Restore CV

Author: arnaud-lb

Zend/tests/context_managers/using_restores_cv_001.phpt

@@ -0,0 +1,38 @@
+--TEST--
+using() restores CV
+--FILE--
+<?php
+
+require 'basic_manager.inc';
+
+class A {}
+
+$value = new A;
+$value2 = $value;
+
+echo "# \$value before using():\n";
+var_dump($value);
+
+using (new Manager() as $value) {
+    echo "# \$value in using():\n";
+    var_dump($value);
+}
+
+echo "# \$value after using():\n";
+var_dump($value);
+var_dump($value === $value2);
+
+?>
+--EXPECTF--
+# $value before using():
+object(A)#%d (0) {
+}
+Manager::enterContext()
+# $value in using():
+object(stdClass)#%d (0) {
+}
+Manager::exitContext(null)
+# $value after using():
+object(A)#%d (0) {
+}
+bool(true)

Zend/tests/context_managers/using_restores_cv_002.phpt

@@ -0,0 +1,24 @@
+--TEST--
+using() restores CV iff it was set
+--FILE--
+<?php
+
+require 'basic_manager.inc';
+
+using (new Manager() as $value) {
+    var_dump($value);
+}
+
+echo "\$value is set after using():\n";
+var_dump(isset($value));
+var_dump(array_key_exists('value', get_defined_vars()));
+
+?>
+--EXPECTF--
+Manager::enterContext()
+object(stdClass)#%d (0) {
+}
+Manager::exitContext(null)
+$value is set after using():
+bool(false)
+bool(false)

Zend/tests/context_managers/using_restores_cv_003.phpt

@@ -0,0 +1,44 @@
+--TEST--
+using() restores CV and preserves references
+--FILE--
+<?php
+
+require 'basic_manager.inc';
+
+class A {}
+class B {}
+
+$value = new A;
+$value2 = &$value;
+
+echo "# \$value before using():\n";
+var_dump($value);
+
+using (new Manager() as $value) {
+    echo "# \$value in using():\n";
+    var_dump($value);
+    $value = null;
+}
+
+echo "# \$value after using():\n";
+var_dump($value);
+$value = new B;
+
+echo "# \$value2 references \$value:\n";
+var_dump($value2 === $value);
+
+?>
+--EXPECTF--
+# $value before using():
+object(A)#%d (0) {
+}
+Manager::enterContext()
+# $value in using():
+object(stdClass)#%d (0) {
+}
+Manager::exitContext(null)
+# $value after using():
+object(A)#%d (0) {
+}
+# $value2 references $value:
+bool(true)

Zend/zend_ast.h

@@ -154,6 +154,7 @@ enum _zend_ast_kind {
 	ZEND_AST_NAMED_ARG,
 	ZEND_AST_PARENT_PROPERTY_HOOK_CALL,
 	ZEND_AST_PIPE,
+	ZEND_AST_RESTORE_CV,
 
 	/* 3 child nodes */
 	ZEND_AST_METHOD_CALL = 3 << ZEND_AST_NUM_CHILDREN_SHIFT,

Zend/zend_compile.c

@@ -5836,10 +5836,15 @@ static void zend_compile_using(zend_ast *ast)
 			zend_ast_create_znode(&tmp),
 			zend_ast_create_zval_from_str(ZSTR_KNOWN(ZEND_STR_ENTER_CONTEXT)),
 			zend_ast_create_list(0, ZEND_AST_ARG_LIST));
+	znode var_backup;
+	znode var_node;
 	if (var_ast) {
-		if (var_ast->kind != ZEND_AST_VAR) {
-			zend_throw_error(NULL, "TODO: support non-var on right side of 'as'");
-		}
+		/* backup $var */
+		zend_compile_var(&var_node, var_ast, BP_VAR_IS, false);
+		zend_emit_op(&var_backup, ZEND_BACKUP_CV, &var_node, NULL);
+
+		/* assign $var */
+		zend_compile_stmt(zend_ast_create(ZEND_AST_UNSET, var_ast));
 		zend_compile_assign(&tmp, zend_ast_create(ZEND_AST_ASSIGN, var_ast, enter_ast));
 	} else {
 		zend_compile_method_call(&tmp, enter_ast, BP_VAR_R);
@@ -5940,13 +5945,32 @@ static void zend_compile_using(zend_ast *ast)
 		/* unset($var) */
 		finally_stmt = zend_ast_list_add(finally_stmt,
 			zend_ast_create(ZEND_AST_UNSET, var_ast));
+		/* restore $var */
+		finally_stmt = zend_ast_list_add(finally_stmt,
+			zend_ast_create(ZEND_AST_RESTORE_CV, var_ast,
+				zend_ast_create_znode(&var_backup)));
 	}
 
 	zend_compile_try(zend_ast_create(ZEND_AST_TRY, stmts_ast, catch_list, finally_stmt));
 
 	zend_end_loop(get_next_op_number(), NULL);
 }
 
+static void zend_compile_restore_cv(zend_ast *ast)
+{
+	zend_ast *var_ast = ast->child[0];
+	zend_ast *backup_ast = ast->child[1];
+
+	znode var_node;
+	znode backup_node;
+
+	zend_compile_expr(&var_node, var_ast);
+	zend_compile_expr(&backup_node, backup_ast);
+
+	zend_op *opline = zend_emit_op(NULL, ZEND_RESTORE_CV, &backup_node, NULL);
+	SET_NODE(opline->result, &var_node);
+}
+
 static void zend_compile_echo(zend_ast *ast) /* {{{ */
 {
 	zend_op *opline;
@@ -11982,6 +12006,9 @@ static void zend_compile_stmt(zend_ast *ast) /* {{{ */
 		case ZEND_AST_USING:
 			zend_compile_using(ast);
 			break;
+		case ZEND_AST_RESTORE_CV:
+			zend_compile_restore_cv(ast);
+			break;
 		default:
 		{
 			znode result;

Zend/zend_language_parser.y

@@ -548,11 +548,10 @@ statement:
 ;
 
 optional_using_as_variable:
-		%empty { $$ = NULL; }
-	|	T_AS variable { $$ = $2; }
+		%empty          { $$ = NULL; }
+	|   T_AS T_VARIABLE { $$ = zend_ast_create(ZEND_AST_VAR, $2); }
 ;
 
-
 catch_list:
 		%empty
 			{ $$ = zend_ast_create_list(0, ZEND_AST_CATCH_LIST); }

Zend/zend_vm_def.h

@@ -9983,6 +9983,26 @@ ZEND_VM_C_LABEL(type_error):
 	HANDLE_EXCEPTION();
 }
 
+ZEND_VM_HANDLER(212, ZEND_BACKUP_CV, CV, UNUSED)
+{
+	USE_OPLINE;
+
+	zval *var = EX_VAR(opline->result.var);
+	zval *value = GET_OP1_ZVAL_PTR(BP_VAR_IS);
+	ZVAL_COPY(var, value);
+	ZEND_VM_NEXT_OPCODE();
+}
+
+ZEND_VM_HANDLER(213, ZEND_RESTORE_CV, VAR, UNUSED)
+{
+	USE_OPLINE;
+
+	zval *var = EX_VAR(opline->result.var);
+	zval *value = GET_OP1_ZVAL_PTR(BP_VAR_IS);
+	ZVAL_COPY_VALUE(var, value);
+	ZEND_VM_NEXT_OPCODE();
+}
+
 ZEND_VM_HOT_TYPE_SPEC_HANDLER(ZEND_JMP, (OP_JMP_ADDR(op, op->op1) > op), ZEND_JMP_FORWARD, JMP_ADDR, ANY)
 {
 	USE_OPLINE