From f22266b2ff31e34f07dc9769ed2379739044dc5a Mon Sep 17 00:00:00 2001
From: Brown <github@muglug.com>
Date: Mon, 11 Nov 2019 17:42:46 -0500
Subject: [PATCH] Improve reasoning around try/catch possibly-undefined vars

---
 .../Analyzer/Statements/Block/TryAnalyzer.php | 20 +++++++++----------
 tests/TryCatchTest.php                        | 18 +++++++++++++++++
 2 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/src/Psalm/Internal/Analyzer/Statements/Block/TryAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Block/TryAnalyzer.php
index 139489bb0..fd7568f2f 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Block/TryAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Block/TryAnalyzer.php
@@ -109,9 +109,6 @@ class TryAnalyzer
                 if (!isset($try_context->vars_in_scope[$var_id])) {
                     $try_context->vars_in_scope[$var_id] = clone $type;
                     $try_context->vars_in_scope[$var_id]->from_docblock = true;
-                    $type = clone $type;
-                    $type->possibly_undefined_from_try = true;
-                    $context->vars_in_scope[$var_id] = $type;
                 } else {
                     $try_context->vars_in_scope[$var_id] = Type::combineUnionTypes(
                         $try_context->vars_in_scope[$var_id],
@@ -172,7 +169,9 @@ class TryAnalyzer
 
             foreach ($catch_context->vars_in_scope as $var_id => $type) {
                 if (!isset($old_context->vars_in_scope[$var_id])) {
+                    $type = clone $type;
                     $type->possibly_undefined_from_try = true;
+                    $catch_context->vars_in_scope[$var_id] = $type;
                 } else {
                     $catch_context->vars_in_scope[$var_id] = Type::combineUnionTypes(
                         $type,
@@ -403,21 +402,20 @@ class TryAnalyzer
                 }
             }
 
-            if ($catch_actions[$i] !== [ScopeAnalyzer::ACTION_END]) {
+            if ($catch_actions[$i] !== [ScopeAnalyzer::ACTION_END]
+                && $catch_actions[$i] !== [ScopeAnalyzer::ACTION_CONTINUE]
+                && $catch_actions[$i] !== [ScopeAnalyzer::ACTION_BREAK]
+            ) {
                 $definitely_newly_assigned_var_ids = array_intersect_key(
                     $new_catch_assigned_var_ids,
                     $definitely_newly_assigned_var_ids
                 );
 
                 foreach ($catch_context->vars_in_scope as $var_id => $type) {
-                    if (!isset($old_context->vars_in_scope[$var_id])) {
-                        $type->possibly_undefined_from_try = false;
-                    }
-
                     if ($stmt_control_actions === [ScopeAnalyzer::ACTION_END]) {
                         $context->vars_in_scope[$var_id] = $type;
                     } elseif (isset($context->vars_in_scope[$var_id])
-                        && $context->vars_in_scope[$var_id]->getId() !== $type->getId()
+                        && !$context->vars_in_scope[$var_id]->equals($type)
                     ) {
                         $context->vars_in_scope[$var_id] = Type::combineUnionTypes(
                             $context->vars_in_scope[$var_id],
@@ -442,7 +440,9 @@ class TryAnalyzer
 
         foreach ($definitely_newly_assigned_var_ids as $var_id => $_) {
             if (isset($context->vars_in_scope[$var_id])) {
-                $context->vars_in_scope[$var_id]->possibly_undefined_from_try = false;
+                $new_type = clone $context->vars_in_scope[$var_id];
+                $new_type->possibly_undefined_from_try = false;
+                $context->vars_in_scope[$var_id] = $new_type;
             }
         }
 
diff --git a/tests/TryCatchTest.php b/tests/TryCatchTest.php
index 9eaf54ac1..c2025e956 100644
--- a/tests/TryCatchTest.php
+++ b/tests/TryCatchTest.php
@@ -128,6 +128,24 @@ class TryCatchTest extends TestCase
 
                     echo $a;',
             ],
+            'issetAfterTryCatchWithoutAssignmentInCatchButReturn' => [
+                '<?php
+                    function test(): string {
+                        throw new Exception("bad");
+                    }
+
+                    $a = "foo";
+
+                    try {
+                        $var = test();
+                    } catch (Exception $e) {
+                        return;
+                    }
+
+                    echo $var;
+
+                    echo $a;',
+            ],
             'issetAfterTryCatchWithAssignmentInCatch' => [
                 '<?php
                     function test(): string {