X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=clippy_lints%2Fsrc%2Fmap_unit_fn.rs;h=57cd907e77e8da975a56773a5e357e0125de3394;hb=ebf88c9734246a790305f6faaba0bf8e3f150dff;hp=7d46478a6fd3a652e32e3415e2a42e7dd271d528;hpb=cd3df6bee0ee07c7dbb562b29576a0b513a4331b;p=rust.git diff --git a/clippy_lints/src/map_unit_fn.rs b/clippy_lints/src/map_unit_fn.rs index 7d46478a6fd..57cd907e77e 100644 --- a/clippy_lints/src/map_unit_fn.rs +++ b/clippy_lints/src/map_unit_fn.rs @@ -1,16 +1,19 @@ -use crate::utils::paths; -use crate::utils::{iter_input_pats, match_type, method_chain_args, snippet, span_lint_and_then}; +use clippy_utils::diagnostics::span_lint_and_then; +use clippy_utils::source::snippet; +use clippy_utils::ty::is_type_diagnostic_item; +use clippy_utils::{iter_input_pats, method_chain_args}; use if_chain::if_chain; -use rustc::hir; -use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass}; -use rustc::ty::{self, Ty}; -use rustc::{declare_lint_pass, declare_tool_lint}; use rustc_errors::Applicability; -use syntax::source_map::Span; +use rustc_hir as hir; +use rustc_lint::{LateContext, LateLintPass}; +use rustc_middle::ty::{self, Ty}; +use rustc_session::{declare_lint_pass, declare_tool_lint}; +use rustc_span::source_map::Span; +use rustc_span::sym; declare_clippy_lint! { /// **What it does:** Checks for usage of `option.map(f)` where f is a function - /// or closure that returns the unit type. + /// or closure that returns the unit type `()`. /// /// **Why is this bad?** Readability, this can be written more clearly with /// an if let statement @@ -47,12 +50,12 @@ /// ``` pub OPTION_MAP_UNIT_FN, complexity, - "using `option.map(f)`, where f is a function or closure that returns ()" + "using `option.map(f)`, where `f` is a function or closure that returns `()`" } declare_clippy_lint! { /// **What it does:** Checks for usage of `result.map(f)` where f is a function - /// or closure that returns the unit type. + /// or closure that returns the unit type `()`. /// /// **Why is this bad?** Readability, this can be written more clearly with /// an if let statement @@ -88,23 +91,23 @@ /// ``` pub RESULT_MAP_UNIT_FN, complexity, - "using `result.map(f)`, where f is a function or closure that returns ()" + "using `result.map(f)`, where `f` is a function or closure that returns `()`" } declare_lint_pass!(MapUnit => [OPTION_MAP_UNIT_FN, RESULT_MAP_UNIT_FN]); fn is_unit_type(ty: Ty<'_>) -> bool { - match ty.sty { + match ty.kind() { ty::Tuple(slice) => slice.is_empty(), ty::Never => true, _ => false, } } -fn is_unit_function(cx: &LateContext<'_, '_>, expr: &hir::Expr) -> bool { - let ty = cx.tables.expr_ty(expr); +fn is_unit_function(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool { + let ty = cx.typeck_results().expr_ty(expr); - if let ty::FnDef(id, _) = ty.sty { + if let ty::FnDef(id, _) = *ty.kind() { if let Some(fn_type) = cx.tcx.fn_sig(id).no_bound_vars() { return is_unit_type(fn_type.output()); } @@ -112,26 +115,26 @@ fn is_unit_function(cx: &LateContext<'_, '_>, expr: &hir::Expr) -> bool { false } -fn is_unit_expression(cx: &LateContext<'_, '_>, expr: &hir::Expr) -> bool { - is_unit_type(cx.tables.expr_ty(expr)) +fn is_unit_expression(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool { + is_unit_type(cx.typeck_results().expr_ty(expr)) } /// The expression inside a closure may or may not have surrounding braces and /// semicolons, which causes problems when generating a suggestion. Given an /// expression that evaluates to '()' or '!', recursively remove useless braces /// and semi-colons until is suitable for including in the suggestion template -fn reduce_unit_expression<'a>(cx: &LateContext<'_, '_>, expr: &'a hir::Expr) -> Option { +fn reduce_unit_expression<'a>(cx: &LateContext<'_>, expr: &'a hir::Expr<'_>) -> Option { if !is_unit_expression(cx, expr) { return None; } - match expr.node { - hir::ExprKind::Call(_, _) | hir::ExprKind::MethodCall(_, _, _) => { + match expr.kind { + hir::ExprKind::Call(_, _) | hir::ExprKind::MethodCall(_, _, _, _) => { // Calls can't be reduced any more Some(expr.span) }, - hir::ExprKind::Block(ref block, _) => { - match (&block.stmts[..], block.expr.as_ref()) { + hir::ExprKind::Block(block, _) => { + match (block.stmts, block.expr.as_ref()) { (&[], Some(inner_expr)) => { // If block only contains an expression, // reduce `{ X }` to `X` @@ -140,9 +143,9 @@ fn reduce_unit_expression<'a>(cx: &LateContext<'_, '_>, expr: &'a hir::Expr) -> (&[ref inner_stmt], None) => { // If block only contains statements, // reduce `{ X; }` to `X` or `X;` - match inner_stmt.node { - hir::StmtKind::Local(ref local) => Some(local.span), - hir::StmtKind::Expr(ref e) => Some(e.span), + match inner_stmt.kind { + hir::StmtKind::Local(local) => Some(local.span), + hir::StmtKind::Expr(e) => Some(e.span), hir::StmtKind::Semi(..) => Some(inner_stmt.span), hir::StmtKind::Item(..) => None, } @@ -161,18 +164,19 @@ fn reduce_unit_expression<'a>(cx: &LateContext<'_, '_>, expr: &'a hir::Expr) -> } } -fn unit_closure<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'a hir::Expr) -> Option<(&'tcx hir::Arg, &'a hir::Expr)> { - if let hir::ExprKind::Closure(_, ref decl, inner_expr_id, _, _) = expr.node { +fn unit_closure<'tcx>( + cx: &LateContext<'tcx>, + expr: &hir::Expr<'_>, +) -> Option<(&'tcx hir::Param<'tcx>, &'tcx hir::Expr<'tcx>)> { + if_chain! { + if let hir::ExprKind::Closure(_, decl, inner_expr_id, _, _) = expr.kind; let body = cx.tcx.hir().body(inner_expr_id); let body_expr = &body.value; - - if_chain! { - if decl.inputs.len() == 1; - if is_unit_expression(cx, body_expr); - if let Some(binding) = iter_input_pats(&decl, body).next(); - then { - return Some((binding, body_expr)); - } + if decl.inputs.len() == 1; + if is_unit_expression(cx, body_expr); + if let Some(binding) = iter_input_pats(decl, body).next(); + then { + return Some((binding, body_expr)); } } None @@ -183,51 +187,53 @@ fn unit_closure<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'a hir::Expr) -> Op /// `x.field` => `x_field` /// `y` => `_y` /// -/// Anything else will return `_`. -fn let_binding_name(cx: &LateContext<'_, '_>, var_arg: &hir::Expr) -> String { - match &var_arg.node { +/// Anything else will return `a`. +fn let_binding_name(cx: &LateContext<'_>, var_arg: &hir::Expr<'_>) -> String { + match &var_arg.kind { hir::ExprKind::Field(_, _) => snippet(cx, var_arg.span, "_").replace(".", "_"), hir::ExprKind::Path(_) => format!("_{}", snippet(cx, var_arg.span, "")), - _ => "_".to_string(), + _ => "a".to_string(), } } +#[must_use] fn suggestion_msg(function_type: &str, map_type: &str) -> String { format!( - "called `map(f)` on an {0} value where `f` is a unit {1}", + "called `map(f)` on an `{0}` value where `f` is a {1} that returns the unit type `()`", map_type, function_type ) } -fn lint_map_unit_fn(cx: &LateContext<'_, '_>, stmt: &hir::Stmt, expr: &hir::Expr, map_args: &[hir::Expr]) { +fn lint_map_unit_fn(cx: &LateContext<'_>, stmt: &hir::Stmt<'_>, expr: &hir::Expr<'_>, map_args: &[hir::Expr<'_>]) { let var_arg = &map_args[0]; - let (map_type, variant, lint) = if match_type(cx, cx.tables.expr_ty(var_arg), &paths::OPTION) { - ("Option", "Some", OPTION_MAP_UNIT_FN) - } else if match_type(cx, cx.tables.expr_ty(var_arg), &paths::RESULT) { - ("Result", "Ok", RESULT_MAP_UNIT_FN) - } else { - return; - }; + let (map_type, variant, lint) = + if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(var_arg), sym::option_type) { + ("Option", "Some", OPTION_MAP_UNIT_FN) + } else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(var_arg), sym::result_type) { + ("Result", "Ok", RESULT_MAP_UNIT_FN) + } else { + return; + }; let fn_arg = &map_args[1]; if is_unit_function(cx, fn_arg) { let msg = suggestion_msg("function", map_type); let suggestion = format!( - "if let {0}({1}) = {2} {{ {3}(...) }}", + "if let {0}({binding}) = {1} {{ {2}({binding}) }}", variant, - let_binding_name(cx, var_arg), snippet(cx, var_arg.span, "_"), - snippet(cx, fn_arg.span, "_") + snippet(cx, fn_arg.span, "_"), + binding = let_binding_name(cx, var_arg) ); - span_lint_and_then(cx, lint, expr.span, &msg, |db| { - db.span_suggestion(stmt.span, "try this", suggestion, Applicability::Unspecified); + span_lint_and_then(cx, lint, expr.span, &msg, |diag| { + diag.span_suggestion(stmt.span, "try this", suggestion, Applicability::MachineApplicable); }); } else if let Some((binding, closure_expr)) = unit_closure(cx, fn_arg) { let msg = suggestion_msg("closure", map_type); - span_lint_and_then(cx, lint, expr.span, &msg, |db| { + span_lint_and_then(cx, lint, expr.span, &msg, |diag| { if let Some(reduced_expr_span) = reduce_unit_expression(cx, closure_expr) { let suggestion = format!( "if let {0}({1}) = {2} {{ {3} }}", @@ -236,7 +242,7 @@ fn lint_map_unit_fn(cx: &LateContext<'_, '_>, stmt: &hir::Stmt, expr: &hir::Expr snippet(cx, var_arg.span, "_"), snippet(cx, reduced_expr_span, "_") ); - db.span_suggestion( + diag.span_suggestion( stmt.span, "try this", suggestion, @@ -247,21 +253,21 @@ fn lint_map_unit_fn(cx: &LateContext<'_, '_>, stmt: &hir::Stmt, expr: &hir::Expr "if let {0}({1}) = {2} {{ ... }}", variant, snippet(cx, binding.pat.span, "_"), - snippet(cx, var_arg.span, "_") + snippet(cx, var_arg.span, "_"), ); - db.span_suggestion(stmt.span, "try this", suggestion, Applicability::Unspecified); + diag.span_suggestion(stmt.span, "try this", suggestion, Applicability::HasPlaceholders); } }); } } -impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MapUnit { - fn check_stmt(&mut self, cx: &LateContext<'_, '_>, stmt: &hir::Stmt) { +impl<'tcx> LateLintPass<'tcx> for MapUnit { + fn check_stmt(&mut self, cx: &LateContext<'_>, stmt: &hir::Stmt<'_>) { if stmt.span.from_expansion() { return; } - if let hir::StmtKind::Semi(ref expr) = stmt.node { + if let hir::StmtKind::Semi(expr) = stmt.kind { if let Some(arglists) = method_chain_args(expr, &["map"]) { lint_map_unit_fn(cx, stmt, expr, arglists[0]); }