diff options
Diffstat (limited to 'clippy_lints/src/methods/mod.rs')
| -rw-r--r-- | clippy_lints/src/methods/mod.rs | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs index 02592da1aae..e327bdcf578 100644 --- a/clippy_lints/src/methods/mod.rs +++ b/clippy_lints/src/methods/mod.rs @@ -47,6 +47,7 @@ mod manual_saturating_arithmetic; mod manual_str_repeat; mod map_clone; mod map_collect_result_unit; +mod map_err_ignore; mod map_flatten; mod map_identity; mod map_unwrap_or; @@ -2541,6 +2542,106 @@ declare_clippy_lint! { "using `iterator.map(|x| x.clone())`, or dereferencing closures for `Copy` types" } +declare_clippy_lint! { + /// ### What it does + /// Checks for instances of `map_err(|_| Some::Enum)` + /// + /// ### Why is this bad? + /// This `map_err` throws away the original error rather than allowing the enum to contain and report the cause of the error + /// + /// ### Example + /// Before: + /// ```rust + /// use std::fmt; + /// + /// #[derive(Debug)] + /// enum Error { + /// Indivisible, + /// Remainder(u8), + /// } + /// + /// impl fmt::Display for Error { + /// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + /// match self { + /// Error::Indivisible => write!(f, "could not divide input by three"), + /// Error::Remainder(remainder) => write!( + /// f, + /// "input is not divisible by three, remainder = {}", + /// remainder + /// ), + /// } + /// } + /// } + /// + /// impl std::error::Error for Error {} + /// + /// fn divisible_by_3(input: &str) -> Result<(), Error> { + /// input + /// .parse::<i32>() + /// .map_err(|_| Error::Indivisible) + /// .map(|v| v % 3) + /// .and_then(|remainder| { + /// if remainder == 0 { + /// Ok(()) + /// } else { + /// Err(Error::Remainder(remainder as u8)) + /// } + /// }) + /// } + /// ``` + /// + /// After: + /// ```rust + /// use std::{fmt, num::ParseIntError}; + /// + /// #[derive(Debug)] + /// enum Error { + /// Indivisible(ParseIntError), + /// Remainder(u8), + /// } + /// + /// impl fmt::Display for Error { + /// fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + /// match self { + /// Error::Indivisible(_) => write!(f, "could not divide input by three"), + /// Error::Remainder(remainder) => write!( + /// f, + /// "input is not divisible by three, remainder = {}", + /// remainder + /// ), + /// } + /// } + /// } + /// + /// impl std::error::Error for Error { + /// fn source(&self) -> Option<&(dyn std::error::Error + 'static)> { + /// match self { + /// Error::Indivisible(source) => Some(source), + /// _ => None, + /// } + /// } + /// } + /// + /// fn divisible_by_3(input: &str) -> Result<(), Error> { + /// input + /// .parse::<i32>() + /// .map_err(Error::Indivisible) + /// .map(|v| v % 3) + /// .and_then(|remainder| { + /// if remainder == 0 { + /// Ok(()) + /// } else { + /// Err(Error::Remainder(remainder as u8)) + /// } + /// }) + /// } + /// ``` + #[clippy::version = "1.48.0"] + pub MAP_ERR_IGNORE, + restriction, + "`map_err` should not ignore the original error" +} + pub struct Methods { avoid_breaking_exported_api: bool, msrv: Option<RustcVersion>, @@ -2651,6 +2752,7 @@ impl_lint_pass!(Methods => [ GET_FIRST, MANUAL_OK_OR, MAP_CLONE, + MAP_ERR_IGNORE, ]); /// Extracts a method call name, args, and `Span` of the method name. @@ -2982,6 +3084,8 @@ impl Methods { (name @ ("map" | "map_err"), [m_arg]) => { if name == "map" { map_clone::check(cx, expr, recv, m_arg, self.msrv); + } else { + map_err_ignore::check(cx, expr, m_arg); } if let Some((name, [recv2, args @ ..], span2)) = method_call(recv) { match (name, args) { |