52 lines
22 KiB
Plaintext
52 lines
22 KiB
Plaintext
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rust
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yW #rustc 1.93.0 (254b59607 2026-01-19)Á“õ…·fÊvŠ ¦%g- -c48c539199cbc88bÁ ³VOÐêùÿ²?ÑL¼�§Ì± -a7a40eb546f9e2b0Á á\ƒ¦è3$|]åŒ[IÚ tæ -14b12edc9f8cd90bÁ ë&Gf·Ã ¬ëñq:¤»b -bb76018b1173caf6Áà 9m Ù„«ÐÒþá•c‘B; -030c5b0bba47cc8fÁ rustc_std_workspace_coreÁÛ¹þÓ7>H%¸ÚÉ’› -4b81d37a5530864dÁ üÃùs<Uß7VyóHr#QÏ -c66cc7807550ce25Á miniz_oxideÁõFÖˆÚ™ª‹"ÞXzLVª -62cbc7af83058505Á adler2Á—wÉD‘嵯�|6¨%Œ
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+ -2f171dd2394b4b62Á hashbrownÁ,ïcV¼¨ø¢:Ê\'È߈ -9571ba9e0f6c7a90Á rustc_std_workspace_allocÁ%¥Èxµù·¼5Ä3Bœ -aac566ad65903fa4Á
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std_detectÁMmáýZ^9õ Îà§e˜÷e -2edb296e590136d8Á rustc_demangleÁ@¼§VÉNb˜æ¨fHÌ+V3 -53b132e4a2fa6e26Á cfg_ifÁfÝv�.Å"ÒÜuPp¹ˆ¶ -f76b385d7d4d7f3eÁ addr2lineÁÕú-WiúQVÓ¬
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µT§�5 -fe25100bd73e48e4Á gimliÁ¹xLáÇí÷‘o ±Ñ8£Å -265ba9e6e4f70b3fÁ objectÁÔ³ÝzÓÿ¶ò°öM›¼òü` -9ae0d1f8ea52a318Á memchrÁRÎ÷׎™te~QÓ¿ØC\Ò -0bff3c8e8f4e489eÁ –©H�tGNÏ ·ˆ!á -d69228d077d46f36Á thiserror_implÁ•>ùÕ ãdø ;,iV½N. -153d8d97a97ffd5fÁ provideÁ<ãD error_generic_member_accessÁÜÁD A ThiserrorProvideÁ„‹G ‹Ü¾F “ aserrorÁ
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>é,?ä+ T * ;$A“ ”ýç6 È @ü žG ü š — [![github]](https://github.com/dtolnay/thiserror) [![crates-io]](https://crates.io/crates/thiserror) [![docs-rs]](https://docs.rs/thiserror)Á › Ë üŸj g [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=githubÁ üŠn k [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rustÁ üùm j [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rsÁ ç Ë Dë <br>Á ô Ë üøN K This library provides a convenient derive macro for the standard library'sÁ üÇ [`std::error::Error`] trait.Á è Ë üìO L [`std::error::Error`]: https://doc.rust-lang.org/std/error/trait.Error.htmlÁ ¼ Ë DÀ ø É Ë lÍ
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# ExampleÁ Û Ë \ß ```rustÁ ”ë # use std::io;Á Ìþ use thiserror::Error;Á ˜ Ë Üœ #[derive(Error, Debug)]Á ì¸ pub enum DataStoreError {Á üÖ+ ( #[error("data store disconnected")]Á ü‚& # Disconnect(#[from] io::Error),Á ü©; 8 #[error("the data for key `{0}` is not available")]Á Ôå Redaction(String),Á ü€K H #[error("invalid header (expected {expected:?}, found {found:?})")]Á ¼Ì InvalidHeader {Á ìä expected: String,Á Ô‚ found: String,Á T� },Á ü¨ , ) #[error("unknown data store error")]Á „Õ
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# DetailsÁ “
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Ë ü—
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L I - Thiserror deliberately does not appear in your public API. You get theÁ üä
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O L same thing as if you had written an implementation of `std::error::Error`Á ü´ N K by hand, and switching from handwritten impls to thiserror or vice versaÁ üƒ is not a breaking change.Á £ Ë ü§ L I - Errors may be enums, structs with named fields, tuple structs, or unitÁ tô structs.Á ƒ
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Ë ü‡
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A > - A `Display` impl is generated for your error if you provideÁ üÉ
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O L `#[error("...")]` messages on the struct or each variant of your enum, asÁ ü™! shown above in the example.Á » Ë ü¿O L The messages support a shorthand for interpolating fields from the error.Á � Ë ü“D A - `#[error("{var}")]` ⟶ `write!("{}", self.var)`Á üØ@ = - `#[error("{0}")]` ⟶ `write!("{}", self.0)`Á ü™H E - `#[error("{var:?}")]` ⟶ `write!("{:?}", self.var)`Á üâD A - `#[error("{0:?}")]` ⟶ `write!("{:?}", self.0)`Á § Ë ü«L I These shorthands can be used together with any additional format args,Á üø6 3 which may be arbitrary expressions. For example:Á ¯ Ë l³
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```rustÁ ´Á # use core::i32;Á ìØ # use thiserror::Error;Á <ö #Á ìþ #[derive(Error, Debug)]Á ´œ pub enum Error {Á ü³P M #[error("invalid rdo_lookahead_frames {0} (expected < {})", i32::MAX)]Á ü„ InvalidLookahead(u32),Á <¥ }Á L ```Á · Ë ü»P M If one of the additional expression arguments needs to refer to a field ofÁ üŒO L the struct or enum, then refer to named fields as `.var` and tuple fieldsÁ tÜ as `.0`.Á ë Ë lï Ü& ìý �' <› ´' ü£+ ( # fn first_char(s: &String) -> char {Á üÏ% " # s.chars().next().unwrap()Á Lõ # }Á <ÿ ´' ć # #[derive(Debug)]Á ¼ # struct Limits {Á ´¸ # lo: usize,Á ´Ï # hi: usize,Á Læ ˆ, <ð ´' ìø Ã' ´– è' üQ N #[error("first letter must be lowercase but was {:?}", first_char(.0))]Á äÿ WrongCase(String),Á üœf c #[error("invalid index {idx}, expected at least {} and at most {}", .limits.lo, .limits.hi)]Á üƒ5 2 OutOfBounds { idx: usize, limits: Limits },Á <¹ ˆ) LÁ —) Ë Ë üÏK H - A `From` impl is generated for each variant that contains a `#[from]`Á „›
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attribute.Á ¬ Ë ü°N K The variant using `#[from]` must not contain any other fields beyond theÁ üÿH E source error (and possibly a backtrace — see below). UsuallyÁ üÈ M J `#[from]` fields are unnamed, but `#[from]` is allowed on a named fieldÁ T– too.Á ¡ Ë l¥ Ü& ü³ ' $ # use core::fmt::{self, Display};Á ¤Û # use std::io;Á ìð �' <Ž ´' ¬– # mod globset {Á ü¬ . + # #[derive(thiserror::Error, Debug)]Á ÜÛ # #[error("...")]Á ì÷ # pub struct Error;Á L• ˆ, <Ÿ ´' ì§ Ã' ÄÅ pub enum MyError {Á üÞ Io(#[from] io::Error),Á üÿ ' $ Glob(#[from] globset::Error),Á <§ ˆ) <¯ ´' ü· " # impl Display for MyError {Á üÚ J G # fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {Á ü¥! # unimplemented!()Á lÆ!
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# }Á LÔ! ˆ, LÞ! —) è! Ë üì!L I - The Error trait's `source()` method is implemented to return whicheverÁ ü¹"M J field has a `#[source]` attribute or is named `source`, if any. This isÁ ü‡#N K for identifying the underlying lower level error that caused your error.Á Ö# Ë üÚ#P M The `#[from]` attribute always implies that the same field is `#[source]`,Á ü«$8 5 so you don't ever need to specify both attributes.Á ä$ Ë üè$P M Any error type that implements `std::error::Error` or dereferences to `dynÁ ü¹%/ , std::error::Error` will work as a source.Á é% Ë lí% Ü& üû%' µ3 ì£& �' <Á& ´' ìÉ& Ã' Ôç& pub struct MyError {Á ´‚' msg: String,Á ü™': 7 #[source] // optional if field name is `source`Á üÔ' source: anyhow::Error,Á <õ' ˆ) <ý' ´' ü…(" ã6 ü¨(J Ž7 üó( á7 l”) ‰8 L¢) ˆ, L¬) —) ¶) Ë üº)N K - The Error trait's `provide()` method is implemented to provide whicheverÁ ü‰*6 3 field has a type named `Backtrace`, if any, as aÁ üÀ*I F `std::backtrace::Backtrace`. Using `Backtrace` in errors requires aÁ üŠ+7 4 nightly compiler with Rust version 1.73 or newer.Á Â+ Ë lÆ+ Ü& üÔ+) & # const IGNORE: &str = stringify! {Á üþ+$ ! use std::backtrace::Backtrace;Á £, Ë ì§, Ã' ÔÅ, Å= ´à, ç= ü÷,: 7 backtrace: Backtrace, // automatically detectedÁ <²- ˆ) Tº- # };Á LÅ- —) Ï- Ë üÓ-H E - If a field is both a source (named `source`, or has `#[source]` orÁ üœ.I F `#[from]` attribute) *and* is marked `#[backtrace]`, then the ErrorÁ üæ.O L trait's `provide()` method is forwarded to the source's `provide` so thatÁ ü¶/K H both layers of the error share the same backtrace. The `#[backtrace]`Á ü‚0L I attribute requires a nightly compiler with Rust version 1.73 or newer.Á Ï0 Ë lÓ0 Ü& üá0) –B ì‹1 Ã' Ä©1 Ó5 tÂ1 Io {Á ÔÑ1 #[backtrace]Á üì1 source: io::Error,Á d�2 },Á <š2 ˆ) T¢2 îC L2 —) ·2 Ë ü»2M J - For variants that use `#[from]` and also contain a `Backtrace` field, aÁ ü‰38 5 backtrace is captured from within the `From` impl.Á Â3 Ë lÆ3 Ü& üÔ3) –B ìþ3 Ã' Äœ4 Ó5 tµ4 òG ¬Ä4 #[from]Á üÚ4 «H üû4# backtrace: Backtrace,Á dŸ5 ÓH <¬5 ˆ) T´5 îC L¿5 —) É5 Ë üÍ5K H - Errors may use `error(transparent)` to forward the source and DisplayÁ ü™6G D methods straight through to an underlying error without adding anÁ üá6J G additional message. This would be appropriate for enums that need anÁ ô¬7 "anything else" variant.Á Ë7 Ë LÏ7 —) ìÙ7 �' <÷7 ´' ìÿ7 Ã' Ä�8 Ó5 t¶8 # /*Á lÅ8
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...Á tÓ8 # */Á â8 Ë üæ8 #[error(transparent)]Á ü†9X U Other(#[from] anyhow::Error), // source and Display delegate to anyhow::ErrorÁ <ß9 ˆ) Lç9 —) ñ9 Ë üõ9C @ Another use case is hiding implementation details of an errorÁ ü¹:O L representation behind an opaque error type, so that the representation isÁ ü‰;= : able to evolve without breaking the crate's public API.Á Ç; Ë LË; —) ìÕ; �' <ó; ´' üû;G D // PublicError is public, but opaque and easy to keep compatible.Á ìÃ< Ã' Üá< #[error(transparent)]Á üý<0 - pub struct PublicError(#[from] ErrorRepr);Á ®= Ë Ä²= impl PublicError {Á üË=B ? // Accessors for anything we do want to expose publicly.Á <Ž> ˆ) –> Ë üš>F C // Private and free to change across minor version of the crate.Á ìá> Ã' ´ÿ> enum ErrorRepr {Á t–? ØN l¥? îN t³? ƒO <Â? ˆ) LÊ? —) Ô? Ë üØ?O L - See also the [`anyhow`] library for a convenient single error type to useÁ Ô¨@ in application code.Á Ã@ Ë üÇ@3 0 [`anyhow`]: https://github.com/dtolnay/anyhowÁ¡ ÿ@ ‚A µA 8¹ lƒA ‘A 7 https://docs.rs/thiserror/1.0.69Á ü“A" üü@; $A“/ ”? È @///\¡D <¥D
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