-use crate::utils::{is_adjusted, iter_input_pats, snippet_opt, span_lint_and_then, type_is_unsafe_function};
use if_chain::if_chain;
-use rustc::hir::*;
-use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, LintPass};
-use rustc::ty;
-use rustc::{declare_tool_lint, lint_array};
+use matches::matches;
+use rustc::lint::in_external_macro;
+use rustc::ty::{self, Ty};
use rustc_errors::Applicability;
+use rustc_hir::*;
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+
+use crate::utils::{
+ implements_trait, is_adjusted, iter_input_pats, snippet_opt, span_lint_and_then, type_is_unsafe_function,
+};
-pub struct EtaPass;
-
-/// **What it does:** Checks for closures which just call another function where
-/// the function can be called directly. `unsafe` functions or calls where types
-/// get adjusted are ignored.
-///
-/// **Why is this bad?** Needlessly creating a closure adds code for no benefit
-/// and gives the optimizer more work.
-///
-/// **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 https://github.com/rust-lang/rust-clippy/issues/1439 for more
-/// details.
-///
-/// **Example:**
-/// ```rust
-/// xs.map(|x| foo(x))
-/// ```
-/// where `foo(_)` is a plain function that takes the exact argument type of
-/// `x`.
declare_clippy_lint! {
+ /// **What it does:** Checks for closures which just call another function where
+ /// the function can be called directly. `unsafe` functions or calls where types
+ /// get adjusted are ignored.
+ ///
+ /// **Why is this bad?** Needlessly creating a closure adds code for no benefit
+ /// and gives the optimizer more work.
+ ///
+ /// **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.
+ ///
+ /// **Example:**
+ /// ```rust,ignore
+ /// xs.map(|x| foo(x))
+ /// ```
+ /// where `foo(_)` is a plain function that takes the exact argument type of
+ /// `x`.
pub REDUNDANT_CLOSURE,
style,
- "redundant closures, i.e. `|a| foo(a)` (which can be written as just `foo`)"
+ "redundant closures, i.e., `|a| foo(a)` (which can be written as just `foo`)"
}
-impl LintPass for EtaPass {
- fn get_lints(&self) -> LintArray {
- lint_array!(REDUNDANT_CLOSURE)
- }
-
- fn name(&self) -> &'static str {
- "EtaReduction"
- }
+declare_clippy_lint! {
+ /// **What it does:** Checks for closures which only invoke a method on the closure
+ /// argument and can be replaced by referencing the method directly.
+ ///
+ /// **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
+ ///
+ ///
+ /// **Example:**
+ /// ```rust,ignore
+ /// Some('a').map(|s| s.to_uppercase());
+ /// ```
+ /// may be rewritten as
+ /// ```rust,ignore
+ /// Some('a').map(char::to_uppercase);
+ /// ```
+ pub REDUNDANT_CLOSURE_FOR_METHOD_CALLS,
+ pedantic,
+ "redundant closures for method calls"
}
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EtaPass {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
+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<'_>) {
if in_external_macro(cx.sess(), expr.span) {
return;
}
- match expr.node {
- ExprKind::Call(_, ref args) | ExprKind::MethodCall(_, _, ref args) => {
+ match expr.kind {
+ ExprKind::Call(_, args) | ExprKind::MethodCall(_, _, args) => {
for arg in args {
check_closure(cx, arg)
}
}
}
-fn check_closure(cx: &LateContext<'_, '_>, expr: &Expr) {
- if let ExprKind::Closure(_, ref decl, eid, _, _) = expr.node {
+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_chain!(
- if let ExprKind::Call(ref caller, ref args) = ex.node;
+ if let ExprKind::Call(ref caller, ref args) = ex.kind;
+
+ if let ExprKind::Path(_) = caller.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();
if !(is_adjusted(cx, ex) || args.iter().any(|arg| is_adjusted(cx, arg)));
let fn_ty = cx.tables.expr_ty(caller);
+
+ 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| {
);
if_chain!(
- if let ExprKind::MethodCall(ref path, _, ref args) = ex.node;
+ 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_defs()[ex.hir_id].def_id();
+ let method_def_id = cx.tables.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, expr.span, "redundant closure found", |db| {
+ 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",
}
/// 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> {
- let expected_type_of_self = &cx.tcx.fn_sig(method_def_id).inputs_and_output().skip_binder()[0].sty;
- let actual_type_of_self = &cx.tables.node_type(self_arg.hir_id).sty;
+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);
if let Some(trait_id) = cx.tcx.trait_of_item(method_def_id) {
- //if the method expectes &self, ufcs requires explicit borrowing so closure can't be removed
- return match (expected_type_of_self, actual_type_of_self) {
- (ty::Ref(_, _, _), ty::Ref(_, _, _)) => Some(cx.tcx.item_path_str(trait_id)),
- (l, r) => match (l, r) {
- (ty::Ref(_, _, _), _) | (_, ty::Ref(_, _, _)) => None,
- (_, _) => Some(cx.tcx.item_path_str(trait_id)),
- },
- };
+ if match_borrow_depth(expected_type_of_self, &actual_type_of_self)
+ && implements_trait(cx, actual_type_of_self, trait_id, &[])
+ {
+ return Some(cx.tcx.def_path_str(trait_id));
+ }
}
cx.tcx.impl_of_method(method_def_id).and_then(|_| {
- //a type may implicitly implement other types methods (e.g. Deref)
- if match_types(expected_type_of_self, actual_type_of_self) {
+ //a type may implicitly implement other type's methods (e.g. Deref)
+ if match_types(expected_type_of_self, &actual_type_of_self) {
return Some(get_type_name(cx, &actual_type_of_self));
}
None
})
}
-fn match_types(lhs: &ty::TyKind<'_>, rhs: &ty::TyKind<'_>) -> bool {
- match (lhs, rhs) {
+fn match_borrow_depth(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
+ 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,
+ },
+ }
+}
+
+fn match_types(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
+ match (&lhs.kind, &rhs.kind) {
(ty::Bool, ty::Bool)
| (ty::Char, ty::Char)
| (ty::Int(_), ty::Int(_))
| (ty::Uint(_), ty::Uint(_))
| (ty::Str, ty::Str) => true,
- (ty::Ref(_, t1, _), ty::Ref(_, t2, _))
- | (ty::Array(t1, _), ty::Array(t2, _))
- | (ty::Slice(t1), ty::Slice(t2)) => match_types(&t1.sty, &t2.sty),
+ (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),
(ty::Adt(def1, _), ty::Adt(def2, _)) => def1 == def2,
(_, _) => false,
}
}
-fn get_type_name(cx: &LateContext<'_, '_>, kind: &ty::TyKind<'_>) -> String {
- match kind {
- ty::Adt(t, _) => cx.tcx.item_path_str(t.did),
- ty::Ref(_, r, _) => get_type_name(cx, &r.sty),
- _ => kind.to_string(),
+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 = &Arg>, call_args: &mut dyn Iterator<Item = &Expr>) -> bool {
+fn compare_inputs(
+ 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.node {
+ if let PatKind::Binding(_, _, ident, _) = closure_input.pat.kind {
// XXXManishearth Should I be checking the binding mode here?
- if let ExprKind::Path(QPath::Resolved(None, ref p)) = function_arg.node {
+ if let ExprKind::Path(QPath::Resolved(None, ref p)) = function_arg.kind {
if p.segments.len() != 1 {
// If it's a proper path, it can't be a local variable
return false;
projects / rust.git / blobdiff