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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,69 @@ | ||
| use clippy_utils::diagnostics::span_lint_and_sugg; | ||
| use clippy_utils::in_macro; | ||
| use clippy_utils::source::snippet_opt; | ||
| use clippy_utils::ty::is_type_diagnostic_item; | ||
| use rustc_errors::Applicability; | ||
| use rustc_hir::{Expr, ExprKind}; | ||
| use rustc_lint::{LateContext, LateLintPass}; | ||
| use rustc_middle::ty::TyS; | ||
| use rustc_session::{declare_lint_pass, declare_tool_lint}; | ||
| use rustc_span::symbol::sym; | ||
|
|
||
| declare_clippy_lint! { | ||
| /// ### What it does | ||
| /// Checks for no-op uses of Option::{as_deref,as_deref_mut}, | ||
| /// for example, `Option<&T>::as_deref()` returns the same type. | ||
| /// | ||
| /// ### Why is this bad? | ||
| /// Redundant code and improving readability. | ||
| /// | ||
| /// ### Example | ||
| /// ```rust | ||
| /// let a = Some(&1); | ||
| /// let b = a.as_deref(); // goes from Option<&i32> to Option<&i32> | ||
| /// ``` | ||
| /// Could be written as: | ||
| /// ```rust | ||
| /// let a = Some(&1); | ||
| /// let b = a; | ||
| /// ``` | ||
| pub NEEDLESS_OPTION_AS_DEREF, | ||
| complexity, | ||
| "no-op use of `deref` or `deref_mut` method to `Option`." | ||
| } | ||
|
|
||
| declare_lint_pass!(OptionNeedlessDeref=> [ | ||
| NEEDLESS_OPTION_AS_DEREF, | ||
| ]); | ||
|
|
||
| impl<'tcx> LateLintPass<'tcx> for OptionNeedlessDeref { | ||
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { | ||
| if expr.span.from_expansion() { | ||
| return; | ||
| } | ||
| if in_macro(expr.span) { | ||
| return; | ||
| } | ||
| let typeck = cx.typeck_results(); | ||
| let outer_ty = typeck.expr_ty(expr); | ||
|
|
||
| if_chain! { | ||
| if is_type_diagnostic_item(cx,outer_ty,sym::option_type); | ||
| if let ExprKind::MethodCall(path, _, [sub_expr], _) = expr.kind; | ||
| let symbol = path.ident.as_str(); | ||
| if symbol=="as_deref" || symbol=="as_deref_mut"; | ||
| if TyS::same_type( outer_ty, typeck.expr_ty(sub_expr) ); | ||
| then{ | ||
| span_lint_and_sugg( | ||
| cx, | ||
| NEEDLESS_OPTION_AS_DEREF, | ||
| expr.span, | ||
| "derefed type is same as origin", | ||
| "try this", | ||
| snippet_opt(cx,sub_expr.span).unwrap(), | ||
| Applicability::MachineApplicable | ||
| ); | ||
| } | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,13 @@ | ||
| // run-rustfix | ||
|
|
||
| #[warn(clippy::needless_option_as_deref)] | ||
|
|
||
| fn main() { | ||
| // should lint | ||
| let _: Option<&usize> = Some(&1); | ||
| let _: Option<&mut usize> = Some(&mut 1); | ||
|
|
||
| // should not lint | ||
| let _ = Some(Box::new(1)).as_deref(); | ||
| let _ = Some(Box::new(1)).as_deref_mut(); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,13 @@ | ||
| // run-rustfix | ||
|
|
||
| #[warn(clippy::needless_option_as_deref)] | ||
|
|
||
| fn main() { | ||
| // should lint | ||
| let _: Option<&usize> = Some(&1).as_deref(); | ||
| let _: Option<&mut usize> = Some(&mut 1).as_deref_mut(); | ||
|
|
||
| // should not lint | ||
| let _ = Some(Box::new(1)).as_deref(); | ||
| let _ = Some(Box::new(1)).as_deref_mut(); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,16 @@ | ||
| error: derefed type is same as origin | ||
| --> $DIR/needless_option_as_deref.rs:7:29 | ||
| | | ||
| LL | let _: Option<&usize> = Some(&1).as_deref(); | ||
| | ^^^^^^^^^^^^^^^^^^^ help: try this: `Some(&1)` | ||
| | | ||
| = note: `-D clippy::needless-option-as-deref` implied by `-D warnings` | ||
|
|
||
| error: derefed type is same as origin | ||
| --> $DIR/needless_option_as_deref.rs:8:33 | ||
| | | ||
| LL | let _: Option<&mut usize> = Some(&mut 1).as_deref_mut(); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `Some(&mut 1)` | ||
|
|
||
| error: aborting due to 2 previous errors | ||
|
|