Re: [Patch] Fortran: Accept -std=f2023 support, update line-length for Fortran 2023

[Harald Anlauf <anlauf@gmx.de>]

Hi Tobias,

On 11/16/23 14:01, Tobias Burnus wrote:
> This adds -std=f2023, which is mostly a prep patch for future changes.
>
> However, Fortran 2023, https://j3-fortran.org/doc/year/23/23-007r1.pdf
> changes two things which is taken
> care in this patch:
>
> (A) In "6.3.2.1 Free form line length":
>
> Fortran 2018: "If a line consists entirely of characters of default kind
> (7.4.4), it shall contain at most 132 characters"
> Fortran 2023: "A line shall contain at most ten thousand characters."
>
> (B) In "6.3.2.6 Free form statements":
> Fortran 2018: "A statement shall not have more than 255 continuation
> lines."
> Fortran 2023: "A statement shall not have more than one million
> characters."

this is really a funny change: we're not really prepared to handle
this.  According to the standard one can have 999999 lines with only
"&" and then an ";", but then only 100 lines with 10000 characters.

There is a similar wording for fixed-form which you overlooked:

6.3.3.5 Fixed form statements

Fortran 2023: "A statement shall not have more than one million characters"

Please adjust the fixed-form limits in your patch.

If you think that we need testcases for fixed-form, add them,
or forget them.  I don't bother.

> I have not added a testcase for exceeding the latter but otherwise there
> are new
> tests and I had to add a couple of -std=f2018 to existing tests.
>
> Comments, suggestions, approval?

I have the following comments:

- there are existing testcases continuation_5.f, continuation_6.f,
   thus I suggest to rename your new continuation_{5,6}.f90 to
   continuation_17.f90+ .

- I don't understand your new testcase line_length_14.f90 .
   This is supposed to test -std=gnu, but then -std=gnu is not a
   standard but a moving target, which is why you had to adjust
   existing testcases.
   So what does it buy us beyond line_length_1{2,3}.f90 ?

> Tobias
>
> PS: I find it funny that -std=c23, -std=c++23 and -std=f2023 will get
> added in the same GCC release.

:-)

> PPS: I did not bother adding .f23 as file extension; I believe that also
> .f18 is unsupported.

I never use extensions other than .f90 for portable code.

With the above fixed, I am fine with your patch.

Thanks,
Harald

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