* Questions about const.
@ 2005-07-19 6:02 Ryan Lortie
2005-07-19 6:22 ` Ian Lance Taylor
0 siblings, 1 reply; 2+ messages in thread
From: Ryan Lortie @ 2005-07-19 6:02 UTC (permalink / raw)
To: gcc-help
[please excuse if this is re-post. i don't think the first message made
it]
GCC generates some warnings when doing type conversions in places that I
don't believe the warnings are required. It'd be be cool if someone
could explain it to me. I have an example program here:
http://manic.desrt.ca/const.c
I'm guessing that, by the C standard, arrays that contain items of
different types are always considered incompatible and since 'char *'
and 'const char *' are different types then 'const char **' and 'char
**' are incompatible pointers. This just doesn't seem very useful when
one of the base types is always safe to automatically promote to the
other (in this case, char * -> const char *) and there is no chance that
an unnoticed conversion could ever occur in the other direction without
generating another warning/error.
Any feedback at all is appreciated -- many thanks.
Cheers.
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Questions about const.
2005-07-19 6:02 Questions about const Ryan Lortie
@ 2005-07-19 6:22 ` Ian Lance Taylor
0 siblings, 0 replies; 2+ messages in thread
From: Ian Lance Taylor @ 2005-07-19 6:22 UTC (permalink / raw)
To: Ryan Lortie; +Cc: gcc-help
Ryan Lortie <desrt@desrt.ca> writes:
> GCC generates some warnings when doing type conversions in places that I
> don't believe the warnings are required. It'd be be cool if someone
> could explain it to me. I have an example program here:
>
> http://manic.desrt.ca/const.c
>
> I'm guessing that, by the C standard, arrays that contain items of
> different types are always considered incompatible and since 'char *'
> and 'const char *' are different types then 'const char **' and 'char
> **' are incompatible pointers. This just doesn't seem very useful when
> one of the base types is always safe to automatically promote to the
> other (in this case, char * -> const char *) and there is no chance that
> an unnoticed conversion could ever occur in the other direction without
> generating another warning/error.
As you say, this is from the C standard. gcc tries to follow the
standard.
Ian
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