Constify methods that "dereference" raw pointers

* AsciiStr::as_str()
* AsciiStr::as_bytes()

Author: tormol

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [1.57.0, stable, beta, nightly]
+        rust: [1.58.1, stable, beta, nightly]
     steps:
       - uses: actions/checkout@v2
       - uses: hecrj/setup-rust-action@v1

README.md

@@ -35,7 +35,7 @@ ascii = { version = "1.0", default-features = false, features = ["alloc"] }
 
 ## Minimum supported Rust version
 
-The minimum Rust version for 1.1.\* releases is 1.57.0.
+The minimum Rust version for 1.1.\* releases is 1.58.0.
 Later 1.y.0 releases might require newer Rust versions, but the three most
 recent stable releases at the time of publishing will always be supported.  
 For example this means that if the current stable Rust version is 1.70 when

src/ascii_str.rs

@@ -48,15 +48,15 @@ impl AsciiStr {
     /// Converts `&self` to a `&str` slice.
     #[inline]
     #[must_use]
-    pub fn as_str(&self) -> &str {
+    pub const fn as_str(&self) -> &str {
         // SAFETY: All variants of `AsciiChar` are valid bytes for a `str`.
         unsafe { &*(self as *const AsciiStr as *const str) }
     }
 
     /// Converts `&self` into a byte slice.
     #[inline]
     #[must_use]
-    pub fn as_bytes(&self) -> &[u8] {
+    pub const fn as_bytes(&self) -> &[u8] {
         // SAFETY: All variants of `AsciiChar` are valid `u8`, given they're `repr(u8)`.
         unsafe { &*(self as *const AsciiStr as *const [u8]) }
     }

src/lib.rs

@@ -15,7 +15,7 @@
 //!
 //! # Minimum supported Rust version
 //!
-//! The minimum Rust version for 1.1.\* releases is 1.57.0.
+//! The minimum Rust version for 1.1.\* releases is 1.58.0.
 //! Later 1.y.0 releases might require newer Rust versions, but the three most
 //! recent stable releases at the time of publishing will always be supported.  
 //! For example this means that if the current stable Rust version is 1.70 when