rtic-macros: forward attributes applied to app module

Instead of ignoring additional attributes applied to the app
module, we can forward them to the generated code.

rtic-macros/src/codegen.rs

@@ -44,12 +44,14 @@ pub fn app(app: &App, analysis: &Analysis) -> TokenStream2 {
     let user_code = &app.user_code;
     let name = &app.name;
     let device = &app.args.device;
+    let attribute_metas = &app.attribute_metas;
 
     let rt_err = util::rt_err_ident();
     let async_limit = bindings::async_prio_limit(app, analysis);
 
     quote!(
         /// The RTIC application module
+        #(#[#attribute_metas])*
         pub mod #name {
             /// Always include the device crate which contains the vector table
             use #device as #rt_err;

rtic-macros/src/syntax/ast.rs

@@ -1,6 +1,6 @@
 //! Abstract Syntax Tree
 
-use syn::{Attribute, Expr, Ident, Item, ItemUse, Pat, PatType, Path, Stmt, Type};
+use syn::{Attribute, Expr, Ident, Item, ItemUse, Meta, Pat, PatType, Path, Stmt, Type};
 
 use crate::syntax::{backend::BackendArgs, Map};
 
@@ -11,6 +11,9 @@ pub struct App {
     /// The arguments to the `#[app]` attribute
     pub args: AppArgs,
 
+    /// All attributes applied to the `#[app]` module (meta only)
+    pub attribute_metas: Vec<Meta>,
+
     /// The name of the `const` item on which the `#[app]` attribute has been placed
     pub name: Ident,
 

rtic-macros/src/syntax/parse.rs

@@ -11,7 +11,7 @@ use syn::{
     braced,
     parse::{self, Parse, ParseStream, Parser},
     token::Brace,
-    Ident, Item, LitInt, Token,
+    Attribute, Ident, Item, LitInt, Meta, Token,
 };
 
 use crate::syntax::{
@@ -28,6 +28,7 @@ pub fn app(args: TokenStream2, input: TokenStream2) -> parse::Result<App> {
 }
 
 pub(crate) struct Input {
+    pub attribute_metas: Vec<Meta>,
     _mod_token: Token![mod],
     pub ident: Ident,
     _brace_token: Brace,
@@ -48,12 +49,18 @@ impl Parse for Input {
 
         let content;
 
+        let mut attributes = input.call(Attribute::parse_outer)?;
         let _mod_token = input.parse()?;
         let ident = input.parse()?;
         let _brace_token = braced!(content in input);
+        let inner_attributes = content.call(Attribute::parse_inner)?;
         let items = content.call(parse_items)?;
 
+        attributes.extend(inner_attributes);
+        let attribute_metas = attributes.into_iter().map(|a| a.meta).collect();
+
         Ok(Input {
+            attribute_metas,
             _mod_token,
             ident,
             _brace_token,

rtic-macros/src/syntax/parse/app.rs

@@ -531,6 +531,7 @@ impl App {
         }
 
         Ok(App {
+            attribute_metas: input.attribute_metas,
             args,
             name: input.ident,
             init,

rtic/ui/inner_attribute.rs

@@ -0,0 +1,21 @@
+#![no_main]
+#![deny(unfulfilled_lint_expectations)]
+
+#[rtic::app(device = lm3s6965)]
+mod app {
+    #![expect(while_true)]
+    
+    #[shared]
+    struct Shared {
+        #[unsafe(link_section = ".custom_section")]
+        foo: (),
+    }
+
+    #[local]
+    struct Local {}
+
+    #[init]
+    fn init(_cx: init::Context) -> (Shared, Local) {
+        (Shared { foo: () }, Local {})
+    }
+}

rtic/ui/inner_attribute.stderr

@@ -0,0 +1,11 @@
+error: this lint expectation is unfulfilled
+ --> ui/inner_attribute.rs:6:15
+  |
+6 |     #![expect(while_true)]
+  |               ^^^^^^^^^^
+  |
+note: the lint level is defined here
+ --> ui/inner_attribute.rs:2:9
+  |
+2 | #![deny(unfulfilled_lint_expectations)]
+  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

rtic/ui/outer_attribute.rs

@@ -0,0 +1,20 @@
+#![no_main]
+#![deny(unfulfilled_lint_expectations)]
+
+#[rtic::app(device = lm3s6965)]
+#[expect(while_true)]
+mod app {
+    #[shared]
+    struct Shared {
+        #[unsafe(link_section = ".custom_section")]
+        foo: (),
+    }
+
+    #[local]
+    struct Local {}
+
+    #[init]
+    fn init(_cx: init::Context) -> (Shared, Local) {
+        (Shared { foo: () }, Local {})
+    }
+}

rtic/ui/outer_attribute.stderr

@@ -0,0 +1,11 @@
+error: this lint expectation is unfulfilled
+ --> ui/outer_attribute.rs:5:10
+  |
+5 | #[expect(while_true)]
+  |          ^^^^^^^^^^
+  |
+note: the lint level is defined here
+ --> ui/outer_attribute.rs:2:9
+  |
+2 | #![deny(unfulfilled_lint_expectations)]
+  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^