On 11/10/2023 10:10, Florian Weimer wrote:
* 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.
The gcc manual has "-permissive" under "C++ Dialect Options". Are you
planning to have it for C as well? That sounds like a good idea
(perhaps with some examples in the documentation?). Ideally (and I
realise I like stricter checking than many people) some long-obsolescent
features like non-prototype function declarations could be marked as
errors unless "-permissive" were used, even in C89 standards.
(As a side note, I wonder if "-fwrapv" and "-fno-strict-aliasing" should
be listed under "C Dialect Options", as they give specific semantics to
normally undefined behaviour.)
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 have long lists of explicit warnings and flags in my makefiles, so I
am not concerned for my own projects. But I always worry about the less
vigilant users - the ones who don't know the details of the language or
the features of the compiler, and don't bother finding out. I don't
want default settings to be less strict for them, as it means higher
risks of bugs escaping out to released code.
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%.
Fair enough. My experience is mostly within a particular field that is
probably more conservative than a lot of other areas of programming.
David
