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use crate::mir::interpret::LitToConstInput;
use crate::mir::ConstantKind;
use crate::ty::{
self, InlineConstSubsts, InlineConstSubstsParts, InternalSubsts, ParamEnv, ParamEnvAnd, Ty,
TyCtxt, TypeVisitable,
};
use rustc_data_structures::intern::Interned;
use rustc_errors::ErrorGuaranteed;
use rustc_hir as hir;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_macros::HashStable;
use std::fmt;
mod int;
mod kind;
mod valtree;
pub use int::*;
pub use kind::*;
pub use valtree::*;
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
#[rustc_pass_by_value]
pub struct Const<'tcx>(pub Interned<'tcx, ConstS<'tcx>>);
impl<'tcx> fmt::Debug for Const<'tcx> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "Const {{ ty: {:?}, kind: {:?} }}", self.ty(), self.kind())
}
}
#[derive(PartialEq, Eq, PartialOrd, Ord, Hash, HashStable, TyEncodable, TyDecodable)]
pub struct ConstS<'tcx> {
pub ty: Ty<'tcx>,
pub kind: ConstKind<'tcx>,
}
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
static_assert_size!(ConstS<'_>, 40);
impl<'tcx> Const<'tcx> {
#[inline]
pub fn ty(self) -> Ty<'tcx> {
self.0.ty
}
#[inline]
pub fn kind(self) -> ConstKind<'tcx> {
self.0.kind
}
pub fn from_anon_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
Self::from_opt_const_arg_anon_const(tcx, ty::WithOptConstParam::unknown(def_id))
}
#[instrument(skip(tcx), level = "debug")]
pub fn from_opt_const_arg_anon_const(
tcx: TyCtxt<'tcx>,
def: ty::WithOptConstParam<LocalDefId>,
) -> Self {
let body_id = match tcx.hir().get_by_def_id(def.did) {
hir::Node::AnonConst(ac) => ac.body,
_ => span_bug!(
tcx.def_span(def.did.to_def_id()),
"from_anon_const can only process anonymous constants"
),
};
let expr = &tcx.hir().body(body_id).value;
debug!(?expr);
let ty = tcx.type_of(def.def_id_for_type_of());
match Self::try_eval_lit_or_param(tcx, ty, expr) {
Some(v) => v,
None => tcx.mk_const(ty::ConstS {
kind: ty::ConstKind::Unevaluated(ty::Unevaluated {
def: def.to_global(),
substs: InternalSubsts::identity_for_item(tcx, def.did.to_def_id()),
promoted: (),
}),
ty,
}),
}
}
#[instrument(skip(tcx), level = "debug")]
fn try_eval_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,
};
let lit_input = match expr.kind {
hir::ExprKind::Lit(ref lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
hir::ExprKind::Unary(hir::UnOp::Neg, ref expr) => match expr.kind {
hir::ExprKind::Lit(ref 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(e) => {
tcx.sess.delay_span_bug(
expr.span,
&format!("Const::from_anon_const: couldn't lit_to_const {:?}", e),
);
}
}
}
use hir::{def::DefKind::ConstParam, def::Res, ExprKind, Path, QPath};
match expr.kind {
ExprKind::Path(QPath::Resolved(_, &Path { res: Res::Def(ConstParam, def_id), .. })) => {
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
let item_id = tcx.hir().get_parent_node(hir_id);
let item_def_id = tcx.hir().local_def_id(item_id);
let generics = tcx.generics_of(item_def_id.to_def_id());
let index = generics.param_def_id_to_index[&def_id];
let name = tcx.hir().name(hir_id);
Some(tcx.mk_const(ty::ConstS {
kind: ty::ConstKind::Param(ty::ParamConst::new(index, name)),
ty,
}))
}
_ => None,
}
}
pub fn from_inline_const(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
debug!("Const::from_inline_const(def_id={:?})", def_id);
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
let body_id = match tcx.hir().get(hir_id) {
hir::Node::AnonConst(ac) => ac.body,
_ => span_bug!(
tcx.def_span(def_id.to_def_id()),
"from_inline_const can only process anonymous constants"
),
};
let expr = &tcx.hir().body(body_id).value;
let ty = tcx.typeck(def_id).node_type(hir_id);
let ret = match Self::try_eval_lit_or_param(tcx, ty, expr) {
Some(v) => v,
None => {
let typeck_root_def_id = tcx.typeck_root_def_id(def_id.to_def_id());
let parent_substs =
tcx.erase_regions(InternalSubsts::identity_for_item(tcx, typeck_root_def_id));
let substs =
InlineConstSubsts::new(tcx, InlineConstSubstsParts { parent_substs, ty })
.substs;
tcx.mk_const(ty::ConstS {
kind: ty::ConstKind::Unevaluated(ty::Unevaluated {
def: ty::WithOptConstParam::unknown(def_id).to_global(),
substs,
promoted: (),
}),
ty,
})
}
};
debug_assert!(!ret.has_free_regions());
ret
}
#[inline]
pub fn from_value(tcx: TyCtxt<'tcx>, val: ty::ValTree<'tcx>, ty: Ty<'tcx>) -> Self {
tcx.mk_const(ConstS { kind: ConstKind::Value(val), ty })
}
pub fn to_valtree(self) -> ty::ValTree<'tcx> {
match self.kind() {
ty::ConstKind::Value(valtree) => valtree,
_ => bug!("expected ConstKind::Value, got {:?}", self.kind()),
}
}
pub fn from_scalar_int(tcx: TyCtxt<'tcx>, i: ScalarInt, ty: Ty<'tcx>) -> Self {
let valtree = ty::ValTree::from_scalar_int(i);
Self::from_value(tcx, valtree, ty)
}
#[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;
Self::from_scalar_int(tcx, ScalarInt::try_from_uint(bits, size).unwrap(), ty.value)
}
#[inline]
pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Self {
let valtree = ty::ValTree::zst();
Self::from_value(tcx, valtree, 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_usize(tcx: TyCtxt<'tcx>, n: u64) -> Self {
Self::from_bits(tcx, n as u128, ParamEnv::empty().and(tcx.types.usize))
}
#[inline]
pub fn try_eval_bits(
self,
tcx: TyCtxt<'tcx>,
param_env: ParamEnv<'tcx>,
ty: Ty<'tcx>,
) -> Option<u128> {
assert_eq!(self.ty(), ty);
let size = tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size;
self.kind().eval(tcx, param_env).try_to_bits(size)
}
#[inline]
pub fn try_eval_bool(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<bool> {
self.kind().eval(tcx, param_env).try_to_bool()
}
#[inline]
pub fn try_eval_usize(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<u64> {
self.kind().eval(tcx, param_env).try_to_machine_usize(tcx)
}
#[inline]
pub fn eval(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Const<'tcx> {
if let Some(val) = self.kind().try_eval_for_typeck(tcx, param_env) {
match val {
Ok(val) => Const::from_value(tcx, val, self.ty()),
Err(ErrorGuaranteed { .. }) => tcx.const_error(self.ty()),
}
} else {
self
}
}
#[inline]
pub fn eval_for_mir(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> ConstantKind<'tcx> {
if let Some(val) = self.kind().try_eval_for_mir(tcx, param_env) {
match val {
Ok(const_val) => ConstantKind::from_value(const_val, self.ty()),
Err(ErrorGuaranteed { .. }) => ConstantKind::Ty(tcx.const_error(self.ty())),
}
} else {
ConstantKind::Ty(self)
}
}
#[inline]
pub fn eval_bits(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 {
self.try_eval_bits(tcx, param_env, ty)
.unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", ty, self))
}
#[inline]
pub fn eval_usize(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> u64 {
self.try_eval_usize(tcx, param_env)
.unwrap_or_else(|| bug!("expected usize, got {:#?}", self))
}
}
pub fn const_param_default<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Const<'tcx> {
let default_def_id = match tcx.hir().get_by_def_id(def_id.expect_local()) {
hir::Node::GenericParam(hir::GenericParam {
kind: hir::GenericParamKind::Const { ty: _, default: Some(ac) },
..
}) => tcx.hir().local_def_id(ac.hir_id),
_ => span_bug!(
tcx.def_span(def_id),
"`const_param_default` expected a generic parameter with a constant"
),
};
Const::from_anon_const(tcx, default_def_id)
}