From d151f0cce7fca1fc156a9ea1dc98c59e1be512c9 Mon Sep 17 00:00:00 2001 From: Derrick Stolee Date: Tue, 27 Sep 2022 13:57:01 +0000 Subject: [PATCH] string-list: document iterator behavior on NULL input The for_each_string_list_item() macro takes a string_list and automatically constructs a for loop to iterate over its contents. This macro will segfault if the list is non-NULL. We cannot change the macro to be careful around NULL values because there are many callers that use the address of a local variable, which will never be NULL and will cause compile errors with -Werror=address. For now, leave a documentation comment to try to avoid mistakes in the future where a caller does not check for a NULL list. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano --- string-list.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/string-list.h b/string-list.h index d5a744e143..c7b0d5d000 100644 --- a/string-list.h +++ b/string-list.h @@ -141,7 +141,12 @@ void string_list_clear_func(struct string_list *list, string_list_clear_func_t c int for_each_string_list(struct string_list *list, string_list_each_func_t func, void *cb_data); -/** Iterate over each item, as a macro. */ +/** + * Iterate over each item, as a macro. + * + * Be sure that 'list' is non-NULL. The macro cannot perform NULL + * checks due to -Werror=address errors. + */ #define for_each_string_list_item(item,list) \ for (item = (list)->items; \ item && item < (list)->items + (list)->nr; \