diff options
| -rw-r--r-- | compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs | 11 | ||||
| -rw-r--r-- | compiler/rustc_middle/src/ty/consts.rs | 117 | ||||
| -rw-r--r-- | compiler/rustc_middle/src/ty/mod.rs | 2 |
3 files changed, 86 insertions, 44 deletions
diff --git a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs index 0d2d83bc43f..62d12756832 100644 --- a/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs +++ b/compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs @@ -470,13 +470,10 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ { (&GenericParamDefKind::Type { has_default, .. }, GenericArg::Infer(inf)) => { handle_ty_args(has_default, &inf.to_ty()) } - (GenericParamDefKind::Const { .. }, GenericArg::Const(ct)) => match &ct.kind { - hir::ConstArgKind::Anon(anon) => { - let did = anon.def_id; - tcx.feed_anon_const_type(did, tcx.type_of(param.def_id)); - ty::Const::from_anon_const(tcx, did).into() - } - }, + (GenericParamDefKind::Const { .. }, GenericArg::Const(ct)) => { + ty::Const::from_const_arg(tcx, ct, ty::FeedConstTy::Param(param.def_id)) + .into() + } (&GenericParamDefKind::Const { .. }, hir::GenericArg::Infer(inf)) => { self.lowerer.ct_infer(Some(param), inf.span).into() } diff --git a/compiler/rustc_middle/src/ty/consts.rs b/compiler/rustc_middle/src/ty/consts.rs index 32d01d07c17..6eae30dc3e4 100644 --- a/compiler/rustc_middle/src/ty/consts.rs +++ b/compiler/rustc_middle/src/ty/consts.rs @@ -3,9 +3,9 @@ use crate::mir::interpret::{ErrorHandled, LitToConstInput, Scalar}; use crate::ty::{self, GenericArgs, ParamEnv, ParamEnvAnd, Ty, TyCtxt, TypeVisitableExt}; use rustc_data_structures::intern::Interned; use rustc_error_messages::MultiSpan; -use rustc_hir as hir; use rustc_hir::def::{DefKind, Res}; -use rustc_hir::def_id::LocalDefId; +use rustc_hir::def_id::{DefId, LocalDefId}; +use rustc_hir::{self as hir, HirId}; use rustc_macros::HashStable; use rustc_type_ir::{self as ir, TypeFlags, WithCachedTypeInfo}; use tracing::{debug, instrument}; @@ -182,16 +182,52 @@ impl<'tcx> rustc_type_ir::inherent::Const<TyCtxt<'tcx>> for Const<'tcx> { } } +/// In some cases, [`hir::ConstArg`]s that are being used in the type system +/// through const generics need to have their type "fed" to them +/// using the query system. +/// +/// Use this enum with [`Const::from_const_arg`] to instruct it with the +/// desired behavior. +#[derive(Debug, Clone, Copy)] +pub enum FeedConstTy { + /// Feed the type. + /// + /// The `DefId` belongs to the const param that we are supplying + /// this (anon) const arg to. + Param(DefId), + /// Don't feed the type. + No, +} + impl<'tcx> Const<'tcx> { + /// Convert a [`hir::ConstArg`] to a [`ty::Const`](Self). + #[instrument(skip(tcx), level = "debug")] + #[allow(irrefutable_let_patterns)] + pub fn from_const_arg( + tcx: TyCtxt<'tcx>, + const_arg: &'tcx hir::ConstArg<'tcx>, + feed: FeedConstTy, + ) -> Self { + if let FeedConstTy::Param(param_def_id) = feed + && let hir::ConstArgKind::Anon(anon) = &const_arg.kind + { + tcx.feed_anon_const_type(anon.def_id, tcx.type_of(param_def_id)); + } + + match const_arg.kind { + hir::ConstArgKind::Anon(anon) => Self::from_anon_const(tcx, anon.def_id), + } + } + /// Literals and const generic parameters are eagerly converted to a constant, everything else /// becomes `Unevaluated`. #[instrument(skip(tcx), level = "debug")] pub fn from_anon_const(tcx: TyCtxt<'tcx>, def: LocalDefId) -> Self { let body_id = match tcx.hir_node_by_def_id(def) { hir::Node::AnonConst(ac) => ac.body, - _ => span_bug!( + node => span_bug!( tcx.def_span(def.to_def_id()), - "from_anon_const can only process anonymous constants" + "from_anon_const can only process anonymous constants, not {node:?}" ), }; @@ -200,7 +236,7 @@ impl<'tcx> Const<'tcx> { let ty = tcx.type_of(def).no_bound_vars().expect("const parameter types cannot be generic"); - match Self::try_from_lit_or_param(tcx, ty, expr) { + match Self::try_from_lit(tcx, ty, expr) { Some(v) => v, None => ty::Const::new_unevaluated( tcx, @@ -212,12 +248,36 @@ impl<'tcx> Const<'tcx> { } } + /// Lower a const param to a [`Const`]. + /// + /// IMPORTANT: `qpath` must be a const param, otherwise this will panic + fn from_param(tcx: TyCtxt<'tcx>, qpath: hir::QPath<'tcx>, hir_id: HirId) -> Self { + let hir::QPath::Resolved(_, &hir::Path { res: Res::Def(DefKind::ConstParam, def_id), .. }) = + qpath + else { + span_bug!(qpath.span(), "non-param {qpath:?} passed to Const::from_param") + }; + + match tcx.named_bound_var(hir_id) { + Some(rbv::ResolvedArg::EarlyBound(_)) => { + // Find the name and index of the const parameter by indexing the generics of + // the parent item and construct a `ParamConst`. + let item_def_id = tcx.parent(def_id); + let generics = tcx.generics_of(item_def_id); + let index = generics.param_def_id_to_index[&def_id]; + let name = tcx.item_name(def_id); + ty::Const::new_param(tcx, ty::ParamConst::new(index, name)) + } + Some(rbv::ResolvedArg::LateBound(debruijn, index, _)) => { + ty::Const::new_bound(tcx, debruijn, ty::BoundVar::from_u32(index)) + } + Some(rbv::ResolvedArg::Error(guar)) => ty::Const::new_error(tcx, guar), + arg => bug!("unexpected bound var resolution for {:?}: {arg:?}", hir_id), + } + } + #[instrument(skip(tcx), level = "debug")] - fn try_from_lit_or_param( - tcx: TyCtxt<'tcx>, - ty: Ty<'tcx>, - expr: &'tcx hir::Expr<'tcx>, - ) -> Option<Self> { + fn try_from_lit(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, expr: &'tcx hir::Expr<'tcx>) -> Option<Self> { // Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments // currently have to be wrapped in curly brackets, so it's necessary to special-case. let expr = match &expr.kind { @@ -250,34 +310,19 @@ impl<'tcx> Const<'tcx> { } } - // FIXME(const_generics): We currently have to special case parameters because `min_const_generics` - // does not provide the parents generics to anonymous constants. We still allow generic const - // parameters by themselves however, e.g. `N`. These constants would cause an ICE if we were to - // ever try to instantiate the generic parameters in their bodies. - match expr.kind { - hir::ExprKind::Path(hir::QPath::Resolved( + if let hir::ExprKind::Path( + qpath @ hir::QPath::Resolved( _, - &hir::Path { res: Res::Def(DefKind::ConstParam, def_id), .. }, - )) => { - match tcx.named_bound_var(expr.hir_id) { - Some(rbv::ResolvedArg::EarlyBound(_)) => { - // Find the name and index of the const parameter by indexing the generics of - // the parent item and construct a `ParamConst`. - let item_def_id = tcx.parent(def_id); - let generics = tcx.generics_of(item_def_id); - let index = generics.param_def_id_to_index[&def_id]; - let name = tcx.item_name(def_id); - Some(ty::Const::new_param(tcx, ty::ParamConst::new(index, name))) - } - Some(rbv::ResolvedArg::LateBound(debruijn, index, _)) => { - Some(ty::Const::new_bound(tcx, debruijn, ty::BoundVar::from_u32(index))) - } - Some(rbv::ResolvedArg::Error(guar)) => Some(ty::Const::new_error(tcx, guar)), - arg => bug!("unexpected bound var resolution for {:?}: {arg:?}", expr.hir_id), - } - } - _ => None, + &hir::Path { res: Res::Def(DefKind::ConstParam, _), .. }, + ), + ) = expr.kind + { + // FIXME: once ConstArgKind::Path added, uncomment span_bug and delete return + // span_bug!(expr.span, "try_from_lit: received const param which shouldn't be possible") + return Some(Self::from_param(tcx, qpath, expr.hir_id)); } + + None } #[inline] diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs index 9a4562e9cfc..bd073cd891f 100644 --- a/compiler/rustc_middle/src/ty/mod.rs +++ b/compiler/rustc_middle/src/ty/mod.rs @@ -86,7 +86,7 @@ pub use self::closure::{ CAPTURE_STRUCT_LOCAL, }; pub use self::consts::{ - Const, ConstInt, ConstKind, Expr, ExprKind, ScalarInt, UnevaluatedConst, ValTree, + Const, ConstInt, ConstKind, Expr, ExprKind, FeedConstTy, ScalarInt, UnevaluatedConst, ValTree, }; pub use self::context::{ tls, CtxtInterners, CurrentGcx, DeducedParamAttrs, Feed, FreeRegionInfo, GlobalCtxt, Lift, |