C89 question: Do we need to accept -Wint-conversion warnings

[Florian Weimer]

* David Brown:

> So IMHO (and as I am not a code contributor to GCC, my opinion really
> is humble) it is better to be stricter than permissive, even in old
> standards.  It is particularly important for "-std=c89", while
> "-std=gnu89" is naturally more permissive.  (I have seen more than
> enough terrible code in embedded programs - I don't want to make it
> easier for them to write even worse code!)

We can probably make (say) -std=gnu89 -fno-permissive work, in a way
that is a bit less picky than -std=gnu89 -pedantic-errors today.

And of course there's still -Werror, that's not going to go away.  So if
you are using -Werror=implicit-function-declaration today (as you
probably should 8-), nothing changes for you in GCC 14.

> I suspect (again with numbers taken from thin air) that the proportion
> of C programmers or projects that actively choose C11 or C17 modes, as
> distinct from using the compiler defaults, will be less than 1%.  C99
> (or gnu99) is the most commonly chosen standard for small-systems
> embedded programming, combining C90 libraries, stacks, and RTOS's with
> user code in C99.  So again, my preference is towards stricter
> control, not more permissive tools.

I don't think the estimate is accurate.  Several upstream build systems
I've seen enable -std=gnu11 and similar options once they are supported.
Usually, it's an attempt to upgrade to newer language standards that
hasn't aged well, not a downgrade.  It's probably quite bit more than
1%.

Thanks,
Florian