Backport #2015

macro/src/lib.rs

@@ -102,7 +102,17 @@ fn subxt_inner(args: TokenStream, item_mod: syn::ItemMod) -> Result<TokenStream,
         .map_err(|e| TokenStream::from(e.write_errors()))?;
 
     // Fetch metadata first, because we need it to validate some of the chosen codegen options.
-    let metadata = fetch_metadata(&args)?;
+    let metadata = {
+        let mut metadata = fetch_metadata(&args)?;
+
+        // Run this first to ensure type paths are unique (which may result in 1,2,3 suffixes being added
+        // to type paths), so that when we validate derives/substitutions below, they are allowed for such
+        // types. See <https://github.com/paritytech/subxt/issues/2011>.
+        scale_typegen::utils::ensure_unique_type_paths(metadata.types_mut())
+            .expect("ensure_unique_type_paths should not fail; please report an issue.");
+
+        metadata
+    };
 
     let mut codegen = CodegenBuilder::new();
 
@@ -135,6 +145,7 @@ fn subxt_inner(args: TokenStream, item_mod: syn::ItemMod) -> Result<TokenStream,
             .into_iter()
             .collect(),
     );
+
     for d in args.derive_for_type {
         validate_type_path(&d.path.path, &metadata);
         codegen.add_derives_for_type(d.path, d.derive.into_iter(), d.recursive);