-use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use crate::rustc::{declare_tool_lint, lint_array};
-use crate::rustc::ty;
-use crate::rustc::hir::*;
-use crate::utils::{is_adjusted, iter_input_pats, snippet_opt, span_lint_and_then};
-use crate::rustc_errors::Applicability;
-
-#[allow(missing_copy_implementations)]
-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-nursery/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`.
+use if_chain::if_chain;
+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::{is_adjusted, iter_input_pats, snippet_opt, span_lint_and_then, type_is_unsafe_function};
+
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)
- }
-}
+declare_lint_pass!(EtaReduction => [REDUNDANT_CLOSURE]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EtaPass {
+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) => for arg in args {
- check_closure(cx, arg)
+ ExprKind::Call(_, ref args) | ExprKind::MethodCall(_, _, ref 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 {
- let body = cx.tcx.hir.body(eid);
+ let body = cx.tcx.hir().body(eid);
let ex = &body.value;
- if let ExprKind::Call(ref caller, ref args) = ex.node {
- if args.len() != decl.inputs.len() {
- // Not the same number of arguments, there
- // is no way the closure is the same as the function
- return;
- }
- if is_adjusted(cx, ex) || args.iter().any(|arg| is_adjusted(cx, arg)) {
- // Are the expression or the arguments type-adjusted? Then we need the closure
- return;
- }
+
+ if_chain!(
+ if let ExprKind::Call(ref caller, ref args) = ex.node;
+
+ // 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)));
+
let fn_ty = cx.tables.expr_ty(caller);
- match fn_ty.sty {
- // Is it an unsafe function? They don't implement the closure traits
- ty::FnDef(..) | ty::FnPtr(_) => {
- let sig = fn_ty.fn_sig(cx.tcx);
- if sig.skip_binder().unsafety == Unsafety::Unsafe || sig.skip_binder().output().sty == ty::Never {
- return;
- }
- },
- _ => (),
- }
- for (a1, a2) in iter_input_pats(decl, body).zip(args) {
- if let PatKind::Binding(_, _, ident, _) = a1.pat.node {
- // XXXManishearth Should I be checking the binding mode here?
- if let ExprKind::Path(QPath::Resolved(None, ref p)) = a2.node {
- if p.segments.len() != 1 {
- // If it's a proper path, it can't be a local variable
- return;
- }
- if p.segments[0].ident.name != ident.name {
- // The two idents should be the same
- return;
- }
- } else {
- return;
+ if !type_is_unsafe_function(cx, fn_ty);
+
+ if compare_inputs(&mut iter_input_pats(decl, body), &mut args.into_iter());
+
+ then {
+ span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure found", |db| {
+ if let Some(snippet) = snippet_opt(cx, caller.span) {
+ db.span_suggestion(
+ expr.span,
+ "remove closure as shown",
+ snippet,
+ Applicability::MachineApplicable,
+ );
}
- } else {
- return;
- }
+ });
}
- span_lint_and_then(cx, REDUNDANT_CLOSURE, expr.span, "redundant closure found", |db| {
- if let Some(snippet) = snippet_opt(cx, caller.span) {
- db.span_suggestion_with_applicability(
+ );
+
+ if_chain!(
+ if let ExprKind::MethodCall(ref path, _, ref args) = ex.node;
+
+ // 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();
+ 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 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| {
+ db.span_suggestion(
expr.span,
"remove closure as shown",
- snippet,
- Applicability::Unspecified,
+ 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> {
+ 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 match_borrow_depth(expected_type_of_self, &actual_type_of_self) {
+ 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 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_borrow_depth(lhs: Ty<'_>, rhs: Ty<'_>) -> bool {
+ match (&lhs.sty, &rhs.sty) {
+ (ty::Ref(_, t1, _), ty::Ref(_, t2, _)) => 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.sty, &rhs.sty) {
+ (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, t2),
+ (ty::Adt(def1, _), ty::Adt(def2, _)) => def1 == def2,
+ (_, _) => false,
+ }
+}
+
+fn get_type_name(cx: &LateContext<'_, '_>, ty: Ty<'_>) -> String {
+ match ty.sty {
+ 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 {
+ for (closure_input, function_arg) in closure_inputs.zip(call_args) {
+ if let PatKind::Binding(_, _, ident, _) = closure_input.pat.node {
+ // XXXManishearth Should I be checking the binding mode here?
+ if let ExprKind::Path(QPath::Resolved(None, ref p)) = function_arg.node {
+ if p.segments.len() != 1 {
+ // If it's a proper path, it can't be a local variable
+ return false;
}
- });
+ if p.segments[0].ident.name != ident.name {
+ // The two idents should be the same
+ return false;
+ }
+ } else {
+ return false;
+ }
+ } else {
+ return false;
}
}
+ true
}
projects / rust.git / blobdiff