]>
Commit | Line | Data |
---|---|---|
9fa01778 | 1 | //! Simplification of where-clauses and parameter bounds into a prettier and |
9346a6ac AL |
2 | //! more canonical form. |
3 | //! | |
ba9703b0 | 4 | //! Currently all cross-crate-inlined function use `rustc_middle::ty` to reconstruct |
0731742a | 5 | //! the AST (e.g., see all of `clean::inline`), but this is not always a |
9fa01778 | 6 | //! non-lossy transformation. The current format of storage for where-clauses |
9346a6ac | 7 | //! for functions and such is simply a list of predicates. One example of this |
9fa01778 | 8 | //! is that the AST predicate of: `where T: Trait<Foo = Bar>` is encoded as: |
ea8adc8c | 9 | //! `where T: Trait, <T as Trait>::Foo = Bar`. |
9346a6ac AL |
10 | //! |
11 | //! This module attempts to reconstruct the original where and/or parameter | |
12 | //! bounds by special casing scenarios such as these. Fun! | |
13 | ||
c295e0f8 | 14 | use rustc_data_structures::fx::FxIndexMap; |
dfeec247 | 15 | use rustc_hir::def_id::DefId; |
ba9703b0 | 16 | use rustc_middle::ty; |
9346a6ac | 17 | |
dfeec247 | 18 | use crate::clean; |
9fa01778 XL |
19 | use crate::clean::GenericArgs as PP; |
20 | use crate::clean::WherePredicate as WP; | |
9fa01778 | 21 | use crate::core::DocContext; |
9346a6ac | 22 | |
923072b8 | 23 | pub(crate) fn where_clauses(cx: &DocContext<'_>, clauses: Vec<WP>) -> Vec<WP> { |
c295e0f8 XL |
24 | // First, partition the where clause into its separate components. |
25 | // | |
26 | // We use `FxIndexMap` so that the insertion order is preserved to prevent messing up to | |
27 | // the order of the generated bounds. | |
2b03887a | 28 | let mut tybounds = FxIndexMap::default(); |
9346a6ac AL |
29 | let mut lifetimes = Vec::new(); |
30 | let mut equalities = Vec::new(); | |
ff7c6d11 | 31 | |
9346a6ac AL |
32 | for clause in clauses { |
33 | match clause { | |
2b03887a FG |
34 | WP::BoundPredicate { ty, bounds, bound_params } => { |
35 | let (b, p): &mut (Vec<_>, Vec<_>) = tybounds.entry(ty).or_default(); | |
36 | b.extend(bounds); | |
37 | p.extend(bound_params); | |
38 | } | |
9346a6ac AL |
39 | WP::RegionPredicate { lifetime, bounds } => { |
40 | lifetimes.push((lifetime, bounds)); | |
41 | } | |
2b03887a | 42 | WP::EqPredicate { lhs, rhs, bound_params } => equalities.push((lhs, rhs, bound_params)), |
9346a6ac AL |
43 | } |
44 | } | |
45 | ||
9346a6ac | 46 | // Look for equality predicates on associated types that can be merged into |
2b03887a FG |
47 | // general bound predicates. |
48 | equalities.retain(|&(ref lhs, ref rhs, ref bound_params)| { | |
49 | let Some((ty, trait_did, name)) = lhs.projection() else { return true; }; | |
50 | let Some((bounds, _)) = tybounds.get_mut(ty) else { return true }; | |
51 | let bound_params = bound_params | |
52 | .into_iter() | |
53 | .map(|param| clean::GenericParamDef { | |
54 | name: param.0, | |
55 | kind: clean::GenericParamDefKind::Lifetime { outlives: Vec::new() }, | |
56 | }) | |
57 | .collect(); | |
58 | merge_bounds(cx, bounds, bound_params, trait_did, name, rhs) | |
9346a6ac AL |
59 | }); |
60 | ||
61 | // And finally, let's reassemble everything | |
62 | let mut clauses = Vec::new(); | |
dfeec247 XL |
63 | clauses.extend( |
64 | lifetimes.into_iter().map(|(lt, bounds)| WP::RegionPredicate { lifetime: lt, bounds }), | |
65 | ); | |
136023e0 XL |
66 | clauses.extend(tybounds.into_iter().map(|(ty, (bounds, bound_params))| WP::BoundPredicate { |
67 | ty, | |
68 | bounds, | |
69 | bound_params, | |
70 | })); | |
2b03887a FG |
71 | clauses.extend(equalities.into_iter().map(|(lhs, rhs, bound_params)| WP::EqPredicate { |
72 | lhs, | |
73 | rhs, | |
74 | bound_params, | |
75 | })); | |
9346a6ac AL |
76 | clauses |
77 | } | |
78 | ||
923072b8 | 79 | pub(crate) fn merge_bounds( |
e1599b0c XL |
80 | cx: &clean::DocContext<'_>, |
81 | bounds: &mut Vec<clean::GenericBound>, | |
2b03887a | 82 | mut bound_params: Vec<clean::GenericParamDef>, |
e1599b0c | 83 | trait_did: DefId, |
5e7ed085 | 84 | assoc: clean::PathSegment, |
5099ac24 | 85 | rhs: &clean::Term, |
e1599b0c XL |
86 | ) -> bool { |
87 | !bounds.iter_mut().any(|b| { | |
88 | let trait_ref = match *b { | |
89 | clean::GenericBound::TraitBound(ref mut tr, _) => tr, | |
90 | clean::GenericBound::Outlives(..) => return false, | |
91 | }; | |
e1599b0c XL |
92 | // If this QPath's trait `trait_did` is the same as, or a supertrait |
93 | // of, the bound's trait `did` then we can keep going, otherwise | |
94 | // this is just a plain old equality bound. | |
c295e0f8 | 95 | if !trait_is_same_or_supertrait(cx, trait_ref.trait_.def_id(), trait_did) { |
dfeec247 | 96 | return false; |
e1599b0c | 97 | } |
c295e0f8 | 98 | let last = trait_ref.trait_.segments.last_mut().expect("segments were empty"); |
2b03887a FG |
99 | |
100 | trait_ref.generic_params.append(&mut bound_params); | |
101 | // Since the parameters (probably) originate from `tcx.collect_*_late_bound_regions` which | |
102 | // returns a hash set, sort them alphabetically to guarantee a stable and deterministic | |
103 | // output (and to fully deduplicate them). | |
104 | trait_ref.generic_params.sort_unstable_by(|p, q| p.name.as_str().cmp(q.name.as_str())); | |
105 | trait_ref.generic_params.dedup_by_key(|p| p.name); | |
106 | ||
e1599b0c XL |
107 | match last.args { |
108 | PP::AngleBracketed { ref mut bindings, .. } => { | |
109 | bindings.push(clean::TypeBinding { | |
5e7ed085 | 110 | assoc: assoc.clone(), |
5099ac24 | 111 | kind: clean::TypeBindingKind::Equality { term: rhs.clone() }, |
e1599b0c XL |
112 | }); |
113 | } | |
e74abb32 | 114 | PP::Parenthesized { ref mut output, .. } => match output { |
5099ac24 | 115 | Some(o) => assert_eq!(&clean::Term::Type(o.as_ref().clone()), rhs), |
dfeec247 | 116 | None => { |
5099ac24 FG |
117 | if *rhs != clean::Term::Type(clean::Type::Tuple(Vec::new())) { |
118 | *output = Some(Box::new(rhs.ty().unwrap().clone())); | |
dfeec247 | 119 | } |
e1599b0c | 120 | } |
dfeec247 | 121 | }, |
e1599b0c XL |
122 | }; |
123 | true | |
124 | }) | |
125 | } | |
126 | ||
dfeec247 | 127 | fn trait_is_same_or_supertrait(cx: &DocContext<'_>, child: DefId, trait_: DefId) -> bool { |
9346a6ac | 128 | if child == trait_ { |
dfeec247 | 129 | return true; |
9346a6ac | 130 | } |
a1dfa0c6 | 131 | let predicates = cx.tcx.super_predicates_of(child); |
e1599b0c XL |
132 | debug_assert!(cx.tcx.generics_of(child).has_self); |
133 | let self_ty = cx.tcx.types.self_param; | |
dfeec247 XL |
134 | predicates |
135 | .predicates | |
136 | .iter() | |
137 | .filter_map(|(pred, _)| { | |
94222f64 | 138 | if let ty::PredicateKind::Trait(pred) = pred.kind().skip_binder() { |
3dfed10e | 139 | if pred.trait_ref.self_ty() == self_ty { Some(pred.def_id()) } else { None } |
9e0c209e SL |
140 | } else { |
141 | None | |
9346a6ac | 142 | } |
dfeec247 XL |
143 | }) |
144 | .any(|did| trait_is_same_or_supertrait(cx, did, trait_)) | |
9346a6ac | 145 | } |