fmt: fix broken formatting in fn struct fields (#7794)

vlib/v/fmt/fmt.v

@@ -622,7 +622,7 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl) {
 			max = comments_len + field.name.len
 		}
 		mut ft := f.no_cur_mod(f.table.type_to_str(field.typ))
-		if !ft.contains('C.') && !ft.contains('JS.') {
+		if !ft.contains('C.') && !ft.contains('JS.') && !ft.contains('fn (') {
 			ft = f.short_module(ft)
 		}
 		field_types << ft

vlib/v/fmt/tests/struct_fn_fields_expected.vv

@@ -0,0 +1,6 @@
+import v.ast
+
+struct Data {
+	a fn (string, voidptr) bool
+	b fn (ast.Stmt, voidptr) bool
+}

vlib/v/fmt/tests/struct_fn_fields_input.vv

@@ -0,0 +1,6 @@
+import v.ast
+
+struct Data {
+	a fn (s string, f voidptr) bool
+	b fn (stmt ast.Stmt, f voidptr) bool
+}

vlib/v/table/types.v

@@ -744,13 +744,19 @@ pub fn (table &Table) type_to_str_using_aliases(t Type, import_aliases map[strin
 			}
 		}
 		.function {
-			if !table.is_fmt {
 			info := sym.info as FnType
+			if !table.is_fmt {
 				res = table.fn_signature(info.func, type_only: true)
 			} else {
+				if res.starts_with('fn (') {
+					// fn foo ()
+					res = table.fn_signature(info.func, type_only: true)
+				} else {
+					// FnFoo
 					res = table.shorten_user_defined_typenames(res, import_aliases)
 				}
 			}
+		}
 		.map {
 			if int(t) == map_type_idx {
 				return 'map'