Use autocfg instead of a feature for try_exists

Per comments on #48 this moves from gating `try_exists` behind a feature to using `autocfg`. This is a build time library that inspects the current runtime and adds flags to the build so if a user is building with Rust 1.63 or higher then this feature will be enabled.

.github/workflows/ci.yml

@@ -54,9 +54,9 @@ jobs:
  args: --tests -- -D warnings
  if: matrix.rust_version == 'stable'
 
- - name: cargo check --features "io_safety path_try_exists"
+ - name: cargo check --features "io_safety"
  uses: actions-rs/cargo@v1
  with:
  command: clippy
- args: --features "io_safety path_try_exists"
+ args: --features "io_safety"
  if: matrix.rust_version == 'stable'

CHANGELOG.md

@@ -1,6 +1,6 @@
 # fs-err Changelog
 
-* Add `fs_err_try_exists` to `std::path::Path` via extension trait. This feature requires Rust 1.63 or later and is gated behind the `path_try_exists` feature flag. ([#48](https://github.com/andrewhickman/fs-err/pull/48))
+* Add `fs_err_try_exists` to `std::path::Path` via extension trait. This feature requires Rust 1.63 or later. ([#48](https://github.com/andrewhickman/fs-err/pull/48))
 
 ## 2.9.0
 

Cargo.toml

@@ -14,12 +14,13 @@ exclude = [".github", ".gitignore", "README.tpl"]
 [dependencies]
 tokio = { version = "1.21", optional = true, default_features = false, features = ["fs"] }
 
+[build-dependencies]
+autocfg = "1"
+
 [dev-dependencies]
 serde_json = "1.0.64"
 
 [features]
-# Adds `fs_err_try_exists` to `Path`, introduced in Rust 1.6.3
-path_try_exists = []
 # Adds I/O safety traits, introduced in Rust 1.63
 io_safety = []
 

build.rs

@@ -0,0 +1,7 @@
+extern crate autocfg;
+
+fn main() {
+ let ac = autocfg::new();
+ // Allows `#[cfg(rustc_1_63)]` to be used in code
+ ac.emit_rustc_version(1, 63);
+}

src/path.rs

@@ -11,7 +11,7 @@ use std::path::{Path, PathBuf};
 // Because no one else can implement it, we can add methods backwards-compatibly.
 pub trait PathExt: crate::Sealed {
  /// Wrapper for [`Path::try_exists`](https://doc.rust-lang.org/std/path/struct.Path.html#method.try_exists).
- #[cfg(feature = "path_try_exists")]
+ #[cfg(rustc_1_63)]
  fn fs_err_try_exists(&self) -> io::Result<bool>;
  /// Wrapper for [`crate::metadata`].
  fn fs_err_metadata(&self) -> io::Result<fs::Metadata>;
@@ -26,7 +26,7 @@ pub trait PathExt: crate::Sealed {
 }
 
 impl PathExt for Path {
- #[cfg(feature = "path_try_exists")]
+ #[cfg(rustc_1_63)]
  fn fs_err_try_exists(&self) -> io::Result<bool> {
  self.try_exists()
  .map_err(|source| Error::build(source, ErrorKind::FileExists, self))