From a87a1f0dc9b95584bad6b0109b857dea3900bea6 Mon Sep 17 00:00:00 2001
From: Matthew Brown <github@muglug.com>
Date: Wed, 6 Dec 2017 00:35:41 -0500
Subject: [PATCH] Make sure undeclared array offset vars have type mixed

Fixes #360
---
 .../Checker/Statements/ExpressionChecker.php  | 37 ++++++++++++-------
 tests/RedundantConditionTest.php              | 12 ++++++
 2 files changed, 36 insertions(+), 13 deletions(-)

diff --git a/src/Psalm/Checker/Statements/ExpressionChecker.php b/src/Psalm/Checker/Statements/ExpressionChecker.php
index 0bc82bdd8..354249403 100644
--- a/src/Psalm/Checker/Statements/ExpressionChecker.php
+++ b/src/Psalm/Checker/Statements/ExpressionChecker.php
@@ -611,14 +611,19 @@ class ExpressionChecker
                         );
                     }
                 } elseif ($context->check_variables) {
-                    IssueBuffer::add(
+                    if (IssueBuffer::accepts(
                         new UndefinedVariable(
                             'Cannot find referenced variable ' . $var_name,
                             new CodeLocation($statements_checker->getSource(), $stmt)
-                        )
-                    );
+                        ),
+                        $statements_checker->getSuppressedIssues()
+                    )) {
+                        return false;
+                    }
 
-                    return false;
+                    $stmt->inferredType = Type::getMixed();
+
+                    return null;
                 }
             }
 
@@ -1884,14 +1889,17 @@ class ExpressionChecker
 
                 if (!isset($context->vars_possibly_in_scope[$use_var_id])) {
                     if ($context->check_variables) {
-                        IssueBuffer::add(
+                        if (IssueBuffer::accepts(
                             new UndefinedVariable(
                                 'Cannot find referenced variable ' . $use_var_id,
                                 new CodeLocation($statements_checker->getSource(), $use)
-                            )
-                        );
+                            ),
+                            $statements_checker->getSuppressedIssues()
+                        )) {
+                            return false;
+                        }
 
-                        return false;
+                        return null;
                     }
                 }
 
@@ -1909,18 +1917,21 @@ class ExpressionChecker
                         return false;
                     }
 
-                    return null;
+                    continue;
                 }
 
                 if ($context->check_variables) {
-                    IssueBuffer::add(
+                    if (IssueBuffer::accepts(
                         new UndefinedVariable(
                             'Cannot find referenced variable ' . $use_var_id,
                             new CodeLocation($statements_checker->getSource(), $use)
-                        )
-                    );
+                        ),
+                        $statements_checker->getSuppressedIssues()
+                    )) {
+                        return false;
+                    }
 
-                    return false;
+                    continue;
                 }
             }
         }
diff --git a/tests/RedundantConditionTest.php b/tests/RedundantConditionTest.php
index 5a2086deb..3df1bc6e5 100644
--- a/tests/RedundantConditionTest.php
+++ b/tests/RedundantConditionTest.php
@@ -144,6 +144,18 @@ class RedundantConditionTest extends TestCase
 
                     if ($a->foo() || $a->bar()) {}',
             ],
+            'noEmptyUndefinedArrayVar' => [
+                '<?php
+                    if (rand(0,1)) {
+                      /** @psalm-suppress UndefinedVariable */
+                      $a = $b[0];
+                    } else {
+                      $a = null;
+                    }
+                    if ($a) {}',
+                'assertions' => [],
+                'error_levels' => ['MixedAssignment', 'MixedArrayAccess'],
+            ],
         ];
     }