From 42e496419160d6711d46bf5c066c89bb9dcd8d19 Mon Sep 17 00:00:00 2001
From: Semyon Proshev <Semyon.Proshev@jetbrains.com>
Date: Tue, 20 Mar 2018 15:47:38 +0300
Subject: [PATCH] Visit `else` in `while` in any case even if condition is
 `True` (PY-28972)

But when condition is `True`, edge to `else` is not created.
---
 .../codeInsight/controlflow/PyControlFlowBuilder.java  |  6 ++++--
 .../testData/codeInsight/controlflow/whiletrueelse.py  |  4 ++++
 .../testData/codeInsight/controlflow/whiletrueelse.txt |  6 ++++++
 .../extractmethod/InterruptedOuterLoop.before.py       |  7 +++++++
 .../com/jetbrains/python/PyControlFlowBuilderTest.java |  5 +++++
 .../inspections/PyUnreachableCodeInspectionTest.java   | 10 ++++++++++
 .../python/refactoring/PyExtractMethodTest.java        |  5 +++++
 7 files changed, 41 insertions(+), 2 deletions(-)
 create mode 100644 python/testData/codeInsight/controlflow/whiletrueelse.py
 create mode 100644 python/testData/codeInsight/controlflow/whiletrueelse.txt
 create mode 100644 python/testData/refactoring/extractmethod/InterruptedOuterLoop.before.py

diff --git a/python/src/com/jetbrains/python/codeInsight/controlflow/PyControlFlowBuilder.java b/python/src/com/jetbrains/python/codeInsight/controlflow/PyControlFlowBuilder.java
index 5329e87297ec..eadc9865422d 100644
--- a/python/src/com/jetbrains/python/codeInsight/controlflow/PyControlFlowBuilder.java
+++ b/python/src/com/jetbrains/python/codeInsight/controlflow/PyControlFlowBuilder.java
@@ -489,11 +489,13 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
       myBuilder.addEdge(myBuilder.prevInstruction, instruction);
     }
     myBuilder.checkPending(instruction);
-    myBuilder.prevInstruction = head;
-    if (elsePart != null && !isStaticallyTrue) {
+
+    if (elsePart != null) {
+      myBuilder.prevInstruction = !isStaticallyTrue ? head : null;
       elsePart.accept(this);
       myBuilder.addPendingEdge(node, myBuilder.prevInstruction);
     }
+
     myBuilder.flowAbrupted();
   }
 
diff --git a/python/testData/codeInsight/controlflow/whiletrueelse.py b/python/testData/codeInsight/controlflow/whiletrueelse.py
new file mode 100644
index 000000000000..66aebac4804f
--- /dev/null
+++ b/python/testData/codeInsight/controlflow/whiletrueelse.py
@@ -0,0 +1,4 @@
+while True:
+    pass
+else:
+    print("ok")
\ No newline at end of file
diff --git a/python/testData/codeInsight/controlflow/whiletrueelse.txt b/python/testData/codeInsight/controlflow/whiletrueelse.txt
new file mode 100644
index 000000000000..cbe98737cb19
--- /dev/null
+++ b/python/testData/codeInsight/controlflow/whiletrueelse.txt
@@ -0,0 +1,6 @@
+0(1) element: null
+1(2) element: PyWhileStatement
+2(3) READ ACCESS: True
+3(1) element: PyStatementList. Condition: True:true
+4(5) element: PyPrintStatement
+5() element: null
\ No newline at end of file
diff --git a/python/testData/refactoring/extractmethod/InterruptedOuterLoop.before.py b/python/testData/refactoring/extractmethod/InterruptedOuterLoop.before.py
new file mode 100644
index 000000000000..937a2e121790
--- /dev/null
+++ b/python/testData/refactoring/extractmethod/InterruptedOuterLoop.before.py
@@ -0,0 +1,7 @@
+while True:
+    <selection>
+    while True:
+        pass
+    else:
+        break
+    </selection>
\ No newline at end of file
diff --git a/python/testSrc/com/jetbrains/python/PyControlFlowBuilderTest.java b/python/testSrc/com/jetbrains/python/PyControlFlowBuilderTest.java
index 7f63515f4c87..98a11f56aade 100644
--- a/python/testSrc/com/jetbrains/python/PyControlFlowBuilderTest.java
+++ b/python/testSrc/com/jetbrains/python/PyControlFlowBuilderTest.java
@@ -274,6 +274,11 @@ public class PyControlFlowBuilderTest extends LightMarkedTestCase {
     doTest();
   }
 
+  // PY-28972
+  public void testWhileTrueElse() {
+    doTest();
+  }
+
   private void doTestFirstStatement() {
     final String testName = getTestName(false).toLowerCase();
     configureByFile(testName + ".py");
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyUnreachableCodeInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyUnreachableCodeInspectionTest.java
index 78c7cda03dac..d6f409cf4b9e 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyUnreachableCodeInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyUnreachableCodeInspectionTest.java
@@ -117,6 +117,16 @@ public class PyUnreachableCodeInspectionTest extends PyInspectionTestCase {
     );
   }
 
+  // PY-28972
+  public void testWhileTrueElse() {
+    doTestByText(
+      "while True:\n" +
+      "    pass\n" +
+      "else:\n" +
+      "    <warning descr=\"This code is unreachable\">print(\"ok\")</warning>"
+    );
+  }
+
   @NotNull
   @Override
   protected Class<? extends PyInspection> getInspectionClass() {
diff --git a/python/testSrc/com/jetbrains/python/refactoring/PyExtractMethodTest.java b/python/testSrc/com/jetbrains/python/refactoring/PyExtractMethodTest.java
index 1b6a87ec44bb..84af949916d4 100644
--- a/python/testSrc/com/jetbrains/python/refactoring/PyExtractMethodTest.java
+++ b/python/testSrc/com/jetbrains/python/refactoring/PyExtractMethodTest.java
@@ -270,4 +270,9 @@ public class PyExtractMethodTest extends LightMarkedTestCase {
   public void testCommentsPrecedingSourceStatement() {
     doTest("func");
   }
+
+  // PY-28972
+  public void testInterruptedOuterLoop() {
+    doFail("foo", "Cannot perform refactoring when execution flow is interrupted");
+  }
 }