Fix mutex send

rtic-macros/CHANGELOG.md

@@ -7,6 +7,10 @@ For each category, *Added*, *Changed*, *Fixed* add new entries at the top!
 
 ## [Unreleased]
 
+### Fixed
+
+- Generated mutexes for shared resourses no longer implement `Send`. They are meant to be used inside a task locally.
+
 ### Added
 
 - Outer attributes applied to RTIC app module are now forwarded to the generated code.

rtic-macros/src/codegen/shared_resources.rs

@@ -62,9 +62,14 @@ pub fn codegen(app: &App, analysis: &Analysis) -> TokenStream2 {
                 #[allow(non_camel_case_types)]
                 #(#cfgs)*
                 pub struct #shared_name<'a> {
-                    __rtic_internal_p: ::core::marker::PhantomData<&'a ()>,
+                    __rtic_internal_p: ::core::marker::PhantomData<(&'a (), *const u8)>,
                 }
 
+                // Opt out from `Send`.
+                // `#shared_name` is trivially `Sync` because there are no `&self` methods.
+                // See https://doc.rust-lang.org/std/sync/struct.Exclusive.html .
+                unsafe impl<'a> Sync for #shared_name<'a> {}
+
                 #(#cfgs)*
                 impl<'a> #shared_name<'a> {
                     #[inline(always)]