Const functions are stable since 1.61, so no need to feature guard them.

.github/workflows/rust.yml

@@ -22,5 +22,9 @@ jobs:
       run: rustup default ${{ matrix.rust }}
     - name: Build
       run: cargo build --verbose
+    - name: Build without default features
+      run: cargo build --no-default-features --verbose
+    - name: Build with all features
+      run: cargo build --all-features --verbose
     - name: Run tests
       run: cargo test --verbose

Cargo.toml

@@ -6,14 +6,17 @@ homepage = "https://github.com/rcore-os/buddy_system_allocator"
 repository = "https://github.com/rcore-os/buddy_system_allocator"
 keywords = ["allocator", "no_std", "heap"]
 version = "0.9.1"
-authors = ["Jiajie Chen <[email protected]>", "Vinay Chandra Dommeti <[email protected]>", "Andrew Walbran <[email protected]>"]
+authors = [
+  "Jiajie Chen <[email protected]>",
+  "Vinay Chandra Dommeti <[email protected]>",
+  "Andrew Walbran <[email protected]>",
+]
 edition = "2021"
 license = "MIT"
 
 [features]
 default = ["use_spin"]
 use_spin = ["spin"]
-const_fn = []
 
 [dependencies.spin]
 version = "0.9.8"

README.md

@@ -30,8 +30,8 @@ You can also use `FrameAllocator` and `LockedHeapWithRescue`, see their document
 
 ## Features
 
-- **`use_spin`** (default): Provide a `LockedHeap` type that implements the [`GlobalAlloc`] trait by using a spinlock.
-- **`const_fn`** (nightly only): Provide const fn version of `LockedHeapWithRescue::new`.
+- **`use_spin`** (default): Provide a `LockedHeap` type that implements the [`GlobalAlloc`] trait by
+  using a spinlock.
 
 [`GlobalAlloc`]: https://doc.rust-lang.org/nightly/core/alloc/trait.GlobalAlloc.html
 
@@ -41,7 +41,7 @@ Some code comes from phil-opp's linked-list-allocator.
 
 Licensed under MIT License. Thanks phill-opp's linked-list-allocator for inspirations and interface.
 
-[crate-img]:     https://img.shields.io/crates/v/buddy_system_allocator.svg
-[crate]:         https://crates.io/crates/buddy_system_allocator
-[docs-img]:      https://docs.rs/buddy_system_allocator/badge.svg
-[docs]:          https://docs.rs/buddy_system_allocator
+[crate-img]: https://img.shields.io/crates/v/buddy_system_allocator.svg
+[crate]: https://crates.io/crates/buddy_system_allocator
+[docs-img]: https://docs.rs/buddy_system_allocator/badge.svg
+[docs]: https://docs.rs/buddy_system_allocator

src/lib.rs

@@ -1,4 +1,3 @@
-#![cfg_attr(feature = "const_fn", feature(const_mut_refs, const_fn_fn_ptr_basics))]
 #![no_std]
 
 #[cfg(test)]
@@ -290,22 +289,12 @@ pub struct LockedHeapWithRescue<const ORDER: usize> {
 #[cfg(feature = "use_spin")]
 impl<const ORDER: usize> LockedHeapWithRescue<ORDER> {
     /// Creates an empty heap
-    #[cfg(feature = "const_fn")]
     pub const fn new(rescue: fn(&mut Heap<ORDER>, &Layout)) -> Self {
         LockedHeapWithRescue {
             inner: Mutex::new(Heap::<ORDER>::new()),
             rescue,
         }
     }
-
-    /// Creates an empty heap
-    #[cfg(not(feature = "const_fn"))]
-    pub fn new(rescue: fn(&mut Heap<ORDER>, &Layout)) -> Self {
-        LockedHeapWithRescue {
-            inner: Mutex::new(Heap::<ORDER>::new()),
-            rescue,
-        }
-    }
 }
 
 #[cfg(feature = "use_spin")]