Fix and undeprecate home_dir()
`home_dir()` has been deprecated for 6 years due to using `HOME` env var on Windows.
It's been a long time, and having a perpetually buggy and deprecated function in the standard library is not useful. I propose fixing and undeprecating it.
6 years seems more than long enough to warn users against relying on this function. The change in behavior is minor, and it's more of a bug fix than breakage. The old behavior is unlikely to be useful, and even if anybody actually needed to specifically use the non-standard `HOME` on Windows, they can trivially mitigate this change by reading the env var themselves.
----
Use of `USERPROFILE` is in line with the `home` crate: 37bc5f0232/crates/home/src/windows.rs (L12)
The `home` crate uses `SHGetKnownFolderPath` instead of `GetUserProfileDirectoryW`. AFAIK it doesn't make any difference in practice, because `SHGetKnownFolderPath` merely adds support for more kinds of folders, including virtual (non-filesystem) folders identified by a GUID, but the specific case of [`FOLDERID_Profile`](https://learn.microsoft.com/en-us/windows/win32/shell/knownfolderid#FOLDERID_Profile) is documented as a FIXED folder (a regular filesystem path). Just in case, I've added a note to documentation that the use of `GetUserProfileDirectoryW` can change.
I've used `CURRENT_RUSTC_VERSION` in a doccomment. `replace-version-placeholder` tool seems to perform a simple string replacement, so hopefully it'll get updated.
doc: std::env::var: Returns None for names with '=' or NUL byte
The documentation incorrectly stated that std::env::var could return an error for variable names containing '=' or the NUL byte. Copy the correct documentation from var_os.
var_os was fixed in Commit 8a7a665, Pull Request #109894, which closed Issue #109893.
This documentation was incorrectly added in commit f2c0f292, which replaced a panic in var_os by returning None, but documented the change as "May error if ...".
Reference the specific error values and link to them.
The documentation incorrectly stated that std::env::var could return
an error for variable names containing '=' or the NUL byte. Copy the
correct documentation from var_os.
var_os was fixed in Commit 8a7a665, Pull Request #109894, which
closed Issue #109893.
This documentation was incorrectly added in commit f2c0f292, which
replaced a panic in var_os by returning None, but documented the
change as "May error if ...".
Reference the specific error values and link to them.
Simplify environment variable examples
I’ve found myself visiting the documentation for `std::env::vars` every few months, and every time I do, it is because I want to quickly get a snippet to print out all environment variables :-)
So I think it could be nice to simplify the examples a little to make them self-contained. It is of course a style question if one should import a module a not, but I personally don’t import modules used just once in a code snippet.
Allow calling these functions without `unsafe` blocks in editions up
until 2021, but don't trigger the `unused_unsafe` lint for `unsafe`
blocks containing these functions.
Fixes#27970.
Fixes#90308.
CC #124866.
I’ve found myself visiting the documentation for `std::env::vars`
every few months, and every time I do, it is because I want to quickly
get a snippet to print out all environment variables :-)
So I think it could be nice to simplify the examples a little to make
them self-contained. It is of course a style question if one should
import a module a not, but I personally don’t import modules used just
once in a code snippet.
Increase visibility of `join_path` and `split_paths`
Add some crosslinking among `std::env` pages to make it easier to discover `join_paths` and `split_paths`. Also add aliases to help anyone searching for `PATH`.
The bug report #27970 has existed for 8 years, the actual bug dates back
to Rust pre-1.0. I documented it since it's in the interest of the user
to be aware of it. The note can be removed once #27970 is fixed.
Original `var_os` description said that it _may_ return an error if the value contains `=` or NUL. Let's make no promises on the `None` return value in these situation either, keep it in the [potential mood](https://en.wikipedia.org/wiki/Grammatical_mood#Potential).
Better documentation for env::home_dir()'s broken behaviour
This improves the documentation to say *why* it was deprecated. The reason was because it reads `HOME` on Windows which is meaningless there. Note that the PR that deprecated it stated that returning an empty string if `HOME` is set to an empty string was a problem, however I can find no evidence that this is the case. `cd` handles it fine whereas if `HOME` is unset it gives an explicit `HOME not set` error.
* Original deprecation reason: https://internals.rust-lang.org/t/deprecate-or-break-fix-std-env-home-dir/7315
* Original deprecation PR: https://github.com/rust-lang/rust/pull/51656
See #71684
This improves the documentation to say *why* it was deprecated. The reason was because it reads `HOME` on Windows which is meaningless there. Note that the PR that deprecated it stated that returning an empty string if `HOME` is set to an empty string was a problem, however I can find no evidence that this is the case. `cd` handles it fine whereas if `HOME` is unset it gives an explicit `HOME not set` error.
* Original deprecation reason: https://internals.rust-lang.org/t/deprecate-or-break-fix-std-env-home-dir/7315
* Original deprecation PR: https://github.com/rust-lang/rust/pull/51656
See #71684
