`error[E0433]: failed to resolve: could not find 'mount' in 'backend'`

[polarathene]

TL;DR: I think this was meant to be removed from lib.rs with this Sep 2024 PR, but was missed?

rustix/src/lib.rs

Lines 296 to 300 in ec96121

	// Temporarily provide some mount functions for use in the fs module for
	// backwards compatibility.
	#[cfg(linux_kernel)]
	#[cfg(all(feature = "fs", not(feature = "mount")))]
	pub(crate) mod mount;

---

I wanted to try the recently implemented select method, and realized it's not available in a release yet, so I switched to git for rustix:

rustix = { git = "https://github.com/bytecodealliance/rustix.git", features = ["procfs", "event"] }

Compiling fails however due to various errors about the backend lacking the mount module (All errors are from src/mount/ files referring to the backend mount module):

error[E0433]: failed to resolve: could not find `mount` in `backend`
  --> /root/.cargo/git/checkouts/rustix-8fafe793515fde97/ec96121/src/mount/fsopen.rs:3:21
   |
3  | use crate::backend::mount::types::{
   |                     ^^^^^ could not find `mount` in `backend`
   |
note: found an item that was configured out
  --> /root/.cargo/git/checkouts/rustix-8fafe793515fde97/ec96121/src/backend/linux_raw/mod.rs:49:16
   |
49 | pub(crate) mod mount;
   |                ^^^^^
note: the item is gated behind the `mount` feature
  --> /root/.cargo/git/checkouts/rustix-8fafe793515fde97/ec96121/src/backend/linux_raw/mod.rs:48:7
   |
48 | #[cfg(feature = "mount")]
   |       ^^^^^^^^^^^^^^^^^

The fs feature is implicitly enabled from procfs feature (so lib.rs then enables the mount module):

rustix/Cargo.toml

Lines 161 to 162 in ec96121

	# Enable this to enable `rustix::io::proc_self_*` (on Linux) and `ttyname`.
	procfs = ["once_cell", "itoa", "fs"]

Context

• Earlier PR: Factor out a new top-level mount module. #763
• Recent Sep 2024 PR (removed for backends, but not lib.rs): Remove deprecated features. #1154

NOTE: This comment line was removed, not sure if that context was intended to be dropped along with the deprecation comment above it.

Config attributes for mod mount:

rustix/src/lib.rs

Lines 217 to 220 in ec96121

	#[cfg(linux_kernel)]
	#[cfg(feature = "mount")]
	#[cfg_attr(docsrs, doc(cfg(feature = "mount")))]
	pub mod mount;

rustix/src/lib.rs

Lines 296 to 300 in ec96121

	// Temporarily provide some mount functions for use in the fs module for
	// backwards compatibility.
	#[cfg(linux_kernel)]
	#[cfg(all(feature = "fs", not(feature = "mount")))]
	pub(crate) mod mount;

rustix/src/lib.rs

Lines 176 to 180 in ec96121

	// Pick the backend implementation to use.
	#[cfg_attr(libc, path = "backend/libc/mod.rs")]
	#[cfg_attr(linux_raw, path = "backend/linux_raw/mod.rs")]
	#[cfg_attr(wasi, path = "backend/wasi/mod.rs")]
	mod backend;

rustix/src/backend/linux_raw/mod.rs

Lines 48 to 49 in ec96121

	#[cfg(feature = "mount")]
	pub(crate) mod mount;

[sunfishcode]

Thanks for tracking this down!