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improve and generalize
option_and_then_some lint
- rename it to bind_instead_of_map
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,309 @@ | ||
| use super::{contains_return, BIND_INSTEAD_OF_MAP}; | ||
| use crate::utils::{ | ||
| in_macro, match_qpath, match_type, method_calls, multispan_sugg_with_applicability, paths, remove_blocks, snippet, | ||
| snippet_with_macro_callsite, span_lint_and_sugg, span_lint_and_then, | ||
| }; | ||
| use if_chain::if_chain; | ||
| use rustc_errors::Applicability; | ||
| use rustc_hir as hir; | ||
| use rustc_hir::intravisit::{self, Visitor}; | ||
| use rustc_lint::LateContext; | ||
| use rustc_middle::hir::map::Map; | ||
| use rustc_span::Span; | ||
|
|
||
| pub(crate) struct OptionAndThenSome; | ||
| impl BindInsteadOfMap for OptionAndThenSome { | ||
| const TYPE_NAME: &'static str = "Option"; | ||
| const TYPE_QPATH: &'static [&'static str] = &paths::OPTION; | ||
|
|
||
| const BAD_METHOD_NAME: &'static str = "and_then"; | ||
| const BAD_VARIANT_NAME: &'static str = "Some"; | ||
| const BAD_VARIANT_QPATH: &'static [&'static str] = &paths::OPTION_SOME; | ||
|
|
||
| const GOOD_METHOD_NAME: &'static str = "map"; | ||
| } | ||
|
|
||
| pub(crate) struct ResultAndThenOk; | ||
| impl BindInsteadOfMap for ResultAndThenOk { | ||
| const TYPE_NAME: &'static str = "Result"; | ||
| const TYPE_QPATH: &'static [&'static str] = &paths::RESULT; | ||
|
|
||
| const BAD_METHOD_NAME: &'static str = "and_then"; | ||
| const BAD_VARIANT_NAME: &'static str = "Ok"; | ||
| const BAD_VARIANT_QPATH: &'static [&'static str] = &paths::RESULT_OK; | ||
|
|
||
| const GOOD_METHOD_NAME: &'static str = "map"; | ||
| } | ||
|
|
||
| pub(crate) struct ResultOrElseErrInfo; | ||
| impl BindInsteadOfMap for ResultOrElseErrInfo { | ||
| const TYPE_NAME: &'static str = "Result"; | ||
| const TYPE_QPATH: &'static [&'static str] = &paths::RESULT; | ||
|
|
||
| const BAD_METHOD_NAME: &'static str = "or_else"; | ||
| const BAD_VARIANT_NAME: &'static str = "Err"; | ||
| const BAD_VARIANT_QPATH: &'static [&'static str] = &paths::RESULT_ERR; | ||
|
|
||
| const GOOD_METHOD_NAME: &'static str = "map_err"; | ||
| } | ||
|
|
||
| pub(crate) trait BindInsteadOfMap { | ||
| const TYPE_NAME: &'static str; | ||
| const TYPE_QPATH: &'static [&'static str]; | ||
|
|
||
| const BAD_METHOD_NAME: &'static str; | ||
| const BAD_VARIANT_NAME: &'static str; | ||
| const BAD_VARIANT_QPATH: &'static [&'static str]; | ||
|
|
||
| const GOOD_METHOD_NAME: &'static str; | ||
|
|
||
| fn no_op_msg() -> String { | ||
| format!( | ||
| "using `{}.{}({})`, which is a no-op", | ||
| Self::TYPE_NAME, | ||
| Self::BAD_METHOD_NAME, | ||
| Self::BAD_VARIANT_NAME | ||
| ) | ||
| } | ||
|
|
||
| fn lint_msg() -> String { | ||
| format!( | ||
| "using `{}.{}(|x| {}(y))`, which is more succinctly expressed as `{}(|x| y)`", | ||
| Self::TYPE_NAME, | ||
| Self::BAD_METHOD_NAME, | ||
| Self::BAD_VARIANT_NAME, | ||
| Self::GOOD_METHOD_NAME | ||
| ) | ||
| } | ||
|
|
||
| fn lint_closure_autofixable( | ||
| cx: &LateContext<'_, '_>, | ||
| expr: &hir::Expr<'_>, | ||
| args: &[hir::Expr<'_>], | ||
| closure_expr: &hir::Expr<'_>, | ||
| closure_args_span: Span, | ||
| ) -> bool { | ||
| if_chain! { | ||
| if let hir::ExprKind::Call(ref some_expr, ref some_args) = closure_expr.kind; | ||
| if let hir::ExprKind::Path(ref qpath) = some_expr.kind; | ||
| if match_qpath(qpath, Self::BAD_VARIANT_QPATH); | ||
| if some_args.len() == 1; | ||
| then { | ||
| let inner_expr = &some_args[0]; | ||
|
|
||
| if contains_return(inner_expr) { | ||
| return false; | ||
| } | ||
|
|
||
| let some_inner_snip = if inner_expr.span.from_expansion() { | ||
| snippet_with_macro_callsite(cx, inner_expr.span, "_") | ||
| } else { | ||
| 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!("{}.{}({} {})", option_snip, Self::GOOD_METHOD_NAME, closure_args_snip, some_inner_snip); | ||
| span_lint_and_sugg( | ||
| cx, | ||
| BIND_INSTEAD_OF_MAP, | ||
| expr.span, | ||
| Self::lint_msg().as_ref(), | ||
| "try this", | ||
| note, | ||
| Applicability::MachineApplicable, | ||
| ); | ||
| true | ||
| } else { | ||
| false | ||
| } | ||
| } | ||
| } | ||
|
|
||
| fn lint_closure(cx: &LateContext<'_, '_>, expr: &hir::Expr<'_>, closure_expr: &hir::Expr<'_>) { | ||
| let mut suggs = Vec::new(); | ||
| let can_sugg = find_all_ret_expressions(cx, closure_expr, |ret_expr| { | ||
| if_chain! { | ||
| if !in_macro(ret_expr.span); | ||
| if let hir::ExprKind::Call(ref func_path, ref args) = ret_expr.kind; | ||
| if let hir::ExprKind::Path(ref qpath) = func_path.kind; | ||
| if match_qpath(qpath, Self::BAD_VARIANT_QPATH); | ||
| if args.len() == 1; | ||
| if !contains_return(&args[0]); | ||
| then { | ||
| suggs.push((ret_expr.span, args[0].span.source_callsite())); | ||
| true | ||
| } else { | ||
| false | ||
| } | ||
| } | ||
| }); | ||
|
|
||
| if can_sugg { | ||
| span_lint_and_then(cx, BIND_INSTEAD_OF_MAP, expr.span, Self::lint_msg().as_ref(), |diag| { | ||
| multispan_sugg_with_applicability( | ||
| diag, | ||
| "try this", | ||
| Applicability::MachineApplicable, | ||
| std::iter::once((*method_calls(expr, 1).2.get(0).unwrap(), Self::GOOD_METHOD_NAME.into())).chain( | ||
| suggs | ||
| .into_iter() | ||
| .map(|(span1, span2)| (span1, snippet(cx, span2, "_").into())), | ||
| ), | ||
| ) | ||
| }); | ||
| } | ||
| } | ||
|
|
||
| /// Lint use of `_.and_then(|x| Some(y))` for `Option`s | ||
| fn lint(cx: &LateContext<'_, '_>, expr: &hir::Expr<'_>, args: &[hir::Expr<'_>]) { | ||
| if !match_type(cx, cx.tables.expr_ty(&args[0]), Self::TYPE_QPATH) { | ||
| return; | ||
| } | ||
|
|
||
| match args[1].kind { | ||
| 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); | ||
|
|
||
| if !Self::lint_closure_autofixable(cx, expr, args, closure_expr, closure_args_span) { | ||
| Self::lint_closure(cx, expr, closure_expr); | ||
| } | ||
| }, | ||
| // `_.and_then(Some)` case, which is no-op. | ||
| hir::ExprKind::Path(ref qpath) if match_qpath(qpath, Self::BAD_VARIANT_QPATH) => { | ||
| span_lint_and_sugg( | ||
| cx, | ||
| BIND_INSTEAD_OF_MAP, | ||
| expr.span, | ||
| Self::no_op_msg().as_ref(), | ||
| "use the expression directly", | ||
| snippet(cx, args[0].span, "..").into(), | ||
| Applicability::MachineApplicable, | ||
| ); | ||
| }, | ||
| _ => {}, | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /// returns `true` if expr contains match expr desugared from try | ||
| fn contains_try(expr: &hir::Expr<'_>) -> bool { | ||
| struct TryFinder { | ||
| found: bool, | ||
| } | ||
|
|
||
| impl<'hir> intravisit::Visitor<'hir> for TryFinder { | ||
| type Map = Map<'hir>; | ||
|
|
||
| fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> { | ||
| intravisit::NestedVisitorMap::None | ||
| } | ||
|
|
||
| fn visit_expr(&mut self, expr: &'hir hir::Expr<'hir>) { | ||
| if self.found { | ||
| return; | ||
| } | ||
| match expr.kind { | ||
| hir::ExprKind::Match(_, _, hir::MatchSource::TryDesugar) => self.found = true, | ||
| _ => intravisit::walk_expr(self, expr), | ||
| } | ||
| } | ||
| } | ||
|
|
||
| let mut visitor = TryFinder { found: false }; | ||
| visitor.visit_expr(expr); | ||
| visitor.found | ||
| } | ||
|
|
||
| fn find_all_ret_expressions<'hir, F>(_cx: &LateContext<'_, '_>, expr: &'hir hir::Expr<'hir>, callback: F) -> bool | ||
| where | ||
| F: FnMut(&'hir hir::Expr<'hir>) -> bool, | ||
| { | ||
| struct RetFinder<F> { | ||
| in_stmt: bool, | ||
| failed: bool, | ||
| cb: F, | ||
| } | ||
|
|
||
| struct WithStmtGuarg<'a, F> { | ||
| val: &'a mut RetFinder<F>, | ||
| prev_in_stmt: bool, | ||
| } | ||
|
|
||
| impl<F> RetFinder<F> { | ||
| fn inside_stmt(&mut self, in_stmt: bool) -> WithStmtGuarg<'_, F> { | ||
| let prev_in_stmt = std::mem::replace(&mut self.in_stmt, in_stmt); | ||
| WithStmtGuarg { | ||
| val: self, | ||
| prev_in_stmt, | ||
| } | ||
| } | ||
| } | ||
|
|
||
| impl<F> std::ops::Deref for WithStmtGuarg<'_, F> { | ||
| type Target = RetFinder<F>; | ||
|
|
||
| fn deref(&self) -> &Self::Target { | ||
| self.val | ||
| } | ||
| } | ||
|
|
||
| impl<F> std::ops::DerefMut for WithStmtGuarg<'_, F> { | ||
| fn deref_mut(&mut self) -> &mut Self::Target { | ||
| self.val | ||
| } | ||
| } | ||
|
|
||
| impl<F> Drop for WithStmtGuarg<'_, F> { | ||
| fn drop(&mut self) { | ||
| self.val.in_stmt = self.prev_in_stmt; | ||
| } | ||
| } | ||
|
|
||
| impl<'hir, F: FnMut(&'hir hir::Expr<'hir>) -> bool> intravisit::Visitor<'hir> for RetFinder<F> { | ||
| type Map = Map<'hir>; | ||
|
|
||
| fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> { | ||
| intravisit::NestedVisitorMap::None | ||
| } | ||
|
|
||
| fn visit_stmt(&mut self, stmt: &'hir hir::Stmt<'_>) { | ||
| intravisit::walk_stmt(&mut *self.inside_stmt(true), stmt) | ||
| } | ||
|
|
||
| fn visit_expr(&mut self, expr: &'hir hir::Expr<'_>) { | ||
| if self.failed { | ||
| return; | ||
| } | ||
| if self.in_stmt { | ||
| match expr.kind { | ||
| hir::ExprKind::Ret(Some(expr)) => self.inside_stmt(false).visit_expr(expr), | ||
| _ => intravisit::walk_expr(self, expr), | ||
| } | ||
| } else { | ||
| match expr.kind { | ||
| hir::ExprKind::Match(cond, arms, _) => { | ||
| self.inside_stmt(true).visit_expr(cond); | ||
| for arm in arms { | ||
| self.visit_expr(arm.body); | ||
| } | ||
| }, | ||
| hir::ExprKind::Block(..) => intravisit::walk_expr(self, expr), | ||
| hir::ExprKind::Ret(Some(expr)) => self.visit_expr(expr), | ||
| _ => self.failed |= !(self.cb)(expr), | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| !contains_try(expr) && { | ||
| let mut ret_finder = RetFinder { | ||
| in_stmt: false, | ||
| failed: false, | ||
| cb: callback, | ||
| }; | ||
| ret_finder.visit_expr(expr); | ||
| !ret_finder.failed | ||
| } | ||
| } |
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