-
Notifications
You must be signed in to change notification settings - Fork 1.6k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
- Loading branch information
Showing
7 changed files
with
626 additions
and
1 deletion.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,262 @@ | ||
| use crate::utils::{ | ||
| is_type_diagnostic_item, match_def_path, paths, peel_hir_expr_refs, peel_mid_ty_refs_is_mutable, | ||
| snippet_with_applicability, span_lint_and_sugg, | ||
| }; | ||
| use rustc_ast::util::parser::PREC_POSTFIX; | ||
| use rustc_errors::Applicability; | ||
| use rustc_hir::{Arm, BindingAnnotation, Block, Expr, ExprKind, Mutability, Pat, PatKind, Path, QPath}; | ||
| use rustc_lint::{LateContext, LateLintPass, LintContext}; | ||
| use rustc_middle::lint::in_external_macro; | ||
| use rustc_session::{declare_lint_pass, declare_tool_lint}; | ||
| use rustc_span::symbol::{sym, Ident}; | ||
|
|
||
| declare_clippy_lint! { | ||
| /// **What it does:** Checks for usages of `match` which could be implemented using `map` | ||
| /// | ||
| /// **Why is this bad?** Using the `map` method is clearer and more concise. | ||
| /// | ||
| /// **Known problems:** None. | ||
| /// | ||
| /// **Example:** | ||
| /// | ||
| /// ```rust | ||
| /// match Some(0) { | ||
| /// Some(x) => Some(x + 1), | ||
| /// None => None, | ||
| /// }; | ||
| /// ``` | ||
| /// Use instead: | ||
| /// ```rust | ||
| /// Some(0).map(|x| x + 1); | ||
| /// ``` | ||
| pub MANUAL_MAP, | ||
| style, | ||
| "reimplementation of `map`" | ||
| } | ||
|
|
||
| declare_lint_pass!(ManualMap => [MANUAL_MAP]); | ||
|
|
||
| impl LateLintPass<'_> for ManualMap { | ||
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { | ||
| if in_external_macro(cx.sess(), expr.span) { | ||
| return; | ||
| } | ||
|
|
||
| if let ExprKind::Match(scrutinee, [arm1 @ Arm { guard: None, .. }, arm2 @ Arm { guard: None, .. }], _) = | ||
| expr.kind | ||
| { | ||
| let (scrutinee_ty, ty_ref_count, ty_mutability) = | ||
| peel_mid_ty_refs_is_mutable(cx.typeck_results().expr_ty(scrutinee)); | ||
| if !is_type_diagnostic_item(cx, scrutinee_ty, sym::option_type) | ||
| || !is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(expr), sym::option_type) | ||
| { | ||
| return; | ||
| } | ||
|
|
||
| let (some_expr, some_pat, pat_ref_count, is_wild_none) = | ||
| match (try_parse_pattern(cx, arm1.pat), try_parse_pattern(cx, arm2.pat)) { | ||
| (Some(OptionPat::Wild), Some(OptionPat::Some { pattern, ref_count })) | ||
| if is_none_expr(cx, arm1.body) => | ||
| { | ||
| (arm2.body, pattern, ref_count, true) | ||
| }, | ||
| (Some(OptionPat::None), Some(OptionPat::Some { pattern, ref_count })) | ||
| if is_none_expr(cx, arm1.body) => | ||
| { | ||
| (arm2.body, pattern, ref_count, false) | ||
| }, | ||
| (Some(OptionPat::Some { pattern, ref_count }), Some(OptionPat::Wild)) | ||
| if is_none_expr(cx, arm2.body) => | ||
| { | ||
| (arm1.body, pattern, ref_count, true) | ||
| }, | ||
| (Some(OptionPat::Some { pattern, ref_count }), Some(OptionPat::None)) | ||
| if is_none_expr(cx, arm2.body) => | ||
| { | ||
| (arm1.body, pattern, ref_count, false) | ||
| }, | ||
| _ => return, | ||
| }; | ||
|
|
||
| // Top level or patterns aren't allowed in closures. | ||
| if matches!(some_pat.kind, PatKind::Or(_)) { | ||
| return; | ||
| } | ||
|
|
||
| let some_expr = match get_some_expr(cx, some_expr) { | ||
| Some(expr) => expr, | ||
| None => return, | ||
| }; | ||
|
|
||
| // Determine which binding mode to use. | ||
| let explicit_ref = some_pat.contains_explicit_ref_binding(); | ||
| let binding_mutability = explicit_ref.or(if ty_ref_count != pat_ref_count { | ||
| Some(ty_mutability) | ||
| } else { | ||
| None | ||
| }); | ||
| let as_ref_str = match binding_mutability { | ||
| Some(Mutability::Mut) => ".as_mut()", | ||
| Some(Mutability::Not) => ".as_ref()", | ||
| None => "", | ||
| }; | ||
|
|
||
| let mut app = Applicability::MachineApplicable; | ||
|
|
||
| // Remove address-of expressions from the scrutinee. `as_ref` will be called, | ||
| // the type is copyable, or the option is being passed by value. | ||
| let scrutinee = peel_hir_expr_refs(scrutinee).0; | ||
| let scrutinee_str = snippet_with_applicability(cx, scrutinee.span, "_", &mut app); | ||
| let scrutinee_str = if expr.precedence().order() < PREC_POSTFIX { | ||
| // Parens are needed to chain method calls. | ||
| format!("({})", scrutinee_str) | ||
| } else { | ||
| scrutinee_str.into() | ||
| }; | ||
|
|
||
| let body_str = if let PatKind::Binding(annotation, _, some_binding, None) = some_pat.kind { | ||
| if let Some(func) = can_pass_as_func(cx, some_binding, some_expr) { | ||
| snippet_with_applicability(cx, func.span, "..", &mut app).into_owned() | ||
| } else { | ||
| // `ref` and `ref mut` annotations were handled earlier. | ||
| let annotation = if matches!(annotation, BindingAnnotation::Mutable) { | ||
| "mut " | ||
| } else { | ||
| "" | ||
| }; | ||
| format!( | ||
| "|{}{}| {}", | ||
| annotation, | ||
| some_binding, | ||
| snippet_with_applicability(cx, some_expr.span, "..", &mut app) | ||
| ) | ||
| } | ||
| } else if !is_wild_none && explicit_ref.is_none() { | ||
| // TODO: handle explicit reference annotations. | ||
| format!( | ||
| "|{}| {}", | ||
| snippet_with_applicability(cx, some_pat.span, "..", &mut app), | ||
| snippet_with_applicability(cx, some_expr.span, "..", &mut app) | ||
| ) | ||
| } else { | ||
| // Refutable bindings and mixed reference annotations can't be handled by `map`. | ||
| return; | ||
| }; | ||
|
|
||
| span_lint_and_sugg( | ||
| cx, | ||
| MANUAL_MAP, | ||
| expr.span, | ||
| "manual implementation of `Option::map`", | ||
| "try this", | ||
| format!("{}{}.map({})", scrutinee_str, as_ref_str, body_str), | ||
| app, | ||
| ); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // Checks whether the expression could be passed as a function, or whether a closure is needed. | ||
| // Returns the function to be passed to `map` if it exists. | ||
| fn can_pass_as_func(cx: &LateContext<'tcx>, binding: Ident, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> { | ||
| match expr.kind { | ||
| ExprKind::Call(func, [arg]) | ||
| if matches!(arg.kind, | ||
| ExprKind::Path(QPath::Resolved(None, Path { segments: [path], ..})) | ||
| if path.ident == binding | ||
| ) && cx.typeck_results().expr_adjustments(arg).is_empty() => | ||
| { | ||
| Some(func) | ||
| }, | ||
| _ => None, | ||
| } | ||
| } | ||
|
|
||
| enum OptionPat<'a> { | ||
| Wild, | ||
| None, | ||
| Some { | ||
| // The pattern contained in the `Some` tuple. | ||
| pattern: &'a Pat<'a>, | ||
| // The number of references before the `Some` tuple. | ||
| // e.g. `&&Some(_)` has a ref count of 2. | ||
| ref_count: usize, | ||
| }, | ||
| } | ||
|
|
||
| // Try to parse into a recognized `Option` pattern. | ||
| // i.e. `_`, `None`, `Some(..)`, or a reference to any of those. | ||
| fn try_parse_pattern(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>) -> Option<OptionPat<'tcx>> { | ||
| fn f(cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>, ref_count: usize) -> Option<OptionPat<'tcx>> { | ||
| match pat.kind { | ||
| PatKind::Wild => Some(OptionPat::Wild), | ||
| PatKind::Ref(pat, _) => f(cx, pat, ref_count + 1), | ||
| PatKind::Path(QPath::Resolved(None, path)) | ||
| if path | ||
| .res | ||
| .opt_def_id() | ||
| .map_or(false, |id| match_def_path(cx, id, &paths::OPTION_NONE)) => | ||
| { | ||
| Some(OptionPat::None) | ||
| }, | ||
| PatKind::TupleStruct(QPath::Resolved(None, path), [pattern], _) | ||
| if path | ||
| .res | ||
| .opt_def_id() | ||
| .map_or(false, |id| match_def_path(cx, id, &paths::OPTION_SOME)) => | ||
| { | ||
| Some(OptionPat::Some { pattern, ref_count }) | ||
| }, | ||
| _ => None, | ||
| } | ||
| } | ||
| f(cx, pat, 0) | ||
| } | ||
|
|
||
| // Checks for an expression wrapped by the `Some` constructor. Returns the contained expression. | ||
| fn get_some_expr(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> { | ||
| // TODO: Allow more complex expressions. | ||
| match expr.kind { | ||
| ExprKind::Call( | ||
| Expr { | ||
| kind: ExprKind::Path(QPath::Resolved(None, path)), | ||
| .. | ||
| }, | ||
| [arg], | ||
| ) => { | ||
| if match_def_path(cx, path.res.opt_def_id()?, &paths::OPTION_SOME) { | ||
| Some(arg) | ||
| } else { | ||
| None | ||
| } | ||
| }, | ||
| ExprKind::Block( | ||
| Block { | ||
| stmts: [], | ||
| expr: Some(expr), | ||
| .. | ||
| }, | ||
| _, | ||
| ) => get_some_expr(cx, expr), | ||
| _ => None, | ||
| } | ||
| } | ||
|
|
||
| // Checks for the `None` value. | ||
| fn is_none_expr(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool { | ||
| match expr.kind { | ||
| ExprKind::Path(QPath::Resolved(None, path)) => path | ||
| .res | ||
| .opt_def_id() | ||
| .map_or(false, |id| match_def_path(cx, id, &paths::OPTION_NONE)), | ||
| ExprKind::Block( | ||
| Block { | ||
| stmts: [], | ||
| expr: Some(expr), | ||
| .. | ||
| }, | ||
| _, | ||
| ) => is_none_expr(cx, expr), | ||
| _ => false, | ||
| } | ||
| } |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.