Fix processing normal exits from try-except when they goes out of scope (PY-22184)

python/src/com/jetbrains/python/codeInsight/controlflow/PyControlFlowBuilder.java

@@ -396,7 +396,8 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
     }
     else {
       myBuilder.prevInstruction = null;
-      final Instruction instruction = ContainerUtil.getFirstItem(InstructionBuilder.addAssertInstructions(myBuilder, negativeAssertionEvaluator));
+      final Instruction instruction =
+        ContainerUtil.getFirstItem(InstructionBuilder.addAssertInstructions(myBuilder, negativeAssertionEvaluator));
       if (instruction != null) {
         lastBranchingPoints.forEach(p -> myBuilder.addEdge(p.getSecond(), instruction));
       }
@@ -597,11 +598,11 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
     myBuilder.addPendingEdge(node, myBuilder.prevInstruction);
 
     // Process except parts
-    final List<Instruction> exceptInstructions = emptyMutableList();
-    List<Pair<PsiElement, Instruction>> pendingBackup = emptyMutableList();
+    final List<Instruction> exceptInstructions = new ArrayList<>();
+    List<Pair<PsiElement, Instruction>> pendingBackup = new ArrayList<>();
     for (PyExceptPart exceptPart : node.getExceptParts()) {
       pendingBackup.addAll(myBuilder.pending);
-      myBuilder.pending = emptyMutableList();
+      myBuilder.pending = new ArrayList<>();
       myBuilder.flowAbrupted();
       final Instruction exceptInstruction = myBuilder.startNode(exceptPart);
       exceptPart.accept(this);
@@ -612,7 +613,7 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
       myBuilder.addPendingEdge(pair.first, pair.second);
     }
 
-    final List<Instruction> normalExits = new ArrayList<>();
+    final List<Pair<PsiElement, Instruction>> pendingNormalExits = new ArrayList<>();
     final PyFinallyPart finallyPart = node.getFinallyPart();
     final Instruction finallyFailInstruction;
 
@@ -624,7 +625,7 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
           final boolean isPending = PsiTreeUtil.isAncestor(node, pendingElement, false) &&
                                     !PsiTreeUtil.isAncestor(finallyPart, pendingElement, false);
           if (isPending && pendingScope != null) {
-            normalExits.add(instruction);
+            pendingNormalExits.add(Pair.createNonNull(pendingScope, instruction));
           }
           else {
             myBuilder.addPendingEdge(pendingScope, instruction);
@@ -640,7 +641,8 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
       finallyPart.accept(this);
       myBuilder.addPendingEdge(null, myBuilder.prevInstruction);
       myBuilder.flowAbrupted();
-    } else {
+    }
+    else {
       finallyFailInstruction = null;
     }
 
@@ -691,16 +693,15 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
         }
       });
 
-      // Duplicate CFG for finally (-fail and -success) only if there are some successfull exits from the
+      // Duplicate CFG for finally (-fail and -success) only if there are some successful exits from the
       // try part. Otherwise a single CFG for finally provides the correct control flow
       final Instruction finallyInstruction;
-      if (!normalExits.isEmpty()) {
+      if (!pendingNormalExits.isEmpty()) {
         // Finally-success part handling
-        pendingBackup = emptyMutableList();
-        pendingBackup.addAll(myBuilder.pending);
-        myBuilder.pending = emptyMutableList();
+        pendingBackup = new ArrayList<>(myBuilder.pending);
+        myBuilder.pending = new ArrayList<>();
         myBuilder.flowAbrupted();
-        Instruction finallySuccessInstruction = myBuilder.startNode(finallyPart);
+        final Instruction finallySuccessInstruction = myBuilder.startNode(finallyPart);
         finallyPart.accept(this);
         for (Pair<PsiElement, Instruction> pair : pendingBackup) {
           myBuilder.addPendingEdge(pair.first, pair.second);
@@ -712,16 +713,21 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
       }
 
       // Connect normal exits from try and else parts to the finally part
-      for (Instruction instr : normalExits) {
-        myBuilder.addEdge(instr, finallyInstruction);
+      for (Pair<PsiElement, Instruction> pendingScopeAndInstruction : pendingNormalExits) {
+        final PsiElement pendingScope = pendingScopeAndInstruction.first;
+        final Instruction instruction = pendingScopeAndInstruction.second;
+
+        myBuilder.addEdge(instruction, finallyInstruction);
+
+        // When instruction continues outside of try-except statement scope
+        // the last instruction in finally-block is marked as pointing to that continuation
+        if (PsiTreeUtil.isAncestor(pendingScope, node, true)) {
+          myBuilder.addPendingEdge(pendingScope, myBuilder.prevInstruction);
+        }
       }
     }
   }
 
-  private static <T> List<T> emptyMutableList() {
-    return new ArrayList<>();
-  }
-
   @Override
   public void visitPyComprehensionElement(final PyComprehensionElement node) {
     PyExpression prevCondition = null;
@@ -730,7 +736,7 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
 
     for (PyComprehensionComponent component : node.getComponents()) {
       if (component instanceof PyComprehensionForComponent) {
-        final PyComprehensionForComponent c = (PyComprehensionForComponent) component;
+        final PyComprehensionForComponent c = (PyComprehensionForComponent)component;
         final PyExpression iteratedList = c.getIteratedList();
         final PyExpression iteratorVariable = c.getIteratorVariable();
         if (prevCondition != null) {
@@ -755,7 +761,7 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
         iterators.add(iterator);
       }
       else if (component instanceof PyComprehensionIfComponent) {
-        final PyComprehensionIfComponent c = (PyComprehensionIfComponent) component;
+        final PyComprehensionIfComponent c = (PyComprehensionIfComponent)component;
         final PyExpression condition = c.getTest();
         if (condition == null) {
           continue;
@@ -832,7 +838,7 @@ public class PyControlFlowBuilder extends PyRecursiveElementVisitor {
       else {
         myBuilder.addPendingEdge(pendingScope, instruction);
       }
-  });
+    });
   }
 
   private void abruptFlow(final PsiElement node) {

python/testData/codeInsight/controlflow/trytry.txt

@@ -40,7 +40,7 @@
 39(45) WRITE ACCESS: f
 40(41,45) element: PyFinallyPart
 41(42,45) element: PyAssignmentStatement
-42(43,45) WRITE ACCESS: f
+42(43,45,48) WRITE ACCESS: f
 43(44,45) element: PyAssignmentStatement
 44(45,48) WRITE ACCESS: g
 45(46,55) element: PyFinallyPart
@@ -48,7 +48,7 @@
 47(55) WRITE ACCESS: h
 48(49,55) element: PyFinallyPart
 49(50,55) element: PyAssignmentStatement
-50(51,55) WRITE ACCESS: h
+50(51,53,55) WRITE ACCESS: h
 51(52,55) element: PyAssignmentStatement
 52(8,53,55) WRITE ACCESS: i
 53(54,55) element: PyAssignmentStatement

python/testData/inspections/PyUnreachableCodeInspection/WhileTrueTryBreakFinally.py

@@ -0,0 +1,7 @@
+def foo():
+    while True:
+        try:
+            break
+        finally:
+            pass
+    print('b')

python/testSrc/com/jetbrains/python/inspections/PyUnreachableCodeInspectionTest.java

@@ -38,6 +38,11 @@ public class PyUnreachableCodeInspectionTest extends PyInspectionTestCase {
     doTest();
   }
 
+  // PY-22184
+  public void testWhileTrueTryBreakFinally() {
+    doTest();
+  }
+
   @NotNull
   @Override
   protected Class<? extends PyInspection> getInspectionClass() {