Re: [PATCH] Assert that 'length' > 0 on infcmd.c:construct_inferior_arguments

[Sergio Durigan Junior <sergiodj at redhat dot com>]

On Wednesday, January 29 2020, Pedro Alves wrote:

> On 1/29/20 7:54 PM, Sergio Durigan Junior wrote:
>> On Wednesday, January 29 2020, Pedro Alves wrote:
>
>>> Uppercase ARGC.  But putting
>>>
>>>  gdb_assert (argc > 0);
>>>
>>> at the top of the function instead as I originally suggested also works
>>> for me (tried current gcc master), which seems a bit better to me, as it
>>> covers both branches at once.  Did it not work for you?  This makes gcc see
>>> that the loops always run at least once.
>> 
>> Yes, this should work.
>> 
>> Updated patch below.
>
> The version you sent won't build for sure -- you're checking
> length instead of argc:
>
>  @@ -268,6 +268,11 @@ construct_inferior_arguments (int argc, char **argv)
>   {
>     char *result;
>   
>  +  /* argc should always be at least 1, but we double check this
>  +     here.  This is also needed to silence -Werror-stringop
>  +     warnings.  */
>  +  gdb_assert (length > 0);

Congrats, this is the new challenge called "How many interactions does
it take to get a simple patch accepted?"

Sorry about this brain fart.  I should slow down.

> This is OK with that fixed, but please update the commit log, here:
>
>  "The solution here is to explicit check that 'length' is greater than
>  0.  Since we're dealing with 'argc', I think it's pretty much
>  guaranteed that it's going to be at least 1."
>
> I'd go with:
>
>  The solution here is to assert that 'argc' is greater than
>  0 on entry, which makes GCC understand that the loops always
>  run at least once, and thus 'length' is always > 0.
>
> ... and also update the commit's subject.  I'd use
>
>  Fix -Werror-stringop error on infcmd.c:construct_inferior_arguments
>
> instead, to talk in terms of what you're fixing instead of how
> you're fixing it.

OK, I'll do those things *calmly* and put your name as the author of the
patch.

Thanks,

-- 
Sergio
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