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

[Harald Anlauf <anlauf@gmx.de>]

Dear all,

we might want to update changes.html to reflect this.  How about:

diff --git a/htdocs/gcc-14/changes.html b/htdocs/gcc-14/changes.html
index 403feb06..9b16f5e3 100644
--- a/htdocs/gcc-14/changes.html
+++ b/htdocs/gcc-14/changes.html
@@ -284,6 +284,11 @@ a work-in-progress.</p>

  <h3 id="fortran">Fortran</h3>
  <ul>
+  <li>The compiler now accepts the <code>-std=f2023</code> option, which
+    has been added in preparation of support of Fortran 2023.  This option
+    increases the line-length limit for source in free-form to 10000, and
+    statements may have up to 1 million characters.
+  </li>
    <li> With the <code>-save-temps</code> option, preprocessed files
      with the <code>.fii</code> extension will be generated from
      free-form source files such as <code>.F90</code> and


Cheers,
Harald


Am 17.11.23 um 12:38 schrieb Tobias Burnus:
> Hi Harald, hi all,
>
> On 16.11.23 20:30, Harald Anlauf wrote:
>> On 11/16/23 14:01, Tobias Burnus wrote:
>>> This adds -std=f2023, which is mostly a prep patch for future changes.
> ...
>>> (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.
>
> I can confirm this. I tried to get it working in scanner.cc but due to
> the re-parsing it is quite difficult to get it right; the main problem
> is that we keep reparsing code ("gfc_current_locus = old_loc"), such
> that a simple count will be wrong.
>
> → Now tracked at https://gcc.gnu.org/PR112586
>
>
>> According to the standard one can have 999999 lines with only
>> "&" and then an ";", but then only 100 lines with 10000 characters.
>
> I believe a single '&' is not valid, you either need '&&' or something
> else + '&'; thus, you can have only half a million lines + 1.
>
> In the code, I still use 1,000,000 but now with a comment.
>
>> There is a similar wording for fixed-form which you overlooked:
> Ups - fixed.
>> If you think that we need testcases for fixed-form, add them,
>> or forget them.  I don't bother.
> I added one.
>
>> - 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+ .
>
> Done. We are rather inconsistent whether we enumerate <file>.f{,90}
> together or separately; as the suffix is shown, either works.
>
>>
>> - 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 ?
>
> Well, it ensures that the warning is not only shown for -std=f2023 but
> also for -std=f2028 and (current -std=gnu). In general, I think it is
> useful to check the lower and the upper bound.
>
> I have now removed it - as it is unlikely that we would regress on such
> changes.
>
>>> 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.
>
> Likewise  - especially as '.f95' starts out as Fortran code that
> complies to -std=f95 but slowly Fortran 2003 or later code creeps in. I
> think that's fine but then one can also directly use .f90. (Most code
> does so.)
>
> Unless there are follow up comments, I will commit it later today.
>
> Thanks for the comments!
>
> Tobias
>
> PS: I fixed the wording issue in the subject line of the email and
> header. I first wrote 'support' but that sounded a bit as if F2023 is
> supported. Hence, I wrote 'Accept' and did not remove 'support'.
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