substitute-in-file-name and "$"

[Michael Albinus]

Hello,

In file name operations, the character "$" is masked by "$$" in order
to pass substitute-in-file-name handling. Unfortunately, this works
only onces, because after the first call of substitute-in-file-name,
"$$" reduces to "$".

There is no rule that substitute-in-file-name must be called only
once. For example, if you use partial-completion-mode, the filename in
the minibuffer will be passed through substitute-in-file-name by
PC-do-completion. Later file name operations which call internally
substitute-in-file-name will fail therefore.

This happens permanently in tramp-smb.el, where "$" is a part of file
names of default shares.

As workaround, I've written a defadvice for PC-do-completion which
requotes "$", but this is far from being perfect. Better would be a
general solution.

What I'ld like to know: Is it a general rule, that
substitute-in-file-name can be called only once for a given file name?
Then it should be documented in the Elisp manual, and it is a bug in
PC-do-completion. Or is it a more general design problem?

Best regards, Michael.