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Rollup merge of #133610 - camelid:move-from_anon_const, r=BoxyUwU

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Move `Const::{from_anon_const,try_from_lit}` to hir_ty_lowering

Fixes #128176.
This accomplishes one of the followup items from #131081.

These operations are much more about lowering the HIR than about
`Const`s themselves. They fit better in hir_ty_lowering with
`lower_const_arg` (formerly `Const::from_const_arg`) and the rest.

To accomplish this, `const_evaluatable_predicates_of` had to be changed
to not use `from_anon_const` anymore. Instead of visiting the HIR and
lowering anon consts on the fly, it now visits the `rustc_middle::ty`
data structures instead and directly looks for `UnevaluatedConst`s. This
approach was proposed in:
https://github.com/rust-lang/rust/pull/131081#discussion_r1821189257

r? `@BoxyUwU`
This commit is contained in:
Guillaume Gomez 2024-12-02 23:08:54 +01:00 • committed by GitHub
commit 6f0d15a144
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11 changed files with 245 additions and 168 deletions
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21
compiler/rustc_hir_analysis/src/check/wfcheck.rs
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@ -13,6 +13,7 @@ use rustc_hir::lang_items::LangItem;
use rustc_infer::infer::outlives::env::OutlivesEnvironment;
use rustc_infer::infer::{self, InferCtxt, TyCtxtInferExt};
use rustc_macros::LintDiagnostic;
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::query::Providers;
use rustc_middle::ty::print::with_no_trimmed_paths;
use rustc_middle::ty::trait_def::TraitSpecializationKind;
@ -1170,19 +1171,13 @@ fn check_type_defn<'tcx>(
// Explicit `enum` discriminant values must const-evaluate successfully.
if let ty::VariantDiscr::Explicit(discr_def_id) = variant.discr {
let cause = traits::ObligationCause::new(
tcx.def_span(discr_def_id),
wfcx.body_def_id,
ObligationCauseCode::Misc,
);
wfcx.register_obligation(Obligation::new(
tcx,
cause,
wfcx.param_env,
ty::Binder::dummy(ty::PredicateKind::Clause(ty::ClauseKind::ConstEvaluatable(
ty::Const::from_anon_const(tcx, discr_def_id.expect_local()),
))),
));
match tcx.const_eval_poly(discr_def_id) {
Ok(_) => {}
Err(ErrorHandled::Reported(..)) => {}
Err(ErrorHandled::TooGeneric(sp)) => {
span_bug!(sp, "enum variant discr was too generic to eval")
}
}
}
}