Respect `DEFAULT-FILENAME' argument of `read-file-name'

[Alexander-Shukaev]

The read-file-name function offers the DEFAULT-FILENAME argument. I would have expected that whenever I run an interactive command that asks to supply a file path and utilizes this argument internally to guess the default (usually displayed in parentheses of the prompt), that file would be selected initially so that I can just tap RET and be done with it. Am I missing some configuration for this to be available or is this not implemented (yet)?

[Alexander-Shukaev]

By the way, when using rgrep, on the second prompt, I see for example:

Search for "..." in files (default *.gz): /.../

and *.gz is already selected by ivy as the default so I can just tap RET to continue. This is good but why the same does not happen for read-file-name?

[Alexander-Shukaev]

Furthermore, this is also somewhat related to #1142, where in case of rgrep there used to be all completion candidate and is not there anymore after one of the upgrades.

[darkfeline]

I experience this bug as well, this other bug provides a workaround that I would be satisfied with: #1209

[darkfeline]

For what it's worth, I've figured out why read-file-name-default with ivy-mode doesn't respect the default.

        (if (and default-filename
                 (string-equal val (if (consp insdef) (car insdef) insdef)))
            (setq val default-filename))
        (setq val (substitute-in-file-name val))

This fragment in read-file-name-default is responsible for replacing the "inserted default" value with the "real" default.

For example, if you're running read-abbrev-file from your home directory, read-file-name-default inserts "~/" into the minibuffer initially. If you press RET, read-file-name-default will then replace the inserted default "~/" with the "read" default "~/.emacs.d/abbrev_defs".

However, ivy-mode makes the completing-read return "/home/bob/" instead of "~/". read-file-name-default doesn't know that this is actually the initial value and thus doesn't swap it out for the "real" default.

This also means that read-abbrev-file will correctly read the default value if you're not inside your home directory, for example if you're in /. completing-read would then return "/" and read-file-name-default would swap it out with the "real" default.

[abo-abo]

@darkfeline Thanks for the info. It will take some work to reconcile things:

1. I don't want ivy-read to replicate all the quirks of completing-read-default.
2. I don't want the "incompatibility" to cause major issues for the users.

If you'd like to help, I'd appreciate a PR in this direction.

[darkfeline]

My instinct would be to define a ivy-read-file-name to replace read-file-name-default when ivy-mode is enabled. The issue here is strictly a mismatch between ivy-completing-read API and the completing-read API that read-file-name-default expects.

However, that API mismatch concerns me. I don't intend on touching ivy-read of course, but perhaps ivy-completing-read should be fixed to comply with completing-read-default.

[abo-abo]

but perhaps ivy-completing-read should be fixed to comply with completing-read-default.

This is the way to go, I think.

[nxtr]

Hey, I took another route with a ivy-immediate-done exit fix, check the PR above

[nxtr]

Another related fix to choose the caller default etc. with an empty input exit.
May be radical with a prefix, but this is an explicit use case and previously not possible to enter empty string, as far as I know.