From f4839c89ea37ea0f674d2a2f63522fea1178ba5b Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Wed, 13 Jun 2018 11:10:57 +0700
Subject: [PATCH] BaseStreamApiMigration: when deleting the initializer replace
 type with explicit if possible

Fixes IDEA-193618 Invalid code generated after "Can be replaced with 'collect' call"
---
 .../streamMigration/BaseStreamApiMigration.java   | 11 ++++++++++-
 .../streamApiMigration/java10/afterVarJava10.java | 12 ++++++++++++
 .../java10/beforeVarJava10.java                   | 15 +++++++++++++++
 3 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/java10/afterVarJava10.java
 create mode 100644 java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/java10/beforeVarJava10.java

diff --git a/java/java-impl/src/com/intellij/codeInspection/streamMigration/BaseStreamApiMigration.java b/java/java-impl/src/com/intellij/codeInspection/streamMigration/BaseStreamApiMigration.java
index ad0a397f8fbe..b94b0018623d 100644
--- a/java/java-impl/src/com/intellij/codeInspection/streamMigration/BaseStreamApiMigration.java
+++ b/java/java-impl/src/com/intellij/codeInspection/streamMigration/BaseStreamApiMigration.java
@@ -17,6 +17,7 @@ package com.intellij.codeInspection.streamMigration;
 
 import com.intellij.openapi.project.Project;
 import com.intellij.psi.*;
+import com.intellij.psi.util.PsiTypesUtil;
 import com.siyeh.ig.psiutils.CommentTracker;
 import com.siyeh.ig.psiutils.ControlFlowUtils;
 import com.siyeh.ig.psiutils.ControlFlowUtils.InitializerUsageStatus;
@@ -77,7 +78,15 @@ abstract class BaseStreamApiMigration {
     }
     else {
       if (status == ControlFlowUtils.InitializerUsageStatus.AT_WANTED_PLACE_ONLY) {
-        ct.delete(initializer);
+        PsiTypeElement typeElement = var.getTypeElement();
+        if (typeElement != null && typeElement.isInferredType()) {
+          if (PsiTypesUtil.isDenotableType(typeElement.getType(), var)) {
+            PsiTypesUtil.replaceWithExplicitType(typeElement);
+            ct.delete(initializer);
+          }
+        } else {
+          ct.delete(initializer);
+        }
       }
       return ct.replaceAndRestoreComments(loopStatement, var.getName() + " = " + replacement + ";");
     }
diff --git a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/java10/afterVarJava10.java b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/java10/afterVarJava10.java
new file mode 100644
index 000000000000..ee09bfbaf4d9
--- /dev/null
+++ b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/java10/afterVarJava10.java
@@ -0,0 +1,12 @@
+// "Fix all 'Loop can be collapsed with Stream API' problems in file" "true"
+import java.util.*;
+import java.util.stream.Collectors;
+
+class Test {
+  public List<Integer> someMethod() {
+      ArrayList<Integer> listOfInteger;
+    Integer[] arrayOfInteger = {2, 4, 8};
+      listOfInteger = Arrays.stream(arrayOfInteger).filter(number -> number >= 4).collect(Collectors.toCollection(ArrayList::new));
+    return listOfInteger;
+  }
+}
\ No newline at end of file
diff --git a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/java10/beforeVarJava10.java b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/java10/beforeVarJava10.java
new file mode 100644
index 000000000000..d35f56e92469
--- /dev/null
+++ b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/streamApiMigration/java10/beforeVarJava10.java
@@ -0,0 +1,15 @@
+// "Fix all 'Loop can be collapsed with Stream API' problems in file" "true"
+import java.util.*;
+
+class Test {
+  public List<Integer> someMethod() {
+    var listOfInteger = new ArrayList<Integer>();
+    Integer[] arrayOfInteger = {2, 4, 8};
+    f<caret>or (var number: arrayOfInteger) {
+      if (number >= 4) {
+        listOfInteger.add(number);
+      }
+    }
+    return listOfInteger;
+  }
+}
\ No newline at end of file