Document warning 'readline() on unopened filehandle %s'

[jkeenan]

Place it in category: (W unopened).

Signed-off-by: James E Keenan jkeenan@cpan.org

For: #17935

[tonycoz]

This is one of a set of messages generated by report_evil_fh(), which match:

/(opname_with_parens) on (unopened|closed) (socket|filehandle)/

where opname_with_parens is readline() or -s etc.

Technically the message covered by the patch is covered by the:

=item %s() on unopened %s

(W unopened) An I/O operation was attempted on a filehandle that was
never initialized.  You need to do an open(), a sysopen(), or a socket()
call, or call a constructor from the FileHandle package.

entry, but so are several others.

[jkeenan]

This is one of a set of messages generated by report_evil_fh(), which match:

/(opname_with_parens) on (unopened|closed) (socket|filehandle)/

where opname_with_parens is readline() or -s etc.

Technically the message covered by the patch is covered by the:

=item %s() on unopened %s

(W unopened) An I/O operation was attempted on a filehandle that was
never initialized.  You need to do an open(), a sysopen(), or a socket()
call, or call a constructor from the FileHandle package.

entry, but so are several others.

Could we list in this item all the I/O operations which might be represented by the %s there? I believe that if the string readline had been present in this item I would have found it by grepping the document and never have had to file #17935 in the first place.

[tonycoz]

The entry pointed out isn't the easiest to find (though diagnostics finds it:

$ ./perl -Ilib -Mdiagnostics -we 'readline(FOO); readline(FOO)'
readline() on unopened filehandle at -e line 1 (#1)
    (W unopened) An I/O operation was attempted on a filehandle that was
    never initialized.  You need to do an open(), a sysopen(), or a socket()
    call, or call a constructor from the FileHandle package.

)

I think exploding the messages from report_evil_fh() out to separate messages is reasonable (which is your patch does at least for readline).

So is filling out the entry I pointed out to include the ops would work too.

Either works for me.