@@ -37,6 +37,7 @@ mod storage_alias;
3737mod transactional;
3838mod tt_macro;
3939
40+ use frame_support_procedural_tools:: generate_crate_access_2018;
4041use macro_magic:: import_tokens_attr;
4142use proc_macro:: TokenStream ;
4243use quote:: { quote, ToTokens } ;
@@ -952,28 +953,6 @@ pub fn storage_alias(_: TokenStream, input: TokenStream) -> TokenStream {
952953///
953954/// # Advanced Usage
954955///
955- /// ## Importing & Re-Exporting
956- ///
957- /// Since `#[derive_impl(..)]` is a
958- /// [`macro_magic`](https://docs.rs/macro_magic/latest/macro_magic/)-based attribute macro, special
959- /// care must be taken when importing and re-exporting it. Glob imports will work properly, such as
960- /// `use frame_support::*` to bring `derive_impl` into scope, however any other use statements
961- /// involving `derive_impl` should have
962- /// [`#[macro_magic::use_attr]`](https://docs.rs/macro_magic/latest/macro_magic/attr.use_attr.html)
963- /// attached or your use statement will fail to fully bring the macro into scope.
964- ///
965- /// This brings `derive_impl` into scope in the current context:
966- /// ```ignore
967- /// #[use_attr]
968- /// use frame_support::derive_impl;
969- /// ```
970- ///
971- /// This brings `derive_impl` into scope and publicly re-exports it from the current context:
972- /// ```ignore
973- /// #[use_attr]
974- /// pub use frame_support::derive_impl;
975- /// ```
976- ///
977956/// ## Expansion
978957///
979958/// The `#[derive_impl(default_impl_path as disambiguation_path)]` attribute will expand to the
@@ -987,7 +966,18 @@ pub fn storage_alias(_: TokenStream, input: TokenStream) -> TokenStream {
987966/// Items that lack a `syn::Ident` for whatever reason are first checked to see if they exist,
988967/// verbatim, in the local/destination trait before they are copied over, so you should not need to
989968/// worry about collisions between identical unnamed items.
990- #[ import_tokens_attr( frame_support:: macro_magic) ]
969+ #[ import_tokens_attr {
970+ format!(
971+ "{}::macro_magic" ,
972+ match generate_crate_access_2018( "frame-support" ) {
973+ Ok ( path) => Ok ( path) ,
974+ Err ( _) => generate_crate_access_2018( "frame" ) ,
975+ }
976+ . expect( "Failed to find either `frame-support` or `frame` in `Cargo.toml` dependencies." )
977+ . to_token_stream( )
978+ . to_string( )
979+ )
980+ } ]
991981#[ with_custom_parsing( derive_impl:: DeriveImplAttrArgs ) ]
992982#[ proc_macro_attribute]
993983pub fn derive_impl ( attrs : TokenStream , input : TokenStream ) -> TokenStream {
@@ -1034,8 +1024,41 @@ pub fn no_default(_: TokenStream, _: TokenStream) -> TokenStream {
10341024/// type MaxConsumers = frame_support::traits::ConstU32<16>;
10351025/// }
10361026/// ```
1027+ ///
1028+ /// ## Advanced Usage
1029+ ///
10371030/// This macro acts as a thin wrapper around macro_magic's `#[export_tokens]`. See the docs
1038- /// [here](https://docs.rs/macro_magic/latest/macro_magic/attr.export_tokens.html) for more info.
1031+ /// [here](https://docs.rs/macro_magic/latest/macro_magic/attr.export_tokens.html) for more
1032+ /// info.
1033+ ///
1034+ /// There are some caveats when applying a `use` statement to bring a
1035+ /// `#[register_default_impl]` item into scope. If you have a `#[register_default_impl]`
1036+ /// defined in `my_crate::submodule::MyItem`, it is currently not sufficient to do something
1037+ /// like:
1038+ ///
1039+ /// ```ignore
1040+ /// use my_crate::submodule::MyItem;
1041+ /// #[derive_impl(MyItem as Whatever)]
1042+ /// ```
1043+ ///
1044+ /// This will fail with a mysterious message about `__export_tokens_tt_my_item` not being
1045+ /// defined.
1046+ ///
1047+ /// You can, however, do any of the following:
1048+ /// ```ignore
1049+ /// // partial path works
1050+ /// use my_crate::submodule;
1051+ /// #[derive_impl(submodule::MyItem as Whatever)]
1052+ /// ```
1053+ /// ```ignore
1054+ /// // full path works
1055+ /// #[derive_impl(my_crate::submodule::MyItem as Whatever)]
1056+ /// ```
1057+ /// ```ignore
1058+ /// // wild-cards work
1059+ /// use my_crate::submodule::*;
1060+ /// #[derive_impl(MyItem as Whatever)]
1061+ /// ```
10391062#[ proc_macro_attribute]
10401063pub fn register_default_impl ( attrs : TokenStream , tokens : TokenStream ) -> TokenStream {
10411064 // ensure this is a impl statement
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