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Auto merge of #125507 - compiler-errors:type-length-limit, r=lcnr

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Re-implement a type-size based limit

r? lcnr

This PR reintroduces the type length limit added in #37789, which was accidentally made practically useless by the caching changes to `Ty::walk` in #72412, which caused the `walk` function to no longer walk over identical elements.

Hitting this length limit is not fatal unless we are in codegen -- so it shouldn't affect passes like the mir inliner which creates potentially very large types (which we observed, for example, when the new trait solver compiles `itertools` in `--release` mode).

This also increases the type length limit from `1048576 == 2 ** 20` to `2 ** 24`, which covers all of the code that can be reached with craterbot-check. Individual crates can increase the length limit further if desired.

Perf regression is mild and I think we should accept it -- reinstating this limit is important for the new trait solver and to make sure we don't accidentally hit more type-size related regressions in the future.

Fixes #125460
This commit is contained in:
bors 2024-07-03 11:56:36 +00:00
commit c872a1418a
54 changed files with 360 additions and 268 deletions
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4
compiler/rustc_ty_utils/src/instance.rs
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@ -16,7 +16,7 @@ use traits::{translate_args, Reveal};
use crate::errors::UnexpectedFnPtrAssociatedItem;
fn resolve_instance<'tcx>(
fn resolve_instance_raw<'tcx>(
tcx: TyCtxt<'tcx>,
key: ty::ParamEnvAnd<'tcx, (DefId, GenericArgsRef<'tcx>)>,
) -> Result<Option<Instance<'tcx>>, ErrorGuaranteed> {
@ -364,5 +364,5 @@ fn resolve_associated_item<'tcx>(
}
pub(crate) fn provide(providers: &mut Providers) {
*providers = Providers { resolve_instance, ..*providers };
*providers = Providers { resolve_instance_raw, ..*providers };
}