From d7762778a2c8b45f8fdca0ab50ca4d7b10faddeb Mon Sep 17 00:00:00 2001
From: Valentin Kipyatkov <valentin@jetbrains.com>
Date: Tue, 5 Apr 2016 20:46:42 +0300
Subject: [PATCH] Cannot transform to flatMap if old working variable used in
 the nested loop

---
 .../loopToCallChain/sequence/FlatMapTransformation.kt  |  6 ++++--
 .../loopToCallChain/flatMap_workingVarStillNeeded.kt   | 10 ++++++++++
 2 files changed, 14 insertions(+), 2 deletions(-)
 create mode 100644 idea/testData/intentions/loopToCallChain/flatMap_workingVarStillNeeded.kt

diff --git a/idea/src/org/jetbrains/kotlin/idea/intentions/loopToCallChain/sequence/FlatMapTransformation.kt b/idea/src/org/jetbrains/kotlin/idea/intentions/loopToCallChain/sequence/FlatMapTransformation.kt
index 80064894c31..7d60b43c67c 100644
--- a/idea/src/org/jetbrains/kotlin/idea/intentions/loopToCallChain/sequence/FlatMapTransformation.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/intentions/loopToCallChain/sequence/FlatMapTransformation.kt
@@ -64,12 +64,14 @@ class FlatMapTransformation(
             val iterableType = FuzzyType(builtIns.iterableType, builtIns.iterable.declaredTypeParameters)
             if (iterableType.checkIsSuperTypeOf(nestedSequenceType) == null) return null
 
+            val nestedLoopBody = nestedLoop.body ?: return null
+            if (state.workingVariable.hasUsages(listOf(nestedLoopBody))) return null // workingVariable is still needed - cannot transform
+
             val newWorkingVariable = nestedLoop.loopParameter ?: return null
-            val loopBody = nestedLoop.body ?: return null
             val transformation = FlatMapTransformation(state.workingVariable, transform)
             val newState = state.copy(
                     innerLoop = nestedLoop,
-                    statements = listOf(loopBody),
+                    statements = listOf(nestedLoopBody),
                     workingVariable = newWorkingVariable
             )
             return SequenceTransformationMatch(transformation, newState)
diff --git a/idea/testData/intentions/loopToCallChain/flatMap_workingVarStillNeeded.kt b/idea/testData/intentions/loopToCallChain/flatMap_workingVarStillNeeded.kt
new file mode 100644
index 00000000000..0b878edc866
--- /dev/null
+++ b/idea/testData/intentions/loopToCallChain/flatMap_workingVarStillNeeded.kt
@@ -0,0 +1,10 @@
+// WITH_RUNTIME
+// IS_APPLICABLE: false
+fun foo(list: List<String>): String? {
+    <caret>for (s in list) {
+        for (line in s.lines()) {
+            if (line.isNotBlank() && line.length < s.length / 10) return line
+        }
+    }
+    return null
+}
\ No newline at end of file