[RFC] Type Aliases

Zend/tests/type_aliases/basic_type_alias.phpt

@@ -0,0 +1,55 @@
+--TEST--
+Basic type alias functionality
+--FILE--
+<?php
+use type int|float as Number;
+use type string as Text;
+use type ?int as OptionalInt;
+use type Number|string as Scalar;
+
+function add(Number $a, Number $b): Number {
+    return $a + $b;
+}
+
+function greet(Text $name): Text {
+    return "Hello, " . $name;
+}
+
+function maybeInt(OptionalInt $value): OptionalInt {
+    return $value;
+}
+
+function identity(Scalar $v): Scalar {
+    return $v;
+}
+
+// Test int|float alias
+var_dump(add(1, 2));
+var_dump(add(1.5, 2.5));
+var_dump(add(1, 2.5));
+
+// Test string alias
+var_dump(greet("World"));
+
+// Test nullable alias
+var_dump(maybeInt(42));
+var_dump(maybeInt(null));
+
+// Test nested alias (Scalar = Number|string = int|float|string)
+var_dump(identity(42));
+var_dump(identity(3.14));
+var_dump(identity("hello"));
+
+echo "Done\n";
+?>
+--EXPECT--
+int(3)
+float(4)
+float(3.5)
+string(12) "Hello, World"
+int(42)
+NULL
+int(42)
+float(3.14)
+string(5) "hello"
+Done

Zend/tests/type_aliases/error_duplicate_alias.phpt

@@ -0,0 +1,9 @@
+--TEST--
+Type alias name cannot be used twice
+--FILE--
+<?php
+use type int as Number;
+use type float as Number;
+?>
+--EXPECTF--
+Fatal error: Cannot use type alias 'Number' because the name is already in use in %s on line %d

Zend/tests/type_aliases/error_reserved_type_name_int.phpt

@@ -0,0 +1,8 @@
+--TEST--
+Type alias cannot use reserved type name (int)
+--FILE--
+<?php
+use type int|float as int;
+?>
+--EXPECTF--
+Fatal error: Cannot use 'int' as type alias name as it is reserved in %s on line %d

Zend/tests/type_aliases/error_reserved_type_name_mixed.phpt

@@ -0,0 +1,8 @@
+--TEST--
+Type alias cannot use reserved type name (mixed)
+--FILE--
+<?php
+use type int|string as mixed;
+?>
+--EXPECTF--
+Fatal error: Cannot use 'mixed' as type alias name as it is reserved in %s on line %d

Zend/tests/type_aliases/error_reserved_type_name_string.phpt

@@ -0,0 +1,8 @@
+--TEST--
+Type alias cannot use reserved type name (string)
+--FILE--
+<?php
+use type int as string;
+?>
+--EXPECTF--
+Fatal error: Cannot use 'string' as type alias name as it is reserved in %s on line %d

Zend/tests/type_aliases/error_reserved_type_name_void.phpt

@@ -0,0 +1,8 @@
+--TEST--
+Type alias cannot use reserved type name (void)
+--FILE--
+<?php
+use type int as void;
+?>
+--EXPECTF--
+Fatal error: Cannot use 'void' as type alias name as it is reserved in %s on line %d

Zend/tests/type_aliases/error_self_referential.phpt

@@ -0,0 +1,8 @@
+--TEST--
+Type alias cannot reference itself
+--FILE--
+<?php
+use type Foo|int as Foo;
+?>
+--EXPECTF--
+Fatal error: Type alias 'Foo' cannot reference itself in %s on line %d

Zend/tests/type_aliases/error_self_referential_dnf.phpt

@@ -0,0 +1,8 @@
+--TEST--
+Type alias cannot reference itself in DNF type
+--FILE--
+<?php
+use type Bar|(Foo&Baz) as Foo;
+?>
+--EXPECTF--
+Fatal error: Type alias 'Foo' cannot reference itself in %s on line %d

Zend/tests/type_aliases/error_self_referential_union.phpt

@@ -0,0 +1,8 @@
+--TEST--
+Type alias cannot reference itself in union type
+--FILE--
+<?php
+use type int|string|MyType as MyType;
+?>
+--EXPECTF--
+Fatal error: Type alias 'MyType' cannot reference itself in %s on line %d

Zend/tests/type_aliases/include_types.phpt

@@ -0,0 +1,42 @@
+--TEST--
+include types functionality
+--FILE--
+<?php
+include types 'types.php';
+
+function add(Number $a, Number $b): Number {
+    return $a + $b;
+}
+
+function identity(Scalar $v): Scalar {
+    return $v;
+}
+
+function greet(OptionalString $name): OptionalString {
+    return $name ? "Hello, " . $name : null;
+}
+
+// Test Number alias (int|float)
+var_dump(add(1, 2));
+var_dump(add(1.5, 2.5));
+
+// Test Scalar alias (Number|string = int|float|string)
+var_dump(identity(42));
+var_dump(identity(3.14));
+var_dump(identity("hello"));
+
+// Test OptionalString alias (?string)
+var_dump(greet("World"));
+var_dump(greet(null));
+
+echo "Done\n";
+?>
+--EXPECT--
+int(3)
+float(4)
+int(42)
+float(3.14)
+string(5) "hello"
+string(12) "Hello, World"
+NULL
+Done

Zend/tests/type_aliases/include_types_invalid_file.phpt

@@ -0,0 +1,8 @@
+--TEST--
+include types with invalid file (contains non-type-alias code)
+--FILE--
+<?php
+include types 'invalid_types.php';
+?>
+--EXPECTF--
+Fatal error: include types: Types file 'invalid_types.php' must only contain type aliases (use type ... as ...;) in %s on line %d

Zend/zend_ast.h

@@ -105,6 +105,7 @@ enum _zend_ast_kind {
 	ZEND_AST_LABEL,
 	ZEND_AST_REF,
 	ZEND_AST_HALT_COMPILER,
+	ZEND_AST_INCLUDE_TYPES,
 	ZEND_AST_ECHO,
 	ZEND_AST_THROW,
 	ZEND_AST_GOTO,
@@ -146,6 +147,7 @@ enum _zend_ast_kind {
 	ZEND_AST_METHOD_REFERENCE,
 	ZEND_AST_NAMESPACE,
 	ZEND_AST_USE_ELEM,
+	ZEND_AST_TYPE_ALIAS,
 	ZEND_AST_TRAIT_ALIAS,
 	ZEND_AST_GROUP_USE,
 	ZEND_AST_ATTRIBUTE,