Use static_assertions instead of trybuild.

Cargo.toml

@@ -52,6 +52,7 @@ stable_deref_trait = { version = "1", default-features = false }
 
 [dev-dependencies]
 ufmt = "0.2"
+static_assertions = "1.1.0"
 
 [package.metadata.docs.rs]
 features = ["ufmt", "serde", "defmt-03", "mpmc_large", "portable-atomic-critical-section"]

cfail/ui/not-send.rs

@@ -1,24 +0,0 @@
-//! Collections of non-`Send`-able things are *not* `Send`
-
-use core::marker::PhantomData;
-
-use heapless::{
-    spsc::{Consumer, Producer, Queue},
-    HistoryBuffer, Vec,
-};
-
-type NotSend = PhantomData<*const ()>;
-
-fn is_send<T>()
-where
-    T: Send,
-{
-}
-
-fn main() {
-    is_send::<Consumer<NotSend, 4>>();
-    is_send::<Producer<NotSend, 4>>();
-    is_send::<Queue<NotSend, 4>>();
-    is_send::<Vec<NotSend, 4>>();
-    is_send::<HistoryBuffer<NotSend, 4>>();
-}

cfail/ui/not-send.stderr

@@ -1,159 +0,0 @@
-error[E0277]: `*const ()` cannot be sent between threads safely
-  --> ui/not-send.rs:19:15
-   |
-19 |     is_send::<Consumer<NotSend, 4>>();
-   |               ^^^^^^^^^^^^^^^^^^^^ `*const ()` cannot be sent between threads safely
-   |
-   = help: within `PhantomData<*const ()>`, the trait `Send` is not implemented for `*const ()`
-note: required because it appears within the type `PhantomData<*const ()>`
-  --> $RUST/core/src/marker.rs
-   |
-   | pub struct PhantomData<T: ?Sized>;
-   |            ^^^^^^^^^^^
-   = note: required for `Consumer<'_, PhantomData<*const ()>, 4>` to implement `Send`
-note: required by a bound in `is_send`
-  --> ui/not-send.rs:14:8
-   |
-12 | fn is_send<T>()
-   |    ------- required by a bound in this function
-13 | where
-14 |     T: Send,
-   |        ^^^^ required by this bound in `is_send`
-
-error[E0277]: `*const ()` cannot be sent between threads safely
-  --> ui/not-send.rs:20:15
-   |
-20 |     is_send::<Producer<NotSend, 4>>();
-   |               ^^^^^^^^^^^^^^^^^^^^ `*const ()` cannot be sent between threads safely
-   |
-   = help: within `PhantomData<*const ()>`, the trait `Send` is not implemented for `*const ()`
-note: required because it appears within the type `PhantomData<*const ()>`
-  --> $RUST/core/src/marker.rs
-   |
-   | pub struct PhantomData<T: ?Sized>;
-   |            ^^^^^^^^^^^
-   = note: required for `Producer<'_, PhantomData<*const ()>, 4>` to implement `Send`
-note: required by a bound in `is_send`
-  --> ui/not-send.rs:14:8
-   |
-12 | fn is_send<T>()
-   |    ------- required by a bound in this function
-13 | where
-14 |     T: Send,
-   |        ^^^^ required by this bound in `is_send`
-
-error[E0277]: `*const ()` cannot be sent between threads safely
-  --> ui/not-send.rs:21:15
-   |
-21 |     is_send::<Queue<NotSend, 4>>();
-   |               ^^^^^^^^^^^^^^^^^ `*const ()` cannot be sent between threads safely
-   |
-   = help: within `Queue<PhantomData<*const ()>, 4>`, the trait `Send` is not implemented for `*const ()`
-note: required because it appears within the type `PhantomData<*const ()>`
-  --> $RUST/core/src/marker.rs
-   |
-   | pub struct PhantomData<T: ?Sized>;
-   |            ^^^^^^^^^^^
-note: required because it appears within the type `ManuallyDrop<PhantomData<*const ()>>`
-  --> $RUST/core/src/mem/manually_drop.rs
-   |
-   | pub struct ManuallyDrop<T: ?Sized> {
-   |            ^^^^^^^^^^^^
-note: required because it appears within the type `MaybeUninit<PhantomData<*const ()>>`
-  --> $RUST/core/src/mem/maybe_uninit.rs
-   |
-   | pub union MaybeUninit<T> {
-   |           ^^^^^^^^^^^
-note: required because it appears within the type `UnsafeCell<MaybeUninit<PhantomData<*const ()>>>`
-  --> $RUST/core/src/cell.rs
-   |
-   | pub struct UnsafeCell<T: ?Sized> {
-   |            ^^^^^^^^^^
-   = note: required because it appears within the type `[UnsafeCell<MaybeUninit<PhantomData<*const ()>>>; 4]`
-note: required because it appears within the type `Queue<PhantomData<*const ()>, 4>`
-  --> $HEAPLESS/src/spsc.rs
-   |
-   | pub struct Queue<T, const N: usize> {
-   |            ^^^^^
-note: required by a bound in `is_send`
-  --> ui/not-send.rs:14:8
-   |
-12 | fn is_send<T>()
-   |    ------- required by a bound in this function
-13 | where
-14 |     T: Send,
-   |        ^^^^ required by this bound in `is_send`
-
-error[E0277]: `*const ()` cannot be sent between threads safely
-  --> ui/not-send.rs:22:15
-   |
-22 |     is_send::<Vec<NotSend, 4>>();
-   |               ^^^^^^^^^^^^^^^ `*const ()` cannot be sent between threads safely
-   |
-   = help: within `heapless::vec::VecInner<[MaybeUninit<PhantomData<*const ()>>; 4]>`, the trait `Send` is not implemented for `*const ()`
-note: required because it appears within the type `PhantomData<*const ()>`
-  --> $RUST/core/src/marker.rs
-   |
-   | pub struct PhantomData<T: ?Sized>;
-   |            ^^^^^^^^^^^
-note: required because it appears within the type `ManuallyDrop<PhantomData<*const ()>>`
-  --> $RUST/core/src/mem/manually_drop.rs
-   |
-   | pub struct ManuallyDrop<T: ?Sized> {
-   |            ^^^^^^^^^^^^
-note: required because it appears within the type `MaybeUninit<PhantomData<*const ()>>`
-  --> $RUST/core/src/mem/maybe_uninit.rs
-   |
-   | pub union MaybeUninit<T> {
-   |           ^^^^^^^^^^^
-   = note: required because it appears within the type `[MaybeUninit<PhantomData<*const ()>>; 4]`
-note: required because it appears within the type `heapless::vec::VecInner<[MaybeUninit<PhantomData<*const ()>>; 4]>`
-  --> $HEAPLESS/src/vec.rs
-   |
-   | pub struct VecInner<B: ?Sized + VecDrop> {
-   |            ^^^^^^^^
-note: required by a bound in `is_send`
-  --> ui/not-send.rs:14:8
-   |
-12 | fn is_send<T>()
-   |    ------- required by a bound in this function
-13 | where
-14 |     T: Send,
-   |        ^^^^ required by this bound in `is_send`
-
-error[E0277]: `*const ()` cannot be sent between threads safely
-  --> ui/not-send.rs:23:15
-   |
-23 |     is_send::<HistoryBuffer<NotSend, 4>>();
-   |               ^^^^^^^^^^^^^^^^^^^^^^^^^ `*const ()` cannot be sent between threads safely
-   |
-   = help: within `HistoryBuffer<PhantomData<*const ()>, 4>`, the trait `Send` is not implemented for `*const ()`
-note: required because it appears within the type `PhantomData<*const ()>`
-  --> $RUST/core/src/marker.rs
-   |
-   | pub struct PhantomData<T: ?Sized>;
-   |            ^^^^^^^^^^^
-note: required because it appears within the type `ManuallyDrop<PhantomData<*const ()>>`
-  --> $RUST/core/src/mem/manually_drop.rs
-   |
-   | pub struct ManuallyDrop<T: ?Sized> {
-   |            ^^^^^^^^^^^^
-note: required because it appears within the type `MaybeUninit<PhantomData<*const ()>>`
-  --> $RUST/core/src/mem/maybe_uninit.rs
-   |
-   | pub union MaybeUninit<T> {
-   |           ^^^^^^^^^^^
-   = note: required because it appears within the type `[MaybeUninit<PhantomData<*const ()>>; 4]`
-note: required because it appears within the type `HistoryBuffer<PhantomData<*const ()>, 4>`
-  --> $HEAPLESS/src/histbuf.rs
-   |
-   | pub struct HistoryBuffer<T, const N: usize> {
-   |            ^^^^^^^^^^^^^
-note: required by a bound in `is_send`
-  --> ui/not-send.rs:14:8
-   |
-12 | fn is_send<T>()
-   |    ------- required by a bound in this function
-13 | where
-14 |     T: Send,
-   |        ^^^^ required by this bound in `is_send`

src/deque.rs

@@ -745,7 +745,12 @@ where
 
 #[cfg(test)]
 mod tests {
-    use crate::Deque;
+    use static_assertions::assert_not_impl_any;
+
+    use super::Deque;
+
+    // Ensure a `Deque` containing `!Send` values stays `!Send` itself.
+    assert_not_impl_any!(Deque<*const (), 4>: Send);
 
     #[test]
     fn static_new() {

src/histbuf.rs

@@ -433,10 +433,16 @@ impl<'a, T, const N: usize> Iterator for OldestOrdered<'a, T, N> {
 
 #[cfg(test)]
 mod tests {
-    use crate::HistoryBuffer;
     use core::fmt::Debug;
     use core::sync::atomic::{AtomicUsize, Ordering};
 
+    use static_assertions::assert_not_impl_any;
+
+    use super::HistoryBuffer;
+
+    // Ensure a `HistoryBuffer` containing `!Send` values stays `!Send` itself.
+    assert_not_impl_any!(HistoryBuffer<*const (), 4>: Send);
+
     #[test]
     fn new() {
         let x: HistoryBuffer<u8, 4> = HistoryBuffer::new_with(1);

src/indexmap.rs

@@ -1262,10 +1262,17 @@ where
 
 #[cfg(test)]
 mod tests {
-    use crate::{indexmap::Entry, FnvIndexMap};
-
     use core::mem;
 
+    use static_assertions::assert_not_impl_any;
+
+    use super::{BuildHasherDefault, Entry, FnvIndexMap, IndexMap};
+
+    // Ensure a `IndexMap` containing `!Send` keys stays `!Send` itself.
+    assert_not_impl_any!(IndexMap<*const (), (), BuildHasherDefault<()>, 4>: Send);
+    // Ensure a `IndexMap` containing `!Send` values stays `!Send` itself.
+    assert_not_impl_any!(IndexMap<(), *const (), BuildHasherDefault<()>, 4>: Send);
+
     #[test]
     fn size() {
         const CAP: usize = 4;

src/indexset.rs

@@ -1,11 +1,13 @@
-use crate::indexmap::{self, IndexMap};
 use core::{
     borrow::Borrow,
     fmt,
     hash::{BuildHasher, Hash},
 };
+
 use hash32::{BuildHasherDefault, FnvHasher};
 
+use crate::indexmap::{self, IndexMap};
+
 /// An [`IndexSet`] using the default FNV hasher.
 ///
 /// A list of all Methods and Traits available for `FnvIndexSet` can be found in
@@ -659,3 +661,13 @@ where
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use static_assertions::assert_not_impl_any;
+
+    use super::{BuildHasherDefault, IndexSet};
+
+    // Ensure a `IndexSet` containing `!Send` values stays `!Send` itself.
+    assert_not_impl_any!(IndexSet<*const (), BuildHasherDefault<()>, 4>: Send);
+}

src/linear_map.rs

@@ -1,6 +1,7 @@
-use crate::Vec;
 use core::{borrow::Borrow, fmt, mem, ops, slice};
 
+use crate::Vec;
+
 /// A fixed capacity map/dictionary that performs lookups via linear search.
 ///
 /// Note that as this map doesn't use hashing so most operations are *O*(n) instead of *O*(1).
@@ -492,7 +493,14 @@ where
 
 #[cfg(test)]
 mod test {
-    use crate::LinearMap;
+    use static_assertions::assert_not_impl_any;
+
+    use super::LinearMap;
+
+    // Ensure a `LinearMap` containing `!Send` keys stays `!Send` itself.
+    assert_not_impl_any!(LinearMap<*const (), (), 4>: Send);
+    // Ensure a `LinearMap` containing `!Send` values stays `!Send` itself.
+    assert_not_impl_any!(LinearMap<(), *const (), 4>: Send);
 
     #[test]
     fn static_new() {

src/mpmc.rs

@@ -294,7 +294,12 @@ unsafe fn enqueue<T>(
 
 #[cfg(test)]
 mod tests {
-    use super::Q2;
+    use static_assertions::assert_not_impl_any;
+
+    use super::{MpMcQueue, Q2};
+
+    // Ensure a `MpMcQueue` containing `!Send` values stays `!Send` itself.
+    assert_not_impl_any!(MpMcQueue<*const (), 4>: Send);
 
     #[test]
     fn sanity() {

src/sorted_linked_list.rs

@@ -743,8 +743,13 @@ where
 
 #[cfg(test)]
 mod tests {
+    use static_assertions::assert_not_impl_any;
+
     use super::*;
 
+    // Ensure a `SortedLinkedList` containing `!Send` values stays `!Send` itself.
+    assert_not_impl_any!(SortedLinkedList<*const (), LinkedIndexU8, (), 4>: Send);
+
     #[test]
     fn const_new() {
         static mut _V1: SortedLinkedList<u32, LinkedIndexU8, Max, 100> = SortedLinkedList::new_u8();

src/spsc.rs

@@ -632,7 +632,18 @@ impl<'a, T, const N: usize> Producer<'a, T, N> {
 mod tests {
     use std::hash::{Hash, Hasher};
 
-    use crate::spsc::Queue;
+    use super::{Consumer, Producer, Queue};
+
+    use static_assertions::assert_not_impl_any;
+
+    // Ensure a `Queue` containing `!Send` values stays `!Send` itself.
+    assert_not_impl_any!(Queue<*const (), 4>: Send);
+
+    // Ensure a `Producer` containing `!Send` values stays `!Send` itself.
+    assert_not_impl_any!(Producer<*const (), 4>: Send);
+
+    // Ensure a `Consumer` containing `!Send` values stays `!Send` itself.
+    assert_not_impl_any!(Consumer<*const (), 4>: Send);
 
     #[test]
     fn full() {

src/vec.rs

@@ -1,7 +1,6 @@
 use core::{
     cmp::Ordering,
-    fmt, hash,
+    fmt, hash, mem,
-    mem,
     mem::{ManuallyDrop, MaybeUninit},
     ops, ptr, slice,
 };
@@ -2079,9 +2078,15 @@ where
 
 #[cfg(test)]
 mod tests {
-    use crate::Vec;
     use core::fmt::Write;
 
+    use static_assertions::assert_not_impl_any;
+
+    use crate::Vec;
+
+    // Ensure a `Vec` containing `!Send` values stays `!Send` itself.
+    assert_not_impl_any!(Vec<*const (), 4>: Send);
+
     #[test]
     fn static_new() {
         static mut _V: Vec<i32, 4> = Vec::new();