Track constness while lowering bounds
diff --git a/src/librustc_privacy/lib.rs b/src/librustc_privacy/lib.rs
index 4b2e90e..a914537 100644
--- a/src/librustc_privacy/lib.rs
+++ b/src/librustc_privacy/lib.rs
@@ -1237,7 +1237,7 @@
// The traits' privacy in bodies is already checked as a part of trait object types.
let bounds = rustc_typeck::hir_trait_to_predicates(self.tcx, trait_ref);
- for (trait_predicate, _) in bounds.trait_bounds {
+ for (trait_predicate, _, _) in bounds.trait_bounds {
if self.visit_trait(*trait_predicate.skip_binder()) {
return;
}
diff --git a/src/librustc_typeck/astconv.rs b/src/librustc_typeck/astconv.rs
index 9253c00..6726a14 100644
--- a/src/librustc_typeck/astconv.rs
+++ b/src/librustc_typeck/astconv.rs
@@ -31,7 +31,7 @@
use rustc_span::{MultiSpan, Span, DUMMY_SP};
use rustc_target::spec::abi;
use smallvec::SmallVec;
-use syntax::ast;
+use syntax::ast::{self, Constness};
use syntax::util::lev_distance::find_best_match_for_name;
use std::collections::BTreeSet;
@@ -49,6 +49,8 @@
fn item_def_id(&self) -> Option<DefId>;
+ fn default_constness_for_trait_bounds(&self) -> Constness;
+
/// Returns predicates in scope of the form `X: Foo`, where `X` is
/// a type parameter `X` with the given id `def_id`. This is a
/// subset of the full set of predicates.
@@ -919,6 +921,7 @@
&self,
trait_ref: &hir::TraitRef<'_>,
span: Span,
+ constness: Constness,
self_ty: Ty<'tcx>,
bounds: &mut Bounds<'tcx>,
speculative: bool,
@@ -947,7 +950,7 @@
);
let poly_trait_ref = ty::Binder::bind(ty::TraitRef::new(trait_def_id, substs));
- bounds.trait_bounds.push((poly_trait_ref, span));
+ bounds.trait_bounds.push((poly_trait_ref, span, constness));
let mut dup_bindings = FxHashMap::default();
for binding in &assoc_bindings {
@@ -993,12 +996,14 @@
pub fn instantiate_poly_trait_ref(
&self,
poly_trait_ref: &hir::PolyTraitRef<'_>,
+ constness: Constness,
self_ty: Ty<'tcx>,
bounds: &mut Bounds<'tcx>,
) -> Option<Vec<Span>> {
self.instantiate_poly_trait_ref_inner(
&poly_trait_ref.trait_ref,
poly_trait_ref.span,
+ constness,
self_ty,
bounds,
false,
@@ -1181,18 +1186,22 @@
let mut trait_bounds = Vec::new();
let mut region_bounds = Vec::new();
+ let constness = self.default_constness_for_trait_bounds();
for ast_bound in ast_bounds {
match *ast_bound {
hir::GenericBound::Trait(ref b, hir::TraitBoundModifier::None) => {
- trait_bounds.push(b)
+ trait_bounds.push((b, constness))
+ }
+ hir::GenericBound::Trait(ref b, hir::TraitBoundModifier::MaybeConst) => {
+ trait_bounds.push((b, Constness::NotConst))
}
hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => {}
hir::GenericBound::Outlives(ref l) => region_bounds.push(l),
}
}
- for bound in trait_bounds {
- let _ = self.instantiate_poly_trait_ref(bound, param_ty, bounds);
+ for (bound, constness) in trait_bounds {
+ let _ = self.instantiate_poly_trait_ref(bound, constness, param_ty, bounds);
}
bounds.region_bounds.extend(
@@ -1226,7 +1235,7 @@
let mut bounds = Bounds::default();
self.add_bounds(param_ty, ast_bounds, &mut bounds);
- bounds.trait_bounds.sort_by_key(|(t, _)| t.def_id());
+ bounds.trait_bounds.sort_by_key(|(t, _, _)| t.def_id());
bounds.implicitly_sized = if let SizedByDefault::Yes = sized_by_default {
if !self.is_unsized(ast_bounds, span) { Some(span) } else { None }
@@ -1417,15 +1426,21 @@
let mut potential_assoc_types = Vec::new();
let dummy_self = self.tcx().types.trait_object_dummy_self;
for trait_bound in trait_bounds.iter().rev() {
- let cur_potential_assoc_types =
- self.instantiate_poly_trait_ref(trait_bound, dummy_self, &mut bounds);
+ let cur_potential_assoc_types = self.instantiate_poly_trait_ref(
+ trait_bound,
+ Constness::NotConst,
+ dummy_self,
+ &mut bounds,
+ );
potential_assoc_types.extend(cur_potential_assoc_types.into_iter().flatten());
}
// Expand trait aliases recursively and check that only one regular (non-auto) trait
// is used and no 'maybe' bounds are used.
- let expanded_traits =
- traits::expand_trait_aliases(tcx, bounds.trait_bounds.iter().cloned());
+ let expanded_traits = traits::expand_trait_aliases(
+ tcx,
+ bounds.trait_bounds.iter().map(|&(a, b, _)| (a.clone(), b)),
+ );
let (mut auto_traits, regular_traits): (Vec<_>, Vec<_>) =
expanded_traits.partition(|i| tcx.trait_is_auto(i.trait_ref().def_id()));
if regular_traits.len() > 1 {
@@ -1481,16 +1496,18 @@
let regular_traits_refs_spans = bounds
.trait_bounds
.into_iter()
- .filter(|(trait_ref, _)| !tcx.trait_is_auto(trait_ref.def_id()));
+ .filter(|(trait_ref, _, _)| !tcx.trait_is_auto(trait_ref.def_id()));
- for (base_trait_ref, span) in regular_traits_refs_spans {
+ for (base_trait_ref, span, constness) in regular_traits_refs_spans {
+ assert_eq!(constness, ast::Constness::NotConst);
+
for trait_ref in traits::elaborate_trait_ref(tcx, base_trait_ref) {
debug!(
"conv_object_ty_poly_trait_ref: observing object predicate `{:?}`",
trait_ref
);
match trait_ref {
- ty::Predicate::Trait(pred, constness) => {
+ ty::Predicate::Trait(pred, _) => {
associated_types.entry(span).or_default().extend(
tcx.associated_items(pred.def_id())
.filter(|item| item.kind == ty::AssocKind::Type)
@@ -2949,7 +2966,7 @@
/// A list of trait bounds. So if you had `T: Debug` this would be
/// `T: Debug`. Note that the self-type is explicit here.
- pub trait_bounds: Vec<(ty::PolyTraitRef<'tcx>, Span)>,
+ pub trait_bounds: Vec<(ty::PolyTraitRef<'tcx>, Span, Constness)>,
/// A list of projection equality bounds. So if you had `T:
/// Iterator<Item = u32>` this would include `<T as
@@ -2997,11 +3014,10 @@
let outlives = ty::OutlivesPredicate(param_ty, region_bound);
(ty::Binder::bind(outlives).to_predicate(), span)
})
- .chain(
- self.trait_bounds
- .iter()
- .map(|&(bound_trait_ref, span)| (bound_trait_ref.to_predicate(), span)),
- )
+ .chain(self.trait_bounds.iter().map(|&(bound_trait_ref, span, constness)| {
+ let predicate = bound_trait_ref.with_constness(constness).to_predicate();
+ (predicate, span)
+ }))
.chain(
self.projection_bounds
.iter()
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 1e3927f..5e1b3a7 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -90,6 +90,7 @@
use crate::astconv::{AstConv, PathSeg};
use crate::middle::lang_items;
use crate::namespace::Namespace;
+use rustc::hir::map::blocks::FnLikeNode;
use rustc::hir::map::Map;
use rustc::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse};
use rustc::infer::error_reporting::TypeAnnotationNeeded::E0282;
@@ -2612,6 +2613,16 @@
None
}
+ fn default_constness_for_trait_bounds(&self) -> ast::Constness {
+ // FIXME: refactor this into a method
+ let node = self.tcx.hir().get(self.body_id);
+ if let Some(fn_like) = FnLikeNode::from_node(node) {
+ fn_like.constness()
+ } else {
+ ast::Constness::NotConst
+ }
+ }
+
fn get_type_parameter_bounds(&self, _: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
let tcx = self.tcx;
let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
diff --git a/src/librustc_typeck/collect.rs b/src/librustc_typeck/collect.rs
index 1211075..45d969a 100644
--- a/src/librustc_typeck/collect.rs
+++ b/src/librustc_typeck/collect.rs
@@ -20,6 +20,7 @@
use crate::lint;
use crate::middle::resolve_lifetime as rl;
use crate::middle::weak_lang_items;
+use rustc::hir::map::blocks::FnLikeNode;
use rustc::hir::map::Map;
use rustc::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
use rustc::mir::mono::Linkage;
@@ -288,6 +289,22 @@
Some(self.item_def_id)
}
+ fn default_constness_for_trait_bounds(&self) -> ast::Constness {
+ // FIXME: refactor this into a method
+ let hir_id = self
+ .tcx
+ .hir()
+ .as_local_hir_id(self.item_def_id)
+ .expect("Non-local call to local provider is_const_fn");
+
+ let node = self.tcx.hir().get(hir_id);
+ if let Some(fn_like) = FnLikeNode::from_node(node) {
+ fn_like.constness()
+ } else {
+ ast::Constness::NotConst
+ }
+ }
+
fn get_type_parameter_bounds(&self, span: Span, def_id: DefId) -> ty::GenericPredicates<'tcx> {
self.tcx.at(span).type_param_predicates((self.item_def_id, def_id))
}
@@ -454,6 +471,7 @@
ty: Ty<'tcx>,
only_self_bounds: OnlySelfBounds,
) -> Vec<(ty::Predicate<'tcx>, Span)> {
+ let constness = self.default_constness_for_trait_bounds();
let from_ty_params = ast_generics
.params
.iter()
@@ -462,7 +480,7 @@
_ => None,
})
.flat_map(|bounds| bounds.iter())
- .flat_map(|b| predicates_from_bound(self, ty, b));
+ .flat_map(|b| predicates_from_bound(self, ty, b, constness));
let from_where_clauses = ast_generics
.where_clause
@@ -482,7 +500,7 @@
};
bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b)))
})
- .flat_map(|(bt, b)| predicates_from_bound(self, bt, b));
+ .flat_map(|(bt, b)| predicates_from_bound(self, bt, b, constness));
from_ty_params.chain(from_where_clauses).collect()
}
@@ -2107,6 +2125,7 @@
let mut is_default_impl_trait = None;
let icx = ItemCtxt::new(tcx, def_id);
+ let constness = icx.default_constness_for_trait_bounds();
const NO_GENERICS: &hir::Generics<'_> = &hir::Generics::empty();
@@ -2308,11 +2327,18 @@
for bound in bound_pred.bounds.iter() {
match bound {
- &hir::GenericBound::Trait(ref poly_trait_ref, _) => {
+ &hir::GenericBound::Trait(ref poly_trait_ref, modifier) => {
+ let constness = match modifier {
+ hir::TraitBoundModifier::MaybeConst => ast::Constness::NotConst,
+ hir::TraitBoundModifier::None => constness,
+ hir::TraitBoundModifier::Maybe => bug!("this wasn't handled"),
+ };
+
let mut bounds = Bounds::default();
let _ = AstConv::instantiate_poly_trait_ref(
&icx,
poly_trait_ref,
+ constness,
ty,
&mut bounds,
);
@@ -2488,11 +2514,18 @@
astconv: &dyn AstConv<'tcx>,
param_ty: Ty<'tcx>,
bound: &'tcx hir::GenericBound<'tcx>,
+ constness: ast::Constness,
) -> Vec<(ty::Predicate<'tcx>, Span)> {
match *bound {
- hir::GenericBound::Trait(ref tr, hir::TraitBoundModifier::None) => {
+ hir::GenericBound::Trait(ref tr, modifier) => {
+ let constness = match modifier {
+ hir::TraitBoundModifier::Maybe => return vec![],
+ hir::TraitBoundModifier::MaybeConst => ast::Constness::NotConst,
+ hir::TraitBoundModifier::None => constness,
+ };
+
let mut bounds = Bounds::default();
- let _ = astconv.instantiate_poly_trait_ref(tr, param_ty, &mut bounds);
+ let _ = astconv.instantiate_poly_trait_ref(tr, constness, param_ty, &mut bounds);
bounds.predicates(astconv.tcx(), param_ty)
}
hir::GenericBound::Outlives(ref lifetime) => {
@@ -2500,7 +2533,6 @@
let pred = ty::Binder::bind(ty::OutlivesPredicate(param_ty, region));
vec![(ty::Predicate::TypeOutlives(pred), lifetime.span)]
}
- hir::GenericBound::Trait(_, hir::TraitBoundModifier::Maybe) => vec![],
}
}
diff --git a/src/librustc_typeck/lib.rs b/src/librustc_typeck/lib.rs
index 95cd3c6..b3cf5f2 100644
--- a/src/librustc_typeck/lib.rs
+++ b/src/librustc_typeck/lib.rs
@@ -382,6 +382,7 @@
&item_cx,
hir_trait,
DUMMY_SP,
+ syntax::ast::Constness::NotConst,
tcx.types.err,
&mut bounds,
true,
