Add support for bumpalo

Author: Amanieu

Cargo.toml

@@ -24,6 +24,9 @@ core = { version = "1.0.0", optional = true, package = "rustc-std-workspace-core
 compiler_builtins = { version = "0.1.2", optional = true }
 alloc = { version = "1.0.0", optional = true, package = "rustc-std-workspace-alloc" }
 
+# Optional support for bumpalo
+bumpalo = { version = "3.4.0", optional = true }
+
 [dev-dependencies]
 lazy_static = "1.4"
 rand = { version = "0.7.3", features = ["small_rng"] }

README.md

@@ -105,6 +105,7 @@ This crate has the following Cargo features:
 - `raw`: Enables access to the experimental and unsafe `RawTable` API.
 - `inline-more`: Adds inline hints to most functions, improving run-time performance at the cost
   of compilation time. (enabled by default)
+- `bumpalo`: Allows `Bump` and `&Bump` to be used as allocators.
 - `ahash`: Compiles with ahash as default hasher. (enabled by default)
 - `ahash-compile-time-rng`: Activates the `compile-time-rng` feature of ahash. For targets with no random number generator
 this pre-generates seeds at compile time and embeds them as constants. See [aHash's documentation](https://github.com/tkaitchuck/aHash#flags) (disabled by default)

src/raw/alloc.rs

@@ -47,4 +47,20 @@ mod inner {
     pub fn do_alloc<A: Allocator>(alloc: &A, layout: Layout) -> Result<NonNull<u8>, ()> {
         alloc.allocate(layout).map_err(|_| ())
     }
+
+    #[cfg(feature = "bumpalo")]
+    unsafe impl Allocator for bumpalo::Bump {
+        fn allocate(&self, layout: Layout) -> Result<NonNull<u8>, AllocError> {
+            self.try_alloc_layout(layout).map_err(|_| AllocError)
+        }
+        unsafe fn deallocate(&self, _ptr: NonNull<u8>, _layout: Layout) {}
+    }
+
+    #[cfg(feature = "bumpalo")]
+    unsafe impl Allocator for &'_ bumpalo::Bump {
+        fn allocate(&self, layout: Layout) -> Result<NonNull<u8>, AllocError> {
+            self.try_alloc_layout(layout).map_err(|_| AllocError)
+        }
+        unsafe fn deallocate(&self, _ptr: NonNull<u8>, _layout: Layout) {}
+    }
 }