Add more accurate checks for assignment

lib/StatementsChecker.php

@@ -654,10 +654,13 @@ class StatementsChecker
 
     protected function _checkAssignment(PhpParser\Node\Expr\Assign $stmt, array &$vars_in_scope, array &$vars_possibly_in_scope)
     {
+        $this->_checkExpression($stmt->expr, $vars_in_scope, $vars_possibly_in_scope);
+
         if ($stmt->var instanceof PhpParser\Node\Expr\Variable && is_string($stmt->var->name)) {
             $vars_in_scope[$stmt->var->name] = true;
             $vars_possibly_in_scope[$stmt->var->name] = true;
             $this->registerVariable($stmt->var->name, $stmt->var->getLine());
+
         } elseif ($stmt->var instanceof PhpParser\Node\Expr\List_) {
             foreach ($stmt->var->vars as $var) {
                 if ($var) {
@@ -666,16 +669,14 @@ class StatementsChecker
                     $this->registerVariable($var->name, $var->getLine());
                 }
             }
-        }
+
+        } else if ($stmt->var instanceof PhpParser\Node\Expr\ArrayDimFetch && $stmt->var->var instanceof PhpParser\Node\Expr\Variable) {
             // if it's an array assignment
-        else if ($stmt->var instanceof PhpParser\Node\Expr\ArrayDimFetch && $stmt->var->var instanceof PhpParser\Node\Expr\Variable) {
             $vars_in_scope[$stmt->var->var->name] = true;
             $vars_possibly_in_scope[$stmt->var->var->name] = true;
             $this->registerVariable($stmt->var->var->name, $stmt->var->var->getLine());
         }
 
-        $this->_checkExpression($stmt->expr, $vars_in_scope, $vars_possibly_in_scope);
-
         if ($stmt->var instanceof PhpParser\Node\Expr\Variable && is_string($stmt->var->name)) {
             $comments = [];
             $doc_comment = $stmt->getDocComment();
@@ -690,6 +691,7 @@ class StatementsChecker
                 if ($type[0] === strtoupper($type[0])) {
                     $vars_in_scope[$stmt->var->name] = ClassChecker::getAbsoluteClassFromString($type, $this->_namespace, $this->_aliased_classes);
                 }
+
             } elseif (isset($stmt->expr->returnType)) {
                 $var_name = $stmt->var->name;
 
@@ -697,6 +699,7 @@ class StatementsChecker
                     if (isset($vars_in_scope[$var_name])) {
                         $vars_in_scope[$var_name] = 'mixed';
                     }
+
                 } elseif (isset($vars_in_scope[$var_name])) {
                     $existing_type = $vars_in_scope[$var_name];
 
@@ -711,6 +714,7 @@ class StatementsChecker
                             $vars_in_scope[$stmt->var->name] = 'mixed';
                         }
                     }
+
                 } else {
                     $vars_in_scope[$stmt->var->name] = $stmt->expr->returnType;
                 }
@@ -973,6 +977,9 @@ class StatementsChecker
             } elseif ($method->parts === ['defined']) {
                 $this->_check_consts = false;
 
+            } elseif ($method->parts === ['extract']) {
+                $this->_check_variables = false;
+
             } elseif ($method->parts === ['var_dump'] || $method->parts === ['die'] || $method->parts === ['exit']) {
                 if (FileChecker::shouldCheckVarDumps($this->_file_name)) {
                     throw new CodeException('Unsafe ' . implode('', $method->parts), $this->_file_name, $stmt->getLine());