PoC context managers v2

Zend/tests/context_managers/basic.phpt

@@ -0,0 +1,23 @@
+--TEST--
+Context manager basic
+--FILE--
+<?php
+
+function some_context() {
+    yield 'hello';
+}
+
+using (some_context() => $var) {
+    echo "Body is executed once\n";
+    echo "\$var: ";
+    var_dump($var);
+};
+
+echo "\$var is unset() after the block: ";
+var_dump(!isset($var));
+
+?>
+--EXPECT--
+Body is executed once
+$var: string(5) "hello"
+$var is unset() after the block: bool(true)

Zend/tests/context_managers/basic_manager.inc

@@ -0,0 +1,22 @@
+<?php
+
+class Manager implements ContextManager
+{
+    public function __construct(private bool $rethrow = true)
+    {
+    }
+
+    public function enterContext(): mixed
+    {
+        echo __METHOD__, "()\n";
+        return new stdClass;
+    }
+
+    public function exitContext(?\Throwable $e = null): ?bool
+    {
+        echo __METHOD__, "(", ($e ? get_class($e) . '(' . $e->getMessage() . ')' : 'null'), ")\n";
+        return !$this->rethrow;
+    }
+}
+
+?>

Zend/tests/context_managers/error_must_be_a_generator.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Context manager: manager must be a Generator
+--FILE--
+<?php
+
+try {
+    using (new stdClass) {
+        echo "Not executed\n";
+    };
+} catch (TypeError $e) {
+    echo $e::class, ": ", $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+TypeError: Context Manager must be an instance of Generator (TODO: proper error message)

Zend/tests/context_managers/error_must_not_yield_twice.phpt

@@ -0,0 +1,22 @@
+--TEST--
+Context manager: manager must not yield twice
+--FILE--
+<?php
+
+function invalid_manager() {
+    yield new stdClass;
+    yield new stdClass;
+}
+
+try {
+    using (invalid_manager() => $var) {
+        echo "Body executed\n";
+    };
+} catch (Error $e) {
+    echo $e::class, ": ", $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+Body executed
+Error: Context Manager must yield only once, but it yielded a second time when fetching the return value

Zend/tests/context_managers/error_must_yield.phpt

@@ -0,0 +1,22 @@
+--TEST--
+Context manager: manager must yield once
+--FILE--
+<?php
+
+function invalid_manager() {
+    if (false) {
+        yield;
+    }
+}
+
+try {
+    using (invalid_manager() => $var) {
+        echo "Not executed\n";
+    };
+} catch (Error $e) {
+    echo $e::class, ": ", $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+Error: Context Manager must yield once, but it returned without yielding

Zend/tests/context_managers/evaluates_to_manager_return_value.phpt

@@ -0,0 +1,22 @@
+--TEST--
+Context manager: manager must not yield twice
+--FILE--
+<?php
+
+function some_context() {
+    yield 'hello';
+    return 'world';
+}
+
+$result = using (some_context() => $var) {
+    echo "Body executed: ";
+    var_dump($var);
+};
+
+echo "Result: ";
+var_dump($result);
+
+?>
+--EXPECT--
+Body executed: string(5) "hello"
+Result: string(5) "world"

Zend/tests/context_managers/exception_can_be_caught_by_manager.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Context manager: exception is forwarded to manager
+--FILE--
+<?php
+
+function some_context() {
+    try {
+        yield 'hello';
+    } catch (Exception $e) {
+        echo "From context manager: ", $e::class, ": ", $e->getMessage(), "\n";
+    }
+}
+
+using (some_context() => $var) {
+    throw new Exception('Thrown from body');
+};
+
+echo "\$var is unset() after the block: ";
+var_dump(!isset($var));
+
+?>
+--EXPECT--
+From context manager: Exception: Thrown from body
+$var is unset() after the block: bool(true)

Zend/tests/context_managers/exception_is_forwarded_to_manager.phpt

@@ -0,0 +1,30 @@
+--TEST--
+Context manager: exception is forwarded to manager
+--FILE--
+<?php
+
+function some_context() {
+    try {
+        yield 'hello';
+    } catch (Exception $e) {
+        echo "From context manager: ", $e::class, ": ", $e->getMessage(), "\n";
+        throw $e;
+    }
+}
+
+try {
+    using (some_context() => $var) {
+        throw new Exception('Thrown from body');
+    };
+} catch (Exception $e) {
+    echo $e::class, ": ", $e->getMessage(), "\n";
+}
+
+echo "\$var is unset() after the block: ";
+var_dump(!isset($var));
+
+?>
+--EXPECT--
+From context manager: Exception: Thrown from body
+Exception: Thrown from body
+$var is unset() after the block: bool(true)

Zend/tests/context_managers/var_is_optional.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Context manager: VAR is optional
+--FILE--
+<?php
+
+function some_context() {
+    yield new stdClass;
+}
+
+using (some_context()) {
+    echo "Body is executed once\n";
+};
+
+?>
+--EXPECT--
+Body is executed once

Zend/zend_ast.c

@@ -54,6 +54,12 @@ ZEND_API zend_ast * ZEND_FASTCALL zend_ast_create_znode(const znode *node) {
 	return (zend_ast *) ast;
 }
 
+ZEND_API zend_ast * ZEND_FASTCALL zend_ast_create_copy_znode(const znode *node) {
+	zend_ast *ast = zend_ast_create_znode(node);
+	ast->attr = 1;
+	return ast;
+}
+
 ZEND_API zend_ast * ZEND_FASTCALL zend_ast_create_fcc(zend_ast *args) {
 	zend_ast_fcc *ast;
 

Zend/zend_ast.h

@@ -69,6 +69,7 @@ enum _zend_ast_kind {
 	ZEND_AST_ATTRIBUTE_GROUP,
 	ZEND_AST_MATCH_ARM_LIST,
 	ZEND_AST_MODIFIER_LIST,
+	ZEND_AST_USING_LIST,
 
 	/* 0 child nodes */
 	ZEND_AST_MAGIC_CONST = 0 << ZEND_AST_NUM_CHILDREN_SHIFT,
@@ -153,6 +154,8 @@ enum _zend_ast_kind {
 	ZEND_AST_MATCH_ARM,
 	ZEND_AST_NAMED_ARG,
 	ZEND_AST_PIPE,
+	ZEND_AST_USING,
+	ZEND_AST_USING_ELEM,
 
 	/* 3 child nodes */
 	ZEND_AST_METHOD_CALL = 3 << ZEND_AST_NUM_CHILDREN_SHIFT,

Zend/zend_builtin_functions.c

@@ -32,6 +32,7 @@
 #include "zend_autoload.h"
 #include "zend_builtin_functions_arginfo.h"
 #include "zend_smart_str.h"
+#include "zend_context_managers.h"
 
 /* }}} */
 
@@ -41,6 +42,8 @@ ZEND_MINIT_FUNCTION(core) { /* {{{ */
 
 	zend_standard_class_def = register_class_stdClass();
 
+	ZEND_MINIT(context_managers)(INIT_FUNC_ARGS_PASSTHRU);
+
 	return SUCCESS;
 }
 /* }}} */