Stip null elements from AST_STMT_LIST

Author: nikic

README.md

@@ -420,6 +420,8 @@ Version changelog
 * For `AST_NAME` nodes with `NAME_FQ` the leading backslash is now dropped if syntax like
   `('\bar')()` is used. Previously this would return the name as `'\bar'`, while a normal `\bar()`
   call would return it as `'bar'`. Now always the latter form is used.
+* `null` elements are now stripped from `AST_STMT_LIST`. Previously these could be caused by nop
+  statements (`;`).
 
 ### 30 (current)
 

ast.c

@@ -211,10 +211,14 @@ static void ast_fill_children_ht(HashTable *ht, zend_ast *ast, zend_long version
 			!is_list && version >= 30 ? ast_kind_child_name(ast->kind, i) : NULL;
 		zval child_zv;
 
-		if (version >= 20 && ast->kind == ZEND_AST_STMT_LIST
-				&& child != NULL && child->kind == ZEND_AST_STMT_LIST) {
-			ast_fill_children_ht(ht, child, version);
-			continue;
+		if (version >= 20 && ast->kind == ZEND_AST_STMT_LIST) {
+			if (child != NULL && child->kind == ZEND_AST_STMT_LIST) {
+				ast_fill_children_ht(ht, child, version);
+				continue;
+			}
+			if (version >= 40 && child == NULL) {
+				continue;
+			}
 		}
 
 		if (ast_is_name(child, ast, i)) {

tests/nop_statements.phpt

@@ -0,0 +1,30 @@
+--TEST--
+Nop statements
+--FILE--
+<?php
+
+require __DIR__ . '/../util.php';
+
+$code = <<<'PHP'
+<?php
+$a;
+;
+$b;
+PHP;
+
+echo ast_dump(ast\parse_code($code, $version=30)), "\n";
+echo ast_dump(ast\parse_code($code, $version=40)), "\n";
+
+?>
+--EXPECT--
+AST_STMT_LIST
+    0: AST_VAR
+        name: "a"
+    1: null
+    2: AST_VAR
+        name: "b"
+AST_STMT_LIST
+    0: AST_VAR
+        name: "a"
+    1: AST_VAR
+        name: "b"