Support minimal compilation of associated type

Author: Girgias

Zend/tests/type_declarations/associated/associated_001.phpt

@@ -14,4 +14,4 @@ class C implements I {
 
 ?>
 --EXPECTF--
-Parse error: syntax error, unexpected token "type", expecting "function" in %s on line %d
+Fatal error: Declaration of C::foo(string $param): string must be compatible with I::foo(T $param): T in %s on line %d

Zend/tests/type_declarations/associated/associated_type_in_class.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Associated types in class is invalid
+--FILE--
+<?php
+
+class C {
+    type T;
+    public function foo(T $param): T;
+}
+
+?>
+--EXPECTF--
+Fatal error: Cannot use associated types outside of interfaces, used in C in %s on line %d

Zend/tests/type_declarations/associated/associated_type_in_trait.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Associated types in trait is invalid
+--FILE--
+<?php
+
+trait C {
+    type T;
+    public function foo(T $param): T;
+}
+
+?>
+--EXPECTF--
+Fatal error: Cannot use associated types outside of interfaces, used in C in %s on line %d

Zend/tests/type_declarations/associated/repeated_associated_type.phpt

@@ -0,0 +1,17 @@
+--TEST--
+Associated types basic
+--FILE--
+<?php
+
+interface I {
+    type T;
+    public function foo(T $param): T;
+}
+
+class C implements I {
+    public function foo(string $param): string {}
+}
+
+?>
+--EXPECTF--
+Parse error: syntax error, unexpected token "type", expecting "function" in %s on line %d

Zend/zend_ast.c

@@ -2402,6 +2402,10 @@ static ZEND_COLD void zend_ast_export_ex(smart_str *str, zend_ast *ast, int prio
 			APPEND_NODE_1("break");
 		case ZEND_AST_CONTINUE:
 			APPEND_NODE_1("continue");
+		case ZEND_AST_ASSOCIATED_TYPE:
+			smart_str_appends(str, "type ");
+			zend_ast_export_name(str, ast->child[0], 0, indent);
+			break;
 
 		/* 2 child nodes */
 		case ZEND_AST_DIM:

Zend/zend_ast.h

@@ -99,6 +99,7 @@ enum _zend_ast_kind {
 	ZEND_AST_POST_DEC,
 	ZEND_AST_YIELD_FROM,
 	ZEND_AST_CLASS_NAME,
+	ZEND_AST_ASSOCIATED_TYPE,
 
 	ZEND_AST_GLOBAL,
 	ZEND_AST_UNSET,

Zend/zend_compile.c

@@ -9011,6 +9011,20 @@ static void zend_compile_use_trait(zend_ast *ast) /* {{{ */
 }
 /* }}} */
 
+static void zend_compile_associated_type(zend_ast *ast) {
+	zend_class_entry *ce = CG(active_class_entry);
+
+	if ((ce->ce_flags & ZEND_ACC_INTERFACE) == 0) {
+		zend_error_noreturn(E_COMPILE_ERROR,
+			"Cannot use associated types outside of interfaces, used in %s", ZSTR_VAL(ce->name));
+	}
+
+	zend_ast *name_ast = ast->child[0];
+	zend_string *name = zend_ast_get_str(name_ast);
+	ZEND_ASSERT(name != NULL);
+	// TODO add associated type to CE
+}
+
 static void zend_compile_implements(zend_ast *ast) /* {{{ */
 {
 	zend_ast_list *list = zend_ast_get_list(ast);
@@ -11595,6 +11609,9 @@ static void zend_compile_stmt(zend_ast *ast) /* {{{ */
 		case ZEND_AST_USE_TRAIT:
 			zend_compile_use_trait(ast);
 			break;
+		case ZEND_AST_ASSOCIATED_TYPE:
+			zend_compile_associated_type(ast);
+			break;
 		case ZEND_AST_CLASS:
 			zend_compile_class_decl(NULL, ast, 0);
 			break;

Zend/zend_language_parser.y

@@ -287,6 +287,7 @@ static YYSIZE_T zend_yytnamerr(char*, const char*);
 %type <ast> function_name non_empty_member_modifiers
 %type <ast> property_hook property_hook_list optional_property_hook_list hooked_property property_hook_body
 %type <ast> optional_parameter_list
+%type <ast> associated_type
 
 %type <num> returns_ref function fn is_reference is_variadic property_modifiers property_hook_modifiers
 %type <num> method_modifiers class_const_modifiers member_modifier optional_cpp_modifiers
@@ -662,6 +663,11 @@ enum_case_expr:
 	|	'=' expr { $$ = $2; }
 ;
 
+associated_type:
+        T_TYPE name ';'
+			{ $$ = zend_ast_create(ZEND_AST_ASSOCIATED_TYPE, $2); }
+;
+
 extends_from:
 		%empty				{ $$ = NULL; }
 	|	T_EXTENDS class_name	{ $$ = $2; }
@@ -963,6 +969,7 @@ attributed_class_statement:
 			{ $$ = zend_ast_create_decl(ZEND_AST_METHOD, $3 | $1 | $12, $2, $5,
 				  zend_ast_get_str($4), $7, NULL, $11, $9, NULL); CG(extra_fn_flags) = $10; }
 	|	enum_case { $$ = $1; }
+	|   associated_type { $$ = $1; }
 ;
 
 class_statement: