From 027fe9bb55f26dfdb6b609a5485c207051b7e739 Mon Sep 17 00:00:00 2001
From: fitermay <fiterman@gmail.com>
Date: Mon, 3 Oct 2016 14:19:59 +0300
Subject: [PATCH] PY-1177 Fixed: Control flow analysis doesn't detect
 while/break

Handle control flow for statically true condition in while statement
---
 .../controlflow/PyControlFlowBuilder.java     | 22 +++++++++----------
 .../WhileTrueBreak.py                         |  4 ++++
 .../PyUnboundLocalVariableInspectionTest.java |  7 +++++-
 3 files changed, 21 insertions(+), 12 deletions(-)
 create mode 100644 python/testData/inspections/PyUnboundLocalVariableInspection/WhileTrueBreak.py

diff --git a/python/src/com/jetbrains/python/codeInsight/controlflow/PyControlFlowBuilder.java b/python/src/com/jetbrains/python/codeInsight/controlflow/PyControlFlowBuilder.java
index fbff5c2d8a00..0dd30074a902 100644
--- a/python/src/com/jetbrains/python/codeInsight/controlflow/PyControlFlowBuilder.java
+++ b/python/src/com/jetbrains/python/codeInsight/controlflow/PyControlFlowBuilder.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -404,26 +404,26 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
     final Instruction instruction = myBuilder.startNode(node);
     final PyWhilePart whilePart = node.getWhilePart();
     final PyExpression condition = whilePart.getCondition();
+    boolean isStaticallyTrue = false;
     if (condition != null) {
       condition.accept(this);
+      isStaticallyTrue = (PyConstantExpressionEvaluator.evaluate(condition) == Boolean.TRUE);
     }
     final Instruction head = myBuilder.prevInstruction;
     final PyElsePart elsePart = node.getElsePart();
-    if (elsePart == null) {
+    if (elsePart == null && !isStaticallyTrue) {
       myBuilder.addPendingEdge(node, myBuilder.prevInstruction);
     }
     final PyStatementList list = whilePart.getStatementList();
-    if (list != null) {
-      myBuilder.startConditionalNode(list,  condition, true);
-      list.accept(this);
-      // Loop edges
-      if (myBuilder.prevInstruction != null) {
-        myBuilder.addEdge(myBuilder.prevInstruction, instruction);
-      }
-      myBuilder.checkPending(instruction);
+    myBuilder.startConditionalNode(list, condition, true);
+    list.accept(this);
+    // Loop edges
+    if (myBuilder.prevInstruction != null) {
+      myBuilder.addEdge(myBuilder.prevInstruction, instruction);
     }
+    myBuilder.checkPending(instruction);
     myBuilder.prevInstruction = head;
-    if (elsePart != null) {
+    if (elsePart != null && !isStaticallyTrue) {
       elsePart.accept(this);
       myBuilder.addPendingEdge(node, myBuilder.prevInstruction);
     }
diff --git a/python/testData/inspections/PyUnboundLocalVariableInspection/WhileTrueBreak.py b/python/testData/inspections/PyUnboundLocalVariableInspection/WhileTrueBreak.py
new file mode 100644
index 000000000000..0308cd3758db
--- /dev/null
+++ b/python/testData/inspections/PyUnboundLocalVariableInspection/WhileTrueBreak.py
@@ -0,0 +1,4 @@
+while True:
+    a = 1
+    break
+print(a)  # pass
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyUnboundLocalVariableInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyUnboundLocalVariableInspectionTest.java
index feb634b6faad..5b4f9f8c0abe 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyUnboundLocalVariableInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyUnboundLocalVariableInspectionTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2013 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -183,6 +183,11 @@ public class PyUnboundLocalVariableInspectionTest extends PyTestCase {
     doTest();
   }
 
+  // PY-1177
+  public void testWhileTrueBreak() {
+    doTest();
+  }
+
   private void doTest() {
     myFixture.configureByFile(TEST_DIRECTORY + getTestName(false) + ".py");
     myFixture.enableInspections(PyUnboundLocalVariableInspection.class);