Allow arbitrary const expressions in backed enums

Closes GH-7821
Closes GH-8190
Closes GH-8418

Author: iluuu1994

NEWS

@@ -7,6 +7,8 @@ PHP                                                                        NEWS
     references). (Nicolas Grekas)
   . Fixed bug GH-8661 (Nullsafe in coalesce triggers undefined variable
     warning). (ilutov)
+  . Fixed bug GH-7821 and GH-8418 (Allow arbitrary const expressions in backed
+    enums). (ilutov)
 
 - MBString:
   . Backwards-compatible mappings for 0x5C/0x7E in Shift-JIS are restored,

Zend/tests/enum/backed-duplicate-int.phpt

@@ -8,6 +8,33 @@ enum Foo: int {
     case Baz = 0;
 }
 
+try {
+    var_dump(Foo::Bar);
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Foo::Bar);
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Foo::from(42));
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Foo::tryFrom('bar'));
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
 ?>
---EXPECTF--
-Fatal error: Duplicate value in enum Foo for cases Bar and Baz in %s on line %s
+--EXPECT--
+Duplicate value in enum Foo for cases Bar and Baz
+Duplicate value in enum Foo for cases Bar and Baz
+Duplicate value in enum Foo for cases Bar and Baz
+Foo::tryFrom(): Argument #1 ($value) must be of type int, string given

Zend/tests/enum/backed-duplicate-string.phpt

@@ -10,6 +10,33 @@ enum Suit: string {
     case Spades = 'H';
 }
 
+try {
+    var_dump(Suit::Hearts);
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Suit::Hearts);
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Suit::from(42));
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Suit::tryFrom('bar'));
+} catch (Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
 ?>
---EXPECTF--
-Fatal error: Duplicate value in enum Suit for cases Hearts and Spades in %s on line %s
+--EXPECT--
+Duplicate value in enum Suit for cases Hearts and Spades
+Duplicate value in enum Suit for cases Hearts and Spades
+Duplicate value in enum Suit for cases Hearts and Spades
+Duplicate value in enum Suit for cases Hearts and Spades

Zend/tests/enum/backed-int-const-invalid-expr.phpt

@@ -11,4 +11,4 @@ var_dump(Foo::Bar->value);
 
 ?>
 --EXPECTF--
-Fatal error: Enum case value must be compile-time evaluatable in %s on line %d
+Fatal error: Constant expression contains invalid operations in %s on line %d

Zend/tests/enum/backed-mismatch.phpt

@@ -7,6 +7,33 @@ enum Foo: int {
     case Bar = 'bar';
 }
 
+try {
+    var_dump(Foo::Bar);
+} catch (Error $e) {
+    echo get_class($e), ': ', $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Foo::Bar);
+} catch (Error $e) {
+    echo get_class($e), ': ', $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Foo::from(42));
+} catch (Error $e) {
+    echo get_class($e), ': ', $e->getMessage(), "\n";
+}
+
+try {
+    var_dump(Foo::from('bar'));
+} catch (Error $e) {
+    echo get_class($e), ': ', $e->getMessage(), "\n";
+}
+
 ?>
---EXPECTF--
-Fatal error: Enum case type string does not match enum backing type int in %s on line %d
+--EXPECT--
+TypeError: Enum case type string does not match enum backing type int
+TypeError: Enum case type string does not match enum backing type int
+TypeError: Enum case type string does not match enum backing type int
+TypeError: Foo::from(): Argument #1 ($value) must be of type int, string given

Zend/tests/enum/gh7821.phpt

@@ -0,0 +1,26 @@
+--TEST--
+GH-7821: Can't use arbitrary constant expressions in enum cases
+--FILE--
+<?php
+
+interface I {
+    public const A = 'A';
+    public const B = 'B';
+}
+
+enum B: string implements I {
+    case C = I::A;
+    case D = self::B;
+}
+
+var_dump(B::A);
+var_dump(B::B);
+var_dump(B::C->value);
+var_dump(B::D->value);
+
+?>
+--EXPECT--
+string(1) "A"
+string(1) "B"
+string(1) "A"
+string(1) "B"

Zend/tests/enum/gh8418.phpt

@@ -0,0 +1,20 @@
+--TEST--
+GH-8418: Enum constant expression evaluation doesn't work with warmed cache
+--FILE--
+<?php
+
+class ExampleClass
+{
+    public const EXAMPLE_CONST = 42;
+}
+
+enum ExampleEnum: int
+{
+    case ENUM_CASE = ExampleClass::EXAMPLE_CONST;
+}
+
+var_dump(ExampleEnum::ENUM_CASE->value);
+
+?>
+--EXPECT--
+int(42)

Zend/tests/enum/non-backed-enum-with-expr-value.phpt

@@ -9,4 +9,4 @@ enum Foo {
 
 ?>
 --EXPECTF--
-Fatal error: Case Bar of non-backed enum Foo must not have a value, try adding ": int" to the enum declaration in %s on line %d
+Fatal error: Case Bar of non-backed enum Foo must not have a value in %s on line %d

Zend/tests/enum/non-backed-enum-with-int-value.phpt

@@ -9,4 +9,4 @@ enum Foo {
 
 ?>
 --EXPECTF--
-Fatal error: Case Bar of non-backed enum Foo must not have a value, try adding ": int" to the enum declaration in %s on line %d
+Fatal error: Case Bar of non-backed enum Foo must not have a value in %s on line %d

Zend/tests/enum/non-backed-enum-with-string-value.phpt

@@ -9,4 +9,4 @@ enum Foo {
 
 ?>
 --EXPECTF--
-Fatal error: Case Bar of non-backed enum Foo must not have a value, try adding ": string" to the enum declaration in %s on line %d
+Fatal error: Case Bar of non-backed enum Foo must not have a value in %s on line %d

Zend/tests/enum/update-class-constant-failure.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Test failure of updating class constants
+--FILE--
+<?php
+
+enum Foo: string {
+    const Bar = NONEXISTENT;
+}
+
+var_dump(Foo::Bar);
+
+?>
+--EXPECTF--
+Fatal error: Uncaught Error: Undefined constant "NONEXISTENT" in %s:%d
+Stack trace:
+#0 {main}
+  thrown in %s on line %d

Zend/zend_API.c

@@ -30,6 +30,7 @@
 #include "zend_closures.h"
 #include "zend_inheritance.h"
 #include "zend_ini.h"
+#include "zend_enum.h"
 
 #include <stdarg.h>
 
@@ -1493,6 +1494,12 @@ ZEND_API zend_result zend_update_class_constants(zend_class_entry *class_type) /
 		}
 	}
 
+	if (class_type->type == ZEND_USER_CLASS && class_type->ce_flags & ZEND_ACC_ENUM && class_type->enum_backing_type != IS_UNDEF) {
+		if (zend_enum_build_backed_enum_table(class_type) == FAILURE) {
+			return FAILURE;
+		}
+	}
+
 	ce_flags |= ZEND_ACC_CONSTANTS_UPDATED;
 	ce_flags &= ~ZEND_ACC_HAS_AST_CONSTANTS;
 	ce_flags &= ~ZEND_ACC_HAS_AST_PROPERTIES;

Zend/zend_ast.c

@@ -776,12 +776,18 @@ ZEND_API zend_result ZEND_FASTCALL zend_ast_evaluate(zval *result, zend_ast *ast
 			zend_string *case_name = zend_ast_get_str(case_name_ast);
 
 			zend_ast *case_value_ast = ast->child[2];
-			zval *case_value_zv = case_value_ast != NULL
-				? zend_ast_get_zval(case_value_ast)
-				: NULL;
+
+			zval case_value_zv;
+			ZVAL_UNDEF(&case_value_zv);
+			if (case_value_ast != NULL) {
+				if (UNEXPECTED(zend_ast_evaluate(&case_value_zv, case_value_ast, scope) != SUCCESS)) {
+					return FAILURE;
+				}
+			}
 
 			zend_class_entry *ce = zend_lookup_class(class_name);
-			zend_enum_new(result, ce, case_name, case_value_zv);
+			zend_enum_new(result, ce, case_name, case_value_ast != NULL ? &case_value_zv : NULL);
+			zval_ptr_dtor_nogc(&case_value_zv);
 			break;
 		}
 		case ZEND_AST_CLASS_CONST:

Zend/zend_compile.c

@@ -7578,9 +7578,6 @@ static void zend_compile_enum_backing_type(zend_class_entry *ce, zend_ast *enum_
 		ce->enum_backing_type = IS_STRING;
 	}
 	zend_type_release(type, 0);
-
-	ce->backed_enum_table = emalloc(sizeof(HashTable));
-	zend_hash_init(ce->backed_enum_table, 0, NULL, ZVAL_PTR_DTOR, 0);
 }
 
 static void zend_compile_class_decl(znode *result, zend_ast *ast, bool toplevel) /* {{{ */
@@ -7792,69 +7789,20 @@ static void zend_compile_enum_case(zend_ast *ast)
 	ZVAL_STR_COPY(&case_name_zval, enum_case_name);
 	zend_ast *case_name_ast = zend_ast_create_zval(&case_name_zval);
 
-	zend_ast *case_value_zval_ast = NULL;
 	zend_ast *case_value_ast = ast->child[1];
+	// Remove case_value_ast from the original AST to avoid freeing it, as it will be freed by zend_const_expr_to_zval
+	ast->child[1] = NULL;
 	if (enum_class->enum_backing_type != IS_UNDEF && case_value_ast == NULL) {
 		zend_error_noreturn(E_COMPILE_ERROR, "Case %s of backed enum %s must have a value",
 			ZSTR_VAL(enum_case_name),
 			ZSTR_VAL(enum_class_name));
-	}
-	if (case_value_ast != NULL) {
-		zend_eval_const_expr(&ast->child[1]);
-		case_value_ast = ast->child[1];
-		if (case_value_ast->kind != ZEND_AST_ZVAL) {
-			zend_error_noreturn(
-				E_COMPILE_ERROR, "Enum case value must be compile-time evaluatable");
-		}
-
-		zval case_value_zv;
-		ZVAL_COPY(&case_value_zv, zend_ast_get_zval(case_value_ast));
-		if (enum_class->enum_backing_type == IS_UNDEF) {
-			if (Z_TYPE(case_value_zv) == IS_LONG || Z_TYPE(case_value_zv) == IS_STRING) {
-				zend_error_noreturn(E_COMPILE_ERROR, "Case %s of non-backed enum %s must not have a value, try adding \": %s\" to the enum declaration",
-					ZSTR_VAL(enum_case_name),
-					ZSTR_VAL(enum_class_name),
-					zend_zval_type_name(&case_value_zv));
-			} else {
-				zend_error_noreturn(E_COMPILE_ERROR, "Case %s of non-backed enum %s must not have a value",
-					ZSTR_VAL(enum_case_name),
-					ZSTR_VAL(enum_class_name));
-			}
-		}
-
-		if (enum_class->enum_backing_type != Z_TYPE(case_value_zv)) {
-			zend_error_noreturn(E_COMPILE_ERROR, "Enum case type %s does not match enum backing type %s",
-				zend_get_type_by_const(Z_TYPE(case_value_zv)),
-				zend_get_type_by_const(enum_class->enum_backing_type));
-		}
-
-		case_value_zval_ast = zend_ast_create_zval(&case_value_zv);
-		Z_TRY_ADDREF(case_name_zval);
-		if (enum_class->enum_backing_type == IS_LONG) {
-			zend_long long_key = Z_LVAL(case_value_zv);
-			zval *existing_case_name = zend_hash_index_find(enum_class->backed_enum_table, long_key);
-			if (existing_case_name) {
-				zend_error_noreturn(E_COMPILE_ERROR, "Duplicate value in enum %s for cases %s and %s",
-					ZSTR_VAL(enum_class_name),
-					Z_STRVAL_P(existing_case_name),
-					ZSTR_VAL(enum_case_name));
-			}
-			zend_hash_index_add_new(enum_class->backed_enum_table, long_key, &case_name_zval);
-		} else {
-			ZEND_ASSERT(enum_class->enum_backing_type == IS_STRING);
-			zend_string *string_key = Z_STR(case_value_zv);
-			zval *existing_case_name = zend_hash_find(enum_class->backed_enum_table, string_key);
-			if (existing_case_name != NULL) {
-				zend_error_noreturn(E_COMPILE_ERROR, "Duplicate value in enum %s for cases %s and %s",
-					ZSTR_VAL(enum_class_name),
-					Z_STRVAL_P(existing_case_name),
-					ZSTR_VAL(enum_case_name));
-			}
-			zend_hash_add_new(enum_class->backed_enum_table, string_key, &case_name_zval);
-		}
+	} else if (enum_class->enum_backing_type == IS_UNDEF && case_value_ast != NULL) {
+		zend_error_noreturn(E_COMPILE_ERROR, "Case %s of non-backed enum %s must not have a value",
+			ZSTR_VAL(enum_case_name),
+			ZSTR_VAL(enum_class_name));
 	}
 
-	zend_ast *const_enum_init_ast = zend_ast_create(ZEND_AST_CONST_ENUM_INIT, class_name_ast, case_name_ast, case_value_zval_ast);
+	zend_ast *const_enum_init_ast = zend_ast_create(ZEND_AST_CONST_ENUM_INIT, class_name_ast, case_name_ast, case_value_ast);
 
 	zval value_zv;
 	zend_const_expr_to_zval(&value_zv, &const_enum_init_ast, /* allow_dynamic */ false);