feat: allow diverding software tasks with `'static` context (they never return)

3 files changed, 37 insertions, 15 deletions

diff --git a/rtic-macros/src/codegen/software_tasks.rs b/rtic-macros/src/codegen/software_tasks.rs
index 34fc851..71caec0 100644
--- a/rtic-macros/src/codegen/software_tasks.rs
+++ b/rtic-macros/src/codegen/software_tasks.rs
@@ -31,24 +31,38 @@ pub fn codegen(app: &App, analysis: &Analysis) -> TokenStream2 {
             mod_app.push(constructor);
         }
 
-        if !&task.is_extern {
+        if !task.is_extern {
             let context = &task.context;
             let attrs = &task.attrs;
             let cfgs = &task.cfgs;
             let stmts = &task.stmts;
             let inputs = &task.inputs;
 
-            user_tasks.push(quote!(
-                #(#attrs)*
-                #(#cfgs)*
-                #[allow(non_snake_case)]
-                async fn #name<'a>(#context: #name::Context<'a> #(,#inputs)*) {
-                    use rtic::Mutex as _;
-                    use rtic::mutex::prelude::*;
+            user_tasks.push(if task.is_bottom {
+                quote!(
+                    #(#attrs)*
+                    #(#cfgs)*
+                    #[allow(non_snake_case)]
+                    async fn #name(#context: #name::Context<'static> #(,#inputs)*) {
+                        use rtic::Mutex as _;
+                        use rtic::mutex::prelude::*;
 
-                    #(#stmts)*
-                }
-            ));
+                        #(#stmts)*
+                    }
+                )
+            } else {
+                quote!(
+                    #(#attrs)*
+                    #(#cfgs)*
+                    #[allow(non_snake_case)]
+                    async fn #name<'a>(#context: #name::Context<'a> #(,#inputs)*) {
+                        use rtic::Mutex as _;
+                        use rtic::mutex::prelude::*;
+
+                        #(#stmts)*
+                    }
+                )
+            });
         }
 
         root.push(module::codegen(Context::SoftwareTask(name), app, analysis));
diff --git a/rtic-macros/src/syntax/ast.rs b/rtic-macros/src/syntax/ast.rs
index bc892e3..ad73a89 100644
--- a/rtic-macros/src/syntax/ast.rs
+++ b/rtic-macros/src/syntax/ast.rs
@@ -236,6 +236,9 @@ pub struct SoftwareTask {
 
     /// The task is declared externally
     pub is_extern: bool,
+
+    /// The task will never return `Poll::Ready`
+    pub is_bottom: bool,
 }
 
 /// Software task metadata
diff --git a/rtic-macros/src/syntax/parse/software_task.rs b/rtic-macros/src/syntax/parse/software_task.rs
index 769aa65..175769c 100644
--- a/rtic-macros/src/syntax/parse/software_task.rs
+++ b/rtic-macros/src/syntax/parse/software_task.rs
@@ -8,8 +8,9 @@ use crate::syntax::{
 
 impl SoftwareTask {
     pub(crate) fn parse(args: SoftwareTaskArgs, item: ItemFn) -> parse::Result<Self> {
+        let is_bottom = util::type_is_bottom(&item.sig.output);
         let valid_signature = util::check_fn_signature(&item, true)
-            && util::type_is_unit(&item.sig.output)
+            && (util::type_is_unit(&item.sig.output) || is_bottom)
             && item.sig.asyncness.is_some();
 
         let span = item.sig.ident.span();
@@ -28,13 +29,14 @@ impl SoftwareTask {
                     inputs,
                     stmts: item.block.stmts,
                     is_extern: false,
+                    is_bottom,
                 });
             }
         }
 
         Err(parse::Error::new(
             span,
-            format!("this task handler must have type signature `async fn({name}::Context, ..)`"),
+            format!("this task handler must have type signature `async fn({name}::Context, ..)` or `async fn({name}::Context, ..) -> !`"),
         ))
     }
 }
@@ -44,8 +46,10 @@ impl SoftwareTask {
         args: SoftwareTaskArgs,
         item: ForeignItemFn,
     ) -> parse::Result<Self> {
+        let is_bottom = util::type_is_bottom(&item.sig.output);
+
         let valid_signature = util::check_foreign_fn_signature(&item, true)
-            && util::type_is_unit(&item.sig.output)
+            && (util::type_is_unit(&item.sig.output) || is_bottom)
             && item.sig.asyncness.is_some();
 
         let span = item.sig.ident.span();
@@ -64,13 +68,14 @@ impl SoftwareTask {
                     inputs,
                     stmts: Vec::<Stmt>::new(),
                     is_extern: true,
+                    is_bottom,
                 });
             }
         }
 
         Err(parse::Error::new(
             span,
-            format!("this task handler must have type signature `async fn({name}::Context, ..)`"),
+            format!("this task handler must have type signature `async fn({name}::Context, ..)` or `async fn({name}::Context, ..) -> !`"),
         ))
     }
 }