Implement phpGH-18261: Allow cast to be used in constant expressions (php#18264)

Author: nielsdos

NEWS

@@ -44,6 +44,7 @@ PHP                                                                        NEWS
     (timwolla, Volker Dusch)
   . Added get_error_handler(), get_exception_handler() functions. (Arnaud)
   . Fixed bug GH-15753 and GH-16198 (Bind traits before parent class). (ilutov)
+  . Added support for casts in constant expressions. (nielsdos)
 
 - Curl:
   . Added curl_multi_get_handles(). (timwolla)

UPGRADING

@@ -130,6 +130,7 @@ PHP 8.5 UPGRADE NOTES
     RFC: https://wiki.php.net/rfc/marking_return_value_as_important
   . Added asymmetric visibility support for static properties.
     RFC: https://wiki.php.net/rfc/static-aviz
+  . Added support for casts in constant expressions.
 
 - Curl:
   . Added support for share handles that are persisted across multiple PHP

Zend/tests/constexpr/constant_expressions_cast.phpt

@@ -0,0 +1,64 @@
+--TEST--
+Constant expressions with cast
+--FILE--
+<?php
+class X {
+    public int $foo = 3;
+}
+
+const T1 = (int) 0.3;
+const T2 = (bool) 0.3;
+const T3 = (string) [];
+const T4 = (object) ["a" => 1];
+const T5 = (float) 5;
+const T6 = (array) "";
+const T7 = (array) var_dump(...);
+const T8 = (array) new X;
+const T9 = (array) new DateTime;
+const T10 = (int) new DateTime;
+
+var_dump(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10);
+?>
+--EXPECTF--
+Warning: Array to string conversion in %s on line %d
+
+Warning: Object of class DateTime could not be converted to int in %s on line %d
+int(0)
+bool(true)
+string(5) "Array"
+object(stdClass)#%d (1) {
+  ["a"]=>
+  int(1)
+}
+float(5)
+array(1) {
+  [0]=>
+  string(0) ""
+}
+array(1) {
+  [0]=>
+  object(Closure)#%d (2) {
+    ["function"]=>
+    string(8) "var_dump"
+    ["parameter"]=>
+    array(2) {
+      ["$value"]=>
+      string(10) "<required>"
+      ["$values"]=>
+      string(10) "<optional>"
+    }
+  }
+}
+array(1) {
+  ["foo"]=>
+  int(3)
+}
+array(3) {
+  ["date"]=>
+  string(%d) "%s"
+  ["timezone_type"]=>
+  int(%d)
+  ["timezone"]=>
+  string(%d) "%s"
+}
+int(1)

Zend/tests/constexpr/constant_expressions_cast_object_property.phpt

@@ -0,0 +1,10 @@
+--TEST--
+Constant expressions with object cast in property
+--FILE--
+<?php
+class X {
+    public $foo = (object) [];
+}
+?>
+--EXPECTF--
+Fatal error: Object casts are not supported in this context in %s on line %d

Zend/zend_ast.c

@@ -702,6 +702,41 @@ ZEND_API zend_result ZEND_FASTCALL zend_ast_evaluate_inner(
 			}
 			zval_ptr_dtor_nogc(&op1);
 			break;
+		case ZEND_AST_CAST:
+			if (UNEXPECTED(zend_ast_evaluate_ex(&op1, ast->child[0], scope, &short_circuited, ctx) != SUCCESS)) {
+				ret = FAILURE;
+				break;
+			}
+			if (ast->attr == Z_TYPE(op1)) {
+				ZVAL_COPY_VALUE(result, &op1);
+			} else {
+				switch (ast->attr) {
+					case _IS_BOOL:
+						ZVAL_BOOL(result, zend_is_true(&op1));
+						break;
+					case IS_LONG:
+						ZVAL_LONG(result, zval_get_long_func(&op1, false));
+						break;
+					case IS_DOUBLE:
+						ZVAL_DOUBLE(result, zval_get_double_func(&op1));
+						break;
+					case IS_STRING:
+						ZVAL_STR(result, zval_get_string_func(&op1));
+						break;
+					case IS_ARRAY:
+						zend_cast_zval_to_array(result, &op1, IS_VAR);
+						break;
+					case IS_OBJECT:
+						zend_cast_zval_to_object(result, &op1, IS_VAR);
+						break;
+					EMPTY_SWITCH_DEFAULT_CASE();
+				}
+				zval_ptr_dtor_nogc(&op1);
+				if (UNEXPECTED(EG(exception))) {
+					ret = FAILURE;
+				}
+			}
+			break;
 		case ZEND_AST_OR:
 			if (UNEXPECTED(zend_ast_evaluate_ex(&op1, ast->child[0], scope, &short_circuited, ctx) != SUCCESS)) {
 				ret = FAILURE;

Zend/zend_compile.c

@@ -11121,6 +11121,7 @@ static bool zend_is_allowed_in_const_expr(zend_ast_kind kind) /* {{{ */
 		|| kind == ZEND_AST_AND || kind == ZEND_AST_OR
 		|| kind == ZEND_AST_UNARY_OP
 		|| kind == ZEND_AST_UNARY_PLUS || kind == ZEND_AST_UNARY_MINUS
+		|| kind == ZEND_AST_CAST
 		|| kind == ZEND_AST_CONDITIONAL || kind == ZEND_AST_DIM
 		|| kind == ZEND_AST_ARRAY || kind == ZEND_AST_ARRAY_ELEM
 		|| kind == ZEND_AST_UNPACK
@@ -11395,6 +11396,12 @@ static void zend_compile_const_expr(zend_ast **ast_ptr, void *context) /* {{{ */
 		case ZEND_AST_MAGIC_CONST:
 			zend_compile_const_expr_magic_const(ast_ptr);
 			break;
+		case ZEND_AST_CAST:
+			if (ast->attr == IS_OBJECT && !ctx->allow_dynamic) {
+				zend_error_noreturn(E_COMPILE_ERROR,
+					"Object casts are not supported in this context");
+			}
+			break;
 		case ZEND_AST_NEW:
 			if (!ctx->allow_dynamic) {
 				zend_error_noreturn(E_COMPILE_ERROR,

Zend/zend_execute.h

@@ -219,6 +219,60 @@ static zend_always_inline void zend_safe_assign_to_variable_noref(zval *variable
 	}
 }
 
+static zend_always_inline void zend_cast_zval_to_object(zval *result, zval *expr, uint8_t op1_type) {
+	HashTable *ht;
+
+	ZVAL_OBJ(result, zend_objects_new(zend_standard_class_def));
+	if (Z_TYPE_P(expr) == IS_ARRAY) {
+		ht = zend_symtable_to_proptable(Z_ARR_P(expr));
+		if (GC_FLAGS(ht) & IS_ARRAY_IMMUTABLE) {
+			/* TODO: try not to duplicate immutable arrays as well ??? */
+			ht = zend_array_dup(ht);
+		}
+		Z_OBJ_P(result)->properties = ht;
+	} else if (Z_TYPE_P(expr) != IS_NULL) {
+		Z_OBJ_P(result)->properties = ht = zend_new_array(1);
+		expr = zend_hash_add_new(ht, ZSTR_KNOWN(ZEND_STR_SCALAR), expr);
+		if (op1_type == IS_CONST) {
+			if (UNEXPECTED(Z_OPT_REFCOUNTED_P(expr))) Z_ADDREF_P(expr);
+		} else {
+			if (Z_OPT_REFCOUNTED_P(expr)) Z_ADDREF_P(expr);
+		}
+	}
+}
+
+static zend_always_inline void zend_cast_zval_to_array(zval *result, zval *expr, uint8_t op1_type) {
+	extern zend_class_entry *zend_ce_closure;
+	if (op1_type == IS_CONST || Z_TYPE_P(expr) != IS_OBJECT || Z_OBJCE_P(expr) == zend_ce_closure) {
+		if (Z_TYPE_P(expr) != IS_NULL) {
+			ZVAL_ARR(result, zend_new_array(1));
+			expr = zend_hash_index_add_new(Z_ARRVAL_P(result), 0, expr);
+			if (op1_type == IS_CONST) {
+				if (UNEXPECTED(Z_OPT_REFCOUNTED_P(expr))) Z_ADDREF_P(expr);
+			} else {
+				if (Z_OPT_REFCOUNTED_P(expr)) Z_ADDREF_P(expr);
+			}
+		} else {
+			ZVAL_EMPTY_ARRAY(result);
+		}
+	} else if (ZEND_STD_BUILD_OBJECT_PROPERTIES_ARRAY_COMPATIBLE(expr)) {
+		/* Optimized version without rebuilding properties HashTable */
+		ZVAL_ARR(result, zend_std_build_object_properties_array(Z_OBJ_P(expr)));
+	} else {
+		HashTable *obj_ht = zend_get_properties_for(expr, ZEND_PROP_PURPOSE_ARRAY_CAST);
+		if (obj_ht) {
+			/* fast copy */
+			ZVAL_ARR(result, zend_proptable_to_symtable(obj_ht,
+				(Z_OBJCE_P(expr)->default_properties_count ||
+				 Z_OBJ_P(expr)->handlers != &std_object_handlers ||
+				 GC_IS_RECURSIVE(obj_ht))));
+			zend_release_properties(obj_ht);
+		} else {
+			ZVAL_EMPTY_ARRAY(result);
+		}
+	}
+}
+
 ZEND_API zend_result ZEND_FASTCALL zval_update_constant(zval *pp);
 ZEND_API zend_result ZEND_FASTCALL zval_update_constant_ex(zval *pp, zend_class_entry *scope);
 ZEND_API zend_result ZEND_FASTCALL zval_update_constant_with_ctx(zval *pp, zend_class_entry *scope, zend_ast_evaluate_ctx *ctx);

Zend/zend_vm_def.h

@@ -6459,7 +6459,6 @@ ZEND_VM_COLD_CONST_HANDLER(51, ZEND_CAST, CONST|TMP|VAR|CV, ANY, TYPE)
 	USE_OPLINE
 	zval *expr;
 	zval *result = EX_VAR(opline->result.var);
-	HashTable *ht;
 
 	SAVE_OPLINE();
 	expr = GET_OP1_ZVAL_PTR(BP_VAR_R);
@@ -6493,53 +6492,10 @@ ZEND_VM_COLD_CONST_HANDLER(51, ZEND_CAST, CONST|TMP|VAR|CV, ANY, TYPE)
 			}
 
 			if (opline->extended_value == IS_ARRAY) {
-				if (OP1_TYPE == IS_CONST || Z_TYPE_P(expr) != IS_OBJECT || Z_OBJCE_P(expr) == zend_ce_closure) {
-					if (Z_TYPE_P(expr) != IS_NULL) {
-						ZVAL_ARR(result, zend_new_array(1));
-						expr = zend_hash_index_add_new(Z_ARRVAL_P(result), 0, expr);
-						if (OP1_TYPE == IS_CONST) {
-							if (UNEXPECTED(Z_OPT_REFCOUNTED_P(expr))) Z_ADDREF_P(expr);
-						} else {
-							if (Z_OPT_REFCOUNTED_P(expr)) Z_ADDREF_P(expr);
-						}
-					} else {
-						ZVAL_EMPTY_ARRAY(result);
-					}
-				} else if (ZEND_STD_BUILD_OBJECT_PROPERTIES_ARRAY_COMPATIBLE(expr)) {
-					/* Optimized version without rebuilding properties HashTable */
-					ZVAL_ARR(result, zend_std_build_object_properties_array(Z_OBJ_P(expr)));
-				} else {
-					HashTable *obj_ht = zend_get_properties_for(expr, ZEND_PROP_PURPOSE_ARRAY_CAST);
-					if (obj_ht) {
-						/* fast copy */
-						ZVAL_ARR(result, zend_proptable_to_symtable(obj_ht,
-							(Z_OBJCE_P(expr)->default_properties_count ||
-							 Z_OBJ_P(expr)->handlers != &std_object_handlers ||
-							 GC_IS_RECURSIVE(obj_ht))));
-						zend_release_properties(obj_ht);
-					} else {
-						ZVAL_EMPTY_ARRAY(result);
-					}
-				}
+				zend_cast_zval_to_array(result, expr, OP1_TYPE);
 			} else {
 				ZEND_ASSERT(opline->extended_value == IS_OBJECT);
-				ZVAL_OBJ(result, zend_objects_new(zend_standard_class_def));
-				if (Z_TYPE_P(expr) == IS_ARRAY) {
-					ht = zend_symtable_to_proptable(Z_ARR_P(expr));
-					if (GC_FLAGS(ht) & IS_ARRAY_IMMUTABLE) {
-						/* TODO: try not to duplicate immutable arrays as well ??? */
-						ht = zend_array_dup(ht);
-					}
-					Z_OBJ_P(result)->properties = ht;
-				} else if (Z_TYPE_P(expr) != IS_NULL) {
-					Z_OBJ_P(result)->properties = ht = zend_new_array(1);
-					expr = zend_hash_add_new(ht, ZSTR_KNOWN(ZEND_STR_SCALAR), expr);
-					if (OP1_TYPE == IS_CONST) {
-						if (UNEXPECTED(Z_OPT_REFCOUNTED_P(expr))) Z_ADDREF_P(expr);
-					} else {
-						if (Z_OPT_REFCOUNTED_P(expr)) Z_ADDREF_P(expr);
-					}
-				}
+				zend_cast_zval_to_object(result, expr, OP1_TYPE);
 			}
 	}