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canonical: yeet EvalCtxt, mk Canonicalizer private

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This commit is contained in:
lcnr
2025-09-16 15:30:25 +02:00
parent a08e6499e6
commit b83c0f0e94
3 changed files with 245 additions and 223 deletions
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compiler/rustc_next_trait_solver/src/canonical/canonicalizer.rs
+3 -4
View File
@@ -57,7 +57,7 @@ enum CanonicalizeMode {
},
}
pub struct Canonicalizer<'a, D: SolverDelegate<Interner = I>, I: Interner> {
pub(super) struct Canonicalizer<'a, D: SolverDelegate<Interner = I>, I: Interner> {
delegate: &'a D,
// Immutable field.
@@ -83,7 +83,7 @@ pub struct Canonicalizer<'a, D: SolverDelegate<Interner = I>, I: Interner> {
}
impl<'a, D: SolverDelegate<Interner = I>, I: Interner> Canonicalizer<'a, D, I> {
pub fn canonicalize_response<T: TypeFoldable<I>>(
pub(super) fn canonicalize_response<T: TypeFoldable<I>>(
delegate: &'a D,
max_input_universe: ty::UniverseIndex,
variables: &'a mut Vec<I::GenericArg>,
@@ -112,7 +112,6 @@ pub fn canonicalize_response<T: TypeFoldable<I>>(
let (max_universe, variables) = canonicalizer.finalize();
Canonical { max_universe, variables, value }
}
fn canonicalize_param_env(
delegate: &'a D,
variables: &'a mut Vec<I::GenericArg>,
@@ -195,7 +194,7 @@ fn canonicalize_param_env(
///
/// We want to keep the option of canonicalizing `'static` to an existential
/// variable in the future by changing the way we detect global where-bounds.
pub fn canonicalize_input<P: TypeFoldable<I>>(
pub(super) fn canonicalize_input<P: TypeFoldable<I>>(
delegate: &'a D,
variables: &'a mut Vec<I::GenericArg>,
input: QueryInput<I, P>,
compiler/rustc_next_trait_solver/src/canonical/mod.rs
+233 -210
View File
@@ -24,7 +24,7 @@
use crate::delegate::SolverDelegate;
use crate::resolve::eager_resolve_vars;
use crate::solve::{
CanonicalInput, CanonicalResponse, Certainty, EvalCtxt, ExternalConstraintsData, Goal,
CanonicalInput, CanonicalResponse, Certainty, ExternalConstraintsData, Goal,
NestedNormalizationGoals, PredefinedOpaquesData, QueryInput, Response, inspect,
};
@@ -46,226 +46,248 @@ fn var_values(&self) -> CanonicalVarValues<I> {
}
}
impl<D, I> EvalCtxt<'_, D>
/// Canonicalizes the goal remembering the original values
/// for each bound variable.
///
/// This expects `goal` and `opaque_types` to be eager resolved.
pub(super) fn canonicalize_goal<D, I>(
delegate: &D,
goal: Goal<I, I::Predicate>,
opaque_types: Vec<(ty::OpaqueTypeKey<I>, I::Ty)>,
) -> (Vec<I::GenericArg>, CanonicalInput<I, I::Predicate>)
where
D: SolverDelegate<Interner = I>,
I: Interner,
{
/// Canonicalizes the goal remembering the original values
/// for each bound variable.
///
/// This expects `goal` and `opaque_types` to be eager resolved.
pub(super) fn canonicalize_goal(
delegate: &D,
goal: Goal<I, I::Predicate>,
opaque_types: Vec<(ty::OpaqueTypeKey<I>, I::Ty)>,
) -> (Vec<I::GenericArg>, CanonicalInput<I, I::Predicate>) {
let mut orig_values = Default::default();
let canonical = Canonicalizer::canonicalize_input(
delegate,
&mut orig_values,
QueryInput {
goal,
predefined_opaques_in_body: delegate
.cx()
.mk_predefined_opaques_in_body(PredefinedOpaquesData { opaque_types }),
},
);
let query_input =
ty::CanonicalQueryInput { canonical, typing_mode: delegate.typing_mode() };
(orig_values, query_input)
let mut orig_values = Default::default();
let canonical = Canonicalizer::canonicalize_input(
delegate,
&mut orig_values,
QueryInput {
goal,
predefined_opaques_in_body: delegate
.cx()
.mk_predefined_opaques_in_body(PredefinedOpaquesData { opaque_types }),
},
);
let query_input = ty::CanonicalQueryInput { canonical, typing_mode: delegate.typing_mode() };
(orig_values, query_input)
}
pub(super) fn canonicalize_response<D, I, T>(
delegate: &D,
max_input_universe: ty::UniverseIndex,
value: T,
) -> ty::Canonical<I, T>
where
D: SolverDelegate<Interner = I>,
I: Interner,
T: TypeFoldable<I>,
{
let mut orig_values = Default::default();
let canonical =
Canonicalizer::canonicalize_response(delegate, max_input_universe, &mut orig_values, value);
canonical
}
/// After calling a canonical query, we apply the constraints returned
/// by the query using this function.
///
/// This happens in three steps:
/// - we instantiate the bound variables of the query response
/// - we unify the `var_values` of the response with the `original_values`
/// - we apply the `external_constraints` returned by the query, returning
/// the `normalization_nested_goals`
pub(super) fn instantiate_and_apply_query_response<D, I>(
delegate: &D,
param_env: I::ParamEnv,
original_values: &[I::GenericArg],
response: CanonicalResponse<I>,
span: I::Span,
) -> (NestedNormalizationGoals<I>, Certainty)
where
D: SolverDelegate<Interner = I>,
I: Interner,
{
let instantiation =
compute_query_response_instantiation_values(delegate, &original_values, &response, span);
let Response { var_values, external_constraints, certainty } =
delegate.instantiate_canonical(response, instantiation);
unify_query_var_values(delegate, param_env, &original_values, var_values, span);
let ExternalConstraintsData { region_constraints, opaque_types, normalization_nested_goals } =
&*external_constraints;
register_region_constraints(delegate, region_constraints, span);
register_new_opaque_types(delegate, opaque_types, span);
(normalization_nested_goals.clone(), certainty)
}
/// This returns the canonical variable values to instantiate the bound variables of
/// the canonical response. This depends on the `original_values` for the
/// bound variables.
fn compute_query_response_instantiation_values<D, I, T>(
delegate: &D,
original_values: &[I::GenericArg],
response: &Canonical<I, T>,
span: I::Span,
) -> CanonicalVarValues<I>
where
D: SolverDelegate<Interner = I>,
I: Interner,
T: ResponseT<I>,
{
// FIXME: Longterm canonical queries should deal with all placeholders
// created inside of the query directly instead of returning them to the
// caller.
let prev_universe = delegate.universe();
let universes_created_in_query = response.max_universe.index();
for _ in 0..universes_created_in_query {
delegate.create_next_universe();
}
/// After calling a canonical query, we apply the constraints returned
/// by the query using this function.
///
/// This happens in three steps:
/// - we instantiate the bound variables of the query response
/// - we unify the `var_values` of the response with the `original_values`
/// - we apply the `external_constraints` returned by the query, returning
/// the `normalization_nested_goals`
pub(super) fn instantiate_and_apply_query_response(
delegate: &D,
param_env: I::ParamEnv,
original_values: &[I::GenericArg],
response: CanonicalResponse<I>,
span: I::Span,
) -> (NestedNormalizationGoals<I>, Certainty) {
let instantiation = Self::compute_query_response_instantiation_values(
delegate,
&original_values,
&response,
span,
);
let var_values = response.value.var_values();
assert_eq!(original_values.len(), var_values.len());
let Response { var_values, external_constraints, certainty } =
delegate.instantiate_canonical(response, instantiation);
Self::unify_query_var_values(delegate, param_env, &original_values, var_values, span);
let ExternalConstraintsData {
region_constraints,
opaque_types,
normalization_nested_goals,
} = &*external_constraints;
Self::register_region_constraints(delegate, region_constraints, span);
Self::register_new_opaque_types(delegate, opaque_types, span);
(normalization_nested_goals.clone(), certainty)
}
/// This returns the canonical variable values to instantiate the bound variables of
/// the canonical response. This depends on the `original_values` for the
/// bound variables.
fn compute_query_response_instantiation_values<T: ResponseT<I>>(
delegate: &D,
original_values: &[I::GenericArg],
response: &Canonical<I, T>,
span: I::Span,
) -> CanonicalVarValues<I> {
// FIXME: Longterm canonical queries should deal with all placeholders
// created inside of the query directly instead of returning them to the
// caller.
let prev_universe = delegate.universe();
let universes_created_in_query = response.max_universe.index();
for _ in 0..universes_created_in_query {
delegate.create_next_universe();
}
let var_values = response.value.var_values();
assert_eq!(original_values.len(), var_values.len());
// If the query did not make progress with constraining inference variables,
// we would normally create a new inference variables for bound existential variables
// only then unify this new inference variable with the inference variable from
// the input.
//
// We therefore instantiate the existential variable in the canonical response with the
// inference variable of the input right away, which is more performant.
let mut opt_values = IndexVec::from_elem_n(None, response.variables.len());
for (original_value, result_value) in
iter::zip(original_values, var_values.var_values.iter())
{
match result_value.kind() {
ty::GenericArgKind::Type(t) => {
// We disable the instantiation guess for inference variables
// and only use it for placeholders. We need to handle the
// `sub_root` of type inference variables which would make this
// more involved. They are also a lot rarer than region variables.
if let ty::Bound(debruijn, b) = t.kind()
&& !matches!(
response.variables.get(b.var().as_usize()).unwrap(),
CanonicalVarKind::Ty { .. }
)
{
assert_eq!(debruijn, ty::INNERMOST);
opt_values[b.var()] = Some(*original_value);
}
// If the query did not make progress with constraining inference variables,
// we would normally create a new inference variables for bound existential variables
// only then unify this new inference variable with the inference variable from
// the input.
//
// We therefore instantiate the existential variable in the canonical response with the
// inference variable of the input right away, which is more performant.
let mut opt_values = IndexVec::from_elem_n(None, response.variables.len());
for (original_value, result_value) in iter::zip(original_values, var_values.var_values.iter()) {
match result_value.kind() {
ty::GenericArgKind::Type(t) => {
// We disable the instantiation guess for inference variables
// and only use it for placeholders. We need to handle the
// `sub_root` of type inference variables which would make this
// more involved. They are also a lot rarer than region variables.
if let ty::Bound(debruijn, b) = t.kind()
&& !matches!(
response.variables.get(b.var().as_usize()).unwrap(),
CanonicalVarKind::Ty { .. }
)
{
assert_eq!(debruijn, ty::INNERMOST);
opt_values[b.var()] = Some(*original_value);
}
ty::GenericArgKind::Lifetime(r) => {
if let ty::ReBound(debruijn, br) = r.kind() {
assert_eq!(debruijn, ty::INNERMOST);
opt_values[br.var()] = Some(*original_value);
}
}
ty::GenericArgKind::Lifetime(r) => {
if let ty::ReBound(debruijn, br) = r.kind() {
assert_eq!(debruijn, ty::INNERMOST);
opt_values[br.var()] = Some(*original_value);
}
ty::GenericArgKind::Const(c) => {
if let ty::ConstKind::Bound(debruijn, bv) = c.kind() {
assert_eq!(debruijn, ty::INNERMOST);
opt_values[bv.var()] = Some(*original_value);
}
}
ty::GenericArgKind::Const(c) => {
if let ty::ConstKind::Bound(debruijn, bv) = c.kind() {
assert_eq!(debruijn, ty::INNERMOST);
opt_values[bv.var()] = Some(*original_value);
}
}
}
CanonicalVarValues::instantiate(delegate.cx(), response.variables, |var_values, kind| {
if kind.universe() != ty::UniverseIndex::ROOT {
// A variable from inside a binder of the query. While ideally these shouldn't
// exist at all (see the FIXME at the start of this method), we have to deal with
// them for now.
delegate.instantiate_canonical_var(kind, span, &var_values, |idx| {
prev_universe + idx.index()
})
} else if kind.is_existential() {
// As an optimization we sometimes avoid creating a new inference variable here.
//
// All new inference variables we create start out in the current universe of the caller.
// This is conceptually wrong as these inference variables would be able to name
// more placeholders then they should be able to. However the inference variables have
// to "come from somewhere", so by equating them with the original values of the caller
// later on, we pull them down into their correct universe again.
if let Some(v) = opt_values[ty::BoundVar::from_usize(var_values.len())] {
v
} else {
delegate.instantiate_canonical_var(kind, span, &var_values, |_| prev_universe)
}
} else {
// For placeholders which were already part of the input, we simply map this
// universal bound variable back the placeholder of the input.
original_values[kind.expect_placeholder_index()]
}
})
}
/// Unify the `original_values` with the `var_values` returned by the canonical query..
///
/// This assumes that this unification will always succeed. This is the case when
/// applying a query response right away. However, calling a canonical query, doing any
/// other kind of trait solving, and only then instantiating the result of the query
/// can cause the instantiation to fail. This is not supported and we ICE in this case.
///
/// We always structurally instantiate aliases. Relating aliases needs to be different
/// depending on whether the alias is *rigid* or not. We're only really able to tell
/// whether an alias is rigid by using the trait solver. When instantiating a response
/// from the solver we assume that the solver correctly handled aliases and therefore
/// always relate them structurally here.
#[instrument(level = "trace", skip(delegate))]
fn unify_query_var_values(
delegate: &D,
param_env: I::ParamEnv,
original_values: &[I::GenericArg],
var_values: CanonicalVarValues<I>,
span: I::Span,
) {
assert_eq!(original_values.len(), var_values.len());
for (&orig, response) in iter::zip(original_values, var_values.var_values.iter()) {
let goals =
delegate.eq_structurally_relating_aliases(param_env, orig, response, span).unwrap();
assert!(goals.is_empty());
}
}
fn register_region_constraints(
delegate: &D,
outlives: &[ty::OutlivesPredicate<I, I::GenericArg>],
span: I::Span,
) {
for &ty::OutlivesPredicate(lhs, rhs) in outlives {
match lhs.kind() {
ty::GenericArgKind::Lifetime(lhs) => delegate.sub_regions(rhs, lhs, span),
ty::GenericArgKind::Type(lhs) => delegate.register_ty_outlives(lhs, rhs, span),
ty::GenericArgKind::Const(_) => panic!("const outlives: {lhs:?}: {rhs:?}"),
}
}
}
fn register_new_opaque_types(
delegate: &D,
opaque_types: &[(ty::OpaqueTypeKey<I>, I::Ty)],
span: I::Span,
) {
for &(key, ty) in opaque_types {
let prev = delegate.register_hidden_type_in_storage(key, ty, span);
// We eagerly resolve inference variables when computing the query response.
// This can cause previously distinct opaque type keys to now be structurally equal.
CanonicalVarValues::instantiate(delegate.cx(), response.variables, |var_values, kind| {
if kind.universe() != ty::UniverseIndex::ROOT {
// A variable from inside a binder of the query. While ideally these shouldn't
// exist at all (see the FIXME at the start of this method), we have to deal with
// them for now.
delegate.instantiate_canonical_var(kind, span, &var_values, |idx| {
prev_universe + idx.index()
})
} else if kind.is_existential() {
// As an optimization we sometimes avoid creating a new inference variable here.
//
// To handle this, we store any duplicate entries in a separate list to check them
// at the end of typeck/borrowck. We could alternatively eagerly equate the hidden
// types here. However, doing so is difficult as it may result in nested goals and
// any errors may make it harder to track the control flow for diagnostics.
if let Some(prev) = prev {
delegate.add_duplicate_opaque_type(key, prev, span);
// All new inference variables we create start out in the current universe of the caller.
// This is conceptually wrong as these inference variables would be able to name
// more placeholders then they should be able to. However the inference variables have
// to "come from somewhere", so by equating them with the original values of the caller
// later on, we pull them down into their correct universe again.
if let Some(v) = opt_values[ty::BoundVar::from_usize(var_values.len())] {
v
} else {
delegate.instantiate_canonical_var(kind, span, &var_values, |_| prev_universe)
}
} else {
// For placeholders which were already part of the input, we simply map this
// universal bound variable back the placeholder of the input.
original_values[kind.expect_placeholder_index()]
}
})
}
/// Unify the `original_values` with the `var_values` returned by the canonical query..
///
/// This assumes that this unification will always succeed. This is the case when
/// applying a query response right away. However, calling a canonical query, doing any
/// other kind of trait solving, and only then instantiating the result of the query
/// can cause the instantiation to fail. This is not supported and we ICE in this case.
///
/// We always structurally instantiate aliases. Relating aliases needs to be different
/// depending on whether the alias is *rigid* or not. We're only really able to tell
/// whether an alias is rigid by using the trait solver. When instantiating a response
/// from the solver we assume that the solver correctly handled aliases and therefore
/// always relate them structurally here.
#[instrument(level = "trace", skip(delegate))]
fn unify_query_var_values<D, I>(
delegate: &D,
param_env: I::ParamEnv,
original_values: &[I::GenericArg],
var_values: CanonicalVarValues<I>,
span: I::Span,
) where
D: SolverDelegate<Interner = I>,
I: Interner,
{
assert_eq!(original_values.len(), var_values.len());
for (&orig, response) in iter::zip(original_values, var_values.var_values.iter()) {
let goals =
delegate.eq_structurally_relating_aliases(param_env, orig, response, span).unwrap();
assert!(goals.is_empty());
}
}
fn register_region_constraints<D, I>(
delegate: &D,
outlives: &[ty::OutlivesPredicate<I, I::GenericArg>],
span: I::Span,
) where
D: SolverDelegate<Interner = I>,
I: Interner,
{
for &ty::OutlivesPredicate(lhs, rhs) in outlives {
match lhs.kind() {
ty::GenericArgKind::Lifetime(lhs) => delegate.sub_regions(rhs, lhs, span),
ty::GenericArgKind::Type(lhs) => delegate.register_ty_outlives(lhs, rhs, span),
ty::GenericArgKind::Const(_) => panic!("const outlives: {lhs:?}: {rhs:?}"),
}
}
}
fn register_new_opaque_types<D, I>(
delegate: &D,
opaque_types: &[(ty::OpaqueTypeKey<I>, I::Ty)],
span: I::Span,
) where
D: SolverDelegate<Interner = I>,
I: Interner,
{
for &(key, ty) in opaque_types {
let prev = delegate.register_hidden_type_in_storage(key, ty, span);
// We eagerly resolve inference variables when computing the query response.
// This can cause previously distinct opaque type keys to now be structurally equal.
//
// To handle this, we store any duplicate entries in a separate list to check them
// at the end of typeck/borrowck. We could alternatively eagerly equate the hidden
// types here. However, doing so is difficult as it may result in nested goals and
// any errors may make it harder to track the control flow for diagnostics.
if let Some(prev) = prev {
delegate.add_duplicate_opaque_type(key, prev, span);
}
}
}
@@ -274,7 +296,7 @@ fn register_new_opaque_types(
/// evaluating a goal. The `var_values` not only include the bound variables
/// of the query input, but also contain all unconstrained inference vars
/// created while evaluating this goal.
pub fn make_canonical_state<D, T, I>(
pub fn make_canonical_state<D, I, T>(
delegate: &D,
var_values: &[I::GenericArg],
max_input_universe: ty::UniverseIndex,
@@ -293,7 +315,7 @@ pub fn make_canonical_state<D, T, I>(
// FIXME: needs to be pub to be accessed by downstream
// `rustc_trait_selection::solve::inspect::analyse`.
pub fn instantiate_canonical_state<D, I, T: TypeFoldable<I>>(
pub fn instantiate_canonical_state<D, I, T>(
delegate: &D,
span: I::Span,
param_env: I::ParamEnv,
@@ -303,6 +325,7 @@ pub fn instantiate_canonical_state<D, I, T: TypeFoldable<I>>(
where
D: SolverDelegate<Interner = I>,
I: Interner,
T: TypeFoldable<I>,
{
// In case any fresh inference variables have been created between `state`
// and the previous instantiation, extend `orig_values` for it.
@@ -313,11 +336,11 @@ pub fn instantiate_canonical_state<D, I, T: TypeFoldable<I>>(
);
let instantiation =
EvalCtxt::compute_query_response_instantiation_values(delegate, orig_values, &state, span);
compute_query_response_instantiation_values(delegate, orig_values, &state, span);
let inspect::State { var_values, data } = delegate.instantiate_canonical(state, instantiation);
EvalCtxt::unify_query_var_values(delegate, param_env, orig_values, var_values, span);
unify_query_var_values(delegate, param_env, orig_values, var_values, span);
data
}
compiler/rustc_next_trait_solver/src/solve/eval_ctxt/mod.rs
+9 -9
View File
@@ -17,8 +17,10 @@
use tracing::{debug, instrument, trace};
use super::has_only_region_constraints;
use crate::canonical::canonicalizer::Canonicalizer;
use crate::canonical::response_no_constraints_raw;
use crate::canonical::{
canonicalize_goal, canonicalize_response, instantiate_and_apply_query_response,
response_no_constraints_raw,
};
use crate::coherence;
use crate::delegate::SolverDelegate;
use crate::placeholder::BoundVarReplacer;
@@ -465,8 +467,7 @@ pub(super) fn evaluate_goal_raw(
let opaque_types = self.delegate.clone_opaque_types_lookup_table();
let (goal, opaque_types) = eager_resolve_vars(self.delegate, (goal, opaque_types));
let (orig_values, canonical_goal) =
Self::canonicalize_goal(self.delegate, goal, opaque_types);
let (orig_values, canonical_goal) = canonicalize_goal(self.delegate, goal, opaque_types);
let canonical_result = self.search_graph.evaluate_goal(
self.cx(),
canonical_goal,
@@ -481,7 +482,7 @@ pub(super) fn evaluate_goal_raw(
let has_changed =
if !has_only_region_constraints(response) { HasChanged::Yes } else { HasChanged::No };
let (normalization_nested_goals, certainty) = Self::instantiate_and_apply_query_response(
let (normalization_nested_goals, certainty) = instantiate_and_apply_query_response(
self.delegate,
goal.param_env,
&orig_values,
@@ -1319,10 +1320,9 @@ pub(in crate::solve) fn evaluate_added_goals_and_make_canonical_response(
outlives.0.as_region().is_none_or(|re| re != outlives.1) && unique.insert(*outlives)
});
let canonical = Canonicalizer::canonicalize_response(
let canonical = canonicalize_response(
self.delegate,
self.max_input_universe,
&mut Default::default(),
Response {
var_values,
certainty,
@@ -1557,7 +1557,7 @@ pub(super) fn evaluate_root_goal_for_proof_tree<D: SolverDelegate<Interner = I>,
let opaque_types = delegate.clone_opaque_types_lookup_table();
let (goal, opaque_types) = eager_resolve_vars(delegate, (goal, opaque_types));
let (orig_values, canonical_goal) = EvalCtxt::canonicalize_goal(delegate, goal, opaque_types);
let (orig_values, canonical_goal) = canonicalize_goal(delegate, goal, opaque_types);
let (canonical_result, final_revision) =
delegate.cx().evaluate_root_goal_for_proof_tree_raw(canonical_goal);
@@ -1574,7 +1574,7 @@ pub(super) fn evaluate_root_goal_for_proof_tree<D: SolverDelegate<Interner = I>,
Ok(response) => response,
};
let (normalization_nested_goals, _certainty) = EvalCtxt::instantiate_and_apply_query_response(
let (normalization_nested_goals, _certainty) = instantiate_and_apply_query_response(
delegate,
goal.param_env,
&proof_tree.orig_values,