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try to evaluate in try_unify

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This commit is contained in:
b-naber 2022-03-17 11:44:57 +01:00
parent d8e564715e
commit 47f78a2487
4 changed files with 68 additions and 37 deletions
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3
compiler/rustc_infer/src/infer/mod.rs
View file

@ -691,11 +691,12 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
&self,
a: ty::Unevaluated<'tcx, ()>,
b: ty::Unevaluated<'tcx, ()>,
param_env: ty::ParamEnv<'tcx>,
) -> bool {
let canonical = self.canonicalize_query((a, b), &mut OriginalQueryValues::default());
debug!("canonical consts: {:?}", &canonical.value);
self.tcx.try_unify_abstract_consts(canonical.value)
self.tcx.try_unify_abstract_consts(param_env.and(canonical.value))
}
pub fn is_in_snapshot(&self) -> bool {

8
compiler/rustc_middle/src/query/mod.rs
View file

@ -329,12 +329,12 @@ rustc_queries! {
}
}
query try_unify_abstract_consts(key: (
ty::Unevaluated<'tcx, ()>, ty::Unevaluated<'tcx, ()>
)) -> bool {
query try_unify_abstract_consts(key:
ty::ParamEnvAnd<'tcx, (ty::Unevaluated<'tcx, ()>, ty::Unevaluated<'tcx, ()>
)>) -> bool {
desc {
|tcx| "trying to unify the generic constants {} and {}",
tcx.def_path_str(key.0.def.did), tcx.def_path_str(key.1.def.did)
tcx.def_path_str(key.value.0.def.did), tcx.def_path_str(key.value.1.def.did)
}
}

2
compiler/rustc_middle/src/ty/relate.rs
View file

@ -585,7 +585,7 @@ pub fn super_relate_consts<'tcx, R: TypeRelation<'tcx>>(
(ty::ConstKind::Unevaluated(au), ty::ConstKind::Unevaluated(bu))
if tcx.features().generic_const_exprs =>
{
tcx.try_unify_abstract_consts((au.shrink(), bu.shrink()))
tcx.try_unify_abstract_consts(relation.param_env().and((au.shrink(), bu.shrink())))
}
// While this is slightly incorrect, it shouldn't matter for `min_const_generics`

92
compiler/rustc_trait_selection/src/traits/const_evaluatable.rs
View file

@ -28,13 +28,13 @@ use std::iter;
use std::ops::ControlFlow;
/// Check if a given constant can be evaluated.
#[instrument(skip(infcx), level = "debug")]
pub fn is_const_evaluatable<'cx, 'tcx>(
infcx: &InferCtxt<'cx, 'tcx>,
uv: ty::Unevaluated<'tcx, ()>,
param_env: ty::ParamEnv<'tcx>,
span: Span,
) -> Result<(), NotConstEvaluatable> {
debug!("is_const_evaluatable({:?})", uv);
let tcx = infcx.tcx;
if tcx.features().generic_const_exprs {
@ -185,6 +185,7 @@ pub fn is_const_evaluatable<'cx, 'tcx>(
}
}
#[instrument(skip(tcx), level = "debug")]
fn satisfied_from_param_env<'tcx>(
tcx: TyCtxt<'tcx>,
ct: AbstractConst<'tcx>,
@ -197,11 +198,12 @@ fn satisfied_from_param_env<'tcx>(
// Try to unify with each subtree in the AbstractConst to allow for
// `N + 1` being const evaluatable even if theres only a `ConstEvaluatable`
// predicate for `(N + 1) * 2`
let result =
walk_abstract_const(tcx, b_ct, |b_ct| match try_unify(tcx, ct, b_ct) {
let result = walk_abstract_const(tcx, b_ct, |b_ct| {
match try_unify(tcx, ct, b_ct, param_env) {
true => ControlFlow::BREAK,
false => ControlFlow::CONTINUE,
});
}
});
if let ControlFlow::Break(()) = result {
debug!("is_const_evaluatable: abstract_const ~~> ok");
@ -570,11 +572,12 @@ pub(super) fn thir_abstract_const<'tcx>(
pub(super) fn try_unify_abstract_consts<'tcx>(
tcx: TyCtxt<'tcx>,
(a, b): (ty::Unevaluated<'tcx, ()>, ty::Unevaluated<'tcx, ()>),
param_env: ty::ParamEnv<'tcx>,
) -> bool {
(|| {
if let Some(a) = AbstractConst::new(tcx, a)? {
if let Some(b) = AbstractConst::new(tcx, b)? {
return Ok(try_unify(tcx, a, b));
return Ok(try_unify(tcx, a, b, param_env));
}
}
@ -619,32 +622,59 @@ where
recurse(tcx, ct, &mut f)
}
/// Tries to unify two abstract constants using structural equality.
pub(super) fn try_unify<'tcx>(
// Substitutes generics repeatedly to allow AbstractConsts to unify where a
// ConstKind::Unevalated could be turned into an AbstractConst that would unify e.g.
// Param(N) should unify with Param(T), substs: [Unevaluated("T2", [Unevaluated("T3", [Param(N)])])]
#[inline]
#[instrument(skip(tcx), level = "debug")]
fn try_replace_substs_in_root<'tcx>(
tcx: TyCtxt<'tcx>,
mut a: AbstractConst<'tcx>,
mut b: AbstractConst<'tcx>,
) -> bool {
// We substitute generics repeatedly to allow AbstractConsts to unify where a
// ConstKind::Unevalated could be turned into an AbstractConst that would unify e.g.
// Param(N) should unify with Param(T), substs: [Unevaluated("T2", [Unevaluated("T3", [Param(N)])])]
while let Node::Leaf(a_ct) = a.root(tcx) {
match AbstractConst::from_const(tcx, a_ct) {
Ok(Some(a_act)) => a = a_act,
mut abstr_const: AbstractConst<'tcx>,
) -> Option<AbstractConst<'tcx>> {
while let Node::Leaf(ct) = abstr_const.root(tcx) {
match AbstractConst::from_const(tcx, ct) {
Ok(Some(act)) => abstr_const = act,
Ok(None) => break,
Err(_) => return true,
}
}
while let Node::Leaf(b_ct) = b.root(tcx) {
match AbstractConst::from_const(tcx, b_ct) {
Ok(Some(b_act)) => b = b_act,
Ok(None) => break,
Err(_) => return true,
Err(_) => return None,
}
}
match (a.root(tcx), b.root(tcx)) {
Some(abstr_const)
}
/// Tries to unify two abstract constants using structural equality.
#[instrument(skip(tcx), level = "debug")]
pub(super) fn try_unify<'tcx>(
tcx: TyCtxt<'tcx>,
a: AbstractConst<'tcx>,
b: AbstractConst<'tcx>,
param_env: ty::ParamEnv<'tcx>,
) -> bool {
let a = match try_replace_substs_in_root(tcx, a) {
Some(a) => a,
None => {
return true;
}
};
let b = match try_replace_substs_in_root(tcx, b) {
Some(b) => b,
None => {
return true;
}
};
let a_root = a.root(tcx);
let b_root = b.root(tcx);
debug!(?a_root, ?b_root);
match (a_root, b_root) {
(Node::Leaf(a_ct), Node::Leaf(b_ct)) => {
let a_ct = a_ct.eval(tcx, param_env);
debug!("a_ct evaluated: {:?}", a_ct);
let b_ct = b_ct.eval(tcx, param_env);
debug!("b_ct evaluated: {:?}", b_ct);
if a_ct.ty() != b_ct.ty() {
return false;
}
@ -678,23 +708,23 @@ pub(super) fn try_unify<'tcx>(
}
}
(Node::Binop(a_op, al, ar), Node::Binop(b_op, bl, br)) if a_op == b_op => {
try_unify(tcx, a.subtree(al), b.subtree(bl))
&& try_unify(tcx, a.subtree(ar), b.subtree(br))
try_unify(tcx, a.subtree(al), b.subtree(bl), param_env)
&& try_unify(tcx, a.subtree(ar), b.subtree(br), param_env)
}
(Node::UnaryOp(a_op, av), Node::UnaryOp(b_op, bv)) if a_op == b_op => {
try_unify(tcx, a.subtree(av), b.subtree(bv))
try_unify(tcx, a.subtree(av), b.subtree(bv), param_env)
}
(Node::FunctionCall(a_f, a_args), Node::FunctionCall(b_f, b_args))
if a_args.len() == b_args.len() =>
{
try_unify(tcx, a.subtree(a_f), b.subtree(b_f))
try_unify(tcx, a.subtree(a_f), b.subtree(b_f), param_env)
&& iter::zip(a_args, b_args)
.all(|(&an, &bn)| try_unify(tcx, a.subtree(an), b.subtree(bn)))
.all(|(&an, &bn)| try_unify(tcx, a.subtree(an), b.subtree(bn), param_env))
}
(Node::Cast(a_kind, a_operand, a_ty), Node::Cast(b_kind, b_operand, b_ty))
if (a_ty == b_ty) && (a_kind == b_kind) =>
{
try_unify(tcx, a.subtree(a_operand), b.subtree(b_operand))
try_unify(tcx, a.subtree(a_operand), b.subtree(b_operand), param_env)
}
// use this over `_ => false` to make adding variants to `Node` less error prone
(Node::Cast(..), _)