use either::Either;
use rustc_data_structures::intern::Interned;
use rustc_error_messages::MultiSpan;
use rustc_hir::def::{DefKind, Res};
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};
use crate::middle::resolve_bound_vars as rbv;
use crate::mir::interpret::{ErrorHandled, LitToConstInput, Scalar};
use crate::ty::{self, GenericArgs, ParamEnv, ParamEnvAnd, Ty, TyCtxt, TypeVisitableExt};
mod int;
mod kind;
mod valtree;
pub use int::*;
pub use kind::*;
use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span};
pub use valtree::*;
pub type ConstKind<'tcx> = ir::ConstKind<TyCtxt<'tcx>>;
pub type UnevaluatedConst<'tcx> = ir::UnevaluatedConst<TyCtxt<'tcx>>;
#[cfg(target_pointer_width = "64")]
rustc_data_structures::static_assert_size!(ConstKind<'_>, 32);
#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable)]
#[rustc_pass_by_value]
pub struct Const<'tcx>(pub(super) Interned<'tcx, WithCachedTypeInfo<ConstKind<'tcx>>>);
impl<'tcx> rustc_type_ir::inherent::IntoKind for Const<'tcx> {
type Kind = ConstKind<'tcx>;
fn kind(self) -> ConstKind<'tcx> {
self.kind()
}
}
impl<'tcx> rustc_type_ir::visit::Flags for Const<'tcx> {
fn flags(&self) -> TypeFlags {
self.0.flags
}
fn outer_exclusive_binder(&self) -> rustc_type_ir::DebruijnIndex {
self.0.outer_exclusive_binder
}
}
impl<'tcx> Const<'tcx> {
#[inline]
pub fn kind(self) -> ConstKind<'tcx> {
let a: &ConstKind<'tcx> = self.0.0;
*a
}
#[inline]
pub fn flags(self) -> TypeFlags {
self.0.flags
}
#[inline]
pub fn outer_exclusive_binder(self) -> ty::DebruijnIndex {
self.0.outer_exclusive_binder
}
#[inline]
pub fn new(tcx: TyCtxt<'tcx>, kind: ty::ConstKind<'tcx>) -> Const<'tcx> {
tcx.mk_ct_from_kind(kind)
}
#[inline]
pub fn new_param(tcx: TyCtxt<'tcx>, param: ty::ParamConst) -> Const<'tcx> {
Const::new(tcx, ty::ConstKind::Param(param))
}
#[inline]
pub fn new_var(tcx: TyCtxt<'tcx>, infer: ty::ConstVid) -> Const<'tcx> {
Const::new(tcx, ty::ConstKind::Infer(ty::InferConst::Var(infer)))
}
#[inline]
pub fn new_fresh(tcx: TyCtxt<'tcx>, fresh: u32) -> Const<'tcx> {
Const::new(tcx, ty::ConstKind::Infer(ty::InferConst::Fresh(fresh)))
}
#[inline]
pub fn new_infer(tcx: TyCtxt<'tcx>, infer: ty::InferConst) -> Const<'tcx> {
Const::new(tcx, ty::ConstKind::Infer(infer))
}
#[inline]
pub fn new_bound(
tcx: TyCtxt<'tcx>,
debruijn: ty::DebruijnIndex,
var: ty::BoundVar,
) -> Const<'tcx> {
Const::new(tcx, ty::ConstKind::Bound(debruijn, var))
}
#[inline]
pub fn new_placeholder(tcx: TyCtxt<'tcx>, placeholder: ty::PlaceholderConst) -> Const<'tcx> {
Const::new(tcx, ty::ConstKind::Placeholder(placeholder))
}
#[inline]
pub fn new_unevaluated(tcx: TyCtxt<'tcx>, uv: ty::UnevaluatedConst<'tcx>) -> Const<'tcx> {
tcx.debug_assert_args_compatible(uv.def, uv.args);
Const::new(tcx, ty::ConstKind::Unevaluated(uv))
}
#[inline]
pub fn new_value(tcx: TyCtxt<'tcx>, val: ty::ValTree<'tcx>, ty: Ty<'tcx>) -> Const<'tcx> {
Const::new(tcx, ty::ConstKind::Value(ty, val))
}
#[inline]
pub fn new_expr(tcx: TyCtxt<'tcx>, expr: ty::Expr<'tcx>) -> Const<'tcx> {
Const::new(tcx, ty::ConstKind::Expr(expr))
}
#[inline]
pub fn new_error(tcx: TyCtxt<'tcx>, e: ty::ErrorGuaranteed) -> Const<'tcx> {
Const::new(tcx, ty::ConstKind::Error(e))
}
#[track_caller]
pub fn new_misc_error(tcx: TyCtxt<'tcx>) -> Const<'tcx> {
Const::new_error_with_message(
tcx,
DUMMY_SP,
"ty::ConstKind::Error constructed but no error reported",
)
}
#[track_caller]
pub fn new_error_with_message<S: Into<MultiSpan>>(
tcx: TyCtxt<'tcx>,
span: S,
msg: &'static str,
) -> Const<'tcx> {
let reported = tcx.dcx().span_delayed_bug(span, msg);
Const::new_error(tcx, reported)
}
}
impl<'tcx> rustc_type_ir::inherent::Const<TyCtxt<'tcx>> for Const<'tcx> {
fn try_to_target_usize(self, interner: TyCtxt<'tcx>) -> Option<u64> {
self.try_to_target_usize(interner)
}
fn new_infer(tcx: TyCtxt<'tcx>, infer: ty::InferConst) -> Self {
Const::new_infer(tcx, infer)
}
fn new_var(tcx: TyCtxt<'tcx>, vid: ty::ConstVid) -> Self {
Const::new_var(tcx, vid)
}
fn new_bound(interner: TyCtxt<'tcx>, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self {
Const::new_bound(interner, debruijn, var)
}
fn new_anon_bound(tcx: TyCtxt<'tcx>, debruijn: ty::DebruijnIndex, var: ty::BoundVar) -> Self {
Const::new_bound(tcx, debruijn, var)
}
fn new_unevaluated(interner: TyCtxt<'tcx>, uv: ty::UnevaluatedConst<'tcx>) -> Self {
Const::new_unevaluated(interner, uv)
}
fn new_expr(interner: TyCtxt<'tcx>, expr: ty::Expr<'tcx>) -> Self {
Const::new_expr(interner, expr)
}
fn new_error(interner: TyCtxt<'tcx>, guar: ErrorGuaranteed) -> Self {
Const::new_error(interner, guar)
}
}
#[derive(Debug, Clone, Copy)]
pub enum FeedConstTy {
Param(DefId),
No,
}
impl<'tcx> Const<'tcx> {
#[instrument(skip(tcx), level = "debug")]
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::Path(qpath) => {
Self::from_param(tcx, qpath, const_arg.hir_id)
}
hir::ConstArgKind::Anon(anon) => Self::from_anon_const(tcx, anon.def_id),
}
}
#[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,
node => span_bug!(
tcx.def_span(def.to_def_id()),
"from_anon_const can only process anonymous constants, not {node:?}"
),
};
let expr = &tcx.hir().body(body_id).value;
debug!(?expr);
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) {
Some(v) => v,
None => ty::Const::new_unevaluated(tcx, ty::UnevaluatedConst {
def: def.to_def_id(),
args: GenericArgs::identity_for_item(tcx, def.to_def_id()),
}),
}
}
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(_)) => {
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> {
let expr = match &expr.kind {
hir::ExprKind::Block(block, _) if block.stmts.is_empty() && block.expr.is_some() => {
block.expr.as_ref().unwrap()
}
_ => expr,
};
if let hir::ExprKind::Path(hir::QPath::Resolved(
_,
&hir::Path { res: Res::Def(DefKind::ConstParam, _), .. },
)) = expr.kind
{
span_bug!(expr.span, "try_from_lit: received const param which shouldn't be possible");
};
let lit_input = match expr.kind {
hir::ExprKind::Lit(lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
hir::ExprKind::Unary(hir::UnOp::Neg, expr) => match expr.kind {
hir::ExprKind::Lit(lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: true }),
_ => None,
},
_ => None,
};
if let Some(lit_input) = lit_input {
match tcx.at(expr.span).lit_to_const(lit_input) {
Ok(c) => return Some(c),
Err(_) if lit_input.ty.has_aliases() => {
return None;
}
Err(e) => {
tcx.dcx().span_delayed_bug(
expr.span,
format!("Const::from_anon_const: couldn't lit_to_const {e:?}"),
);
}
}
}
None
}
#[inline]
pub fn from_bits(tcx: TyCtxt<'tcx>, bits: u128, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> Self {
let size = tcx
.layout_of(ty)
.unwrap_or_else(|e| panic!("could not compute layout for {ty:?}: {e:?}"))
.size;
ty::Const::new_value(
tcx,
ty::ValTree::from_scalar_int(ScalarInt::try_from_uint(bits, size).unwrap()),
ty.value,
)
}
#[inline]
pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Self {
ty::Const::new_value(tcx, ty::ValTree::zst(), ty)
}
#[inline]
pub fn from_bool(tcx: TyCtxt<'tcx>, v: bool) -> Self {
Self::from_bits(tcx, v as u128, ParamEnv::empty().and(tcx.types.bool))
}
#[inline]
pub fn from_target_usize(tcx: TyCtxt<'tcx>, n: u64) -> Self {
Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
}
#[inline]
pub fn eval_valtree(
self,
tcx: TyCtxt<'tcx>,
param_env: ParamEnv<'tcx>,
span: Span,
) -> Result<(Ty<'tcx>, ValTree<'tcx>), Either<Ty<'tcx>, ErrorHandled>> {
assert!(!self.has_escaping_bound_vars(), "escaping vars in {self:?}");
match self.kind() {
ConstKind::Unevaluated(unevaluated) => {
let (param_env, unevaluated) = unevaluated.prepare_for_eval(tcx, param_env);
match tcx.const_eval_resolve_for_typeck(param_env, unevaluated, span) {
Ok(Ok(c)) => {
Ok((tcx.type_of(unevaluated.def).instantiate(tcx, unevaluated.args), c))
}
Ok(Err(bad_ty)) => Err(Either::Left(bad_ty)),
Err(err) => Err(Either::Right(err)),
}
}
ConstKind::Value(ty, val) => Ok((ty, val)),
ConstKind::Error(g) => Err(Either::Right(g.into())),
ConstKind::Param(_)
| ConstKind::Infer(_)
| ConstKind::Bound(_, _)
| ConstKind::Placeholder(_)
| ConstKind::Expr(_) => Err(Either::Right(ErrorHandled::TooGeneric(span))),
}
}
#[inline]
pub fn normalize_internal(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Self {
match self.eval_valtree(tcx, param_env, DUMMY_SP) {
Ok((ty, val)) => Self::new_value(tcx, val, ty),
Err(Either::Left(_bad_ty)) => {
Self::new_error(
tcx,
tcx.dcx()
.delayed_bug("`ty::Const::eval` called on a non-valtree-compatible type"),
)
}
Err(Either::Right(ErrorHandled::Reported(r, _span))) => Self::new_error(tcx, r.into()),
Err(Either::Right(ErrorHandled::TooGeneric(_span))) => self,
}
}
pub fn to_valtree(self) -> (ty::ValTree<'tcx>, Ty<'tcx>) {
match self.kind() {
ty::ConstKind::Value(ty, valtree) => (valtree, ty),
_ => bug!("expected ConstKind::Value, got {:?}", self.kind()),
}
}
pub fn try_to_valtree(self) -> Option<(ty::ValTree<'tcx>, Ty<'tcx>)> {
match self.kind() {
ty::ConstKind::Value(ty, valtree) => Some((valtree, ty)),
_ => None,
}
}
#[inline]
pub fn try_to_scalar(self) -> Option<(Scalar, Ty<'tcx>)> {
let (valtree, ty) = self.try_to_valtree()?;
Some((valtree.try_to_scalar()?, ty))
}
pub fn try_to_bool(self) -> Option<bool> {
self.try_to_valtree()?.0.try_to_scalar_int()?.try_to_bool().ok()
}
#[inline]
pub fn try_to_target_usize(self, tcx: TyCtxt<'tcx>) -> Option<u64> {
self.try_to_valtree()?.0.try_to_target_usize(tcx)
}
#[inline]
pub fn try_to_bits(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<u128> {
let (scalar, ty) = self.try_to_scalar()?;
let scalar = scalar.try_to_scalar_int().ok()?;
let size = tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size;
Some(scalar.to_bits(size))
}
pub fn is_ct_infer(self) -> bool {
matches!(self.kind(), ty::ConstKind::Infer(_))
}
}
pub fn const_param_default<'tcx>(
tcx: TyCtxt<'tcx>,
def_id: LocalDefId,
) -> ty::EarlyBinder<'tcx, Const<'tcx>> {
let default_ct = match tcx.hir_node_by_def_id(def_id) {
hir::Node::GenericParam(hir::GenericParam {
kind: hir::GenericParamKind::Const { default: Some(ct), .. },
..
}) => ct,
_ => span_bug!(
tcx.def_span(def_id),
"`const_param_default` expected a generic parameter with a constant"
),
};
ty::EarlyBinder::bind(Const::from_const_arg(tcx, default_ct, FeedConstTy::No))
}