use rustc_data_structures::fx::FxIndexMap;
use rustc_hir::def_id::DefId;
use rustc_middle::ty;
use thin_vec::ThinVec;
use crate::clean;
use crate::clean::GenericArgs as PP;
use crate::clean::WherePredicate as WP;
use crate::core::DocContext;
pub(crate) fn where_clauses(cx: &DocContext<'_>, clauses: Vec<WP>) -> ThinVec<WP> {
let mut tybounds = FxIndexMap::default();
let mut lifetimes = Vec::new();
let mut equalities = Vec::new();
for clause in clauses {
match clause {
WP::BoundPredicate { ty, bounds, bound_params } => {
let (b, p): &mut (Vec<_>, Vec<_>) = tybounds.entry(ty).or_default();
b.extend(bounds);
p.extend(bound_params);
}
WP::RegionPredicate { lifetime, bounds } => {
lifetimes.push((lifetime, bounds));
}
WP::EqPredicate { lhs, rhs } => equalities.push((lhs, rhs)),
}
}
equalities.retain(|(lhs, rhs)| {
let Some((ty, trait_did, name)) = lhs.projection() else {
return true;
};
let Some((bounds, _)) = tybounds.get_mut(ty) else { return true };
merge_bounds(cx, bounds, trait_did, name, rhs)
});
let mut clauses = ThinVec::with_capacity(lifetimes.len() + tybounds.len() + equalities.len());
clauses.extend(
lifetimes.into_iter().map(|(lt, bounds)| WP::RegionPredicate { lifetime: lt, bounds }),
);
clauses.extend(tybounds.into_iter().map(|(ty, (bounds, bound_params))| WP::BoundPredicate {
ty,
bounds,
bound_params,
}));
clauses.extend(equalities.into_iter().map(|(lhs, rhs)| WP::EqPredicate { lhs, rhs }));
clauses
}
pub(crate) fn merge_bounds(
cx: &clean::DocContext<'_>,
bounds: &mut Vec<clean::GenericBound>,
trait_did: DefId,
assoc: clean::PathSegment,
rhs: &clean::Term,
) -> bool {
!bounds.iter_mut().any(|b| {
let trait_ref = match *b {
clean::GenericBound::TraitBound(ref mut tr, _) => tr,
clean::GenericBound::Outlives(..) => return false,
};
if !trait_is_same_or_supertrait(cx, trait_ref.trait_.def_id(), trait_did) {
return false;
}
let last = trait_ref.trait_.segments.last_mut().expect("segments were empty");
match last.args {
PP::AngleBracketed { ref mut bindings, .. } => {
bindings.push(clean::TypeBinding {
assoc: assoc.clone(),
kind: clean::TypeBindingKind::Equality { term: rhs.clone() },
});
}
PP::Parenthesized { ref mut output, .. } => match output {
Some(o) => assert_eq!(&clean::Term::Type(o.as_ref().clone()), rhs),
None => {
if *rhs != clean::Term::Type(clean::Type::Tuple(Vec::new())) {
*output = Some(Box::new(rhs.ty().unwrap().clone()));
}
}
},
};
true
})
}
fn trait_is_same_or_supertrait(cx: &DocContext<'_>, child: DefId, trait_: DefId) -> bool {
if child == trait_ {
return true;
}
let predicates = cx.tcx.super_predicates_of(child);
debug_assert!(cx.tcx.generics_of(child).has_self);
let self_ty = cx.tcx.types.self_param;
predicates
.predicates
.iter()
.filter_map(|(pred, _)| {
if let ty::ClauseKind::Trait(pred) = pred.kind().skip_binder() {
if pred.trait_ref.self_ty() == self_ty { Some(pred.def_id()) } else { None }
} else {
None
}
})
.any(|did| trait_is_same_or_supertrait(cx, did, trait_))
}
pub(crate) fn move_bounds_to_generic_parameters(generics: &mut clean::Generics) {
use clean::types::*;
let mut where_predicates = ThinVec::new();
for mut pred in generics.where_predicates.drain(..) {
if let WherePredicate::BoundPredicate { ty: Generic(arg), bounds, .. } = &mut pred
&& let Some(GenericParamDef {
kind: GenericParamDefKind::Type { bounds: param_bounds, .. },
..
}) = generics.params.iter_mut().find(|param| ¶m.name == arg)
{
param_bounds.append(bounds);
} else if let WherePredicate::RegionPredicate { lifetime: Lifetime(arg), bounds } = &mut pred
&& let Some(GenericParamDef {
kind: GenericParamDefKind::Lifetime { outlives: param_bounds },
..
}) = generics.params.iter_mut().find(|param| ¶m.name == arg)
{
param_bounds.extend(bounds.drain(..).map(|bound| match bound {
GenericBound::Outlives(lifetime) => lifetime,
_ => unreachable!(),
}));
} else {
where_predicates.push(pred);
}
}
generics.where_predicates = where_predicates;
}