diff options
Diffstat (limited to 'src/tools/clippy/clippy_lints/src/let_underscore.rs')
-rw-r--r-- | src/tools/clippy/clippy_lints/src/let_underscore.rs | 54 |
1 files changed, 52 insertions, 2 deletions
diff --git a/src/tools/clippy/clippy_lints/src/let_underscore.rs b/src/tools/clippy/clippy_lints/src/let_underscore.rs index 61f87b914..7600777fa 100644 --- a/src/tools/clippy/clippy_lints/src/let_underscore.rs +++ b/src/tools/clippy/clippy_lints/src/let_underscore.rs @@ -84,13 +84,51 @@ declare_clippy_lint! { /// let _ = foo().await; /// # } /// ``` - #[clippy::version = "1.66"] + #[clippy::version = "1.67.0"] pub LET_UNDERSCORE_FUTURE, suspicious, "non-binding `let` on a future" } -declare_lint_pass!(LetUnderscore => [LET_UNDERSCORE_MUST_USE, LET_UNDERSCORE_LOCK, LET_UNDERSCORE_FUTURE]); +declare_clippy_lint! { + /// ### What it does + /// Checks for `let _ = <expr>` without a type annotation, and suggests to either provide one, + /// or remove the `let` keyword altogether. + /// + /// ### Why is this bad? + /// The `let _ = <expr>` expression ignores the value of `<expr>` but will remain doing so even + /// if the type were to change, thus potentially introducing subtle bugs. By supplying a type + /// annotation, one will be forced to re-visit the decision to ignore the value in such cases. + /// + /// ### Known problems + /// The `_ = <expr>` is not properly supported by some tools (e.g. IntelliJ) and may seem odd + /// to many developers. This lint also partially overlaps with the other `let_underscore_*` + /// lints. + /// + /// ### Example + /// ```rust + /// fn foo() -> Result<u32, ()> { + /// Ok(123) + /// } + /// let _ = foo(); + /// ``` + /// Use instead: + /// ```rust + /// fn foo() -> Result<u32, ()> { + /// Ok(123) + /// } + /// // Either provide a type annotation: + /// let _: Result<u32, ()> = foo(); + /// // …or drop the let keyword: + /// _ = foo(); + /// ``` + #[clippy::version = "1.69.0"] + pub LET_UNDERSCORE_UNTYPED, + pedantic, + "non-binding `let` without a type annotation" +} + +declare_lint_pass!(LetUnderscore => [LET_UNDERSCORE_MUST_USE, LET_UNDERSCORE_LOCK, LET_UNDERSCORE_FUTURE, LET_UNDERSCORE_UNTYPED]); const SYNC_GUARD_PATHS: [&[&str]; 3] = [ &paths::PARKING_LOT_MUTEX_GUARD, @@ -148,6 +186,18 @@ impl<'tcx> LateLintPass<'tcx> for LetUnderscore { "consider explicitly using function result", ); } + + if local.pat.default_binding_modes && local.ty.is_none() { + // When `default_binding_modes` is true, the `let` keyword is present. + span_lint_and_help( + cx, + LET_UNDERSCORE_UNTYPED, + local.span, + "non-binding `let` without a type annotation", + None, + "consider adding a type annotation or removing the `let` keyword", + ); + } } } } |