[RFC] Implement dynamic class const fetch

Zend/Optimizer/compact_literals.c

@@ -211,7 +211,9 @@ void zend_optimizer_compact_literals(zend_op_array *op_array, zend_optimizer_ctx
 					if (opline->op1_type == IS_CONST) {
 						LITERAL_INFO(opline->op1.constant, 2);
 					}
-					LITERAL_INFO(opline->op2.constant, 1);
+					if (opline->op2_type == IS_CONST) {
+						LITERAL_INFO(opline->op2.constant, 1);
+					}
 					break;
 				case ZEND_ASSIGN_STATIC_PROP:
 				case ZEND_ASSIGN_STATIC_PROP_REF:
@@ -668,7 +670,7 @@ void zend_optimizer_compact_literals(zend_op_array *op_array, zend_optimizer_ctx
 					}
 					break;
 				case ZEND_FETCH_CLASS_CONSTANT:
-					if (opline->op1_type == IS_CONST) {
+					if (opline->op1_type == IS_CONST && opline->op2_type == IS_CONST) {
 						// op1/op2 class_const
 						opline->extended_value = add_static_slot(&hash, op_array,
 							opline->op1.constant,

Zend/tests/dynamic_class_const_fetch.phpt

@@ -0,0 +1,64 @@
+--TEST--
+Dynamic class constant fetch
+--FILE--
+<?php
+
+class Foo {
+    public const BAR = 'bar';
+}
+
+function test($code) {
+    try {
+        var_dump(eval($code));
+    } catch (Throwable $e) {
+        echo $e->getMessage(), "\n";
+    }
+}
+
+$const_names = [
+    ['', '"BAR"'],
+    ['$bar = "BAR";', '$bar'],
+    ['$ba = "BA"; $r = "R";', '$ba . $r'],
+    ['', 'strtoupper("bar")'],
+    ['', '$barr'],
+    ['$bar = "BAR"; $barRef = &$bar;', '$barRef'],
+    ['', 'strtolower("CLASS")'],
+    ['', '42'],
+    ['$bar = 42;', '$bar'],
+    ['', '[]'],
+    ['$bar = [];', '$bar'],
+];
+
+foreach ($const_names as [$prolog, $const_name]) {
+    test("$prolog return Foo::{{$const_name}};");
+    test("\$foo = 'Foo'; $prolog return \$foo::{{$const_name}};");
+}
+
+?>
+--EXPECTF--
+string(3) "bar"
+string(3) "bar"
+string(3) "bar"
+string(3) "bar"
+string(3) "bar"
+string(3) "bar"
+string(3) "bar"
+string(3) "bar"
+
+Warning: Undefined variable $barr in %s : eval()'d code on line %d
+Cannot use value of type null as class constant name
+
+Warning: Undefined variable $barr in %s : eval()'d code on line %d
+Cannot use value of type null as class constant name
+string(3) "bar"
+string(3) "bar"
+string(3) "Foo"
+string(3) "Foo"
+Cannot use value of type int as class constant name
+Cannot use value of type int as class constant name
+Cannot use value of type int as class constant name
+Cannot use value of type int as class constant name
+Cannot use value of type array as class constant name
+Cannot use value of type array as class constant name
+Cannot use value of type array as class constant name
+Cannot use value of type array as class constant name

Zend/tests/dynamic_class_const_fetch_cache_slot.phpt

@@ -0,0 +1,61 @@
+--TEST--
+Dynamic class constant fetch
+--FILE--
+<?php
+
+class FooParent {
+    public const BAR = 'bar';
+    public const BAZ = 'baz';
+}
+
+class Foo extends FooParent {
+    public const BAZ = 'baz child';
+}
+
+class BarParent {
+    public const BAR = 'bar 2';
+    public const BAZ = 'baz 2';
+}
+
+class Bar extends BarParent {
+    public const BAZ = 'baz 2 child';
+}
+
+function test($const) {
+    echo Foo::{$const}, "\n";
+    $foo = 'Foo';
+    echo $foo::{$const}, "\n";
+}
+
+test('BAR');
+test('BAZ');
+
+$c = function ($const) {
+    echo self::{$const}, "\n";
+    echo static::{$const}, "\n";
+    echo parent::{$const}, "\n";
+};
+
+$c->bindTo(null, Foo::class)('BAR');
+$c->bindTo(null, Bar::class)('BAZ');
+$c->bindTo(null, Foo::class)('class');
+$c->bindTo(null, Bar::class)('class');
+
+?>
+--EXPECT--
+bar
+bar
+baz child
+baz child
+bar
+bar
+bar
+baz 2 child
+baz 2 child
+baz 2
+Foo
+Foo
+FooParent
+Bar
+Bar
+BarParent

Zend/tests/dynamic_class_const_fetch_const_expr.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Dynamic class constant fetch in constant expressions
+--FILE--
+<?php
+
+class Foo {
+    public const BAR = 'bar';
+    public const BA = 'BA';
+    public const R = 'R';
+    public const CLASS_ = 'class';
+    public const A = self::{'BAR'};
+    public const B = self::{'BA' . 'R'};
+    public const C = self::{self::BA . self::R};
+}
+
+var_dump(Foo::A);
+var_dump(Foo::B);
+var_dump(Foo::C);
+
+?>
+--EXPECT--
+string(3) "bar"
+string(3) "bar"
+string(3) "bar"

Zend/tests/dynamic_class_const_fetch_order.phpt

@@ -0,0 +1,37 @@
+--TEST--
+Dynamic class constant fetch DIM order
+--FILE--
+<?php
+
+class Foo {
+    public const FOO = 'Foo';
+}
+
+function foo() {
+    echo "foo()\n";
+    return 'FOO';
+}
+
+function bar() {
+    echo "bar()\n";
+    return 'BAR';
+}
+
+function test($c) {
+    try {
+        echo $c(), "\n";
+    } catch (Throwable $e) {
+        echo $e->getMessage(), "\n";
+    }
+}
+
+test(fn() => Foo::{foo()}::{bar()});
+test(fn() => Foo::{bar()}::{foo()});
+
+?>
+--EXPECT--
+foo()
+bar()
+Undefined constant Foo::BAR
+bar()
+Undefined constant Foo::BAR

Zend/zend_compile.c

@@ -9669,16 +9669,18 @@ static void zend_compile_class_const(znode *result, zend_ast *ast) /* {{{ */
 	class_ast = ast->child[0];
 	const_ast = ast->child[1];
 
-	if (class_ast->kind == ZEND_AST_ZVAL) {
-		zend_string *resolved_name;
-
-		resolved_name = zend_resolve_class_name_ast(class_ast);
-		if (const_ast->kind == ZEND_AST_ZVAL && zend_try_ct_eval_class_const(&result->u.constant, resolved_name, zend_ast_get_str(const_ast))) {
-			result->op_type = IS_CONST;
+	if (class_ast->kind == ZEND_AST_ZVAL && const_ast->kind == ZEND_AST_ZVAL) {
+		zval *const_zv = zend_ast_get_zval(const_ast);
+		if (Z_TYPE_P(const_zv) == IS_STRING) {
+			zend_string *const_str = Z_STR_P(const_zv);
+			zend_string *resolved_name = zend_resolve_class_name_ast(class_ast);
+			if (zend_try_ct_eval_class_const(&result->u.constant, resolved_name, const_str)) {
+				result->op_type = IS_CONST;
+				zend_string_release_ex(resolved_name, 0);
+				return;
+			}
 			zend_string_release_ex(resolved_name, 0);
-			return;
 		}
-		zend_string_release_ex(resolved_name, 0);
 	}
 
 	zend_compile_class_ref(&class_node, class_ast, ZEND_FETCH_CLASS_EXCEPTION);
@@ -9689,7 +9691,9 @@ static void zend_compile_class_const(znode *result, zend_ast *ast) /* {{{ */
 
 	zend_set_class_name_op1(opline, &class_node);
 
-	opline->extended_value = zend_alloc_cache_slots(2);
+	if (opline->op1_type == IS_CONST || opline->op2_type == IS_CONST) {
+		opline->extended_value = zend_alloc_cache_slots(2);
+	}
 }
 /* }}} */
 

Zend/zend_execute.c

@@ -378,6 +378,21 @@ static zend_always_inline zval *_get_zval_ptr_cv_BP_VAR_W(uint32_t var EXECUTE_D
 	return ret;
 }
 
+static zend_always_inline zval *_get_zval_ptr_tmpvarcv(int op_type, znode_op node, int type EXECUTE_DATA_DC)
+{
+	if (op_type & (IS_TMP_VAR|IS_VAR)) {
+		if (op_type == IS_TMP_VAR) {
+			return _get_zval_ptr_tmp(node.var EXECUTE_DATA_CC);
+		} else {
+			ZEND_ASSERT(op_type == IS_VAR);
+			return _get_zval_ptr_var_deref(node.var EXECUTE_DATA_CC);
+		}
+	} else {
+		ZEND_ASSERT(op_type == IS_CV);
+		return _get_zval_ptr_cv_deref(node.var, type EXECUTE_DATA_CC);
+	}
+}
+
 static zend_always_inline zval *_get_zval_ptr(int op_type, znode_op node, int type EXECUTE_DATA_DC OPLINE_DC)
 {
 	if (op_type & (IS_TMP_VAR|IS_VAR)) {

Zend/zend_language_parser.y

@@ -1379,6 +1379,10 @@ class_constant:
 			{ $$ = zend_ast_create_class_const_or_name($1, $3); }
 	|	variable_class_name T_PAAMAYIM_NEKUDOTAYIM identifier
 			{ $$ = zend_ast_create_class_const_or_name($1, $3); }
+	|	class_name T_PAAMAYIM_NEKUDOTAYIM '{' expr '}'
+			{ $$ = zend_ast_create(ZEND_AST_CLASS_CONST, $1, $4); }
+	|	variable_class_name T_PAAMAYIM_NEKUDOTAYIM '{' expr '}'
+			{ $$ = zend_ast_create(ZEND_AST_CLASS_CONST, $1, $4); }
 ;
 
 optional_expr: