From 996a185ba74755cb39a4fe24151ea65e671d4c0d Mon Sep 17 00:00:00 2001 From: Boxy Date: Wed, 12 Mar 2025 11:23:20 +0000 Subject: [PATCH] Introduce `tcx.anon_const_kind` query --- compiler/rustc_hir_analysis/src/collect.rs | 25 +++++++ .../src/collect/generics_of.rs | 71 ++++++++----------- .../src/rmeta/decoder/cstore_impl.rs | 1 + compiler/rustc_metadata/src/rmeta/encoder.rs | 3 + compiler/rustc_metadata/src/rmeta/mod.rs | 1 + compiler/rustc_middle/src/query/erase.rs | 1 + compiler/rustc_middle/src/query/mod.rs | 6 ++ compiler/rustc_middle/src/ty/consts.rs | 10 ++- compiler/rustc_middle/src/ty/mod.rs | 4 +- compiler/rustc_middle/src/ty/parameterized.rs | 1 + .../rustc_trait_selection/src/traits/mod.rs | 9 ++- 11 files changed, 86 insertions(+), 46 deletions(-) diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs index 4520fbe352ce..dfe9d7af3ada 100644 --- a/compiler/rustc_hir_analysis/src/collect.rs +++ b/compiler/rustc_hir_analysis/src/collect.rs @@ -89,6 +89,7 @@ pub(crate) fn provide(providers: &mut Providers) { opaque_ty_origin, rendered_precise_capturing_args, const_param_default, + anon_const_kind, ..*providers }; } @@ -1828,3 +1829,27 @@ fn const_param_default<'tcx>( .lower_const_arg(default_ct, FeedConstTy::Param(def_id.to_def_id(), identity_args)); ty::EarlyBinder::bind(ct) } + +fn anon_const_kind<'tcx>(tcx: TyCtxt<'tcx>, def: LocalDefId) -> ty::AnonConstKind { + let hir_id = tcx.local_def_id_to_hir_id(def); + let const_arg_id = tcx.parent_hir_id(hir_id); + match tcx.hir_node(const_arg_id) { + hir::Node::ConstArg(_) => { + if tcx.features().generic_const_exprs() { + ty::AnonConstKind::GCEConst + } else if tcx.features().min_generic_const_args() { + ty::AnonConstKind::MCGConst + } else if let hir::Node::Expr(hir::Expr { + kind: hir::ExprKind::Repeat(_, repeat_count), + .. + }) = tcx.hir_node(tcx.parent_hir_id(const_arg_id)) + && repeat_count.hir_id == const_arg_id + { + ty::AnonConstKind::RepeatExprCount + } else { + ty::AnonConstKind::MCGConst + } + } + _ => ty::AnonConstKind::NonTypeSystem, + } +} diff --git a/compiler/rustc_hir_analysis/src/collect/generics_of.rs b/compiler/rustc_hir_analysis/src/collect/generics_of.rs index 2bed28d7b710..d261f3f85fe7 100644 --- a/compiler/rustc_hir_analysis/src/collect/generics_of.rs +++ b/compiler/rustc_hir_analysis/src/collect/generics_of.rs @@ -104,19 +104,27 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics { } } - if in_param_ty { - // We do not allow generic parameters in anon consts if we are inside - // of a const parameter type, e.g. `struct Foo` is not allowed. - None - } else if tcx.features().generic_const_exprs() { - let parent_node = tcx.parent_hir_node(hir_id); - debug!(?parent_node); - if let Node::Variant(Variant { disr_expr: Some(constant), .. }) = parent_node - && constant.hir_id == hir_id - { - // enum variant discriminants are not allowed to use any kind of generics - None - } else if let Some(param_id) = tcx.hir_opt_const_param_default_param_def_id(hir_id) + match tcx.anon_const_kind(def_id) { + // Stable: anon consts are not able to use any generic parameters... + ty::AnonConstKind::MCGConst => None, + // we provide generics to repeat expr counts as a backwards compatibility hack. #76200 + ty::AnonConstKind::RepeatExprCount => Some(parent_did), + + // Even GCE anon const should not be allowed to use generic parameters as it would be + // trivially forward declared uses once desugared. E.g. `const N: [u8; ANON::]`. + // + // We could potentially mirror the hack done for defaults of generic parameters but + // this case just doesn't come up much compared to `const N: u32 = ...`. Long term the + // hack for defaulted parameters should be removed eventually anyway. + ty::AnonConstKind::GCEConst if in_param_ty => None, + // GCE anon consts as a default for a generic parameter should have their provided generics + // "truncated" up to whatever generic parameter this anon const is within the default of. + // + // FIXME(generic_const_exprs): This only handles `const N: usize = /*defid*/` but not type + // parameter defaults, e.g. `T = Foo`. + ty::AnonConstKind::GCEConst + if let Some(param_id) = + tcx.hir_opt_const_param_default_param_def_id(hir_id) => { // If the def_id we are calling generics_of on is an anon ct default i.e: // @@ -160,36 +168,17 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics { has_self: generics.has_self, has_late_bound_regions: generics.has_late_bound_regions, }; - } else { - // HACK(eddyb) this provides the correct generics when - // `feature(generic_const_expressions)` is enabled, so that const expressions - // used with const generics, e.g. `Foo<{N+1}>`, can work at all. - // - // Note that we do not supply the parent generics when using - // `min_const_generics`. + } + ty::AnonConstKind::GCEConst => Some(parent_did), + + // Field defaults are allowed to use generic parameters, e.g. `field: u32 = /*defid: N + 1*/` + ty::AnonConstKind::NonTypeSystem + if matches!(tcx.parent_hir_node(hir_id), Node::TyPat(_) | Node::Field(_)) => + { Some(parent_did) } - } else { - let parent_node = tcx.parent_hir_node(hir_id); - let parent_node = match parent_node { - Node::ConstArg(ca) => tcx.parent_hir_node(ca.hir_id), - _ => parent_node, - }; - match parent_node { - // HACK(eddyb) this provides the correct generics for repeat - // expressions' count (i.e. `N` in `[x; N]`), and explicit - // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`), - // as they shouldn't be able to cause query cycle errors. - Node::Expr(Expr { kind: ExprKind::Repeat(_, ct), .. }) - if ct.anon_const_hir_id() == Some(hir_id) => - { - Some(parent_did) - } - Node::TyPat(_) => Some(parent_did), - // Field default values inherit the ADT's generics. - Node::Field(_) => Some(parent_did), - _ => None, - } + // Default to no generic parameters for other kinds of anon consts + ty::AnonConstKind::NonTypeSystem => None, } } Node::ConstBlock(_) diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs index 97d315657336..f40a2374beac 100644 --- a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs +++ b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs @@ -425,6 +425,7 @@ provide! { tcx, def_id, other, cdata, doc_link_traits_in_scope => { tcx.arena.alloc_from_iter(cdata.get_doc_link_traits_in_scope(def_id.index)) } + anon_const_kind => { table } } pub(in crate::rmeta) fn provide(providers: &mut Providers) { diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs index 7ac72ef814a9..3ab989d2d3ba 100644 --- a/compiler/rustc_metadata/src/rmeta/encoder.rs +++ b/compiler/rustc_metadata/src/rmeta/encoder.rs @@ -1569,6 +1569,9 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> { <- tcx.explicit_implied_const_bounds(def_id).skip_binder()); } } + if let DefKind::AnonConst = def_kind { + record!(self.tables.anon_const_kind[def_id] <- self.tcx.anon_const_kind(def_id)); + } if tcx.impl_method_has_trait_impl_trait_tys(def_id) && let Ok(table) = self.tcx.collect_return_position_impl_trait_in_trait_tys(def_id) { diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs index d3d928aa88e5..077835283e96 100644 --- a/compiler/rustc_metadata/src/rmeta/mod.rs +++ b/compiler/rustc_metadata/src/rmeta/mod.rs @@ -480,6 +480,7 @@ define_tables! { doc_link_traits_in_scope: Table>, assumed_wf_types_for_rpitit: Table, Span)>>, opaque_ty_origin: Table>>, + anon_const_kind: Table>, } #[derive(TyEncodable, TyDecodable)] diff --git a/compiler/rustc_middle/src/query/erase.rs b/compiler/rustc_middle/src/query/erase.rs index 5bd111fa2f22..fef1db8799c4 100644 --- a/compiler/rustc_middle/src/query/erase.rs +++ b/compiler/rustc_middle/src/query/erase.rs @@ -311,6 +311,7 @@ trivial! { rustc_middle::ty::Asyncness, rustc_middle::ty::AsyncDestructor, rustc_middle::ty::BoundVariableKind, + rustc_middle::ty::AnonConstKind, rustc_middle::ty::DeducedParamAttrs, rustc_middle::ty::Destructor, rustc_middle::ty::fast_reject::SimplifiedType, diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs index b2133fea08cc..2e8a2bceb38b 100644 --- a/compiler/rustc_middle/src/query/mod.rs +++ b/compiler/rustc_middle/src/query/mod.rs @@ -2586,6 +2586,12 @@ rustc_queries! { desc { "estimating codegen size of `{}`", key } cache_on_disk_if { true } } + + query anon_const_kind(def_id: DefId) -> ty::AnonConstKind { + desc { |tcx| "looking up anon const kind of `{}`", tcx.def_path_str(def_id) } + cache_on_disk_if { def_id.is_local() } + separate_provide_extern + } } rustc_with_all_queries! { define_callbacks! } diff --git a/compiler/rustc_middle/src/ty/consts.rs b/compiler/rustc_middle/src/ty/consts.rs index dc5fe2d8f8b0..f1ea2152f3bd 100644 --- a/compiler/rustc_middle/src/ty/consts.rs +++ b/compiler/rustc_middle/src/ty/consts.rs @@ -2,7 +2,7 @@ use std::borrow::Cow; use rustc_data_structures::intern::Interned; use rustc_error_messages::MultiSpan; -use rustc_macros::HashStable; +use rustc_macros::{HashStable, TyDecodable, TyEncodable}; use rustc_type_ir::walk::TypeWalker; use rustc_type_ir::{self as ir, TypeFlags, WithCachedTypeInfo}; @@ -259,3 +259,11 @@ impl<'tcx> Const<'tcx> { TypeWalker::new(self.into()) } } + +#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable, HashStable)] +pub enum AnonConstKind { + GCEConst, + MCGConst, + RepeatExprCount, + NonTypeSystem, +} diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs index b2a58897c31b..f57329608ef7 100644 --- a/compiler/rustc_middle/src/ty/mod.rs +++ b/compiler/rustc_middle/src/ty/mod.rs @@ -74,8 +74,8 @@ pub use self::closure::{ place_to_string_for_capture, }; pub use self::consts::{ - Const, ConstInt, ConstKind, Expr, ExprKind, ScalarInt, UnevaluatedConst, ValTree, ValTreeKind, - Value, + AnonConstKind, Const, ConstInt, ConstKind, Expr, ExprKind, ScalarInt, UnevaluatedConst, + ValTree, ValTreeKind, Value, }; pub use self::context::{ CtxtInterners, CurrentGcx, DeducedParamAttrs, Feed, FreeRegionInfo, GlobalCtxt, Lift, TyCtxt, diff --git a/compiler/rustc_middle/src/ty/parameterized.rs b/compiler/rustc_middle/src/ty/parameterized.rs index ecd6132b3ef3..3858778bfc8f 100644 --- a/compiler/rustc_middle/src/ty/parameterized.rs +++ b/compiler/rustc_middle/src/ty/parameterized.rs @@ -68,6 +68,7 @@ trivially_parameterized_over_tcx! { ty::AsyncDestructor, ty::AssocItemContainer, ty::Asyncness, + ty::AnonConstKind, ty::DeducedParamAttrs, ty::Destructor, ty::Generics, diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs index 31b075db04b9..e00be6425bc7 100644 --- a/compiler/rustc_trait_selection/src/traits/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/mod.rs @@ -553,7 +553,8 @@ pub fn try_evaluate_const<'tcx>( // // FIXME: `const_eval_resolve_for_typeck` should probably just modify the env itself // instead of having this logic here - let (args, typing_env) = if tcx.features().generic_const_exprs() + let (args, typing_env) = if tcx.def_kind(uv.def) == DefKind::AnonConst + && let ty::AnonConstKind::GCEConst = tcx.anon_const_kind(uv.def) && uv.has_non_region_infer() { // `feature(generic_const_exprs)` causes anon consts to inherit all parent generics. This can cause @@ -582,7 +583,10 @@ pub fn try_evaluate_const<'tcx>( (args, typing_env) } } - } else if tcx.def_kind(uv.def) == DefKind::AnonConst && uv.has_non_region_infer() { + } else if tcx.def_kind(uv.def) == DefKind::AnonConst + && let ty::AnonConstKind::RepeatExprCount = tcx.anon_const_kind(uv.def) + && uv.has_non_region_infer() + { // FIXME: remove this when `const_evaluatable_unchecked` is a hard error. // // Diagnostics will sometimes replace the identity args of anon consts in @@ -599,6 +603,7 @@ pub fn try_evaluate_const<'tcx>( let args = GenericArgs::identity_for_item(tcx, uv.def); let typing_env = ty::TypingEnv::post_analysis(tcx, uv.def); + (args, typing_env) } else { // FIXME: This codepath is reachable under `associated_const_equality` and in the