Refactor `Localize` functions to infallibly return `String`

finchie

Jun 4, 2025, 1:23 PM

QJC4IQITOQP65AFLA5CMH2EXHB6B3SOLW2XBV72U5ZQU2KOR2EIAC

Dependencies

• [2] 7X4MEZJU Use Fluent AST when reporting error spans
• [3] MWN4CAOZ Update `LocalizationError` in `fluent_embed`
• [4] U2PHMYPD Return `String` directly instead of writing to buffer in `Localize::localize`
• [5] UN2XEIEU Migrate from `locale_select` to `env_preferences`
• [6] 73C6NOJ7 Fix minimal `Localize` implementation on errors
• [7] MABGENI7 Refactor `fluent_embed_derive` tests
• [8] JUV7C6ET Create initial prototype of `fluent_embed_interaction`
• [9] BAH2JCJP Add progress bar to `fluent_embed_interaction`
• [10] 3NMKD6I5 Refactor `Localize` trait to use `std::io::Write`
• [11] 7JPOCQEI Add explicit error handling for macro parsing
• [12] IRW6JACS Implement `Localize` for `RelativeTime`
• [13] NO3PDO7P Refactor `fluent_embed` to support structs
• [14] LU6IFZFG Remove `std::io::Write` trait bound from `Localize`
• [15] F5LG7WEN Emit compilation errors from Fluent source code
• [16] YZ6PVVQC Add error handling for common unsupported Rust code
• [17] ARB66QTX Add support for unit structs/variants
• [18] HHJDRLLN Create `fluent_embed_runtime` crate
• [19] 7M4UI3TW Update dependencies to latest versions
• [20] 5TEX4MNU Split `fluent_embed` into `group` and `parse` modules
• [21] BFL2Y7GN Add relative timestamps using `jiff` and `icu_relativetime`
• [22] GJMBIJOE Migrate to latest env_preferences version
• [23] C6W7N6N5 Implement `Localize` for `FixedDecimal` and primitive number types
• [24] WWDZWJTR Implement `Localize` for string types
• [25] CESJ4CTO Move macro-specific code into `macro_impl` module
• [*] XGNME3WR Move `Group::derive_enum` to new `crate::parse_macro` module
• [*] O77KA6C4 Create `fluent_embed` crate

Change contents

• replacement in fluent_embed_interaction/src/prompt/select.rs at line 3
  [5.258]→[5.258:307](∅→∅)
  − use fluent_embed::{LocalizationError, Localize};
  [5.258]

  [5.307]
  + use fluent_embed::Localize;
• replacement in fluent_embed_interaction/src/prompt/select.rs at line 17
  [5.534]→[5.534:629](∅→∅)
  − pub fn with_items<L: Localize>(mut self, items: &[L]) -> Result<Self, LocalizationError> {
  [5.534]

  [5.629]
  + pub fn with_items<L: Localize>(mut self, items: &[L]) -> Self {
• replacement in fluent_embed_interaction/src/prompt/select.rs at line 21
  [4.37]→[5.1013:1080](∅→∅),[5.1013]→[5.1013:1080](∅→∅)
  − .collect::<Result<Vec<String>, LocalizationError>>()?;
  [4.37]

  [5.1080]
  + .collect::<Vec<String>>();
• replacement in fluent_embed_interaction/src/prompt/select.rs at line 24
  [5.1125]→[5.1125:1142](∅→∅)
  − Ok(self)
  [5.1125]

  [5.1142]
  + self
• replacement in fluent_embed_interaction/src/prompt/password.rs at line 3
  [5.2163]→[5.2163:2212](∅→∅)
  − use fluent_embed::{LocalizationError, Localize};
  [5.2163]

  [5.2212]
  + use fluent_embed::Localize;
• replacement in fluent_embed_interaction/src/prompt/password.rs at line 26
  [5.2710]→[5.2710:2753](∅→∅),[5.2753]→[4.38:158](∅→∅)
  − ) -> Result<Self, LocalizationError> {

  − let confirmation_text = confirmation.localize()?;

  − let mismatch_error_text = mismatch_error.localize()?;
  [5.2710]

  [5.2895]
  + ) -> Self {

  + let confirmation_text = confirmation.localize();

  + let mismatch_error_text = mismatch_error.localize();
• replacement in fluent_embed_interaction/src/prompt/password.rs at line 35
  [5.3200]→[5.3200:3217](∅→∅)
  − Ok(self)
  [5.3200]

  [5.3217]
  + self
• replacement in fluent_embed_interaction/src/prompt/macros.rs at line 25
  [5.4938]→[5.4938:5087](∅→∅),[5.5087]→[4.159:216](∅→∅)
  − pub fn with_prompt<L: Localize>(

  − mut self,

  − prompt: L,

  − ) -> Result<Self, LocalizationError> {

  − let localized_text = prompt.localize()?;
  [5.4938]

  [5.5244]
  + pub fn with_prompt<L: fluent_embed::Localize>(mut self, prompt: L) -> Self {

  + let localized_text = prompt.localize();
• replacement in fluent_embed_interaction/src/prompt/macros.rs at line 29
  [5.5297]→[5.5297:5322](∅→∅)
  − Ok(self)
  [5.5297]

  [5.5322]
  + self
• replacement in fluent_embed_interaction/src/prompt/macros.rs at line 38
  [5.5441]→[5.5441:5532](∅→∅)
  − pub fn with_validator<L: Localize, V: Fn(&String) -> Result<(), L> + 'static>(
  [5.5441]

  [5.5532]
  + pub fn with_validator<

  + L: fluent_embed::Localize,

  + V: Fn(&String) -> Result<(), L> + 'static,

  + >(
• replacement in fluent_embed_interaction/src/prompt/macros.rs at line 50
  [5.5892]→[4.217:278](∅→∅)
  − Err(message.localize().unwrap())
  [5.5892]

  [5.6188]
  + Err(message.localize())
• replacement in fluent_embed_interaction/src/prompt/input.rs at line 3
  [5.6639]→[5.6639:6688](∅→∅)
  − use fluent_embed::{LocalizationError, Localize};
  [5.6639]

  [5.6688]
  + use fluent_embed::Localize;
• replacement in fluent_embed_interaction/src/prompt/input.rs at line 17
  [5.6941]→[5.6941:7037](∅→∅),[5.7037]→[4.279:329](∅→∅)
  − pub fn with_default<L: Localize>(mut self, default: L) -> Result<Self, LocalizationError> {

  − let localized_text = default.localize()?;
  [5.6941]

  [5.7171]
  + pub fn with_default<L: Localize>(mut self, default: L) -> Self {

  + let localized_text = default.localize();
• replacement in fluent_embed_interaction/src/prompt/input.rs at line 21
  [5.7217]→[5.7217:7234](∅→∅)
  − Ok(self)
  [5.7217]

  [5.7234]
  + self
• edit in fluent_embed_interaction/src/prompt/confirm.rs at line 3
  [5.8289]→[5.8289:8338](∅→∅)
  − use fluent_embed::{LocalizationError, Localize};
• replacement in fluent_embed_interaction/src/progress.rs at line 2
  [5.549]→[5.549:598](∅→∅)
  − use fluent_embed::{LocalizationError, Localize};
  [5.549]

  [5.598]
  + use fluent_embed::Localize;
• replacement in fluent_embed_interaction/src/progress.rs at line 25
  [5.1231]→[5.1231:1327](∅→∅),[5.1327]→[4.330:380](∅→∅)
  − pub fn with_message<L: Localize>(mut self, message: L) -> Result<Self, LocalizationError> {

  − let localized_text = message.localize()?;
  [5.1231]

  [5.1461]
  + pub fn with_message<L: Localize>(mut self, message: L) -> Self {

  + let localized_text = message.localize();
• replacement in fluent_embed_interaction/src/progress.rs at line 29
  [5.1538]→[5.1538:1555](∅→∅)
  − Ok(self)
  [5.1538]

  [5.1555]
  + self
• replacement in fluent_embed_derive/tests/common/mod.rs at line 9
  [5.3249]→[5.3249:3399](∅→∅)
  − let mut buffer = Vec::new();

  − message.message_for_locale(&mut buffer, &locale).unwrap();

  − let result = String::from_utf8(buffer).unwrap();

  −
  [5.3249]

  [5.3399]
  + let result = message.message_for_locale(&locale);
• replacement in fluent_embed_derive/src/macro_impl/mod.rs at line 87
  [5.564]→[5.564:580](∅→∅)
  − }))
  [5.564]

  [5.580]
  + }));
• replacement in fluent_embed_derive/src/macro_impl/mod.rs at line 100
  [5.790]→[5.790:806](∅→∅)
  − }))
  [5.790]

  [5.806]
  + }));
• replacement in fluent_embed_derive/src/macro_impl/mod.rs at line 121
  [5.1022]→[5.1022:1042](∅→∅)
  − }))
  [5.1022]

  [5.1042]
  + }));
• replacement in fluent_embed_derive/src/macro_impl/mod.rs at line 178
  [5.1868]→[5.283:337](∅→∅)
  − fn message_for_locale<W: std::io::Write>(
  [5.1868]

  [5.454]
  + fn message_for_locale(
• edit in fluent_embed_derive/src/macro_impl/mod.rs at line 180
  [5.477]→[5.477:509](∅→∅)
  − writer: &mut W,
• replacement in fluent_embed_derive/src/macro_impl/mod.rs at line 181
  [5.426]→[5.581:646](∅→∅),[5.581]→[5.581:646](∅→∅)
  − ) -> Result<(), ::fluent_embed::LocalizationError> {
  [5.426]

  [5.646]
  + ) -> String {
• edit in fluent_embed_derive/src/macro_impl/derive.rs at line 41
  [5.510]

  [5.903]
  + let mut buffer = String::new();

  +
• replacement in fluent_embed_derive/src/macro_impl/derive.rs at line 53
  [5.768]→[5.768:795](∅→∅)
  − return Ok(());
  [5.768]

  [5.795]
  + return buffer;
• replacement in fluent_embed_derive/src/macro_impl/derive.rs at line 58
  [5.814]→[5.814:829](∅→∅)
  − Ok(())
  [5.814]

  [5.511]
  + buffer
• replacement in fluent_embed_derive/src/macro_impl/derive.rs at line 111
  [5.2575]→[5.2575:2591](∅→∅)
  − }))
  [5.2575]

  [5.2591]
  + }));
• replacement in fluent_embed_derive/src/macro_impl/derive.rs at line 167
  [5.2906]→[5.2906:2926](∅→∅)
  − }))
  [5.2906]

  [5.2926]
  + }));
• replacement in fluent_embed_derive/src/macro_impl/derive.rs at line 184
  [5.3146]→[5.3146:3166](∅→∅)
  − }))
  [5.3146]

  [5.3166]
  + }));
• replacement in fluent_embed_derive/src/lib.rs at line 53
  [5.2886]→[5.406:476](∅→∅)
  − fn message_for_locale<W: std::io::Write>(
  [5.2886]

  [5.2937]
  + fn message_for_locale(
• edit in fluent_embed_derive/src/lib.rs at line 55
  [5.2976]→[5.2976:3024](∅→∅)
  − writer: &mut W,
• replacement in fluent_embed_derive/src/lib.rs at line 56
  [5.3113]→[5.3113:3194](∅→∅)
  − ) -> Result<(), ::fluent_embed::LocalizationError> {
  [5.3113]

  [5.3194]
  + ) -> String {
• replacement in fluent_embed_derive/src/fluent/ast.rs at line 20
  [2.898]→[5.1029:1219](∅→∅),[5.1029]→[5.1029:1219](∅→∅)
  − let byte_string_literal = proc_macro2::Literal::byte_string(value.as_bytes());

  − write_expressions.push(parse_quote!(writer.write_all(#byte_string_literal)?));
  [2.898]

  [5.1219]
  + write_expressions.push(parse_quote!(buffer.push_str(#value)));
• replacement in fluent_embed_derive/src/fluent/ast.rs at line 72
  [5.2973]→[5.1617:1703](∅→∅)
  − parse_quote!(#expression.message_for_locale(writer, locale)?)
  [5.2973]

  [5.3995]
  + parse_quote!(buffer.push_str(&#expression.message_for_locale(locale)))
• replacement in fluent_embed/src/time.rs at line 1
  [5.53]→[5.3724:3766](∅→∅)
  − use crate::{LocalizationError, Localize};
  [5.53]

  [5.21]
  + use crate::Localize;
• replacement in fluent_embed/src/time.rs at line 5
  [5.143]→[5.143:218](∅→∅)
  − options::Numeric, RelativeTimeFormatter, RelativeTimeFormatterOptions,
  [5.143]

  [5.218]
  + RelativeTimeFormatter, RelativeTimeFormatterOptions, options::Numeric,
• replacement in fluent_embed/src/time.rs at line 7
  [5.221]→[5.1523:1569](∅→∅),[5.1569]→[5.296:350](∅→∅),[5.296]→[5.296:350](∅→∅)
  − use icu_locale::{langid, LanguageIdentifier};

  − use jiff::{tz::TimeZone, SpanRound, Timestamp, Unit};
  [5.221]

  [5.350]
  + use icu_locale::{LanguageIdentifier, langid};

  + use jiff::{SpanRound, Timestamp, Unit, tz::TimeZone};
• replacement in fluent_embed/src/time.rs at line 23
  [5.125]→[5.546:592](∅→∅),[5.592]→[5.4149:4266](∅→∅),[5.4149]→[5.4149:4266](∅→∅)
  − fn message_for_locale<W: std::io::Write>(

  − &self,

  − writer: &mut W,

  − locale: &LanguageIdentifier,

  − ) -> Result<(), LocalizationError> {
  [5.125]

  [5.990]
  + fn message_for_locale(&self, locale: &LanguageIdentifier) -> String {
• replacement in fluent_embed/src/time.rs at line 108
  [5.4323]→[5.4323:4324](∅→∅),[5.4324]→[5.2572:2638](∅→∅),[5.2638]→[5.4396:4421](∅→∅),[5.4396]→[5.4396:4421](∅→∅),[5.4421]→[5.249:250](∅→∅),[5.4358]→[5.249:250](∅→∅),[5.250]→[5.4422:4437](∅→∅)
  −

  − writer.write_all(formatted_text.to_string().as_bytes())?;

  − writer.flush()?;

  −

  − Ok(())
  [5.4323]

  [5.394]
  + formatted_text.to_string()
• replacement in fluent_embed/src/string.rs at line 7
  [5.170]→[5.2639:2685](∅→∅)
  − use icu_locale::{langid, LanguageIdentifier};
  [5.170]

  [5.215]
  + use icu_locale::{LanguageIdentifier, langid};
• replacement in fluent_embed/src/string.rs at line 24
  [5.639]→[5.662:708](∅→∅),[5.708]→[5.666:850](∅→∅),[5.666]→[5.666:850](∅→∅)
  − fn message_for_locale<W: std::io::Write>(

  − &self,

  − writer: &mut W,

  − _locale: &LanguageIdentifier,

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

  − writer.write_all(self.as_bytes())?;

  − Ok(())
  [5.639]

  [5.850]
  + fn message_for_locale(&self, _locale: &LanguageIdentifier) -> String {

  + self.to_string()
• edit in fluent_embed/src/lib.rs at line 17
  [5.406]→[5.4438:4502](∅→∅),[5.4561]→[5.4561:4642](∅→∅),[5.4642]→[5.0:100](∅→∅),[5.100]→[3.57:213](∅→∅),[5.100]→[5.4642:4645](∅→∅),[3.213]→[5.4642:4645](∅→∅),[5.4642]→[5.4642:4645](∅→∅)
  − #[derive(thiserror::Error, Debug)]

  − pub enum LocalizationError {

  − #[error("unable to write localized output")]

  − IO(#[from] std::io::Error),

  − #[error("unable to retrieve system locales")]

  − RetrievalError(env_preferences::LocaleError),

  − #[error("unable to parse localized output as a UTF-8 string. This is a bug in `fluent_embed`.")]

  − InvalidOutput(#[from] std::string::FromUtf8Error),

  − }

  −
• replacement in fluent_embed/src/lib.rs at line 22
  [5.4813]→[5.731:777](∅→∅),[5.777]→[5.4840:4956](∅→∅),[5.4840]→[5.4840:4956](∅→∅)
  − fn message_for_locale<W: std::io::Write>(

  − &self,

  − writer: &mut W,

  − locale: &LanguageIdentifier,

  − ) -> Result<(), LocalizationError>;
  [5.4813]

  [5.4956]
  + fn message_for_locale(&self, locale: &LanguageIdentifier) -> String;
• replacement in fluent_embed/src/lib.rs at line 38
  [5.3447]→[4.381:443](∅→∅),[4.443]→[5.321:460](∅→∅),[5.871]→[5.321:460](∅→∅),[5.5031]→[5.321:460](∅→∅)
  − fn localize(&self) -> Result<String, LocalizationError> {

  − let system_locales = env_preferences::get_locales_lossy()

  − .map_err(|error| LocalizationError::RetrievalError(error))?;
  [5.3447]

  [5.460]
  + fn localize(&self) -> String {

  + let system_locales =

  + env_preferences::get_locales_lossy().unwrap_or(vec![Self::CANONICAL_LOCALE.into()]);
• edit in fluent_embed/src/lib.rs at line 60
  [4.445]→[4.445:482](∅→∅)
  − let mut buffer = Vec::new();
• edit in fluent_embed/src/lib.rs at line 61
  [5.3805]→[4.483:508](∅→∅)
  − &mut buffer,
• replacement in fluent_embed/src/lib.rs at line 62
  [5.3914]→[4.509:606](∅→∅)
  − )?;

  −

  − let localized_text = String::from_utf8(buffer)?;

  − Ok(localized_text)
  [5.3914]

  [5.5304]
  + )
• replacement in fluent_embed/src/decimal.rs at line 37
  [5.4036]→[5.941:987](∅→∅)
  − fn message_for_locale<W: std::io::Write>(
  [5.4036]

  [5.4063]
  + fn message_for_locale(
• edit in fluent_embed/src/decimal.rs at line 39
  [5.4078]→[5.4078:4102](∅→∅)
  − writer: &mut W,
• replacement in fluent_embed/src/decimal.rs at line 40
  [5.4139]→[5.4139:4187](∅→∅)
  − ) -> Result<(), crate::LocalizationError> {
  [5.4139]

  [5.4187]
  + ) -> String {
• replacement in fluent_embed/src/decimal.rs at line 42
  [5.4227]→[5.4227:4284](∅→∅)
  − fixed_decimal.message_for_locale(writer, locale)
  [5.4227]

  [5.4284]
  + fixed_decimal.message_for_locale(locale)
• replacement in fluent_embed/src/decimal.rs at line 54
  [5.4621]→[5.1055:1101](∅→∅)
  − fn message_for_locale<W: std::io::Write>(
  [5.4621]

  [5.4648]
  + fn message_for_locale(
• edit in fluent_embed/src/decimal.rs at line 56
  [5.4663]→[5.4663:4687](∅→∅)
  − writer: &mut W,
• replacement in fluent_embed/src/decimal.rs at line 57
  [5.4724]→[5.4724:4772](∅→∅)
  − ) -> Result<(), crate::LocalizationError> {
  [5.4724]

  [5.4824]
  + ) -> String {
• replacement in fluent_embed/src/decimal.rs at line 63
  [5.5030]→[5.5079:5148](∅→∅),[5.5148]→[5.5105:5120](∅→∅),[5.5105]→[5.5105:5120](∅→∅)
  − writer.write_all(formatted_decimal.to_string().as_bytes())?;

  − Ok(())
  [5.5030]

  [5.5120]
  + formatted_decimal.to_string()