Allow pallet error enum variants to contain fields (#10242)

* Allow pallet errors to contain at most one field * Update docs on pallet::error * Reword documentation * cargo fmt * Introduce CompactPalletError trait and require #[pallet::error] fields to implement them * cargo fmt * Do not assume tuple variants * Add CompactPalletError derive macro * Check for error type compactness in construct_runtime * cargo fmt * Derive CompactPalletError instead of implementing it directly during macro expansion * Implement CompactPalletError on OptionBool instead of Option<bool> * Check for type idents instead of variant ident * Add doc comments for ErrorCompactnessTest * Add an trait implementation of ErrorCompactnessTest for () * Convert the error field of DispatchError to a 4-element byte array * Add static check for pallet error size * Rename to MAX_PALLET_ERROR_ENCODED_SIZE * Remove ErrorCompactnessTest trait * Remove check_compactness * Return only the most significant byte when constructing a custom InvalidTransaction * Rename CompactPalletError to PalletError * Use counter to generate unique idents for assert macros * Make declarative pallet macros compile with pallet error size checks * Remove unused doc comment * Try and fix build errors * Fix build errors * Add macro_use for some test modules * Test fix * Fix compilation errors * Remove unneeded #[macro_use] * Resolve import ambiguity * Make path to pallet Error enum more specific * Fix test expectation * Disambiguate imports * Fix test expectations * Revert appending pallet module name to path * Rename bags_list::list::Error to BagError * Fixes * Fixes * Fixes * Fix test expectations * Fix test expectation * Add more implementations for PalletError * Lift the 1-field requirement for nested pallet errors * Fix UI test expectation * Remove PalletError impl for OptionBool * Use saturating operations * cargo fmt * Delete obsolete test * Fix test expectation * Try and use assert macro in const context * Pull out the pallet error size check macro * Fix UI test for const assertion * cargo fmt * Apply clippy suggestion * Fix doc comment * Docs for create_tt_return_macro * Ensure TryInto is imported in earlier Rust editions * Apply suggestions from code review Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com> * Fix up comments and names * Implement PalletError for Never * cargo fmt * Don't compile example code * Bump API version for block builder * Factor in codec attributes while derving PalletError * Rename module and fix unit test * Add missing attribute * Check API version and convert ApplyExtrinsicResult accordingly * Rename BagError to ListError Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com> * Use codec crate re-exported from frame support * Add links to types mentioned in doc comments Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com> * cargo fmt * cargo fmt * Re-add attribute for hidden docs Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com> Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
2026-06-20 11:41:02 +00:00 · 2022-03-24 09:11:14 +01:00
parent 5c9f23af13
commit 208be86934
38 changed files with 1263 additions and 241 deletions
@@ -15,20 +15,48 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.

-use crate::pallet::Def;
+use crate::{
+	pallet::{parse::error::VariantField, Def},
+	COUNTER,
+};
 use frame_support_procedural_tools::get_doc_literals;
+use syn::spanned::Spanned;

 ///
 /// * impl various trait on Error
 pub fn expand_error(def: &mut Def) -> proc_macro2::TokenStream {
-	let error = if let Some(error) = &def.error { error } else { return Default::default() };
+	let count = COUNTER.with(|counter| counter.borrow_mut().inc());
+	let error_token_unique_id =
+		syn::Ident::new(&format!("__tt_error_token_{}", count), def.item.span());

-	let error_ident = &error.error;
 	let frame_support = &def.frame_support;
 	let frame_system = &def.frame_system;
+	let config_where_clause = &def.config.where_clause;
+
+	let error = if let Some(error) = &def.error {
+		error
+	} else {
+		return quote::quote! {
+			#[macro_export]
+			#[doc(hidden)]
+			macro_rules! #error_token_unique_id {
+				{
+					$caller:tt
+					frame_support = [{ $($frame_support:ident)::* }]
+				} => {
+					$($frame_support::)*tt_return! {
+						$caller
+					}
+				};
+			}
+
+			pub use #error_token_unique_id as tt_error_token;
+		}
+	};
+
+	let error_ident = &error.error;
 	let type_impl_gen = &def.type_impl_generics(error.attr_span);
 	let type_use_gen = &def.type_use_generics(error.attr_span);
-	let config_where_clause = &def.config.where_clause;

 	let phantom_variant: syn::Variant = syn::parse_quote!(
 		#[doc(hidden)]
@@ -39,13 +67,19 @@ pub fn expand_error(def: &mut Def) -> proc_macro2::TokenStream {
 		)
 	);

-	let as_u8_matches = error.variants.iter().enumerate().map(
-		|(i, (variant, _))| quote::quote_spanned!(error.attr_span => Self::#variant => #i as u8,),
-	);
-
-	let as_str_matches = error.variants.iter().map(|(variant, _)| {
-		let variant_str = format!("{}", variant);
-		quote::quote_spanned!(error.attr_span => Self::#variant => #variant_str,)
+	let as_str_matches = error.variants.iter().map(|(variant, field_ty, _)| {
+		let variant_str = variant.to_string();
+		match field_ty {
+			Some(VariantField { is_named: true }) => {
+				quote::quote_spanned!(error.attr_span => Self::#variant { .. } => #variant_str,)
+			},
+			Some(VariantField { is_named: false }) => {
+				quote::quote_spanned!(error.attr_span => Self::#variant(..) => #variant_str,)
+			},
+			None => {
+				quote::quote_spanned!(error.attr_span => Self::#variant => #variant_str,)
+			},
+		}
 	});

 	let error_item = {
@@ -62,9 +96,14 @@ pub fn expand_error(def: &mut Def) -> proc_macro2::TokenStream {
 	let capture_docs = if cfg!(feature = "no-metadata-docs") { "never" } else { "always" };

 	// derive TypeInfo for error metadata
-	error_item
-		.attrs
-		.push(syn::parse_quote!( #[derive(#frame_support::scale_info::TypeInfo)] ));
+	error_item.attrs.push(syn::parse_quote! {
+		#[derive(
+			#frame_support::codec::Encode,
+			#frame_support::codec::Decode,
+			#frame_support::scale_info::TypeInfo,
+			#frame_support::PalletError,
+		)]
+	});
 	error_item.attrs.push(syn::parse_quote!(
 		#[scale_info(skip_type_params(#type_use_gen), capture_docs = #capture_docs)]
 	));
@@ -90,14 +129,6 @@ pub fn expand_error(def: &mut Def) -> proc_macro2::TokenStream {
 		}

 		impl<#type_impl_gen> #error_ident<#type_use_gen> #config_where_clause {
-			#[doc(hidden)]
-			pub fn as_u8(&self) -> u8 {
-				match &self {
-					Self::__Ignore(_, _) => unreachable!("`__Ignore` can never be constructed"),
-					#( #as_u8_matches )*
-				}
-			}
-
 			#[doc(hidden)]
 			pub fn as_str(&self) -> &'static str {
 				match &self {
@@ -120,18 +151,37 @@ pub fn expand_error(def: &mut Def) -> proc_macro2::TokenStream {
 			#config_where_clause
 		{
 			fn from(err: #error_ident<#type_use_gen>) -> Self {
+				use #frame_support::codec::Encode;
 				let index = <
 					<T as #frame_system::Config>::PalletInfo
 					as #frame_support::traits::PalletInfo
 				>::index::<Pallet<#type_use_gen>>()
 					.expect("Every active module has an index in the runtime; qed") as u8;
+				let mut encoded = err.encode();
+				encoded.resize(#frame_support::MAX_MODULE_ERROR_ENCODED_SIZE, 0);

 				#frame_support::sp_runtime::DispatchError::Module(#frame_support::sp_runtime::ModuleError {
 					index,
-					error: err.as_u8(),
+					error: core::convert::TryInto::try_into(encoded).expect("encoded error is resized to be equal to the maximum encoded error size; qed"),
 					message: Some(err.as_str()),
 				})
 			}
 		}
+
+		#[macro_export]
+		#[doc(hidden)]
+		macro_rules! #error_token_unique_id {
+			{
+				$caller:tt
+				frame_support = [{ $($frame_support:ident)::* }]
+			} => {
+				$($frame_support::)*tt_return! {
+					$caller
+					error = [{ #error_ident }]
+				}
+			};
+		}
+
+		pub use #error_token_unique_id as tt_error_token;
 	)
 }
@@ -18,20 +18,26 @@
 use super::helper;
 use frame_support_procedural_tools::get_doc_literals;
 use quote::ToTokens;
-use syn::spanned::Spanned;
+use syn::{spanned::Spanned, Fields};

 /// List of additional token to be used for parsing.
 mod keyword {
 	syn::custom_keyword!(Error);
 }

+/// Records information about the error enum variants.
+pub struct VariantField {
+	/// Whether or not the field is named, i.e. whether it is a tuple variant or struct variant.
+	pub is_named: bool,
+}
+
 /// This checks error declaration as a enum declaration with only variants without fields nor
 /// discriminant.
 pub struct ErrorDef {
 	/// The index of error item in pallet module.
 	pub index: usize,
-	/// Variants ident and doc literals (ordered as declaration order)
-	pub variants: Vec<(syn::Ident, Vec<syn::Lit>)>,
+	/// Variants ident, optional field and doc literals (ordered as declaration order)
+	pub variants: Vec<(syn::Ident, Option<VariantField>, Vec<syn::Lit>)>,
 	/// A set of usage of instance, must be check for consistency with trait.
 	pub instances: Vec<helper::InstanceUsage>,
 	/// The keyword error used (contains span).
@@ -70,18 +76,19 @@ impl ErrorDef {
 			.variants
 			.iter()
 			.map(|variant| {
-				if !matches!(variant.fields, syn::Fields::Unit) {
-					let msg = "Invalid pallet::error, unexpected fields, must be `Unit`";
-					return Err(syn::Error::new(variant.fields.span(), msg))
-				}
+				let field_ty = match &variant.fields {
+					Fields::Unit => None,
+					Fields::Named(_) => Some(VariantField { is_named: true }),
+					Fields::Unnamed(_) => Some(VariantField { is_named: false }),
+				};
 				if variant.discriminant.is_some() {
-					let msg = "Invalid pallet::error, unexpected discriminant, discriminant \
+					let msg = "Invalid pallet::error, unexpected discriminant, discriminants \
 						are not supported";
 					let span = variant.discriminant.as_ref().unwrap().0.span();
 					return Err(syn::Error::new(span, msg))
 				}

-				Ok((variant.ident.clone(), get_doc_literals(&variant.attrs)))
+				Ok((variant.ident.clone(), field_ty, get_doc_literals(&variant.attrs)))
 			})
 			.collect::<Result<_, _>>()?;