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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,95 @@ | ||
| use crate::utils::paths; | ||
| use crate::utils::{in_macro_or_desugar, match_qpath, match_type, remove_blocks, snippet, span_lint_and_sugg}; | ||
| use rustc::hir; | ||
| use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass}; | ||
| use rustc::{declare_lint_pass, declare_tool_lint}; | ||
| use rustc_errors::Applicability; | ||
|
|
||
| declare_clippy_lint! { | ||
| /// **What it does:** Checks for usage of `_.and_then(|x| Some(y))`. | ||
| /// | ||
| /// **Why is this bad?** Readability, this can be written more concisely as | ||
| /// `_.map(|x| y)`. | ||
| /// | ||
| /// **Known problems:** None | ||
| /// | ||
| /// **Example:** | ||
| /// | ||
| /// ```rust | ||
| /// let x = Some("foo"); | ||
| /// x.and_then(|s| Some(s.len())); | ||
| /// ``` | ||
| /// | ||
| /// The correct use would be: | ||
| /// | ||
| /// ```rust | ||
| /// let x = Some("foo"); | ||
| /// x.map(|s| s.len()); | ||
| /// ``` | ||
| pub OPTION_AND_THEN_SOME, | ||
| complexity, | ||
| "using `Option.and_then(|x| Some(y))`, which is more succinctly expressed as `map(|x| y)`" | ||
| } | ||
|
|
||
| declare_lint_pass!(AndThenSomeLint => [OPTION_AND_THEN_SOME]); | ||
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|
||
| const LINT_MSG: &str = "using `Option.and_then(|x| Some(y))`, which is more succinctly expressed as `map(|x| y)`"; | ||
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|
||
| impl LateLintPass<'_, '_> for AndThenSomeLint { | ||
| /// Lint use of `_.and_then(|x| Some(y))` for `Option`s | ||
| fn check_expr(&mut self, cx: &LateContext<'_, '_>, e: &hir::Expr) { | ||
| if in_macro_or_desugar(e.span) { | ||
| return; | ||
| } | ||
|
|
||
| if let hir::ExprKind::MethodCall(ref method, _, ref args) = e.node { | ||
| if args.len() == 2 && method.ident.as_str() == "and_then" { | ||
| let ty = cx.tables.expr_ty(&args[0]); | ||
| if !match_type(cx, ty, &paths::OPTION) { | ||
| return; | ||
| } | ||
| match args[1].node { | ||
| hir::ExprKind::Closure(_, _, body_id, closure_args_span, _) => { | ||
| let closure_body = cx.tcx.hir().body(body_id); | ||
| let closure_expr = remove_blocks(&closure_body.value); | ||
|
|
||
| // let note = format!("{:?}", args[1]); | ||
| // span_note_and_lint(cx, OPTION_AND_THEN_SOME, closure_args_span, "Outer debugging | ||
| // information", closure_args_span, ¬e); | ||
|
|
||
| if let hir::ExprKind::Call(ref some_expr, ref some_args) = closure_expr.node { | ||
| if let hir::ExprKind::Path(ref qpath) = some_expr.node { | ||
| if match_qpath(qpath, &paths::OPTION_SOME) { | ||
| if some_args.len() == 1 { | ||
| let inner_expr = &some_args[0]; | ||
| let some_inner_snip = snippet(cx, inner_expr.span, ".."); | ||
| let closure_args_snip = snippet(cx, closure_args_span, ".."); | ||
| let option_snip = snippet(cx, args[0].span, ".."); | ||
| let note = | ||
| format!("{}.map({} {})", option_snip, closure_args_snip, some_inner_snip); | ||
| span_lint_and_sugg( | ||
| cx, | ||
| OPTION_AND_THEN_SOME, | ||
| e.span, | ||
| LINT_MSG, | ||
| "try this", | ||
| note, | ||
| Applicability::MachineApplicable, | ||
| ); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| }, | ||
| // hir::ExprKind::Path(ref qpath) => { | ||
| // if match_qpath(qpath, &paths::OPTION_SOME) { | ||
| // let note = format!("{:?}", args[1]); | ||
| // span_note_and_lint(cx, OPTION_AND_THEN_SOME, args[1].span, "Some debugging information", | ||
| // args[1].span, ¬e); } | ||
| // }, | ||
| _ => {}, | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,16 @@ | ||
| // run-rustfix | ||
| #![deny(clippy::option_and_then_some)] | ||
|
|
||
| // need a main anyway, use it get rid of unused warnings too | ||
| pub fn main() { | ||
| let x = Some(5); | ||
| // the easiest cases | ||
| x.and_then(Some); | ||
| x.map(|o| o + 1); | ||
| // and an easy counter-example | ||
| x.and_then(|o| if o < 32 { Some(o) } else { None }); | ||
|
|
||
| // Different type | ||
| let x: Result<u32, &str> = Ok(1); | ||
| x.and_then(Ok); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,16 @@ | ||
| // run-rustfix | ||
| #![deny(clippy::option_and_then_some)] | ||
|
|
||
| // need a main anyway, use it get rid of unused warnings too | ||
| pub fn main() { | ||
| let x = Some(5); | ||
| // the easiest cases | ||
| x.and_then(Some); | ||
| x.and_then(|o| Some(o + 1)); | ||
| // and an easy counter-example | ||
| x.and_then(|o| if o < 32 { Some(o) } else { None }); | ||
|
|
||
| // Different type | ||
| let x: Result<u32, &str> = Ok(1); | ||
| x.and_then(Ok); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,14 @@ | ||
| error: using `Option.and_then(|x| Some(y))`, which is more succinctly expressed as `map(|x| y)` | ||
| --> $DIR/option_and_then_some.rs:9:5 | ||
| | | ||
| LL | x.and_then(|o| Some(o + 1)); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `x.map(|o| o + 1)` | ||
| | | ||
| note: lint level defined here | ||
| --> $DIR/option_and_then_some.rs:2:9 | ||
| | | ||
| LL | #![deny(clippy::option_and_then_some)] | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
|
|
||
| error: aborting due to previous error | ||
|
|