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Remove unnecessary res field in for_each_expr visitors #13156

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Jul 25, 2024
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Remove unnecessary res field in for_each_expr visitors #13156

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98 changes: 48 additions & 50 deletions clippy_utils/src/visitors.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
use crate::ty::needs_ordered_drop;
use crate::{get_enclosing_block, path_to_local_id};
use core::ops::ControlFlow;
use rustc_ast::visit::{try_visit, VisitorResult};
use rustc_hir as hir;
use rustc_hir::def::{CtorKind, DefKind, Res};
use rustc_hir::intravisit::{self, walk_block, walk_expr, Visitor};
Expand Down Expand Up @@ -50,44 +51,46 @@ impl Continue for Descend {
/// A type which can be visited.
pub trait Visitable<'tcx> {
/// Calls the corresponding `visit_*` function on the visitor.
fn visit<V: Visitor<'tcx>>(self, visitor: &mut V);
fn visit<V: Visitor<'tcx>>(self, visitor: &mut V) -> V::Result;
}
impl<'tcx, T> Visitable<'tcx> for &'tcx [T]
where
&'tcx T: Visitable<'tcx>,
{
fn visit<V: Visitor<'tcx>>(self, visitor: &mut V) {
fn visit<V: Visitor<'tcx>>(self, visitor: &mut V) -> V::Result {
for x in self {
x.visit(visitor);
try_visit!(x.visit(visitor));
}
V::Result::output()
}
}
impl<'tcx, A, B> Visitable<'tcx> for (A, B)
where
A: Visitable<'tcx>,
B: Visitable<'tcx>,
{
fn visit<V: Visitor<'tcx>>(self, visitor: &mut V) {
fn visit<V: Visitor<'tcx>>(self, visitor: &mut V) -> V::Result {
let (a, b) = self;
a.visit(visitor);
b.visit(visitor);
try_visit!(a.visit(visitor));
b.visit(visitor)
}
}
impl<'tcx, T> Visitable<'tcx> for Option<T>
where
T: Visitable<'tcx>,
{
fn visit<V: Visitor<'tcx>>(self, visitor: &mut V) {
fn visit<V: Visitor<'tcx>>(self, visitor: &mut V) -> V::Result {
if let Some(x) = self {
x.visit(visitor);
try_visit!(x.visit(visitor));
}
V::Result::output()
}
}
macro_rules! visitable_ref {
($t:ident, $f:ident) => {
impl<'tcx> Visitable<'tcx> for &'tcx $t<'tcx> {
fn visit<V: Visitor<'tcx>>(self, visitor: &mut V) {
visitor.$f(self);
fn visit<V: Visitor<'tcx>>(self, visitor: &mut V) -> V::Result {
visitor.$f(self)
}
}
};
Expand All @@ -104,45 +107,37 @@ pub fn for_each_expr_without_closures<'tcx, B, C: Continue>(
node: impl Visitable<'tcx>,
f: impl FnMut(&'tcx Expr<'tcx>) -> ControlFlow<B, C>,
) -> Option<B> {
struct V<B, F> {
struct V<F> {
f: F,
res: Option<B>,
}
impl<'tcx, B, C: Continue, F: FnMut(&'tcx Expr<'tcx>) -> ControlFlow<B, C>> Visitor<'tcx> for V<B, F> {
type Result = ControlFlow<()>;
impl<'tcx, B, C: Continue, F: FnMut(&'tcx Expr<'tcx>) -> ControlFlow<B, C>> Visitor<'tcx> for V<F> {
type Result = ControlFlow<B>;

fn visit_expr(&mut self, e: &'tcx Expr<'tcx>) -> ControlFlow<()> {
if self.res.is_some() {
return ControlFlow::Break(());
}
fn visit_expr(&mut self, e: &'tcx Expr<'tcx>) -> Self::Result {
match (self.f)(e) {
ControlFlow::Continue(c) if c.descend() => walk_expr(self, e),
ControlFlow::Break(b) => {
self.res = Some(b);
ControlFlow::Break(())
},
ControlFlow::Break(b) => ControlFlow::Break(b),
ControlFlow::Continue(_) => ControlFlow::Continue(()),
}
}

// Avoid unnecessary `walk_*` calls.
fn visit_ty(&mut self, _: &'tcx hir::Ty<'tcx>) -> ControlFlow<()> {
fn visit_ty(&mut self, _: &'tcx hir::Ty<'tcx>) -> Self::Result {
ControlFlow::Continue(())
}
fn visit_pat(&mut self, _: &'tcx Pat<'tcx>) -> ControlFlow<()> {
fn visit_pat(&mut self, _: &'tcx Pat<'tcx>) -> Self::Result {
ControlFlow::Continue(())
}
fn visit_qpath(&mut self, _: &'tcx QPath<'tcx>, _: HirId, _: Span) -> ControlFlow<()> {
fn visit_qpath(&mut self, _: &'tcx QPath<'tcx>, _: HirId, _: Span) -> Self::Result {
ControlFlow::Continue(())
}
// Avoid monomorphising all `visit_*` functions.
fn visit_nested_item(&mut self, _: ItemId) -> ControlFlow<()> {
fn visit_nested_item(&mut self, _: ItemId) -> Self::Result {
ControlFlow::Continue(())
}
}
let mut v = V { f, res: None };
node.visit(&mut v);
v.res
let mut v = V { f };
node.visit(&mut v).break_value()
}

/// Calls the given function once for each expression contained. This will enter bodies, but not
Expand All @@ -152,44 +147,47 @@ pub fn for_each_expr<'tcx, B, C: Continue>(
node: impl Visitable<'tcx>,
f: impl FnMut(&'tcx Expr<'tcx>) -> ControlFlow<B, C>,
) -> Option<B> {
struct V<'tcx, B, F> {
struct V<'tcx, F> {
tcx: TyCtxt<'tcx>,
f: F,
res: Option<B>,
}
impl<'tcx, B, C: Continue, F: FnMut(&'tcx Expr<'tcx>) -> ControlFlow<B, C>> Visitor<'tcx> for V<'tcx, B, F> {
impl<'tcx, B, C: Continue, F: FnMut(&'tcx Expr<'tcx>) -> ControlFlow<B, C>> Visitor<'tcx> for V<'tcx, F> {
type NestedFilter = nested_filter::OnlyBodies;
type Result = ControlFlow<B>;

fn nested_visit_map(&mut self) -> Self::Map {
self.tcx.hir()
}

fn visit_expr(&mut self, e: &'tcx Expr<'tcx>) {
if self.res.is_some() {
return;
}
fn visit_expr(&mut self, e: &'tcx Expr<'tcx>) -> Self::Result {
match (self.f)(e) {
ControlFlow::Continue(c) if c.descend() => walk_expr(self, e),
ControlFlow::Break(b) => self.res = Some(b),
ControlFlow::Continue(_) => (),
ControlFlow::Break(b) => ControlFlow::Break(b),
ControlFlow::Continue(_) => ControlFlow::Continue(()),
}
}

// Only walk closures
fn visit_anon_const(&mut self, _: &'tcx AnonConst) {}
fn visit_anon_const(&mut self, _: &'tcx AnonConst) -> Self::Result {
ControlFlow::Continue(())
}
// Avoid unnecessary `walk_*` calls.
fn visit_ty(&mut self, _: &'tcx hir::Ty<'tcx>) {}
fn visit_pat(&mut self, _: &'tcx Pat<'tcx>) {}
fn visit_qpath(&mut self, _: &'tcx QPath<'tcx>, _: HirId, _: Span) {}
fn visit_ty(&mut self, _: &'tcx hir::Ty<'tcx>) -> Self::Result {
ControlFlow::Continue(())
}
fn visit_pat(&mut self, _: &'tcx Pat<'tcx>) -> Self::Result {
ControlFlow::Continue(())
}
fn visit_qpath(&mut self, _: &'tcx QPath<'tcx>, _: HirId, _: Span) -> Self::Result {
ControlFlow::Continue(())
}
// Avoid monomorphising all `visit_*` functions.
fn visit_nested_item(&mut self, _: ItemId) {}
fn visit_nested_item(&mut self, _: ItemId) -> Self::Result {
ControlFlow::Continue(())
}
}
let mut v = V {
tcx: cx.tcx,
f,
res: None,
};
node.visit(&mut v);
v.res
let mut v = V { tcx: cx.tcx, f };
node.visit(&mut v).break_value()
}

/// returns `true` if expr contains match expr desugared from try
Expand Down