From d0ae7cf62d540027e6e6289c61ed2f8452bbd3ba Mon Sep 17 00:00:00 2001 From: Nilstrieb <48135649+Nilstrieb@users.noreply.github.com> Date: Wed, 22 Mar 2023 22:12:19 +0100 Subject: [PATCH 1/2] Cache `has_sig_drop_attr` for `significant_drop_tightening` The lint is very slow as it doesn't cache the deeply nested check for the attribute. If we cache it, we can reduce the time spent on checking `rustc_borrowck` from 28s to 9s, which is a nice improvement. In the profile, the time inside `has_sig_drop_attr` goes from 66% to 0.2%, which is a lot more reasonable. See the PR for nice graphs. --- .../src/significant_drop_tightening.rs | 38 +++++++++++++++---- 1 file changed, 31 insertions(+), 7 deletions(-) diff --git a/src/tools/clippy/clippy_lints/src/significant_drop_tightening.rs b/src/tools/clippy/clippy_lints/src/significant_drop_tightening.rs index e2d90edec5a4c..c3e99aa0055ab 100644 --- a/src/tools/clippy/clippy_lints/src/significant_drop_tightening.rs +++ b/src/tools/clippy/clippy_lints/src/significant_drop_tightening.rs @@ -1,9 +1,9 @@ -use crate::FxHashSet; use clippy_utils::{ diagnostics::span_lint_and_then, get_attr, source::{indent_of, snippet}, }; +use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_errors::{Applicability, Diagnostic}; use rustc_hir::{ self as hir, @@ -58,6 +58,7 @@ impl_lint_pass!(SignificantDropTightening<'_> => [SIGNIFICANT_DROP_TIGHTENING]); pub struct SignificantDropTightening<'tcx> { /// Auxiliary structure used to avoid having to verify the same type multiple times. seen_types: FxHashSet<Ty<'tcx>>, + type_cache: FxHashMap<Ty<'tcx>, bool>, } impl<'tcx> SignificantDropTightening<'tcx> { @@ -118,7 +119,7 @@ impl<'tcx> SignificantDropTightening<'tcx> { stmt: &hir::Stmt<'_>, cb: impl Fn(&mut SigDropAuxParams), ) { - let mut sig_drop_finder = SigDropFinder::new(cx, &mut self.seen_types); + let mut sig_drop_finder = SigDropFinder::new(cx, &mut self.seen_types, &mut self.type_cache); sig_drop_finder.visit_expr(expr); if sig_drop_finder.has_sig_drop { cb(sdap); @@ -296,15 +297,24 @@ impl Default for SigDropAuxParams { struct SigDropChecker<'cx, 'sdt, 'tcx> { cx: &'cx LateContext<'tcx>, seen_types: &'sdt mut FxHashSet<Ty<'tcx>>, + type_cache: &'sdt mut FxHashMap<Ty<'tcx>, bool>, } impl<'cx, 'sdt, 'tcx> SigDropChecker<'cx, 'sdt, 'tcx> { - pub(crate) fn new(cx: &'cx LateContext<'tcx>, seen_types: &'sdt mut FxHashSet<Ty<'tcx>>) -> Self { + pub(crate) fn new( + cx: &'cx LateContext<'tcx>, + seen_types: &'sdt mut FxHashSet<Ty<'tcx>>, + type_cache: &'sdt mut FxHashMap<Ty<'tcx>, bool>, + ) -> Self { seen_types.clear(); - Self { cx, seen_types } + Self { + cx, + seen_types, + type_cache, + } } - pub(crate) fn has_sig_drop_attr(&mut self, ty: Ty<'tcx>) -> bool { + pub(crate) fn has_sig_drop_attr_uncached(&mut self, ty: Ty<'tcx>) -> bool { if let Some(adt) = ty.ty_adt_def() { let mut iter = get_attr( self.cx.sess(), @@ -340,6 +350,16 @@ impl<'cx, 'sdt, 'tcx> SigDropChecker<'cx, 'sdt, 'tcx> { } } + pub(crate) fn has_sig_drop_attr(&mut self, ty: Ty<'tcx>) -> bool { + // The borrow checker prevents us from using something fancier like or_insert_with. + if let Some(ty) = self.type_cache.get(&ty) { + return *ty; + } + let value = self.has_sig_drop_attr_uncached(ty); + self.type_cache.insert(ty, value); + value + } + fn has_seen_ty(&mut self, ty: Ty<'tcx>) -> bool { !self.seen_types.insert(ty) } @@ -353,11 +373,15 @@ struct SigDropFinder<'cx, 'sdt, 'tcx> { } impl<'cx, 'sdt, 'tcx> SigDropFinder<'cx, 'sdt, 'tcx> { - fn new(cx: &'cx LateContext<'tcx>, seen_types: &'sdt mut FxHashSet<Ty<'tcx>>) -> Self { + fn new( + cx: &'cx LateContext<'tcx>, + seen_types: &'sdt mut FxHashSet<Ty<'tcx>>, + type_cache: &'sdt mut FxHashMap<Ty<'tcx>, bool>, + ) -> Self { Self { cx, has_sig_drop: false, - sig_drop_checker: SigDropChecker::new(cx, seen_types), + sig_drop_checker: SigDropChecker::new(cx, seen_types, type_cache), } } } From a615440643f7dc1816926d637f0f43cdf9fc38b6 Mon Sep 17 00:00:00 2001 From: Samuel Moelius <sam@moeli.us> Date: Sat, 25 Feb 2023 15:54:31 -0500 Subject: [PATCH 2/2] Handle ambiguous projections --- .../clippy/clippy_lints/src/dereference.rs | 8 ++++---- .../clippy/tests/ui/crashes/ice-rust-107877.rs | 17 +++++++++++++++++ 2 files changed, 21 insertions(+), 4 deletions(-) create mode 100644 src/tools/clippy/tests/ui/crashes/ice-rust-107877.rs diff --git a/src/tools/clippy/clippy_lints/src/dereference.rs b/src/tools/clippy/clippy_lints/src/dereference.rs index 47501980e6640..7f3f26bed7c7d 100644 --- a/src/tools/clippy/clippy_lints/src/dereference.rs +++ b/src/tools/clippy/clippy_lints/src/dereference.rs @@ -1357,10 +1357,10 @@ fn replace_types<'tcx>( && let Some(term_ty) = projection_predicate.term.ty() && let ty::Param(term_param_ty) = term_ty.kind() { - let item_def_id = projection_predicate.projection_ty.def_id; - let assoc_item = cx.tcx.associated_item(item_def_id); - let projection = cx.tcx - .mk_projection(assoc_item.def_id, cx.tcx.mk_substs_trait(new_ty, [])); + let projection = cx.tcx.mk_ty_from_kind(ty::Alias( + ty::Projection, + projection_predicate.projection_ty.with_self_ty(cx.tcx, new_ty), + )); if let Ok(projected_ty) = cx.tcx.try_normalize_erasing_regions(cx.param_env, projection) && substs[term_param_ty.index as usize] != ty::GenericArg::from(projected_ty) diff --git a/src/tools/clippy/tests/ui/crashes/ice-rust-107877.rs b/src/tools/clippy/tests/ui/crashes/ice-rust-107877.rs new file mode 100644 index 0000000000000..7f5bae60d55d9 --- /dev/null +++ b/src/tools/clippy/tests/ui/crashes/ice-rust-107877.rs @@ -0,0 +1,17 @@ +#![allow(dead_code)] + +struct Foo; + +impl<'a> std::convert::TryFrom<&'a String> for Foo { + type Error = std::convert::Infallible; + + fn try_from(_: &'a String) -> Result<Self, Self::Error> { + Ok(Foo) + } +} + +fn find<E>(_: impl std::convert::TryInto<Foo, Error = E>) {} + +fn main() { + find(&String::new()); +}