2021-03-25 18:29:11 +00:00
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|
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use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
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use clippy_utils::higher::VecArgs;
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use clippy_utils::source::snippet_opt;
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use clippy_utils::ty::{implements_trait, type_is_unsafe_function};
|
2021-07-15 08:44:10 +00:00
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use clippy_utils::usage::UsedAfterExprVisitor;
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use clippy_utils::{get_enclosing_loop_or_closure, higher};
|
2021-03-25 18:29:11 +00:00
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use clippy_utils::{is_adjusted, iter_input_pats};
|
2019-02-10 11:58:51 +00:00
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use if_chain::if_chain;
|
2018-12-29 15:04:45 +00:00
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use rustc_errors::Applicability;
|
2020-02-21 08:39:38 +00:00
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use rustc_hir::{def_id, Expr, ExprKind, Param, PatKind, QPath};
|
2020-01-12 06:08:41 +00:00
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use rustc_lint::{LateContext, LateLintPass, LintContext};
|
2020-03-30 09:02:14 +00:00
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|
use rustc_middle::lint::in_external_macro;
|
2021-07-15 08:44:10 +00:00
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|
|
use rustc_middle::ty::{self, ClosureKind, Ty};
|
2020-01-11 11:37:08 +00:00
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|
use rustc_session::{declare_lint_pass, declare_tool_lint};
|
2015-07-26 14:53:11 +00:00
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|
2018-03-28 13:24:26 +00:00
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|
|
declare_clippy_lint! {
|
2021-07-29 10:16:06 +00:00
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/// ### What it does
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|
|
/// Checks for closures which just call another function where
|
2019-03-05 16:50:33 +00:00
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/// the function can be called directly. `unsafe` functions or calls where types
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/// get adjusted are ignored.
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///
|
2021-07-29 10:16:06 +00:00
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|
|
/// ### Why is this bad?
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|
/// Needlessly creating a closure adds code for no benefit
|
2019-03-05 16:50:33 +00:00
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/// and gives the optimizer more work.
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///
|
2021-07-29 10:16:06 +00:00
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|
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/// ### Known problems
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|
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/// If creating the closure inside the closure has a side-
|
2019-03-05 16:50:33 +00:00
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|
|
/// effect then moving the closure creation out will change when that side-
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/// effect runs.
|
2021-01-15 09:56:44 +00:00
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|
/// See [#1439](https://github.com/rust-lang/rust-clippy/issues/1439) for more details.
|
2019-03-05 16:50:33 +00:00
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///
|
2021-07-29 10:16:06 +00:00
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|
|
/// ### Example
|
2019-03-10 22:01:56 +00:00
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|
/// ```rust,ignore
|
2020-06-09 14:36:01 +00:00
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/// // Bad
|
2019-03-05 16:50:33 +00:00
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/// xs.map(|x| foo(x))
|
2020-06-09 14:36:01 +00:00
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|
///
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/// // Good
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/// xs.map(foo)
|
2019-03-05 16:50:33 +00:00
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|
/// ```
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/// where `foo(_)` is a plain function that takes the exact argument type of
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/// `x`.
|
2016-08-06 08:18:36 +00:00
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pub REDUNDANT_CLOSURE,
|
2018-03-28 13:24:26 +00:00
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|
style,
|
2019-01-31 01:15:29 +00:00
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|
"redundant closures, i.e., `|a| foo(a)` (which can be written as just `foo`)"
|
2016-02-05 23:13:29 +00:00
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|
|
}
|
2015-05-10 05:09:04 +00:00
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|
2019-05-16 06:25:39 +00:00
|
|
|
declare_clippy_lint! {
|
2021-07-29 10:16:06 +00:00
|
|
|
/// ### What it does
|
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|
|
/// Checks for closures which only invoke a method on the closure
|
2019-05-16 06:25:39 +00:00
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|
/// argument and can be replaced by referencing the method directly.
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///
|
2021-07-29 10:16:06 +00:00
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|
|
/// ### Why is this bad?
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|
/// It's unnecessary to create the closure.
|
2019-05-16 06:25:39 +00:00
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///
|
2021-07-29 10:16:06 +00:00
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|
|
/// ### Known problems
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|
|
/// [#3071](https://github.com/rust-lang/rust-clippy/issues/3071),
|
2021-01-15 09:56:44 +00:00
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|
/// [#3942](https://github.com/rust-lang/rust-clippy/issues/3942),
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|
/// [#4002](https://github.com/rust-lang/rust-clippy/issues/4002)
|
2019-05-16 16:43:07 +00:00
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///
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///
|
2021-07-29 10:16:06 +00:00
|
|
|
/// ### Example
|
2019-05-16 06:25:39 +00:00
|
|
|
/// ```rust,ignore
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|
/// Some('a').map(|s| s.to_uppercase());
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|
|
/// ```
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|
|
|
/// may be rewritten as
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|
|
|
/// ```rust,ignore
|
|
|
|
/// Some('a').map(char::to_uppercase);
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|
|
/// ```
|
2019-05-16 16:18:15 +00:00
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|
|
pub REDUNDANT_CLOSURE_FOR_METHOD_CALLS,
|
2019-05-16 06:25:39 +00:00
|
|
|
pedantic,
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"redundant closures for method calls"
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|
}
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|
2019-05-16 16:18:15 +00:00
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|
|
declare_lint_pass!(EtaReduction => [REDUNDANT_CLOSURE, REDUNDANT_CLOSURE_FOR_METHOD_CALLS]);
|
2015-05-10 05:09:04 +00:00
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|
2020-06-25 20:41:36 +00:00
|
|
|
impl<'tcx> LateLintPass<'tcx> for EtaReduction {
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|
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
|
2019-02-25 12:40:28 +00:00
|
|
|
if in_external_macro(cx.sess(), expr.span) {
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|
|
return;
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|
|
}
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|
2019-09-27 15:16:06 +00:00
|
|
|
match expr.kind {
|
2020-06-09 21:44:04 +00:00
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|
ExprKind::Call(_, args) | ExprKind::MethodCall(_, _, args, _) => {
|
2018-11-27 20:14:15 +00:00
|
|
|
for arg in args {
|
2021-03-12 14:30:50 +00:00
|
|
|
// skip `foo(macro!())`
|
|
|
|
if arg.span.ctxt() == expr.span.ctxt() {
|
2021-06-03 06:41:37 +00:00
|
|
|
check_closure(cx, arg);
|
2021-03-12 14:30:50 +00:00
|
|
|
}
|
2018-11-27 20:14:15 +00:00
|
|
|
}
|
2016-12-20 17:21:30 +00:00
|
|
|
},
|
2015-08-14 12:21:05 +00:00
|
|
|
_ => (),
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|
|
|
}
|
|
|
|
}
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|
|
|
}
|
|
|
|
|
2021-07-15 08:44:10 +00:00
|
|
|
fn check_closure<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
|
2021-04-08 15:50:13 +00:00
|
|
|
if let ExprKind::Closure(_, decl, eid, _, _) = expr.kind {
|
2018-12-08 00:56:03 +00:00
|
|
|
let body = cx.tcx.hir().body(eid);
|
2017-01-04 23:48:34 +00:00
|
|
|
let ex = &body.value;
|
2019-02-10 11:58:51 +00:00
|
|
|
|
2021-03-12 14:30:50 +00:00
|
|
|
if ex.span.ctxt() != expr.span.ctxt() {
|
2021-06-03 06:41:37 +00:00
|
|
|
if decl.inputs.is_empty() {
|
|
|
|
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,
|
|
|
|
);
|
|
|
|
}
|
2021-03-12 14:30:50 +00:00
|
|
|
}
|
|
|
|
// skip `foo(|| macro!())`
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
2019-02-10 11:58:51 +00:00
|
|
|
if_chain!(
|
2021-04-08 15:50:13 +00:00
|
|
|
if let ExprKind::Call(caller, args) = ex.kind;
|
2019-02-10 11:58:51 +00:00
|
|
|
|
2019-09-27 15:16:06 +00:00
|
|
|
if let ExprKind::Path(_) = caller.kind;
|
2019-06-10 09:22:33 +00:00
|
|
|
|
2019-02-10 11:58:51 +00:00
|
|
|
// 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().any(|arg| is_adjusted(cx, arg)));
|
|
|
|
|
2020-07-17 08:47:04 +00:00
|
|
|
let fn_ty = cx.typeck_results().expr_ty(caller);
|
2019-03-31 12:10:17 +00:00
|
|
|
|
2020-08-03 22:18:29 +00:00
|
|
|
if matches!(fn_ty.kind(), ty::FnDef(_, _) | ty::FnPtr(_) | ty::Closure(_, _));
|
2019-03-31 12:10:17 +00:00
|
|
|
|
2019-02-10 11:58:51 +00:00
|
|
|
if !type_is_unsafe_function(cx, fn_ty);
|
|
|
|
|
2019-12-27 07:12:26 +00:00
|
|
|
if compare_inputs(&mut iter_input_pats(decl, body), &mut args.iter());
|
2019-02-10 11:58:51 +00:00
|
|
|
|
|
|
|
then {
|
2021-03-12 14:30:50 +00:00
|
|
|
span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure", |diag| {
|
2021-07-15 08:44:10 +00:00
|
|
|
if let Some(mut snippet) = snippet_opt(cx, caller.span) {
|
|
|
|
if_chain! {
|
|
|
|
if let ty::Closure(_, substs) = fn_ty.kind();
|
|
|
|
if let ClosureKind::FnMut = substs.as_closure().kind();
|
|
|
|
if UsedAfterExprVisitor::is_found(cx, caller)
|
|
|
|
|| get_enclosing_loop_or_closure(cx.tcx, expr).is_some();
|
|
|
|
|
|
|
|
then {
|
|
|
|
// Mutable closure is used after current expr; we cannot consume it.
|
|
|
|
snippet = format!("&mut {}", snippet);
|
|
|
|
}
|
|
|
|
}
|
2020-04-17 06:08:00 +00:00
|
|
|
diag.span_suggestion(
|
2019-02-10 11:58:51 +00:00
|
|
|
expr.span,
|
2021-03-12 14:30:50 +00:00
|
|
|
"replace the closure with the function itself",
|
2019-02-10 11:58:51 +00:00
|
|
|
snippet,
|
|
|
|
Applicability::MachineApplicable,
|
|
|
|
);
|
2016-11-16 20:57:56 +00:00
|
|
|
}
|
2019-02-10 11:58:51 +00:00
|
|
|
});
|
2016-11-16 20:57:56 +00:00
|
|
|
}
|
2019-02-10 11:58:51 +00:00
|
|
|
);
|
|
|
|
|
|
|
|
if_chain!(
|
2021-04-08 15:50:13 +00:00
|
|
|
if let ExprKind::MethodCall(path, _, args, _) = ex.kind;
|
2019-02-10 11:58:51 +00:00
|
|
|
|
|
|
|
// 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)));
|
|
|
|
|
2020-07-17 08:47:04 +00:00
|
|
|
let method_def_id = cx.typeck_results().type_dependent_def_id(ex.hir_id).unwrap();
|
2019-02-10 11:58:51 +00:00
|
|
|
if !type_is_unsafe_function(cx, cx.tcx.type_of(method_def_id));
|
|
|
|
|
2019-12-27 07:12:26 +00:00
|
|
|
if compare_inputs(&mut iter_input_pats(decl, body), &mut args.iter());
|
2019-02-10 11:58:51 +00:00
|
|
|
|
|
|
|
if let Some(name) = get_ufcs_type_name(cx, method_def_id, &args[0]);
|
|
|
|
|
|
|
|
then {
|
2020-04-17 14:01:25 +00:00
|
|
|
span_lint_and_sugg(
|
|
|
|
cx,
|
|
|
|
REDUNDANT_CLOSURE_FOR_METHOD_CALLS,
|
|
|
|
expr.span,
|
2021-03-12 14:30:50 +00:00
|
|
|
"redundant closure",
|
|
|
|
"replace the closure with the method itself",
|
2020-04-17 14:01:25 +00:00
|
|
|
format!("{}::{}", name, path.ident.name),
|
|
|
|
Applicability::MachineApplicable,
|
|
|
|
);
|
2019-02-10 11:58:51 +00:00
|
|
|
}
|
|
|
|
);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/// Tries to determine the type for universal function call to be used instead of the closure
|
2020-06-25 20:41:36 +00:00
|
|
|
fn get_ufcs_type_name(cx: &LateContext<'_>, method_def_id: def_id::DefId, self_arg: &Expr<'_>) -> Option<String> {
|
2019-03-15 22:44:42 +00:00
|
|
|
let expected_type_of_self = &cx.tcx.fn_sig(method_def_id).inputs_and_output().skip_binder()[0];
|
2020-07-17 08:47:04 +00:00
|
|
|
let actual_type_of_self = &cx.typeck_results().node_type(self_arg.hir_id);
|
2019-02-10 11:58:51 +00:00
|
|
|
|
|
|
|
if let Some(trait_id) = cx.tcx.trait_of_item(method_def_id) {
|
2021-04-08 15:50:13 +00:00
|
|
|
if match_borrow_depth(expected_type_of_self, actual_type_of_self)
|
2019-06-09 11:24:34 +00:00
|
|
|
&& implements_trait(cx, actual_type_of_self, trait_id, &[])
|
|
|
|
{
|
2019-03-15 22:43:42 +00:00
|
|
|
return Some(cx.tcx.def_path_str(trait_id));
|
2019-02-26 11:12:27 +00:00
|
|
|
}
|
2019-02-10 11:58:51 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
cx.tcx.impl_of_method(method_def_id).and_then(|_| {
|
2019-02-26 11:12:27 +00:00
|
|
|
//a type may implicitly implement other type's methods (e.g. Deref)
|
2021-04-08 15:50:13 +00:00
|
|
|
if match_types(expected_type_of_self, actual_type_of_self) {
|
2021-06-03 06:41:37 +00:00
|
|
|
Some(get_type_name(cx, actual_type_of_self))
|
|
|
|
} else {
|
|
|
|
None
|
2019-02-10 11:58:51 +00:00
|
|
|
}
|
|
|
|
})
|
|
|
|
}
|
|
|
|
|
2019-03-18 11:43:10 +00:00
|
|
|
fn match_borrow_depth(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
|
2020-08-03 22:18:29 +00:00
|
|
|
match (&lhs.kind(), &rhs.kind()) {
|
2021-04-08 15:50:13 +00:00
|
|
|
(ty::Ref(_, t1, mut1), ty::Ref(_, t2, mut2)) => mut1 == mut2 && match_borrow_depth(t1, t2),
|
2020-07-14 12:59:59 +00:00
|
|
|
(l, r) => !matches!((l, r), (ty::Ref(_, _, _), _) | (_, ty::Ref(_, _, _))),
|
2019-02-26 11:12:27 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2019-03-18 11:43:10 +00:00
|
|
|
fn match_types(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
|
2020-08-03 22:18:29 +00:00
|
|
|
match (&lhs.kind(), &rhs.kind()) {
|
2019-02-10 11:58:51 +00:00
|
|
|
(ty::Bool, ty::Bool)
|
|
|
|
| (ty::Char, ty::Char)
|
|
|
|
| (ty::Int(_), ty::Int(_))
|
|
|
|
| (ty::Uint(_), ty::Uint(_))
|
|
|
|
| (ty::Str, ty::Str) => true,
|
2019-06-09 11:24:34 +00:00
|
|
|
(ty::Ref(_, t1, mut1), ty::Ref(_, t2, mut2)) => mut1 == mut2 && match_types(t1, t2),
|
|
|
|
(ty::Array(t1, _), ty::Array(t2, _)) | (ty::Slice(t1), ty::Slice(t2)) => match_types(t1, t2),
|
2019-02-10 11:58:51 +00:00
|
|
|
(ty::Adt(def1, _), ty::Adt(def2, _)) => def1 == def2,
|
|
|
|
(_, _) => false,
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2020-06-25 20:41:36 +00:00
|
|
|
fn get_type_name(cx: &LateContext<'_>, ty: Ty<'_>) -> String {
|
2020-08-03 22:18:29 +00:00
|
|
|
match ty.kind() {
|
2019-03-15 22:43:42 +00:00
|
|
|
ty::Adt(t, _) => cx.tcx.def_path_str(t.did),
|
2021-04-08 15:50:13 +00:00
|
|
|
ty::Ref(_, r, _) => get_type_name(cx, r),
|
2019-03-15 22:44:42 +00:00
|
|
|
_ => ty.to_string(),
|
2019-02-10 11:58:51 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2019-08-28 09:27:06 +00:00
|
|
|
fn compare_inputs(
|
2019-12-27 07:12:26 +00:00
|
|
|
closure_inputs: &mut dyn Iterator<Item = &Param<'_>>,
|
|
|
|
call_args: &mut dyn Iterator<Item = &Expr<'_>>,
|
2019-08-28 09:27:06 +00:00
|
|
|
) -> bool {
|
2019-02-10 11:58:51 +00:00
|
|
|
for (closure_input, function_arg) in closure_inputs.zip(call_args) {
|
2019-09-27 15:16:06 +00:00
|
|
|
if let PatKind::Binding(_, _, ident, _) = closure_input.pat.kind {
|
2019-02-10 11:58:51 +00:00
|
|
|
// XXXManishearth Should I be checking the binding mode here?
|
2021-04-08 15:50:13 +00:00
|
|
|
if let ExprKind::Path(QPath::Resolved(None, p)) = function_arg.kind {
|
2019-02-10 11:58:51 +00:00
|
|
|
if p.segments.len() != 1 {
|
|
|
|
// If it's a proper path, it can't be a local variable
|
|
|
|
return false;
|
2017-08-09 07:30:56 +00:00
|
|
|
}
|
2019-02-10 11:58:51 +00:00
|
|
|
if p.segments[0].ident.name != ident.name {
|
|
|
|
// The two idents should be the same
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
} else {
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
} else {
|
|
|
|
return false;
|
2015-05-10 05:09:04 +00:00
|
|
|
}
|
|
|
|
}
|
2019-02-10 11:58:51 +00:00
|
|
|
true
|
2015-05-10 05:09:04 +00:00
|
|
|
}
|