T defaultT) {
+    T t = opt.<T>map(x -> x).orEl<caret>se(defaultT);
+  }
+}
diff --git a/java/java-tests/testData/inspection/optionalChains/beforeExplicitType2.java b/java/java-tests/testData/inspection/optionalChains/beforeExplicitType2.java
new file mode 100644
index 000000000000..8ed069bf01a9
--- /dev/null
+++ b/java/java-tests/testData/inspection/optionalChains/beforeExplicitType2.java
@@ -0,0 +1,8 @@
+// "Fix all 'Simplify Optional call chains' problems in file" "false"
+import java.util.Optional;
+
+public class Tests {
+  static void test(Optional<Double> opt, Integer defaultT) {
+    Number t = opt.<Number>map(x -> x).orEl<caret>se(defaultT);
+  }
+}