Documenting common C/C++ options

Documenting common C/C++ options

[Florian Weimer]

Currently, -fsigned-char and -funsigned-char are only documented as C
language options, although they work for C++ as well (and Objective-C
and Objective-C++, I assume, but I have not tested this).  There does
not seem to be a place for this kind of options in the manual.

The options -fshort-enums and -fshort-wchar are documented under
code-generation options, but this seems to be a bit of a stretch because
(at least for -fshort-wchar), these too seem to be more about front-end
behavior.

What would be a good way to address this?

Thanks,
Florian

Re: Documenting common C/C++ options

[Richard Earnshaw (lists)]

On 10/10/2023 10:47, Florian Weimer via Gcc wrote:
> Currently, -fsigned-char and -funsigned-char are only documented as C
> language options, although they work for C++ as well (and Objective-C
> and Objective-C++, I assume, but I have not tested this).  There does
> not seem to be a place for this kind of options in the manual.
> 
> The options -fshort-enums and -fshort-wchar are documented under
> code-generation options, but this seems to be a bit of a stretch because
> (at least for -fshort-wchar), these too seem to be more about front-end
> behavior.
> 
> What would be a good way to address this?
> 
> Thanks,
> Florian
> 


All of these are ABI; so where ever it goes, it should be documented that changing them will potentially cause issues with any pre-compiled object files having different settings.

R.

Re: Documenting common C/C++ options

[Richard Earnshaw (lists)]

On 10/10/2023 11:46, Richard Earnshaw (lists) via Gcc wrote:
> On 10/10/2023 10:47, Florian Weimer via Gcc wrote:
>> Currently, -fsigned-char and -funsigned-char are only documented as C
>> language options, although they work for C++ as well (and Objective-C
>> and Objective-C++, I assume, but I have not tested this).  There does
>> not seem to be a place for this kind of options in the manual.
>>
>> The options -fshort-enums and -fshort-wchar are documented under
>> code-generation options, but this seems to be a bit of a stretch because
>> (at least for -fshort-wchar), these too seem to be more about front-end
>> behavior.
>>
>> What would be a good way to address this?
>>
>> Thanks,
>> Florian
>>
> 
> 
> All of these are ABI; so where ever it goes, it should be documented that changing them will potentially cause issues with any pre-compiled object files having different settings.
> 
> R.

And you can add -f[un]signed-bitfield to that list as well.

R.

Re: Documenting common C/C++ options

[Florian Weimer]

* Richard Earnshaw:

> On 10/10/2023 11:46, Richard Earnshaw (lists) via Gcc wrote:
>> On 10/10/2023 10:47, Florian Weimer via Gcc wrote:
>>> Currently, -fsigned-char and -funsigned-char are only documented as C
>>> language options, although they work for C++ as well (and Objective-C
>>> and Objective-C++, I assume, but I have not tested this).  There does
>>> not seem to be a place for this kind of options in the manual.
>>>
>>> The options -fshort-enums and -fshort-wchar are documented under
>>> code-generation options, but this seems to be a bit of a stretch because
>>> (at least for -fshort-wchar), these too seem to be more about front-end
>>> behavior.
>>>
>>> What would be a good way to address this?
>>>
>>> Thanks,
>>> Florian
>>>
>> 
>> 
>> All of these are ABI; so where ever it goes, it should be documented
>> that changing them will potentially cause issues with any
>> pre-compiled object files having different settings.

> And you can add -f[un]signed-bitfield to that list as well.

There's already a section for those ABI options that are like
-fshort-enums:

@node Code Gen Options
@section Options for Code Generation Conventions

Maybe we should move them over there.

But that wasn't really the direction of my question.  I was wondering
where we should document a future C version of -fpermissive.

Thanks,
Florian

Re: Documenting common C/C++ options

[Richard Biener]

On Tue, Oct 10, 2023 at 1:13 PM Florian Weimer via Gcc <gcc@gcc.gnu.org> wrote:
>
> * Richard Earnshaw:
>
> > On 10/10/2023 11:46, Richard Earnshaw (lists) via Gcc wrote:
> >> On 10/10/2023 10:47, Florian Weimer via Gcc wrote:
> >>> Currently, -fsigned-char and -funsigned-char are only documented as C
> >>> language options, although they work for C++ as well (and Objective-C
> >>> and Objective-C++, I assume, but I have not tested this).  There does
> >>> not seem to be a place for this kind of options in the manual.
> >>>
> >>> The options -fshort-enums and -fshort-wchar are documented under
> >>> code-generation options, but this seems to be a bit of a stretch because
> >>> (at least for -fshort-wchar), these too seem to be more about front-end
> >>> behavior.
> >>>
> >>> What would be a good way to address this?
> >>>
> >>> Thanks,
> >>> Florian
> >>>
> >>
> >>
> >> All of these are ABI; so where ever it goes, it should be documented
> >> that changing them will potentially cause issues with any
> >> pre-compiled object files having different settings.
>
> > And you can add -f[un]signed-bitfield to that list as well.
>
> There's already a section for those ABI options that are like
> -fshort-enums:
>
> @node Code Gen Options
> @section Options for Code Generation Conventions
>
> Maybe we should move them over there.
>
> But that wasn't really the direction of my question.  I was wondering
> where we should document a future C version of -fpermissive.

Options common to the C family are documented in 'C Dialect Options'
which says

"The following options control the dialect of C (or languages derived
from C, such as C++, Objective-C and Objective-C++) that the compiler
accepts:"

the options usually specify when they do not apply to all of the above
sibling languages (where it's not obvious).

Richard.

> Thanks,
> Florian
>

Re: Documenting common C/C++ options

[Jason Merrill]

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On Tue, Oct 10, 2023 at 7:12 AM Florian Weimer via Gcc <gcc@gcc.gnu.org>
wrote:

> * Richard Earnshaw:
>
> > On 10/10/2023 11:46, Richard Earnshaw (lists) via Gcc wrote:
> >> On 10/10/2023 10:47, Florian Weimer via Gcc wrote:
> >>> Currently, -fsigned-char and -funsigned-char are only documented as C
> >>> language options, although they work for C++ as well (and Objective-C
> >>> and Objective-C++, I assume, but I have not tested this).  There does
> >>> not seem to be a place for this kind of options in the manual.
> >>>
> >>> The options -fshort-enums and -fshort-wchar are documented under
> >>> code-generation options, but this seems to be a bit of a stretch
> because
> >>> (at least for -fshort-wchar), these too seem to be more about front-end
> >>> behavior.
> >>>
> >>> What would be a good way to address this?
> >>>
> >>> Thanks,
> >>> Florian
> >>>
> >>
> >>
> >> All of these are ABI; so where ever it goes, it should be documented
> >> that changing them will potentially cause issues with any
> >> pre-compiled object files having different settings.
>
> > And you can add -f[un]signed-bitfield to that list as well.
>
> There's already a section for those ABI options that are like
> -fshort-enums:
>
> @node Code Gen Options
> @section Options for Code Generation Conventions
>
> Maybe we should move them over there.
>
> But that wasn't really the direction of my question.  I was wondering
> where we should document a future C version of -fpermissive.
>

My permerror patch proposes moving it to the Warning Options node, right
after -pedantic-errors.

Jason

Re: Documenting common C/C++ options

[Florian Weimer]

* Jason Merrill:

>> But that wasn't really the direction of my question.  I was wondering
>> where we should document a future C version of -fpermissive.
>
> My permerror patch proposes moving it to the Warning Options node,
> right after -pedantic-errors.

Yes, that should work.  I'm basing my patches based on it.

Thanks,
Florian