Add DIM_ALTERNATIVE_SYNTAX flag for 7.4's $x{$i}

Fixes nikic#128

Fix ast\kind_uses_flags(ast\AST_ARROW_FUNC) in php < 7.4

Author: TysonAndre

README.md

@@ -342,6 +342,9 @@ ast\flags\ARRAY_SYNTAX_LIST
 
 // Used by ast\AST_ARRAY_ELEM (exclusive)
 ast\flags\ARRAY_ELEM_REF
+
+// Used by ast\AST_DIM (combinable), since PHP 7.4
+ast\flags\DIM_ALTERNATIVE_SYNTAX
 ```
 
 AST node kinds

ast.c

@@ -56,6 +56,10 @@
 # define ZEND_BIND_REF 1
 #endif
 
+#if PHP_VERSION_ID < 70400
+# define ZEND_DIM_ALTERNATIVE_SYNTAX (1<<1)
+#endif
+
 /* This contains state of the ast Node creator. */
 typedef struct ast_state_info {
 	zend_long version;
@@ -232,6 +236,12 @@ static const char *func_flags[] = {
 	NULL
 };
 
+// Flags of AST_DIM are marked as combinable in case any other flags get added in the future.
+static const char *dim_flags[] = {
+	AST_FLAG(DIM_ALTERNATIVE_SYNTAX),
+	NULL
+};
+
 static const ast_flag_info flag_info[] = {
 	{ AST_NAME, 0, name_flags },
 	{ ZEND_AST_CLASS, 0, class_flags },
@@ -257,6 +267,7 @@ static const ast_flag_info flag_info[] = {
 	{ ZEND_AST_PROP_GROUP, 1, modifier_flags },
 	{ ZEND_AST_CLASS_CONST_DECL, 1, visibility_flags },
 	{ ZEND_AST_TRAIT_ALIAS, 1, modifier_flags },
+	{ ZEND_AST_DIM, 1, dim_flags },
 };
 
 static inline void ast_update_property(zval *object, zend_string *name, zval *value, void **cache_slot) {
@@ -319,14 +330,12 @@ static inline zend_bool ast_kind_uses_attr(zend_ast_kind kind) {
 		|| kind == ZEND_AST_PROP_GROUP
 		|| kind == ZEND_AST_GROUP_USE || kind == ZEND_AST_USE_ELEM
 		|| kind == AST_NAME || kind == AST_CLOSURE_VAR || kind == ZEND_AST_CLASS_CONST_DECL
-		|| kind == ZEND_AST_ARRAY;
+		|| kind == ZEND_AST_ARRAY || kind == ZEND_AST_DIM;
 }
 
 static inline zend_bool ast_kind_is_decl(zend_ast_kind kind) {
 	return kind == ZEND_AST_FUNC_DECL || kind == ZEND_AST_CLOSURE
-#if PHP_VERSION_ID >= 70400
 		|| kind == ZEND_AST_ARROW_FUNC
-#endif
 		|| kind == ZEND_AST_METHOD || kind == ZEND_AST_CLASS;
 }
 
@@ -1327,6 +1336,8 @@ PHP_MINIT_FUNCTION(ast) {
 	ast_register_flag_constant("ARRAY_SYNTAX_LONG", ZEND_ARRAY_SYNTAX_LONG);
 	ast_register_flag_constant("ARRAY_SYNTAX_SHORT", ZEND_ARRAY_SYNTAX_SHORT);
 
+	ast_register_flag_constant("DIM_ALTERNATIVE_SYNTAX", ZEND_DIM_ALTERNATIVE_SYNTAX);
+
 	INIT_CLASS_ENTRY(tmp_ce, "ast\\Node", ast_node_functions);
 	ast_node_ce = zend_register_internal_class(&tmp_ce);
 	ast_declare_property(ast_node_ce, AST_STR(str_kind), &zv_null);

package.xml

@@ -24,6 +24,8 @@
  <license uri="https://github.com/nikic/php-ast/blob/master/LICENSE">BSD-3-Clause</license>
  <notes>
 - Fix build error in php 7.4.0alpha3.
+- Add `DIM_ALTERNATIVE_SYNTAX` as a flag of `AST_DIM` for `$x{'offset'}` (for php 7.4+)
+- Bugfix: Make `ast\kind_uses_flags(ast\AST_ARROW_FUNC)` true in php 7.3 and lower.
  </notes>
  <contents>
   <dir name="/">
@@ -81,6 +83,7 @@
       <file name="parse_file_parse_error.phpt" role="test" />
       <file name="parse_file.phpt" role="test" />
       <file name="php74_ast_assign_coalesce.phpt" role="test" />
+      <file name="php74_dim_alternative_syntax.phpt" role="test" />
       <file name="php74_ordinary_class.phpt" role="test" />
       <file name="php74_type_hints.phpt" role="test" />
       <file name="prop_doc_comments.phpt" role="test" />

tests/metadata.phpt

@@ -9,6 +9,12 @@ foreach ($metadata as $data) {
     foreach ($data->flags as $flag) {
         $flags[] = substr($flag, strrpos($flag, '\\') + 1);
     }
+    $metadataHasFlags = count($flags) > 0;
+    $kindUsesFlags = ast\kind_uses_flags($data->kind);
+    if ($metadataHasFlags != $kindUsesFlags) {
+        echo "kind_uses_flags for $data->name is unexpectedly " . var_export($kindUsesFlags, true) . "\n";
+    }
+
     echo "$data->name: ";
     if ($data->flagsCombinable) {
         echo "(combinable) ";
@@ -74,7 +80,7 @@ AST_GOTO: []
 AST_BREAK: []
 AST_CONTINUE: []
 AST_CLASS_NAME: []
-AST_DIM: []
+AST_DIM: (combinable) [DIM_ALTERNATIVE_SYNTAX]
 AST_PROP: []
 AST_STATIC_PROP: []
 AST_CALL: []

tests/php74_ast_assign_coalesce.phpt

@@ -26,6 +26,7 @@ AST_STMT_LIST
     1: AST_ASSIGN_OP
         flags: BINARY_COALESCE (%d)
         var: AST_DIM
+            flags: 0
             expr: AST_STATIC_PROP
                 class: AST_NAME
                     flags: NAME_NOT_FQ (%d)

tests/php74_dim_alternative_syntax.phpt

@@ -0,0 +1,29 @@
+--TEST--
+'$x{"offset"}' flag in PHP 7.4
+--SKIPIF--
+<?php if (PHP_VERSION_ID < 70400) die('skip PHP >= 7.4 only'); ?>
+--FILE--
+<?php
+
+require __DIR__ . '/../util.php';
+
+$code = <<<'PHP'
+<?php
+var_export($x{'offset'});
+PHP;
+
+$node = ast\parse_code($code, $version=70);
+echo ast_dump($node), "\n";
+?>
+--EXPECTF--
+AST_STMT_LIST
+    0: AST_CALL
+        expr: AST_NAME
+            flags: NAME_NOT_FQ (1)
+            name: "var_export"
+        args: AST_ARG_LIST
+            0: AST_DIM
+                flags: DIM_ALTERNATIVE_SYNTAX (2)
+                expr: AST_VAR
+                    name: "x"
+                dim: "offset"