feat: allow multiline arrow functions

Zend/tests/arrow_functions/multiline_001.phpt

@@ -0,0 +1,21 @@
+--TEST--
+Multiline arrow function
+--FILE--
+<?php
+
+function a($a) {
+    $f = fn($a) => {
+        echo "inside fn($a):\n";
+        return $a;
+    };
+
+    $f($a);
+    echo "inside a($a):\n";
+}
+
+a(12345);
+
+?>
+--EXPECT--
+inside fn(12345):
+inside a(12345):

Zend/tests/arrow_functions/multiline_002.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Arrow functions implicit use must be throwing notices only upon actual use
+--FILE--
+<?php
+
+$b = 1;
+
+var_dump((fn() => {return $b + $c;})());
+
+?>
+--EXPECTF--
+Warning: Undefined variable $c in %s on line %d
+int(1)

Zend/tests/arrow_functions/multiline_gh7900_return.phpt

@@ -0,0 +1,19 @@
+--TEST--
+GH-7900: Arrow function with never return type compile-time errors (multiline, no errors)
+--INI--
+zend.assertions=1
+assert.exception=1
+--FILE--
+<?php
+
+$x = fn(): never => { throw new \Exception('Here'); };
+
+try {
+    var_dump($x());
+} catch (\Exception $e) {
+    echo $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+Here

Zend/tests/arrow_functions/multiline_gh7900_throw.phpt

@@ -0,0 +1,17 @@
+--TEST--
+GH-7900: Arrow function with never return type compile-time errors (multiline, Fatal error)
+--INI--
+zend.assertions=1
+assert.exception=1
+--FILE--
+<?php
+
+try {
+    assert((fn(): never => { return 42; }) && false);
+} catch (\Error $e) {
+    echo $e->getMessage(), "\n";
+}
+
+?>
+--EXPECTF--
+Fatal error: A never-returning function must not return in %s on line %d

Zend/zend_compile.c

@@ -8365,7 +8365,9 @@ static zend_op_array *zend_compile_func_decl_ex(
 		zend_compile_closure_uses(uses_ast);
 	}
 
-	if (ast->kind == ZEND_AST_ARROW_FUNC && decl->child[2]->kind != ZEND_AST_RETURN) {
+	if (ast->kind == ZEND_AST_ARROW_FUNC
+        && stmt_ast->kind != ZEND_AST_RETURN
+        && stmt_ast->kind != ZEND_AST_STMT_LIST) {
 		bool needs_return = true;
 		if (op_array->fn_flags & ZEND_ACC_HAS_RETURN_TYPE) {
 			zend_arg_info *return_info = CG(active_op_array)->arg_info - 1;

Zend/zend_language_parser.y

@@ -1337,13 +1337,15 @@ inline_function:
 		function returns_ref backup_doc_comment '(' parameter_list ')' lexical_vars return_type
 		backup_fn_flags '{' inner_statement_list '}' backup_fn_flags
 			{ $$ = zend_ast_create_decl(ZEND_AST_CLOSURE, $2 | $13, $1, $3,
-				  NULL,
-				  $5, $7, $11, $8, NULL); CG(extra_fn_flags) = $9; }
+				  NULL, $5, $7, $11, $8, NULL); CG(extra_fn_flags) = $9; }
 	|	fn returns_ref backup_doc_comment '(' parameter_list ')' return_type
 		T_DOUBLE_ARROW backup_fn_flags backup_lex_pos expr backup_fn_flags
 			{ $$ = zend_ast_create_decl(ZEND_AST_ARROW_FUNC, $2 | $12, $1, $3,
-				  NULL, $5, NULL, $11, $7, NULL);
-				  CG(extra_fn_flags) = $9; }
+				  NULL, $5, NULL, $11, $7, NULL); CG(extra_fn_flags) = $9; }
+	|	fn returns_ref backup_doc_comment '(' parameter_list ')' return_type
+		T_DOUBLE_ARROW backup_fn_flags '{' inner_statement_list '}' backup_fn_flags
+			{ $$ = zend_ast_create_decl(ZEND_AST_ARROW_FUNC, $2 | $13, $1, $3,
+				  NULL, $5, NULL, $11, $7, NULL); CG(extra_fn_flags) = $9; }
 ;
 
 fn: