From 75a3412a427a1072906f14854446ab2d64f7f1b3 Mon Sep 17 00:00:00 2001
From: Matthew Brown <github@muglug.com>
Date: Thu, 5 Mar 2020 21:24:08 -0500
Subject: [PATCH] Downgrade error when using unknown variable in mixed method

---
 .../Statements/Expression/CallAnalyzer.php         | 14 ++++++++++++++
 tests/UnusedCodeTest.php                           |  4 ++--
 tests/UnusedVariableTest.php                       |  1 +
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/CallAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/CallAnalyzer.php
index e671db43869..9ed9e6d313d 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/CallAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/CallAnalyzer.php
@@ -30,6 +30,7 @@
 use Psalm\Issue\PossiblyFalseArgument;
 use Psalm\Issue\PossiblyInvalidArgument;
 use Psalm\Issue\PossiblyNullArgument;
+use Psalm\Issue\PossiblyUndefinedVariable;
 use Psalm\Issue\TooFewArguments;
 use Psalm\Issue\TooManyArguments;
 use Psalm\Issue\ArgumentTypeCoercion;
@@ -706,6 +707,19 @@ private static function evaluateAribitraryParam(
             if (!$context->hasVariable($var_id, $statements_analyzer)
                 || $context->vars_in_scope[$var_id]->isNull()
             ) {
+                if (!isset($context->vars_in_scope[$var_id])) {
+                    if (IssueBuffer::accepts(
+                        new PossiblyUndefinedVariable(
+                            'Variable ' . $var_id
+                                . ' must be defined prior to use within an unknown function or method',
+                            new CodeLocation($statements_analyzer->getSource(), $arg->value)
+                        ),
+                        $statements_analyzer->getSuppressedIssues()
+                    )) {
+                        // fall through
+                    }
+                }
+
                 // we don't know if it exists, assume it's passed by reference
                 $context->vars_in_scope[$var_id] = Type::getMixed();
                 $context->vars_possibly_in_scope[$var_id] = true;
diff --git a/tests/UnusedCodeTest.php b/tests/UnusedCodeTest.php
index a41287c1f0a..b7a78d7f498 100644
--- a/tests/UnusedCodeTest.php
+++ b/tests/UnusedCodeTest.php
@@ -543,14 +543,14 @@ class Foo {
                         /**
                          * @psalm-suppress MixedArgument
                          */
-                        public function bar(): void {
+                        public function bar(string $request): void {
                             /** @var mixed $action */
                             $action = "";
                             $this->{"execute" . ucfirst($action)}($request);
                         }
                     }
 
-                    (new Foo)->bar();'
+                    (new Foo)->bar("request");'
             ],
             'usedMethodCallForExternalMutationFreeClass' => [
                 '<?php
diff --git a/tests/UnusedVariableTest.php b/tests/UnusedVariableTest.php
index a2f731bdb45..369b742acb5 100644
--- a/tests/UnusedVariableTest.php
+++ b/tests/UnusedVariableTest.php
@@ -522,6 +522,7 @@ function callDangerous(): void {
                 '<?php
                     /** @psalm-suppress MixedMethodCall */
                     function passesByRef(object $a): void {
+                        /** @psalm-suppress PossiblyUndefinedVariable */
                         $a->passedByRef($b);
                     }',
             ],