Fixed match allowing multiple default conditions.

Author: Bilge

Zend/tests/default_expression/match_default_expr.phpt

@@ -0,0 +1,15 @@
+--TEST--
+Tests default as an expression in a match condition is not treated as a default match arm
+--FILE--
+<?php
+
+$F = fn ($V = 1) => $V;
+var_dump($F(
+	match (default) {
+		default + 1 => 2,
+		default => default,
+	}
+));
+?>
+--EXPECT--
+int(1)

Zend/tests/default_expression/match_multiple_default.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Tests declaring multiple default match arms is still prohibited in an argument context
+--FILE--
+<?php
+
+function F($V = 1) {}
+F(
+	match (0) {
+		0,
+		default => 1,
+		default => 2,
+	}
+);
+?>
+--EXPECTF--
+Fatal error: Match expressions may only contain one default arm in %s on line %d

Zend/zend_compile.c

@@ -6375,6 +6375,18 @@ static void zend_compile_switch(zend_ast *ast) /* {{{ */
 }
 /* }}} */
 
+static bool do_match_conditions_contain_default(zend_ast_list *conditions)
+{
+	for (uint32_t i = 0; i < conditions->children; ++i) {
+		// Default as an expression is still allowed, so we don't need to recurse sub-lists.
+		if (conditions->child[i]->kind == ZEND_AST_DEFAULT) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
 static uint32_t count_match_conds(zend_ast_list *arms)
 {
 	uint32_t num_conds = 0;
@@ -6383,7 +6395,7 @@ static uint32_t count_match_conds(zend_ast_list *arms)
 		zend_ast *arm_ast = arms->child[i];
 		zend_ast_list *conds = zend_ast_get_list(arm_ast->child[0]);
 
-		if (conds->child[0]->kind == ZEND_AST_DEFAULT) {
+		if (do_match_conditions_contain_default(conds)) {
 			continue;
 		}
 
@@ -6398,7 +6410,7 @@ static bool can_match_use_jumptable(zend_ast_list *arms) {
 		zend_ast *arm_ast = arms->child[i];
 		zend_ast_list *conds = zend_ast_get_list(arm_ast->child[0]);
 
-		if (conds->child[0]->kind == ZEND_AST_DEFAULT) {
+		if (do_match_conditions_contain_default(conds)) {
 			/* Skip default arm */
 			continue;
 		}
@@ -6445,7 +6457,7 @@ static void zend_compile_match(znode *result, zend_ast *ast)
 		zend_ast *arm_ast = arms->child[i];
 		zend_ast_list *conds = zend_ast_get_list(arm_ast->child[0]);
 
-		if (conds->child[0]->kind == ZEND_AST_DEFAULT) {
+		if (do_match_conditions_contain_default(conds)) {
 			if (has_default_arm) {
 				CG(zend_lineno) = arm_ast->lineno;
 				zend_error_noreturn(E_COMPILE_ERROR,
@@ -6478,7 +6490,7 @@ static void zend_compile_match(znode *result, zend_ast *ast)
 			for (uint32_t j = 0; j < conds->children; j++) {
 				zend_ast *cond_ast = conds->child[j];
 
-				if (conds->child[0]->kind == ZEND_AST_DEFAULT) {
+				if (do_match_conditions_contain_default(conds)) {
 					break;
 				}
 
@@ -6535,7 +6547,7 @@ static void zend_compile_match(znode *result, zend_ast *ast)
 		zend_ast *body_ast = arm_ast->child[1];
 		zend_ast_list *conds = zend_ast_get_list(arm_ast->child[0]);
 
-		if (conds->child[0]->kind != ZEND_AST_DEFAULT) {
+		if (!do_match_conditions_contain_default(conds)) {
 			for (uint32_t j = 0; j < conds->children; j++) {
 				zend_ast *cond_ast = conds->child[j];