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Reduce the duplication in the relation logic for constants

This commit is contained in:
Oli Scherer 2021-03-02 12:13:17 +00:00
parent 4d917faa99
commit 5e8a89b2e5
1 changed files with 44 additions and 66 deletions
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110
compiler/rustc_middle/src/ty/relate.rs
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@ -4,13 +4,12 @@
//! types or regions but can be other things. Examples of type relations are
//! subtyping, type equality, etc.
use crate::mir::interpret::{get_slice_bytes, ConstValue};
use crate::mir::interpret::{get_slice_bytes, ConstValue, GlobalAlloc, Scalar};
use crate::ty::error::{ExpectedFound, TypeError};
use crate::ty::subst::{GenericArg, GenericArgKind, SubstsRef};
use crate::ty::{self, Ty, TyCtxt, TypeFoldable};
use rustc_hir as ast;
use rustc_hir::def_id::DefId;
use rustc_span::DUMMY_SP;
use rustc_target::spec::abi;
use std::iter;
@ -513,81 +512,63 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
// Currently, the values that can be unified are primitive types,
// and those that derive both `PartialEq` and `Eq`, corresponding
// to structural-match types.
match (a.val, b.val) {
let is_match = match (a.val, b.val) {
(ty::ConstKind::Infer(_), _) | (_, ty::ConstKind::Infer(_)) => {
// The caller should handle these cases!
bug!("var types encountered in super_relate_consts: {:?} {:?}", a, b)
}
(ty::ConstKind::Error(_), _) => Ok(a),
(_, ty::ConstKind::Error(_)) => Ok(b),
(ty::ConstKind::Error(_), _) => return Ok(a),
(_, ty::ConstKind::Error(_)) => return Ok(b),
(ty::ConstKind::Param(a_p), ty::ConstKind::Param(b_p)) if a_p.index == b_p.index => {
return Ok(a);
}
(ty::ConstKind::Placeholder(p1), ty::ConstKind::Placeholder(p2)) if p1 == p2 => {
return Ok(a);
}
(ty::ConstKind::Param(a_p), ty::ConstKind::Param(b_p)) => a_p.index == b_p.index,
(ty::ConstKind::Placeholder(p1), ty::ConstKind::Placeholder(p2)) => p1 == p2,
(ty::ConstKind::Value(a_val), ty::ConstKind::Value(b_val)) => {
match (a_val, b_val) {
(ConstValue::Scalar(a_val), ConstValue::Scalar(b_val)) => {
if a_val == b_val {
Ok(a)
} else if let ty::FnPtr(_) = a.ty.kind() {
let a_instance = tcx.global_alloc(a_val.assert_ptr().alloc_id).unwrap_fn();
let b_instance = tcx.global_alloc(b_val.assert_ptr().alloc_id).unwrap_fn();
if a_instance == b_instance {
Ok(a)
} else {
Err(TypeError::ConstMismatch(expected_found(relation, a, b)))
(
ConstValue::Scalar(Scalar::Int(a_val)),
ConstValue::Scalar(Scalar::Int(b_val)),
) => a_val == b_val,
(
ConstValue::Scalar(Scalar::Ptr(a_val)),
ConstValue::Scalar(Scalar::Ptr(b_val)),
) => {
a_val == b_val
|| match (
tcx.global_alloc(a_val.alloc_id),
tcx.global_alloc(b_val.alloc_id),
) {
(
GlobalAlloc::Function(a_instance),
GlobalAlloc::Function(b_instance),
) => a_instance == b_instance,
_ => false,
}
} else {
Err(TypeError::ConstMismatch(expected_found(relation, a, b)))
}
}
(ConstValue::Slice { .. }, ConstValue::Slice { .. }) => {
let a_bytes = get_slice_bytes(&tcx, a_val);
let b_bytes = get_slice_bytes(&tcx, b_val);
if a_bytes == b_bytes {
Ok(a)
} else {
Err(TypeError::ConstMismatch(expected_found(relation, a, b)))
}
get_slice_bytes(&tcx, a_val) == get_slice_bytes(&tcx, b_val)
}
(ConstValue::ByRef { .. }, ConstValue::ByRef { .. }) => {
match a.ty.kind() {
ty::Array(..) | ty::Adt(..) | ty::Tuple(..) => {
let a_destructured = tcx.destructure_const(relation.param_env().and(a));
let b_destructured = tcx.destructure_const(relation.param_env().and(b));
let a_destructured = tcx.destructure_const(relation.param_env().and(a));
let b_destructured = tcx.destructure_const(relation.param_env().and(b));
// Both the variant and each field have to be equal.
if a_destructured.variant == b_destructured.variant {
for (a_field, b_field) in
a_destructured.fields.iter().zip(b_destructured.fields.iter())
{
relation.consts(a_field, b_field)?;
}
// Both the variant and each field have to be equal.
if a_destructured.variant == b_destructured.variant {
for (a_field, b_field) in
a_destructured.fields.iter().zip(b_destructured.fields.iter())
{
relation.consts(a_field, b_field)?;
}
Ok(a)
} else {
Err(TypeError::ConstMismatch(expected_found(relation, a, b)))
}
}
// FIXME(const_generics): There are probably some `TyKind`s
// which should be handled here.
_ => {
tcx.sess.delay_span_bug(
DUMMY_SP,
&format!("unexpected consts: a: {:?}, b: {:?}", a, b),
);
Err(TypeError::ConstMismatch(expected_found(relation, a, b)))
}
true
} else {
false
}
}
_ => Err(TypeError::ConstMismatch(expected_found(relation, a, b))),
_ => false,
}
}
@ -595,11 +576,7 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
ty::ConstKind::Unevaluated(a_def, a_substs, None),
ty::ConstKind::Unevaluated(b_def, b_substs, None),
) if tcx.features().const_evaluatable_checked && !relation.visit_ct_substs() => {
if tcx.try_unify_abstract_consts(((a_def, a_substs), (b_def, b_substs))) {
Ok(a)
} else {
Err(TypeError::ConstMismatch(expected_found(relation, a, b)))
}
tcx.try_unify_abstract_consts(((a_def, a_substs), (b_def, b_substs)))
}
// While this is slightly incorrect, it shouldn't matter for `min_const_generics`
@ -611,13 +588,14 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
) if a_def == b_def && a_promoted == b_promoted => {
let substs =
relation.relate_with_variance(ty::Variance::Invariant, a_substs, b_substs)?;
Ok(tcx.mk_const(ty::Const {
return Ok(tcx.mk_const(ty::Const {
val: ty::ConstKind::Unevaluated(a_def, substs, a_promoted),
ty: a.ty,
}))
}));
}
_ => Err(TypeError::ConstMismatch(expected_found(relation, a, b))),
}
_ => false,
};
if is_match { Ok(a) } else { Err(TypeError::ConstMismatch(expected_found(relation, a, b))) }
}
impl<'tcx> Relate<'tcx> for &'tcx ty::List<ty::Binder<ty::ExistentialPredicate<'tcx>>> {