Allow renaming storage item prefixes

frame/support/procedural/src/pallet/expand/storage.rs

@@ -24,8 +24,7 @@ use std::collections::HashSet;
 /// prefix_ident is used for the prefix struct to be given to storage as first generic param.
 fn prefix_ident(storage: &StorageDef) -> syn::Ident {
 	let storage_ident = &storage.ident;
-	let ident = storage.prefix();
-	syn::Ident::new(&format!("_GeneratedPrefixForStorage{}", ident), storage_ident.span())
+	syn::Ident::new(&format!("_GeneratedPrefixForStorage{}", storage_ident), storage_ident.span())
 }
 
 /// Check for duplicated storage prefixes. This step is necessary since users can specify an

frame/support/procedural/src/pallet/parse/storage.rs

@@ -67,7 +67,15 @@ impl syn::parse::Parse for PalletStorageAttr {
 			content.parse::<keyword::storage_prefix>()?;
 			content.parse::<syn::Token![=]>()?;
 
-			Ok(Self::StorageName(content.parse::<syn::LitStr>()?, attr_span))
+			let renamed_prefix = content.parse::<syn::LitStr>()?;
+			// Ensure the renamed prefix is a proper Rust identifier
+			syn::parse_str::<syn::Ident>(&renamed_prefix.value())
+				.map_err(|_| {
+					let msg = format!("`{}` is not a valid identifier", renamed_prefix.value());
+					syn::Error::new(renamed_prefix.span(), msg)
+				})?;
+
+			Ok(Self::StorageName(renamed_prefix, attr_span))
 		} else {
 			Err(lookahead.error())
 		}

frame/support/test/tests/pallet_ui/storage_invalid_rename_value.rs

@@ -0,0 +1,18 @@
+#[frame_support::pallet]
+mod pallet {
+	use frame_support::pallet_prelude::Hooks;
+	use frame_system::pallet_prelude::BlockNumberFor;
+
+	#[pallet::config]
+	pub trait Config: frame_system::Config {}
+
+	#[pallet::pallet]
+	pub struct Pallet<T>(core::marker::PhantomData<T>);
+
+	#[pallet::storage]
+	#[pallet::storage_prefix = "pub"]
+	type Foo<T> = StorageValue<_, u8>;
+}
+
+fn main() {
+}

frame/support/test/tests/pallet_ui/storage_invalid_rename_value.stderr

@@ -0,0 +1,5 @@
+error: `pub` is not a valid identifier
+  --> $DIR/storage_invalid_rename_value.rs:13:29
+   |
+13 |     #[pallet::storage_prefix = "pub"]
+   |                                ^^^^^