Robust crate names (alternative to #61)

.rustfmt.toml

@@ -19,7 +19,7 @@ fn_single_line = false
 where_single_line = false
 imports_indent = "Block"
 imports_layout = "Vertical" # changed
-merge_imports = true # changed
+imports_granularity = "Crate" # changed
 reorder_imports = true
 reorder_modules = true
 reorder_impl_items = false

CHANGELOG.md

@@ -5,6 +5,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+
+### Changed
+
+### Fixed
+- Derive: use known crate name aliases [(#61)](https://github.com/paritytech/scale-info/pull/61)
 
 ## [0.5.0] - 2021-01-27
 ### Added

derive/Cargo.toml

@@ -18,3 +18,5 @@ proc-macro = true
 quote = "1.0"
 syn = { version = "1.0", features = ["derive", "visit", "visit-mut"] }
 proc-macro2 = "1.0"
+proc-macro-crate = "0.1.5"
+once_cell = "1.5"

derive/src/lib.rs

@@ -17,7 +17,6 @@
 extern crate alloc;
 extern crate proc_macro;
 
-mod impl_wrapper;
 mod trait_bounds;
 
 use alloc::{
@@ -28,7 +27,10 @@ use alloc::{
     vec::Vec,
 };
 use proc_macro::TokenStream;
-use proc_macro2::TokenStream as TokenStream2;
+use proc_macro2::{
+    Span,
+    TokenStream as TokenStream2,
+};
 use quote::quote;
 use syn::{
     parse::{
@@ -48,6 +50,7 @@ use syn::{
     ExprLit,
     Field,
     Fields,
+    Ident,
     Lifetime,
     Lit,
     Meta,
@@ -56,6 +59,26 @@ use syn::{
     Variant,
 };
 
+use once_cell::sync::Lazy;
+
+struct IdentHelper(Lazy<String>);
+
+impl quote::ToTokens for IdentHelper {
+    fn to_tokens(&self, tokens: &mut TokenStream2) {
+        Ident::new(&self.0, Span::call_site()).to_tokens(tokens)
+    }
+}
+/// Get the name of the scale-info crate, to be robust against renamed dependencies.
+static SCALE_INFO: IdentHelper = IdentHelper(Lazy::new(|| {
+    proc_macro_crate::crate_name("scale-info")
+        .expect("Missing scale-info dependency. Please add it to your Cargo.toml")
+}));
+/// Get the name of the parity-scale-codec crate, to be robust against renamed dependencies.
+static CODEC: IdentHelper = IdentHelper(Lazy::new(|| {
+    proc_macro_crate::crate_name("parity-scale-codec")
+        .expect("Missing parity-scale-codec dependency. Please add it to your Cargo.toml")
+}));
+
 #[proc_macro_derive(TypeInfo)]
 pub fn type_info(input: TokenStream) -> TokenStream {
     match generate(input.into()) {
@@ -85,7 +108,7 @@ fn generate_type(input: TokenStream2) -> Result<TokenStream2> {
     let generic_type_ids = ast.generics.type_params().map(|ty| {
         let ty_ident = &ty.ident;
         quote! {
-            ::scale_info::meta_type::<#ty_ident>()
+            :: #SCALE_INFO ::meta_type::<#ty_ident>()
         }
     });
 
@@ -97,18 +120,23 @@ fn generate_type(input: TokenStream2) -> Result<TokenStream2> {
     };
     let generic_types = ast.generics.type_params();
     let type_info_impl = quote! {
-        impl <#( #generic_types ),*> ::scale_info::TypeInfo for #ident #ty_generics #where_clause {
+        impl <#( #generic_types ),*> :: #SCALE_INFO ::TypeInfo for #ident #ty_generics #where_clause {
             type Identity = Self;
-            fn type_info() -> ::scale_info::Type {
-                ::scale_info::Type::builder()
-                    .path(::scale_info::Path::new(stringify!(#ident), module_path!()))
-                    .type_params(::scale_info::prelude::vec![ #( #generic_type_ids ),* ])
+            fn type_info() -> :: #SCALE_INFO ::Type {
+                :: #SCALE_INFO ::Type::builder()
+                    .path(:: #SCALE_INFO ::Path::new(stringify!(#ident), module_path!()))
+                    .type_params(:: #SCALE_INFO ::prelude::vec![ #( #generic_type_ids ),* ])
                     .#build_type
             }
         }
     };
 
-    Ok(impl_wrapper::wrap(ident, "TYPE_INFO", type_info_impl))
+    Ok(quote! {
+        #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+        const _: () = {
+            #type_info_impl;
+        };
+    })
 }
 
 type FieldsList = Punctuated<Field, Comma>;
@@ -198,7 +226,7 @@ fn generate_composite_type(data_struct: &DataStruct) -> TokenStream2 {
         }
     };
     quote! {
-        composite(::scale_info::build::Fields::#fields)
+        composite(:: #SCALE_INFO ::build::Fields::#fields)
     }
 }
 
@@ -228,7 +256,7 @@ fn generate_c_like_enum_def(variants: &VariantList) -> TokenStream2 {
     });
     quote! {
         variant(
-            ::scale_info::build::Variants::fieldless()
+            :: #SCALE_INFO ::build::Variants::fieldless()
                 #( #variants )*
         )
     }
@@ -257,7 +285,7 @@ fn generate_variant_type(data_enum: &DataEnum) -> TokenStream2 {
                 quote! {
                     .variant(
                         #v_name,
-                        ::scale_info::build::Fields::named()
+                        :: #SCALE_INFO ::build::Fields::named()
                             #( #fields)*
                     )
                 }
@@ -267,7 +295,7 @@ fn generate_variant_type(data_enum: &DataEnum) -> TokenStream2 {
                 quote! {
                     .variant(
                         #v_name,
-                        ::scale_info::build::Fields::unnamed()
+                        :: #SCALE_INFO ::build::Fields::unnamed()
                             #( #fields)*
                     )
                 }
@@ -281,7 +309,7 @@ fn generate_variant_type(data_enum: &DataEnum) -> TokenStream2 {
     });
     quote! {
         variant(
-            ::scale_info::build::Variants::with_fields()
+            :: #SCALE_INFO ::build::Variants::with_fields()
                 #( #variants)*
         )
     }

derive/src/trait_bounds.rs

@@ -12,6 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use super::{
+    CODEC,
+    SCALE_INFO,
+};
 use alloc::vec::Vec;
 use proc_macro2::Ident;
 use syn::{
@@ -57,21 +61,21 @@ pub fn make_where_clause<'a>(
         if is_compact {
             where_clause
                 .predicates
-                .push(parse_quote!(#ty : ::scale::HasCompact));
+                .push(parse_quote!(#ty : :: #CODEC ::HasCompact));
             where_clause
                 .predicates
-                .push(parse_quote!(<#ty as ::scale::HasCompact>::Type : ::scale_info::TypeInfo + 'static));
+                .push(parse_quote!(<#ty as :: #CODEC ::HasCompact>::Type : :: #SCALE_INFO ::TypeInfo + 'static));
         } else {
             where_clause
                 .predicates
-                .push(parse_quote!(#ty : ::scale_info::TypeInfo + 'static));
+                .push(parse_quote!(#ty : :: #SCALE_INFO ::TypeInfo + 'static));
         }
     });
 
     generics.type_params().into_iter().for_each(|type_param| {
         let ident = type_param.ident.clone();
         let mut bounds = type_param.bounds.clone();
-        bounds.push(parse_quote!(::scale_info::TypeInfo));
+        bounds.push(parse_quote!(:: #SCALE_INFO ::TypeInfo));
         bounds.push(parse_quote!('static));
         where_clause
             .predicates

test_suite/tests/derive.rs

@@ -15,10 +15,7 @@
 #![cfg_attr(not(feature = "std"), no_std)]
 
 use pretty_assertions::assert_eq;
-use scale::{
-    Compact,
-    Encode,
-};
+use scale::Encode;
 use scale_info::{
     build::*,
     prelude::{