[Bug libfortran/114304] [13/14 Regression] libgfortran I/O – bogus "Semicolon not allowed as separator with DECIMAL='point'"

["burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114304

--- Comment #19 from Tobias Burnus <burnus at gcc dot gnu.org> ---
Regarding the LAPACK issue:

Actually, I am inclined to
* regard it as LAPACK bug
* that was also fixed upstream, see comment 6, to make g95 happy.
as ';' is not a value separator - while ' ;' is fine, where the blank is a
value separator.

My testcase of comment 4 therefore always used a space before the ',' / ';'.

* * *

I have now created an extended testcase, attached to PR105473 as attachment
57695. (Only testing integer/real parsing, not reading the char afterward as in
comment 4.)

The same testcase can also be found at https://godbolt.org/z/14h48167W and
shows the result with gfortran, ifort, ifx and flag. I used this result to add
comments to the testcases.

* * *

For some F2023 wording, see comment 14 above.

And I have to admit that I am rather confused by the results as there does not
seem to be any consistent pattern; there are cases where I agree with
gfortran's error even though neither ifort nor flang show one, while for
others, I think gfortran gets it wrong.

In particular, I think for the following cases:

  call t('point', ';') ! gfortran: no error, others: error
→ IMHO invalid: not a value separator and not an integer.

  call t('point', '5;') ! gfortran: no error shown, others: error
→ This is the LAPACK example but for integers.
  I think ';' is invalid as it is not part of the integer but also not a value
separator.

  call t('comma', '7 ,') ! gfortran: error; others: no error
→ IMHO valid - I think the ' ' as value separator is sufficient.

  call t('point', '3.3,', .true.) ! gfortran/flag: error shown; ifort: no error
→ What's wrong with a comma as value separator?

  call t('comma', '3,3;', .true.) ! gfortran: error shown; others: no error
→ Same, except that ';' is now the value separator


But in the following cases, I think gfortran is *right*:
  call t('point', '5.') ! gfortran/flang: Error shown, ifort: no error
→ '.' is not part of an integer nor a value separator

  call t('comma', '5,') ! gfortran: error; others: no error
→ Likewise for ',' - the ',' is not part of an integer nor a value separator


Disclaimer: I might have easily overlooked some fine print.