From 72d17bfebbf5463dac1a7eb71c513b151b523e1f Mon Sep 17 00:00:00 2001 From: David Wood Date: Tue, 18 Mar 2025 03:06:17 +0000 Subject: re-use sized fast path There's an existing fast path for the `type_op_prove_predicate` predicate, checking for trivially `Sized` types, which can be re-used when evaluating obligations within queries. This should improve performance, particularly in anticipation of new sizedness traits being added which can take advantage of this. --- compiler/rustc_middle/src/ty/sty.rs | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'compiler/rustc_middle/src/ty') diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs index 27ee363f1c1..e1708879946 100644 --- a/compiler/rustc_middle/src/ty/sty.rs +++ b/compiler/rustc_middle/src/ty/sty.rs @@ -1872,14 +1872,14 @@ impl<'tcx> Ty<'tcx> { /// Fast path helper for testing if a type is `Sized`. /// - /// Returning true means the type is known to be sized. Returning - /// `false` means nothing -- could be sized, might not be. + /// Returning true means the type is known to implement `Sized`. Returning `false` means + /// nothing -- could be sized, might not be. /// - /// Note that we could never rely on the fact that a type such as `[_]` is - /// trivially `!Sized` because we could be in a type environment with a - /// bound such as `[_]: Copy`. A function with such a bound obviously never - /// can be called, but that doesn't mean it shouldn't typecheck. This is why - /// this method doesn't return `Option`. + /// Note that we could never rely on the fact that a type such as `[_]` is trivially `!Sized` + /// because we could be in a type environment with a bound such as `[_]: Copy`. A function with + /// such a bound obviously never can be called, but that doesn't mean it shouldn't typecheck. + /// This is why this method doesn't return `Option`. + #[instrument(skip(tcx), level = "debug")] pub fn is_trivially_sized(self, tcx: TyCtxt<'tcx>) -> bool { match self.kind() { ty::Infer(ty::IntVar(_) | ty::FloatVar(_)) -- cgit 1.4.1-3-g733a5