Applied @bwoebi's grammar patch to enable T_DEFAULT in expressions.

Patched match expression to work with the new grammar.
Changed ZEND_FETCH_DEFAULT_ARG VM handler to use reflection_parameter_ptr.

Author: Bilge

Zend/tests/default_expression/global user function.phpt

@@ -1,5 +1,5 @@
 --TEST--
-Test passing default argument to global user function.
+Tests passing default to a global user function parameter
 --FILE--
 <?php
 

Zend/tests/default_expression/multiple arguments.phpt

@@ -1,5 +1,5 @@
 --TEST--
-Test passing multiple default arguments to global user function.
+Test passing multiple default arguments to global user function parameters
 --FILE--
 <?php
 

Zend/tests/default_expression/user class method.phpt

@@ -1,5 +1,5 @@
 --TEST--
-Test passing default argument to user class method.
+Tests passing default to a user class method parameter
 --FILE--
 <?php
 

Zend/zend_ast.c

@@ -2013,6 +2013,9 @@ static ZEND_COLD void zend_ast_export_ex(smart_str *str, zend_ast *ast, int prio
 				EMPTY_SWITCH_DEFAULT_CASE();
 			}
 			break;
+		case ZEND_AST_DEFAULT:
+			smart_str_appends(str, "default");
+			break;
 
 		/* 1 child node */
 		case ZEND_AST_VAR:

Zend/zend_compile.c

@@ -6358,11 +6358,12 @@ static uint32_t count_match_conds(zend_ast_list *arms)
 
 	for (uint32_t i = 0; i < arms->children; i++) {
 		zend_ast *arm_ast = arms->child[i];
-		if (arm_ast->child[0] == NULL) {
+		zend_ast_list *conds = zend_ast_get_list(arm_ast->child[0]);
+
+		if (conds->child[0]->kind == ZEND_AST_DEFAULT) {
 			continue;
 		}
 
-		zend_ast_list *conds = zend_ast_get_list(arm_ast->child[0]);
 		num_conds += conds->children;
 	}
 
@@ -6372,12 +6373,13 @@ static uint32_t count_match_conds(zend_ast_list *arms)
 static bool can_match_use_jumptable(zend_ast_list *arms) {
 	for (uint32_t i = 0; i < arms->children; i++) {
 		zend_ast *arm_ast = arms->child[i];
-		if (!arm_ast->child[0]) {
+		zend_ast_list *conds = zend_ast_get_list(arm_ast->child[0]);
+
+		if (conds->child[0]->kind == ZEND_AST_DEFAULT) {
 			/* Skip default arm */
 			continue;
 		}
 
-		zend_ast_list *conds = zend_ast_get_list(arm_ast->child[0]);
 		for (uint32_t j = 0; j < conds->children; j++) {
 			zend_ast **cond_ast = &conds->child[j];
 
@@ -6418,8 +6420,9 @@ static void zend_compile_match(znode *result, zend_ast *ast)
 
 	for (uint32_t i = 0; i < arms->children; ++i) {
 		zend_ast *arm_ast = arms->child[i];
+		zend_ast_list *conds = zend_ast_get_list(arm_ast->child[0]);
 
-		if (!arm_ast->child[0]) {
+		if (conds->child[0]->kind == ZEND_AST_DEFAULT) {
 			if (has_default_arm) {
 				CG(zend_lineno) = arm_ast->lineno;
 				zend_error_noreturn(E_COMPILE_ERROR,
@@ -6447,15 +6450,15 @@ static void zend_compile_match(znode *result, zend_ast *ast)
 		uint32_t cond_count = 0;
 		for (uint32_t i = 0; i < arms->children; ++i) {
 			zend_ast *arm_ast = arms->child[i];
-
-			if (!arm_ast->child[0]) {
-				continue;
-			}
-
 			zend_ast_list *conds = zend_ast_get_list(arm_ast->child[0]);
+
 			for (uint32_t j = 0; j < conds->children; j++) {
 				zend_ast *cond_ast = conds->child[j];
 
+				if (conds->child[0]->kind == ZEND_AST_DEFAULT) {
+					break;
+				}
+
 				znode cond_node;
 				zend_compile_expr(&cond_node, cond_ast);
 
@@ -6507,10 +6510,9 @@ static void zend_compile_match(znode *result, zend_ast *ast)
 	for (uint32_t i = 0; i < arms->children; ++i) {
 		zend_ast *arm_ast = arms->child[i];
 		zend_ast *body_ast = arm_ast->child[1];
+		zend_ast_list *conds = zend_ast_get_list(arm_ast->child[0]);
 
-		if (arm_ast->child[0] != NULL) {
-			zend_ast_list *conds = zend_ast_get_list(arm_ast->child[0]);
-
+		if (conds->child[0]->kind != ZEND_AST_DEFAULT) {
 			for (uint32_t j = 0; j < conds->children; j++) {
 				zend_ast *cond_ast = conds->child[j];
 

Zend/zend_execute.c

@@ -44,6 +44,7 @@
 #include "zend_system_id.h"
 #include "zend_call_stack.h"
 #include "zend_attributes.h"
+#include "ext/reflection/php_reflection.h"
 #include "Optimizer/zend_func_info.h"
 
 /* Virtual current working directory support */

Zend/zend_language_parser.y

@@ -86,6 +86,9 @@ static YYSIZE_T zend_yytnamerr(char*, const char*);
 %precedence T_ELSEIF
 %precedence T_ELSE
 
+%precedence T_DEFAULT
+%precedence T_SWITCH_DEFAULT
+
 %token <ast> T_LNUMBER   "integer"
 %token <ast> T_DNUMBER   "floating-point number"
 %token <ast> T_STRING    "identifier"
@@ -251,7 +254,7 @@ static YYSIZE_T zend_yytnamerr(char*, const char*);
 %type <ast> group_use_declaration inline_use_declarations inline_use_declaration
 %type <ast> mixed_group_use_declaration use_declaration unprefixed_use_declaration
 %type <ast> unprefixed_use_declarations const_decl inner_statement
-%type <ast> expr expr_with_default optional_expr while_statement for_statement foreach_variable
+%type <ast> expr optional_expr while_statement for_statement foreach_variable
 %type <ast> foreach_statement declare_statement finally_statement unset_variable variable
 %type <ast> extends_from parameter optional_type_without_static argument global_var
 %type <ast> static_var class_statement trait_adaptation trait_precedence trait_alias
@@ -702,9 +705,9 @@ switch_case_list:
 
 case_list:
 		%empty { $$ = zend_ast_create_list(0, ZEND_AST_SWITCH_LIST); }
-	|	case_list T_CASE expr case_separator inner_statement_list
+	|	case_list T_CASE expr case_separator inner_statement_list %prec T_SWITCH_DEFAULT
 			{ $$ = zend_ast_list_add($1, zend_ast_create(ZEND_AST_SWITCH_CASE, $3, $5)); }
-	|	case_list T_DEFAULT case_separator inner_statement_list
+	|	case_list T_DEFAULT case_separator inner_statement_list %prec T_SWITCH_DEFAULT
 			{ $$ = zend_ast_list_add($1, zend_ast_create(ZEND_AST_SWITCH_CASE, NULL, $4)); }
 ;
 
@@ -716,7 +719,7 @@ case_separator:
 
 match:
 		T_MATCH '(' expr ')' '{' match_arm_list '}'
-			{ $$ = zend_ast_create(ZEND_AST_MATCH, $3, $6); };
+			{ $$ = zend_ast_create(ZEND_AST_MATCH, $3, $6); }
 ;
 
 match_arm_list:
@@ -732,8 +735,6 @@ non_empty_match_arm_list:
 match_arm:
 		match_arm_cond_list possible_comma T_DOUBLE_ARROW expr
 			{ $$ = zend_ast_create(ZEND_AST_MATCH_ARM, $1, $4); }
-	|	T_DEFAULT possible_comma T_DOUBLE_ARROW expr
-			{ $$ = zend_ast_create(ZEND_AST_MATCH_ARM, NULL, $4); }
 ;
 
 match_arm_cond_list:
@@ -904,7 +905,7 @@ non_empty_argument_list:
 ;
 
 argument:
-		expr_with_default   { $$ = $1; }
+		expr				{ $$ = $1; }
 	|	identifier ':' expr
 			{ $$ = zend_ast_create(ZEND_AST_NAMED_ARG, $1, $3); }
 	|	T_ELLIPSIS expr	{ $$ = zend_ast_create(ZEND_AST_UNPACK, $2); }
@@ -1321,16 +1322,12 @@ expr:
 	|	inline_function { $$ = $1; }
 	|	attributes inline_function { $$ = zend_ast_with_attributes($2, $1); }
 	|	T_STATIC inline_function { $$ = $2; ((zend_ast_decl *) $$)->flags |= ZEND_ACC_STATIC; }
+	|	T_DEFAULT { $$ = zend_ast_create(ZEND_AST_DEFAULT); }
 	|	attributes T_STATIC inline_function
 			{ $$ = zend_ast_with_attributes($3, $1); ((zend_ast_decl *) $$)->flags |= ZEND_ACC_STATIC; }
 	|	match { $$ = $1; }
 ;
 
-expr_with_default:
-		expr		{ $$ = $1; }
-	|	T_DEFAULT   { $$ = zend_ast_create(ZEND_AST_DEFAULT); }
-;
-
 inline_function:
 		function returns_ref backup_doc_comment '(' parameter_list ')' lexical_vars return_type
 		backup_fn_flags '{' inner_statement_list '}' backup_fn_flags

Zend/zend_vm_def.h

@@ -9815,10 +9815,6 @@ ZEND_VM_HANDLER(210, ZEND_FETCH_DEFAULT_ARG, UNUSED|NUM, UNUSED)
 
 	zend_function *called_func = EX(call)->func;
 
-	zend_string *reflection_class_name = ZSTR_INIT_LITERAL("ReflectionParameter", 0);
-	zend_class_entry *reflection_class = zend_fetch_class(reflection_class_name, ZEND_FETCH_CLASS_DEFAULT);
-	zend_string_release(reflection_class_name);
-
 	/*
 	 * [0]: The function (string) or class method (array) to reflect parameters from.
 	 * [1]: A zero-based integer specifying the parameter position.
@@ -9837,12 +9833,12 @@ ZEND_VM_HANDLER(210, ZEND_FETCH_DEFAULT_ARG, UNUSED|NUM, UNUSED)
 
 	zval reflection_obj;
 	// TODO: Check result.
-	/*zend_result res =*/ object_init_with_constructor(&reflection_obj, reflection_class, 2, constructor_params, NULL);
+	/*zend_result res =*/ object_init_with_constructor(&reflection_obj, reflection_parameter_ptr, 2, constructor_params, NULL);
 	zval_ptr_dtor(&constructor_params[0]);
 	zval_ptr_dtor(&constructor_params[1]);
 
 	zval default_value;
-	zend_call_method_with_0_params(Z_OBJ(reflection_obj), reflection_class, NULL, "getDefaultValue", &default_value);
+	zend_call_method_with_0_params(Z_OBJ(reflection_obj), reflection_parameter_ptr, NULL, "getDefaultValue", &default_value);
 	zval_ptr_dtor(&reflection_obj);
 
 	ZVAL_COPY(EX_VAR(opline->result.var), &default_value);