Problem:
vim.uv.os_setenv gets "stuck" per-key. #32550
Caused by the internal `envmap` cache. #7920
:echo $FOO <-- prints nothing
:lua vim.uv.os_setenv("FOO", "bar")
:echo $FOO <-- prints bar (as expected)
:lua vim.uv.os_setenv("FOO", "fizz")
:echo $FOO <-- prints bar, still (not expected. Should be "fizz")
:lua vim.uv.os_unsetenv("FOO")
:echo $FOO <-- prints bar, still (not expected. Should be nothing)
:lua vim.uv.os_setenv("FOO", "buzz")
:echo $FOO <-- prints bar, still (not expected. Should be "buzz")
Solution:
- Remove the `envmap` cache.
- Callers to `os_getenv` must free the result.
- Update all call-sites.
- Introduce `os_getenv_noalloc`.
- Extend `os_env_exists()` the `nonempty` parameter.