flag usage of get_class outside class without args

src/Psalm/Context.php

@@ -107,6 +107,7 @@ class Context
 
     /**
      * @var string|null
+     * The name of the current class. Null if outside a class.
      */
     public $self;
 

src/Psalm/Internal/Analyzer/Statements/Expression/Call/ArgumentsAnalyzer.php

@@ -868,6 +868,22 @@ public static function checkArgumentsMatch(
             return null;
         }
 
+        if ($method_id === 'get_class' && $args === []) {
+            //get_class without args only works when inside a class
+            if (!$context->self) {
+                IssueBuffer::maybeAdd(
+                    new TooFewArguments(
+                        'Cannot call get_class() without argument outside of class scope',
+                        $code_location,
+                        $method_id
+                    ),
+                    $statements_analyzer->getSuppressedIssues()
+                );
+
+                return null;
+            }
+        }
+
         self::checkArgCount(
             $statements_analyzer,
             $codebase,

tests/FunctionCallTest.php

@@ -2273,6 +2273,12 @@ function takesAString(string $s): void{
                     takesAString(false);',
                 'error_message' => 'InvalidArgument'
             ],
+            'getClassWithoutArgsOutsideClass' => [
+                '<?php
+
+                    echo get_class();',
+                'error_message' => 'TooFewArguments',
+            ],
         ];
     }