From 7bc6c05c41ebf31faa41b9f3df184f2337a5d249 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Fri, 22 Jun 2018 09:53:48 +0700
Subject: [PATCH] RedundantCastUtil#isCastRedundant: skip further checks if
 cast operand type equals to cast type

Fixes IDEA-194278 "Too weak variable type leads to unnecessary cast" does not detect some cases
---
 .../src/com/intellij/psi/util/RedundantCastUtil.java     | 2 ++
 .../afterIncomplete.java                                 | 9 +++++++++
 .../beforeIncomplete.java                                | 9 +++++++++
 3 files changed, 20 insertions(+)
 create mode 100644 java/java-tests/testData/inspection/castCanBeRemovedNarrowingVariableType/afterIncomplete.java
 create mode 100644 java/java-tests/testData/inspection/castCanBeRemovedNarrowingVariableType/beforeIncomplete.java

diff --git a/java/java-psi-api/src/com/intellij/psi/util/RedundantCastUtil.java b/java/java-psi-api/src/com/intellij/psi/util/RedundantCastUtil.java
index 8032c035d75e..a11cd1c4c12c 100644
--- a/java/java-psi-api/src/com/intellij/psi/util/RedundantCastUtil.java
+++ b/java/java-psi-api/src/com/intellij/psi/util/RedundantCastUtil.java
@@ -46,6 +46,8 @@ public class RedundantCastUtil {
 
   public static boolean isCastRedundant (PsiTypeCastExpression typeCast) {
     PsiElement parent = typeCast.getParent();
+    PsiExpression operand = typeCast.getOperand();
+    if (operand != null && operand.getType() != null && operand.getType().equals(typeCast.getType())) return true;
     while(parent instanceof PsiParenthesizedExpression) parent = parent.getParent();
     if (parent instanceof PsiExpressionList) parent = parent.getParent();
     if (parent instanceof PsiReferenceExpression) parent = parent.getParent();
diff --git a/java/java-tests/testData/inspection/castCanBeRemovedNarrowingVariableType/afterIncomplete.java b/java/java-tests/testData/inspection/castCanBeRemovedNarrowingVariableType/afterIncomplete.java
new file mode 100644
index 000000000000..1c1e55d80fd8
--- /dev/null
+++ b/java/java-tests/testData/inspection/castCanBeRemovedNarrowingVariableType/afterIncomplete.java
@@ -0,0 +1,9 @@
+// "Change type of 'list' to 'ArrayList<String>' and remove cast" "true"
+import java.util.*;
+
+class Test {
+  void test() {
+    ArrayList<String> list = new ArrayList<>();
+    list.ensureCapacity();
+  }
+}
\ No newline at end of file
diff --git a/java/java-tests/testData/inspection/castCanBeRemovedNarrowingVariableType/beforeIncomplete.java b/java/java-tests/testData/inspection/castCanBeRemovedNarrowingVariableType/beforeIncomplete.java
new file mode 100644
index 000000000000..fb33241082e0
--- /dev/null
+++ b/java/java-tests/testData/inspection/castCanBeRemovedNarrowingVariableType/beforeIncomplete.java
@@ -0,0 +1,9 @@
+// "Change type of 'list' to 'ArrayList<String>' and remove cast" "true"
+import java.util.*;
+
+class Test {
+  void test() {
+    List<String> list = new ArrayList<>();
+    ((ArrayList<caret><String>) list).ensureCapacity();
+  }
+}
\ No newline at end of file