feat: gate "alloc" requirement behind a feature

stabby-abi/Cargo.toml

@@ -28,7 +28,8 @@ workspace = true
 
 [features]
 default = ["std"]
-std = ["alloc-rs"]
+std = ["alloc", "alloc-rs"]
+alloc = []
 alloc-rs = []
 experimental-ctypes = ["stabby-macros/experimental-ctypes"]
 libc = ["dep:libc"]

stabby-abi/src/lib.rs

@@ -31,6 +31,7 @@
 extern crate alloc as alloc_rs;
 
 /// ABI-stable smart pointers and allocated data structures, with support for custom allocators.
+#[cfg(feature = "alloc")]
 pub mod alloc;
 /// Extending [Non-Zero Types](core::num) to enable niches for other values than 0.
 pub mod num;
@@ -144,6 +145,7 @@ mod fatptr;
 /// Closures, but ABI-stable
 pub mod closure;
 /// Futures, but ABI-stable
+#[cfg(feature = "alloc")]
 pub mod future;
 mod stable_impls;
 /// Support for vtables for multi-trait objects

stabby/Cargo.toml

@@ -28,7 +28,8 @@ workspace = true
 
 [features]
 default = ["std"]
-std = ["stabby-abi/std", "alloc-rs"]
+std = ["stabby-abi/std", "alloc", "alloc-rs"]
+alloc = ["stabby-abi/alloc"]
 alloc-rs = ["stabby-abi/alloc-rs"]
 experimental-ctypes = ["stabby-abi/experimental-ctypes"]
 libloading = ["dep:libloading", "std"]

stabby/src/lib.rs

@@ -30,6 +30,7 @@ pub use stabby_abi::{
 
 pub use stabby_abi as abi;
 
+#[cfg(feature = "alloc")]
 pub use stabby_abi::alloc::{self, boxed, collections, string, sync, vec};
 
 pub use stabby_abi::{Dyn, DynRef};
@@ -42,6 +43,7 @@ pub use stabby_abi::tuple;
     stabby_unsafe_wakers = "true",
     deprecated = "Warning! you are using the `stabby/stabby_unsafe_wakers` feature. This could cause UB if you poll a future received from another shared library with mismatching ABI! (this API isn't actually deprecated)"
 )]
+#[cfg(feature = "alloc")]
 pub mod future {
     pub use crate::abi::future::*;
     use crate::boxed::Box;

stabby/src/tests/traits.rs

@@ -17,6 +17,7 @@
 #![cfg_attr(stabby_unsafe_wakers = "true", allow(deprecated))]
 
 pub use crate as stabby;
+#[cfg(feature = "alloc")]
 use stabby::boxed::Box;
 
 #[stabby::stabby(checked)]
@@ -76,6 +77,7 @@ pub trait MyTrait3<Hi: core::ops::Deref> {
     extern "C" fn test2(&mut self);
 }
 
+#[cfg(feature = "alloc")]
 impl MyTrait3<Box<()>> for u8 {
     type A = u8;
     type B = u8;
@@ -88,6 +90,8 @@ impl MyTrait3<Box<()>> for u8 {
     extern "C" fn test(&mut self) {}
     extern "C" fn test2(&mut self) {}
 }
+
+#[cfg(feature = "alloc")]
 impl MyTrait3<Box<()>> for u16 {
     type A = u8;
     type B = u8;
@@ -101,13 +105,15 @@ impl MyTrait3<Box<()>> for u16 {
     extern "C" fn test2(&mut self) {}
 }
 
+#[cfg(feature = "alloc")]
 #[stabby::stabby(checked)]
 pub trait AsyncRead {
     extern "C" fn read<'a>(
         &'a mut self,
         buffer: stabby::slice::SliceMut<'a, u8>,
     ) -> stabby::future::DynFuture<'a, usize>;
 }
+#[cfg(feature = "alloc")]
 impl AsyncRead for stabby::slice::Slice<'_, u8> {
     extern "C" fn read<'a>(
         &'a mut self,
@@ -125,6 +131,7 @@ impl AsyncRead for stabby::slice::Slice<'_, u8> {
     }
 }
 
+#[cfg(feature = "alloc")]
 #[test]
 fn dyn_traits() {
     let boxed = Box::new(6u8);