Fix and test ast exporting

Since attributes on constants cannot be used in expressions, the normal
`assert()` testing cannot be used - instead, add a function to zend_test to
compile a string to AST and then export it back to a string.

Author: DanielEScherzer

Zend/tests/attributes/constants/ast_export.phpt

@@ -0,0 +1,34 @@
+--TEST--
+AST can be recreated when constants have attributes
+--EXTENSIONS--
+zend_test
+--FILE--
+<?php
+
+#[MyAttrib]
+const WITH_ATTRIBUTE = true;
+
+#[First]
+#[Second]
+const WITH_UNGROUPED = true;
+
+#[First, Second]
+const WITH_GROUPED = true;
+
+#[MyAttrib(5, param: "example")]
+const WITH_PARAMETERS = true;
+
+echo zend_test_compile_to_ast( file_get_contents( __FILE__ ) );
+
+?>
+--EXPECT--
+#[MyAttrib]
+const WITH_ATTRIBUTE = true;
+#[First]
+#[Second]
+const WITH_UNGROUPED = true;
+#[First, Second]
+const WITH_GROUPED = true;
+#[MyAttrib(5, param: 'example')]
+const WITH_PARAMETERS = true;
+echo zend_test_compile_to_ast(file_get_contents(__FILE__));

Zend/zend_ast.c

@@ -1970,6 +1970,25 @@ static ZEND_COLD void zend_ast_export_ex(smart_str *str, zend_ast *ast, int prio
 		}
 
 		case ZEND_AST_CONST_DECL:
+			zend_ast_list *ast_list = (zend_ast_list *)ast;
+			// Attributes are stored at the end of the list if present;
+			if (ast_list->child[ast_list->children - 1]->kind == ZEND_AST_ATTRIBUTE_LIST) {
+				zend_ast_export_attributes(
+					str,
+					ast_list->child[ast_list->children - 1],
+					indent,
+					1
+				);
+				// So that the list printing doesn't try to print the attributes,
+				// decrease the number of children; since we need to increase it
+				// afterwards, instead of jumping to simple_list we need to
+				// put the zend_ast_export_list() call here
+				ast_list->children--;
+				smart_str_appends(str, "const ");
+				zend_ast_export_list(str, ast_list, 1, 20, indent);
+				ast_list->children++;
+				break;
+			}
 			smart_str_appends(str, "const ");
 			goto simple_list;
 		case ZEND_AST_CLASS_CONST_GROUP:
@@ -2708,6 +2727,9 @@ zend_ast * ZEND_FASTCALL zend_ast_with_attributes(zend_ast *ast, zend_ast *attr)
 		ast->child[1] = attr;
 		break;
 	case ZEND_AST_CONST_DECL:
+		// Since constants are already stored in a list, just add the attributes
+		// to that list instead of storing them elsewhere;
+		// zend_compile_const_decl() checks the kind of the list elements
 		zend_ast_list_add(ast, attr);
 		break;
 	EMPTY_SWITCH_DEFAULT_CASE()

ext/zend_test/test.c

@@ -1520,3 +1520,22 @@ static PHP_FUNCTION(zend_test_create_throwing_resource)
 	zend_resource *res = zend_register_resource(NULL, le_throwing_resource);
 	ZVAL_RES(return_value, res);
 }
+
+static PHP_FUNCTION(zend_test_compile_to_ast)
+{
+	zend_string *str;
+
+	ZEND_PARSE_PARAMETERS_START(1, 1)
+		Z_PARAM_STR(str)
+	ZEND_PARSE_PARAMETERS_END();
+
+	zend_arena *ast_arena;
+	zend_ast *ast = zend_compile_string_to_ast(str, &ast_arena, ZSTR_EMPTY_ALLOC());
+	
+	zend_string *result = zend_ast_export("", ast, "");
+
+	zend_ast_destroy(ast);
+	zend_arena_destroy(ast_arena);
+
+	RETVAL_STR(result);
+}

ext/zend_test/test.stub.php

@@ -309,6 +309,8 @@ function zend_test_cast_fread($stream): void {}
     function zend_test_is_zend_ptr(int $addr): bool {}
 
     function zend_test_log_err_debug(string $str): void {}
+
+    function zend_test_compile_to_ast(string $str): string {}
 }
 
 namespace ZendTestNS {