feat: try to recover from missing tempdir #22573

Problem:
If vim_tempdir mysteriously goes missing (typically by "antivirus" on
Windows), any plugins using tempname() will be broken for the rest of
the session. #1432 #9833 https://groups.google.com/g/vim_use/c/ef55jNm5czI
Steps:
    mkdir foo
    TMPDIR=./foo nvim
    :echo tempname()
    !rm -r foo
    :echo tempname()
    tempname() still uses the foo path even though it was deleted.

Solution:
- Don't assume that vim_tempdir exists.
- If it goes missing once, retry vim_mktempdir and log (silently) an error.
- If it goes missing again, retry vim_mktempdir and show an error.

Rejected in Vim for performance reasons:
  https://groups.google.com/g/vim_use/c/qgRob9SWDv8/m/FAOFVVcDTv0J
  https://groups.google.com/g/vim_dev/c/cogp-Vye4oo/m/d_SVFXBbnnoJ
But, logging shows that `vim_gettempdir` is not called frequently.

Fixes #1432
Fixes #9833
Fixes #11250
Related: stdpath("run") f50135a32e11c535e1dc3a8e9460c5b4e640ee86

0 files changed, 0 insertions, 0 deletions