Add explicit error handling for macro parsing

finchie

Apr 15, 2025, 9:42 AM

7JPOCQEISAIOD7LV4JYBE6NNUWUKKNE73MEPQYTIZ7PP44ZAD2RAC

Dependencies

• [2] 73C6NOJ7 Fix minimal `Localize` implementation on errors
• [3] YZ6PVVQC Add error handling for common unsupported Rust code
• [4] VQBJBFEX Improve error handling for missing Fluent messages
• [5] NO3PDO7P Refactor `fluent_embed` to support structs
• [6] XGRU7WZE Add `expand` feature for proc-macro debugging
• [7] QFPQZR4K Refactor `fluent_embed`
• [8] K3G4HK2J Track Fluent files using `include!`
• [9] O77KA6C4 Create `fluent_embed` crate
• [10] LIO32J4B Fix compiler error when `expand` feature is disabled
• [11] OWXLFLRM Merge `cli_macros` shim into `fluent_embed`
• [12] 4BMW4JJO Add support for deriving items with generics
• [13] F5LG7WEN Emit compilation errors from Fluent source code
• [14] CESJ4CTO Move macro-specific code into `macro_impl` module
• [15] TVRANPYB Ignore errors when setting `miette` panic hook
• [16] NFV26FRQ Improve glob error handling

Change contents

• edit in fluent_embed_derive/src/macro_impl/mod.rs at line 28
  [3.320]

  [4.295]
  + #[error("Failed to parse macro input")]

  + pub enum ParseError {

  + #[error("invalid attribute")]

  + InvalidAttribute(syn::Error),

  + #[error("invalid item")]

  + InvalidDeriveInput(syn::Error),

  + }

  +

  + #[derive(Debug, Error)]
• edit in fluent_embed_derive/src/macro_impl/mod.rs at line 42
  [3.364]

  [4.458]
  + ParseError(#[from] ParseError),
• replacement in fluent_embed_derive/src/macro_impl/mod.rs at line 46
  [4.478]→[4.478:544](∅→∅)
  − attribute: &syn::LitStr,

  − derive_input: &syn::DeriveInput,
  [4.478]

  [4.544]
  + attribute_stream: proc_macro2::TokenStream,

  + derive_input_stream: proc_macro2::TokenStream,
• replacement in fluent_embed_derive/src/macro_impl/mod.rs at line 61
  [4.360]→[4.596:646](∅→∅),[4.596]→[4.596:646](∅→∅)
  − let locales = attribute::locales(attribute)?;
  [4.360]

  [4.0]
  + // Parse the token streams

  + let attribute: syn::LitStr = syn::parse2(attribute_stream)

  + .map_err(|parse_error| ParseError::InvalidAttribute(parse_error))?;

  + let derive_input: syn::DeriveInput = syn::parse2(derive_input_stream)

  + .map_err(|parse_error| ParseError::InvalidDeriveInput(parse_error))?;

  +

  + let locales = attribute::locales(&attribute)?;
• replacement in fluent_embed_derive/src/macro_impl/error.rs at line 4
  [3.1562]→[3.1562:1615](∅→∅)
  − MacroError, UnsupportedError, UnsupportedReason,
  [3.1562]

  [3.1615]
  + MacroError, ParseError, UnsupportedError, UnsupportedReason,
• replacement in fluent_embed_derive/src/macro_impl/error.rs at line 115
  [3.2111]→[3.2111:2207](∅→∅)
  − note = "There must be at least one named field (unit structs are unsupported!)"
  [3.2111]

  [3.2207]
  + note = "There must be at least one named field (unit structs are unsupported!)";

  + }

  + }

  + }

  + }

  +

  + fn parse(error: ParseError, attribute_stream: TokenStream, derive_input_stream: TokenStream) {

  + match error {

  + ParseError::InvalidAttribute(invalid_attribute) => {

  + emit_error! { attribute_stream, invalid_attribute;

  + help = "Expected a path glob, for example {}",

  + r#"#[localize("i18n/**/strings.ftl")]"#;

  + }

  + }

  + ParseError::InvalidDeriveInput(invalid_derive_input) => {

  + emit_error! { derive_input_stream, invalid_derive_input;

  + help = "This macro can only be used on structs or enums";
• replacement in fluent_embed_derive/src/macro_impl/error.rs at line 137
  [4.4667]→[4.2971:3035](∅→∅)
  − pub fn emit(error: MacroError, attribute_stream: TokenStream) {
  [4.4667]

  [4.4797]
  + pub fn emit(error: MacroError, attribute_stream: TokenStream, derive_input_stream: TokenStream) {
• edit in fluent_embed_derive/src/macro_impl/error.rs at line 142
  [3.2294]

  [4.5206]
  + MacroError::ParseError(error) => parse(error, attribute_stream, derive_input_stream),
• replacement in fluent_embed_derive/src/lib.rs at line 2
  [4.75]→[4.75:115](∅→∅)
  − use proc_macro_error::proc_macro_error;
  [4.75]

  [4.4348]
  + use proc_macro_error::{proc_macro_error};
• edit in fluent_embed_derive/src/lib.rs at line 4
  [4.4366]→[4.116:144](∅→∅)
  − use syn::parse_macro_input;
• replacement in fluent_embed_derive/src/lib.rs at line 11
  [4.510]→[4.510:580](∅→∅),[4.580]→[4.5096:5174](∅→∅),[4.5174]→[4.580:700](∅→∅),[4.580]→[4.580:700](∅→∅)
  − let original_item = proc_macro2::TokenStream::from(item.clone());

  − let attribute_stream = proc_macro2::TokenStream::from(attribute.clone());

  − let derive_attribute: syn::LitStr = parse_macro_input!(attribute);

  − let derive_input = parse_macro_input!(item);
  [4.510]

  [4.700]
  + let attribute_stream = proc_macro2::TokenStream::from(attribute);

  + let derive_input_stream = proc_macro2::TokenStream::from(item);
• replacement in fluent_embed_derive/src/lib.rs at line 14
  [4.701]→[4.5175:5242](∅→∅)
  − match macro_impl::localize(&derive_attribute, &derive_input) {
  [4.701]

  [4.5242]
  + match macro_impl::localize(attribute_stream.clone(), derive_input_stream.clone()) {
• replacement in fluent_embed_derive/src/lib.rs at line 19
  [4.3498]→[4.789:819](∅→∅)
  − #derive_input
  [4.3498]

  [4.869]
  + #derive_input_stream
• replacement in fluent_embed_derive/src/lib.rs at line 36
  [4.5545]→[4.5545:5607](∅→∅)
  − macro_impl::error::emit(error, attribute_stream);
  [4.5545]

  [4.906]
  + macro_impl::error::emit(error, attribute_stream, derive_input_stream.clone());
• replacement in fluent_embed_derive/src/lib.rs at line 39
  [2.91]→[4.5701:5766](∅→∅),[4.5701]→[4.5701:5766](∅→∅),[4.5766]→[2.92:574](∅→∅)
  − let ident = derive_input.ident;

  − quote! {

  − #original_item

  −

  − impl<W: ::std::io::Write> ::fluent_embed::Localize<W> for #ident {

  − const CANONICAL_LOCALE: ::fluent_embed::icu_locale::LanguageIdentifier =

  − ::fluent_embed::icu_locale::langid!("en-US");

  −

  − fn available_locales(&self) -> Vec<::fluent_embed::icu_locale::LanguageIdentifier> {

  − unimplemented!("Encountered error in derive macro")

  − }
  [2.91]

  [2.574]
  + match syn::parse2::<syn::DeriveInput>(derive_input_stream.clone()) {

  + Ok(derive_input) => {

  + let ident = derive_input.ident;

  + quote! {

  + #derive_input_stream

  +

  + impl<W: ::std::io::Write> ::fluent_embed::Localize<W> for #ident {

  + const CANONICAL_LOCALE: ::fluent_embed::icu_locale::LanguageIdentifier =

  + ::fluent_embed::icu_locale::langid!("en-US");
• replacement in fluent_embed_derive/src/lib.rs at line 49
  [2.583]→[2.583:851](∅→∅),[2.851]→[4.5847:5923](∅→∅),[4.5847]→[4.5847:5923](∅→∅)
  − fn message_for_locale(

  − &self,

  − writer: &mut W,

  − locale: &::fluent_embed::icu_locale::LanguageIdentifier,

  − ) -> Result<(), ::fluent_embed::LocalizationError> {

  − unimplemented!("Encountered error in derive macro")
  [2.583]

  [4.5923]
  + fn available_locales(&self) -> Vec<::fluent_embed::icu_locale::LanguageIdentifier> {

  + unimplemented!("Encountered error in derive macro")

  + }

  +

  + fn message_for_locale(

  + &self,

  + writer: &mut W,

  + locale: &::fluent_embed::icu_locale::LanguageIdentifier,

  + ) -> Result<(), ::fluent_embed::LocalizationError> {

  + unimplemented!("Encountered error in derive macro")

  + }

  + }
• replacement in fluent_embed_derive/src/lib.rs at line 62
  [4.5945]→[4.5945:5963](∅→∅)
  − }
  [4.5945]

  [4.5963]
  + },

  + // Unable to fail gracefully if the ident is unknown, so just return the original input

  + Err(_) => derive_input_stream,
• edit in fluent_embed_derive/src/lib.rs at line 66
  [4.5977]

  [4.5977]
  +