+use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
+use clippy_utils::higher;
+use clippy_utils::higher::VecArgs;
+use clippy_utils::source::snippet_opt;
+use clippy_utils::ty::{implements_trait, type_is_unsafe_function};
+use clippy_utils::{is_adjusted, iter_input_pats};
use if_chain::if_chain;
-use matches::matches;
-use rustc::hir::*;
-use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, LintPass};
-use rustc::ty::{self, Ty};
-use rustc::{declare_lint_pass, declare_tool_lint};
use rustc_errors::Applicability;
-
-use crate::utils::{
- implements_trait, is_adjusted, iter_input_pats, snippet_opt, span_lint_and_then, type_is_unsafe_function,
-};
+use rustc_hir::{def_id, Expr, ExprKind, Param, PatKind, QPath};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
+use rustc_middle::ty::{self, Ty};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// **What it does:** Checks for closures which just call another function where
/// **Known problems:** If creating the closure inside the closure has a side-
/// effect then moving the closure creation out will change when that side-
/// effect runs.
- /// See rust-lang/rust-clippy#1439 for more details.
+ /// See [#1439](https://github.com/rust-lang/rust-clippy/issues/1439) for more details.
///
/// **Example:**
/// ```rust,ignore
+ /// // Bad
/// xs.map(|x| foo(x))
+ ///
+ /// // Good
+ /// xs.map(foo)
/// ```
/// where `foo(_)` is a plain function that takes the exact argument type of
/// `x`.
///
/// **Why is this bad?** It's unnecessary to create the closure.
///
- /// **Known problems:** rust-lang/rust-clippy#3071, rust-lang/rust-clippy#4002,
- /// rust-lang/rust-clippy#3942
+ /// **Known problems:** [#3071](https://github.com/rust-lang/rust-clippy/issues/3071),
+ /// [#3942](https://github.com/rust-lang/rust-clippy/issues/3942),
+ /// [#4002](https://github.com/rust-lang/rust-clippy/issues/4002)
///
///
/// **Example:**
declare_lint_pass!(EtaReduction => [REDUNDANT_CLOSURE, REDUNDANT_CLOSURE_FOR_METHOD_CALLS]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EtaReduction {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
+impl<'tcx> LateLintPass<'tcx> for EtaReduction {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if in_external_macro(cx.sess(), expr.span) {
return;
}
match expr.kind {
- ExprKind::Call(_, ref args) | ExprKind::MethodCall(_, _, ref args) => {
+ ExprKind::Call(_, args) | ExprKind::MethodCall(_, _, args, _) => {
for arg in args {
- check_closure(cx, arg)
+ // skip `foo(macro!())`
+ if arg.span.ctxt() == expr.span.ctxt() {
+ check_closure(cx, arg)
+ }
}
},
_ => (),
}
}
-fn check_closure(cx: &LateContext<'_, '_>, expr: &Expr) {
+fn check_closure(cx: &LateContext<'_>, expr: &Expr<'_>) {
if let ExprKind::Closure(_, ref decl, eid, _, _) = expr.kind {
let body = cx.tcx.hir().body(eid);
let ex = &body.value;
+ if ex.span.ctxt() != expr.span.ctxt() {
+ if let Some(VecArgs::Vec(&[])) = higher::vec_macro(cx, ex) {
+ // replace `|| vec![]` with `Vec::new`
+ span_lint_and_sugg(
+ cx,
+ REDUNDANT_CLOSURE,
+ expr.span,
+ "redundant closure",
+ "replace the closure with `Vec::new`",
+ "std::vec::Vec::new".into(),
+ Applicability::MachineApplicable,
+ );
+ }
+ // skip `foo(|| macro!())`
+ return;
+ }
+
if_chain!(
if let ExprKind::Call(ref caller, ref args) = ex.kind;
// Are the expression or the arguments type-adjusted? Then we need the closure
if !(is_adjusted(cx, ex) || args.iter().any(|arg| is_adjusted(cx, arg)));
- let fn_ty = cx.tables.expr_ty(caller);
+ let fn_ty = cx.typeck_results().expr_ty(caller);
- if matches!(fn_ty.kind, ty::FnDef(_, _) | ty::FnPtr(_) | ty::Closure(_, _));
+ if matches!(fn_ty.kind(), ty::FnDef(_, _) | ty::FnPtr(_) | ty::Closure(_, _));
if !type_is_unsafe_function(cx, fn_ty);
- if compare_inputs(&mut iter_input_pats(decl, body), &mut args.into_iter());
+ if compare_inputs(&mut iter_input_pats(decl, body), &mut args.iter());
then {
- span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure found", |db| {
+ span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure", |diag| {
if let Some(snippet) = snippet_opt(cx, caller.span) {
- db.span_suggestion(
+ diag.span_suggestion(
expr.span,
- "remove closure as shown",
+ "replace the closure with the function itself",
snippet,
Applicability::MachineApplicable,
);
);
if_chain!(
- if let ExprKind::MethodCall(ref path, _, ref args) = ex.kind;
+ if let ExprKind::MethodCall(ref path, _, ref args, _) = ex.kind;
// Not the same number of arguments, there is no way the closure is the same as the function return;
if args.len() == decl.inputs.len();
// Are the expression or the arguments type-adjusted? Then we need the closure
if !(is_adjusted(cx, ex) || args.iter().skip(1).any(|arg| is_adjusted(cx, arg)));
- let method_def_id = cx.tables.type_dependent_def_id(ex.hir_id).unwrap();
+ let method_def_id = cx.typeck_results().type_dependent_def_id(ex.hir_id).unwrap();
if !type_is_unsafe_function(cx, cx.tcx.type_of(method_def_id));
- if compare_inputs(&mut iter_input_pats(decl, body), &mut args.into_iter());
+ if compare_inputs(&mut iter_input_pats(decl, body), &mut args.iter());
if let Some(name) = get_ufcs_type_name(cx, method_def_id, &args[0]);
then {
- span_lint_and_then(cx, REDUNDANT_CLOSURE_FOR_METHOD_CALLS, expr.span, "redundant closure found", |db| {
- db.span_suggestion(
- expr.span,
- "remove closure as shown",
- format!("{}::{}", name, path.ident.name),
- Applicability::MachineApplicable,
- );
- });
+ span_lint_and_sugg(
+ cx,
+ REDUNDANT_CLOSURE_FOR_METHOD_CALLS,
+ expr.span,
+ "redundant closure",
+ "replace the closure with the method itself",
+ format!("{}::{}", name, path.ident.name),
+ Applicability::MachineApplicable,
+ );
}
);
}
}
/// Tries to determine the type for universal function call to be used instead of the closure
-fn get_ufcs_type_name(
- cx: &LateContext<'_, '_>,
- method_def_id: def_id::DefId,
- self_arg: &Expr,
-) -> std::option::Option<String> {
+fn get_ufcs_type_name(cx: &LateContext<'_>, method_def_id: def_id::DefId, self_arg: &Expr<'_>) -> Option<String> {
let expected_type_of_self = &cx.tcx.fn_sig(method_def_id).inputs_and_output().skip_binder()[0];
- let actual_type_of_self = &cx.tables.node_type(self_arg.hir_id);
+ let actual_type_of_self = &cx.typeck_results().node_type(self_arg.hir_id);
if let Some(trait_id) = cx.tcx.trait_of_item(method_def_id) {
if match_borrow_depth(expected_type_of_self, &actual_type_of_self)
}
fn match_borrow_depth(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
- match (&lhs.kind, &rhs.kind) {
+ match (&lhs.kind(), &rhs.kind()) {
(ty::Ref(_, t1, mut1), ty::Ref(_, t2, mut2)) => mut1 == mut2 && match_borrow_depth(&t1, &t2),
- (l, r) => match (l, r) {
- (ty::Ref(_, _, _), _) | (_, ty::Ref(_, _, _)) => false,
- (_, _) => true,
- },
+ (l, r) => !matches!((l, r), (ty::Ref(_, _, _), _) | (_, ty::Ref(_, _, _))),
}
}
fn match_types(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
- match (&lhs.kind, &rhs.kind) {
+ match (&lhs.kind(), &rhs.kind()) {
(ty::Bool, ty::Bool)
| (ty::Char, ty::Char)
| (ty::Int(_), ty::Int(_))
}
}
-fn get_type_name(cx: &LateContext<'_, '_>, ty: Ty<'_>) -> String {
- match ty.kind {
+fn get_type_name(cx: &LateContext<'_>, ty: Ty<'_>) -> String {
+ match ty.kind() {
ty::Adt(t, _) => cx.tcx.def_path_str(t.did),
ty::Ref(_, r, _) => get_type_name(cx, &r),
_ => ty.to_string(),
}
fn compare_inputs(
- closure_inputs: &mut dyn Iterator<Item = &Param>,
- call_args: &mut dyn Iterator<Item = &Expr>,
+ closure_inputs: &mut dyn Iterator<Item = &Param<'_>>,
+ call_args: &mut dyn Iterator<Item = &Expr<'_>>,
) -> bool {
for (closure_input, function_arg) in closure_inputs.zip(call_args) {
if let PatKind::Binding(_, _, ident, _) = closure_input.pat.kind {
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