Re: [Patch, Fortran] Better error messages for type/rank checks

[Tobias Burnus <burnus at net-b dot de>]

Manfred Schwarb wrote:
> Perhaps cutting to some sane numbers is needed?
>
> Or, simply leave the line wrapping to the terminal and
> remove all this trimming code?

Well, the problem with the latter is that it leads to diagnostics like:


Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque 
pellentesque enim in lorem sagittis at elementum ipsum malesuada. Duis 
egestas nibh at erat pharetra id sodales tortor facilisis. Cras tempor, 
sapien eu dapibus posuere, quam dolor
suscipit ante, non iaculis elit lorem vel nunc. Suspendisse ut tempus 
urna. Sed nec nisl sed sapien
                             (1)

Where it is difficult to see where the location (1) actually points to. 
It also clutters the output quite a bit - I find it already now 
sometimes difficult to spot the errors and warnings in all those output 
lines.

On the other hand, showing the full line instead of only the trailing 
comment (cf. remark about the error location in previous email) helps to 
spot the problem. Although, that one can be also solved by using the 
position of the "!" as column for the error display.

As Fortran only allows 132 characters (unless special command-line 
options are used), the problem is less problematic than in the example 
above. Or as in C/C++, from which the 80 + COLUMNS environment variable 
were taken. In C, especially automatically generated code can have 
extremely long line lengths.

Regarding the limit of 80 characters: That's also used by other tools 
like a2ps, hence it is not completely arbitrary. Also IDE windows and 
terminals are often not that wide - they are rarely used in full screen 
width as the code lines are simply not longer. And while the length of 
72 (only later: 80) dates back to punch cards, humans have problems with 
too long lines. Hence, newspapers are printed in columns - and line 
lengths of 50 to 60, maximally 75, characters are regarded as optimal. 
(Due to indenting and avoiding breaking statements into too many new 
lines, slightly longer lines are fine for programming.)

Thus, I am in favour of having some reasonable limited. Whether 80 or 
132 is best, is bikeshadding. I am slightly inclined to 80, but also 132 
is fine with me. Thus, if you want, you can bump the value to 132.

* * *

Ignoring the line length, I would like to see the following two 
improvements:

a) To use the common middle-end diagnostic system (which some special 
Fortran handling); that will make use profit from general improvements 
(cf. PR44054). In particular:
- Color output, cf. http://gcc.gnu.org/gcc-4.9/changes.html
- Show the flag which caused the warning in parentheses
- Handling of -Werror=...  (I think gfortran currently only handles 
-Werror to turn all warnings into errors)

b) To use with %C error diagnostic, the column at the comment character 
or last nonwhitespace character (whatever comes first) instead of of the 
end of the line.

Tobias