Re: [GSoC PATCH] rm: fix sign comparison warnings

[Arnav Bhate <bhatearnav@gmail.com>]

Karthik Nayak <karthik.188@gmail.com> writes:

> Junio C Hamano <gitster@pobox.com> writes:
> 
>> Arnav Bhate <bhatearnav@gmail.com> writes:
>>
>>>  static int get_ours_cache_pos(const char *path, int pos)
>>>  {
>>> -	int i = -pos - 1;
>>> +	/*
>>> +	 * This function is only called when pos < 0, so -pos - 1 is
>>> +	 * greater than or equal to 0, so it can be safely be stored in
>>> +	 * an unsigned int.
>>> +	 */
>>> +	unsigned int i = -pos - 1;
>>
>> "Can be safely stored", sure.
>>
>> But so is "int i" perfectly adequate to hold such a value, no?
>>
>> This is one of the many instances that demonstrate why the
>> "-Wsign-compare" warning is of dubious value, and invites worse code
>> than necessary.
> 
> I have to agree. I think it would a bit cleaner to actually change the
> functions argument type itself. Perhaps, something like:
> 
> -- >8 --
> 
> diff --git a/builtin/rm.c b/builtin/rm.c
> index 12ae086a55..79e47d6e9e 100644
> --- a/builtin/rm.c
> +++ b/builtin/rm.c
> @@ -40,10 +40,8 @@ static struct {
>  	} *entry;
>  } list;
> 
> -static int get_ours_cache_pos(const char *path, int pos)
> +static int get_ours_cache_pos(const char *path, unsigned int i)
>  {
> -	int i = -pos - 1;
> -
>  	while ((i < the_repository->index->cache_nr) &&
> !strcmp(the_repository->index->cache[i]->name, path)) {
>  		if (ce_stage(the_repository->index->cache[i]) == 2)
>  			return i;
> @@ -83,7 +81,7 @@ static void submodules_absorb_gitdir_if_needed(void)
> 
>  		pos = index_name_pos(the_repository->index, name, strlen(name));
>  		if (pos < 0) {
> -			pos = get_ours_cache_pos(name, pos);
> +			pos = get_ours_cache_pos(name, -pos - 1);
>  			if (pos < 0)
>  				continue;
>  		}
> @@ -131,7 +129,7 @@ static int check_local_mod(struct object_id *head,
> int index_only)
>  			 * Skip unmerged entries except for populated submodules
>  			 * that could lose history when removed.
>  			 */
> -			pos = get_ours_cache_pos(name, pos);
> +			pos = get_ours_cache_pos(name, -pos - 1);
>  			if (pos < 0)
>  				continue;

This is a good option, I think, but perhaps 'i' should be renamed to
something more descriptive.

>>> @@ -58,7 +62,7 @@ static void print_error_files(struct string_list *files_list,
>>>  			      int *errs)
>>>  {
>>>  	if (files_list->nr) {
>>> -		int i;
>>> +		unsigned int i;
>>>  		struct strbuf err_msg = STRBUF_INIT;
>>>
>>>  		strbuf_addstr(&err_msg, main_msg);
>>> @@ -271,6 +275,7 @@ int cmd_rm(int argc,
>>>  {
>>>  	struct lock_file lock_file = LOCK_INIT;
>>>  	int i, ret = 0;
>>> +	unsigned int j;
>>>  	struct pathspec pathspec;
>>>  	char *seen;
>>>
>>> @@ -314,8 +319,8 @@ int cmd_rm(int argc,
>>>  	if (pathspec_needs_expanded_index(the_repository->index, &pathspec))
>>>  		ensure_full_index(the_repository->index);
>>>
>>> -	for (i = 0; i < the_repository->index->cache_nr; i++) {
>>> -		const struct cache_entry *ce = the_repository->index->cache[i];
>>> +	for (j = 0; j < the_repository->index->cache_nr; j++) {
>>> +		const struct cache_entry *ce = the_repository->index->cache[j];
>>>
>>>  		if (!include_sparse &&
>>>  		    (ce_skip_worktree(ce) ||

-- 
Regards,
Arnav Bhate
(He/Him)