entry/exception/interrupt: forward static mut attributes

this is required to implement safe interfaces to things like writable
Flash (e.g. EEPROM emulation) which require the `#[link_section]` attribute.

Author: japaric

cortex-m-rt/macros/src/lib.rs

@@ -113,13 +113,15 @@ pub fn entry(args: TokenStream, input: TokenStream) -> TokenStream {
     let vars = statics
         .into_iter()
         .map(|var| {
+            let attrs = var.attrs;
             let ident = var.ident;
             let ty = var.ty;
             let expr = var.expr;
 
             quote!(
                 #[allow(non_snake_case)]
                 let #ident: &'static mut #ty = unsafe {
+                    #(#attrs)*
                     static mut #ident: #ty = #expr;
 
                     &mut #ident
@@ -398,13 +400,15 @@ pub fn exception(args: TokenStream, input: TokenStream) -> TokenStream {
             let vars = statics
                 .into_iter()
                 .map(|var| {
+                    let attrs = var.attrs;
                     let ident = var.ident;
                     let ty = var.ty;
                     let expr = var.expr;
 
                     quote!(
                         #[allow(non_snake_case)]
                         let #ident: &mut #ty = unsafe {
+                            #(#attrs)*
                             static mut #ident: #ty = #expr;
 
                             &mut #ident
@@ -539,13 +543,15 @@ pub fn interrupt(args: TokenStream, input: TokenStream) -> TokenStream {
     let vars = statics
         .into_iter()
         .map(|var| {
+            let attrs = var.attrs;
             let ident = var.ident;
             let ty = var.ty;
             let expr = var.expr;
 
             quote!(
                 #[allow(non_snake_case)]
                 let #ident: &mut #ty = unsafe {
+                    #(#attrs)*
                     static mut #ident: #ty = #expr;
 
                     &mut #ident