Re: [PATCH] fmt-merge-msg: show those involved in a merged series

[Phil Hord <phil.hord@gmail.com>]

On Thu, Mar 8, 2012 at 2:18 PM, Junio C Hamano <gitster@pobox.com> wrote:
> René Scharfe <rene.scharfe@lsrfire.ath.cx> writes:
>
>> Am 07.03.2012 22:59, schrieb Junio C Hamano:
>>> René Scharfe<rene.scharfe@lsrfire.ath.cx>  writes:
>>>
>>>> Am 05.03.2012 22:34, schrieb Junio C Hamano:
>>>>
>>>>> +#define util_as_int(elem) ((intptr_t)((elem)->util))
>>>>
>>>> Something that actually returns an int would fit the name better. ;)
>>>
>>> The particular type would not matter to the callers of the helper
>>> macro, would it?
>>
>> Three of the five callers introduced in that commit cast the result to
>> int and the remaining two don't care, so it actually does seem to
>> matter for most of them, strictly speaking.  When I see a nit, I can't
>> resist the urge to pick it, apparently.
>
> Unfortunately, replacing intptr_t with int or casting the above
> again as int will result in
>
> builtin/fmt-merge-msg.c: In function 'record_person':
> builtin/fmt-merge-msg.c:213: error: cast to pointer from integer of different size
>
> So...

Out of the frying pan, into the fire...

   builtin/fmt-merge-msg.c: In function ‘record_person’:
   builtin/fmt-merge-msg.c:213:34: warning: cast from pointer to
integer of different size [-Wpointer-to-int-cast]
   builtin/fmt-merge-msg.c: In function ‘cmp_string_list_util_as_int’:
   builtin/fmt-merge-msg.c:219:9: warning: cast from pointer to
integer of different size [-Wpointer-to-int-cast]
   builtin/fmt-merge-msg.c:219:26: warning: cast from pointer to
integer of different size [-Wpointer-to-int-cast]
   builtin/fmt-merge-msg.c: In function ‘add_people_count’:
   builtin/fmt-merge-msg.c:229:8: warning: cast from pointer to
integer of different size [-Wpointer-to-int-cast]
   builtin/fmt-merge-msg.c:231:8: warning: cast from pointer to
integer of different size [-Wpointer-to-int-cast]
   builtin/fmt-merge-msg.c:235:8: warning: cast from pointer to
integer of different size [-Wpointer-to-int-cast]

I see slightly different code in pu than in next, but it produces the
same warnings on my 64-bit Linux machine.

Here's a fix against next:

-- >8 --

Subject: [PATCH] Appease compiler pedantry with an extra cast

Recently git repurposed a pointer as an integer to hold some
counter which git fancies.

Casting directly from 'pointer' to 'int' ((int)(void*)&x) causes a
possible size mismatch because pointers can be bigger than ints.
In such a situation, the compiler complains:

   warning: cast from pointer to integer of different size
            [-Wpointer-to-int-cast]

Cast the value through intptr_t first to quell compiler complaints
about how this gun appears to be aimed near our feet.  Then cast this
value to an int; this path assures the compiler we are smarter than we
look, or at least that we intend to aim the gun this way for a reason.
---
 builtin/fmt-merge-msg.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/builtin/fmt-merge-msg.c b/builtin/fmt-merge-msg.c
index 8ddefb3..fee65e0 100644
--- a/builtin/fmt-merge-msg.c
+++ b/builtin/fmt-merge-msg.c
@@ -182,7 +182,7 @@ static void add_branch_desc(struct strbuf *out,
const char *name)
        strbuf_release(&desc);
 }

-#define util_as_int(elem) ((int)((elem)->util))
+#define util_as_int(elem) ((int)(intptr_t)((elem)->util))

 static void record_person(int which, struct string_list *people,
                          struct commit *commit)
-- 
1.7.9.3