riot-rs-macros: make thread macro support both riot-rs and `riot-…

…rs-threads` as deps (#303)

src/riot-rs-macros/src/thread.rs

@@ -39,6 +39,8 @@ pub fn thread(args: TokenStream, item: TokenStream) -> TokenStream {
 
     use quote::quote;
 
+    use crate::utils::find_crate;
+
     let mut attrs = Attributes::default();
     let thread_parser = syn::meta::parser(|meta| attrs.parse(&meta));
     syn::parse_macro_input!(args with thread_parser);
@@ -62,13 +64,19 @@ pub fn thread(args: TokenStream, item: TokenStream) -> TokenStream {
         priority,
     } = Parameters::from(attrs);
 
-    let riot_rs_crate = utils::riot_rs_crate();
+    let thread_crate = {
+        match (find_crate("riot-rs"), find_crate("riot-rs-threads")) {
+            (Some(riot_rs), _) => quote! { #riot_rs::thread },
+            (None, Some(riot_rs_threads)) => quote! { #riot_rs_threads },
+            _ => panic!(r#"neither "riot-rs" nor "riot-rs-threads" found in dependencies!"#),
+        }
+    };
 
     let expanded = quote! {
         #no_mangle_attr
         #thread_function
 
-        #riot_rs_crate::thread::autostart_thread!(#fn_name, stacksize = #stack_size, priority = #priority);
+        #thread_crate::autostart_thread!(#fn_name, stacksize = #stack_size, priority = #priority);
     };
 
     TokenStream::from(expanded)

src/riot-rs-macros/src/utils.rs

@@ -10,16 +10,24 @@ const RIOT_RS_CRATE_NAME: &str = "riot-rs";
 /// this function is called.
 /// - Panics if `riot-rs` is used as a dependency of itself.
 pub fn riot_rs_crate() -> syn::Ident {
-    let riot_rs_crate = proc_macro_crate::crate_name(RIOT_RS_CRATE_NAME)
-        .unwrap_or_else(|_| panic!("{RIOT_RS_CRATE_NAME} should be present in `Cargo.toml`"));
+    find_crate(RIOT_RS_CRATE_NAME)
+        .unwrap_or_else(|| panic!("{RIOT_RS_CRATE_NAME} should be present in `Cargo.toml`"))
+}
 
-    match riot_rs_crate {
-        proc_macro_crate::FoundCrate::Itself => {
-            panic!(
-                "{} cannot be used as a dependency of itself",
-                env!("CARGO_CRATE_NAME"),
-            );
+/// Returns a [`struct@syn::Ident`] identifying the `name` dependency (or `None`).
+///
+/// # Panics
+///
+/// - Panics if `name` is used as a dependency of itself.
+pub fn find_crate(name: &str) -> Option<syn::Ident> {
+    if let Ok(crate_) = proc_macro_crate::crate_name(name) {
+        match crate_ {
+            proc_macro_crate::FoundCrate::Itself => {
+                panic!("{name} cannot be used as a dependency of itself");
+            }
+            proc_macro_crate::FoundCrate::Name(crate_) => Some(format_ident!("{crate_}")),
         }
-        proc_macro_crate::FoundCrate::Name(riot_rs_crate) => format_ident!("{riot_rs_crate}"),
+    } else {
+        None
     }
 }