]>
Commit | Line | Data |
---|---|---|
dc9dc135 | 1 | use super::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; |
dfeec247 | 2 | use super::{FixupError, FixupResult, InferCtxt, Span}; |
ba9703b0 XL |
3 | use rustc_middle::ty::fold::{TypeFolder, TypeVisitor}; |
4 | use rustc_middle::ty::{self, Const, InferConst, Ty, TyCtxt, TypeFoldable}; | |
1a4d82fc JJ |
5 | |
6 | /////////////////////////////////////////////////////////////////////////// | |
dc9dc135 | 7 | // OPPORTUNISTIC VAR RESOLVER |
1a4d82fc | 8 | |
dc9dc135 XL |
9 | /// The opportunistic resolver can be used at any time. It simply replaces |
10 | /// type/const variables that have been unified with the things they have | |
1a4d82fc JJ |
11 | /// been unified with (similar to `shallow_resolve`, but deep). This is |
12 | /// useful for printing messages etc but also required at various | |
13 | /// points for correctness. | |
dc9dc135 XL |
14 | pub struct OpportunisticVarResolver<'a, 'tcx> { |
15 | infcx: &'a InferCtxt<'a, 'tcx>, | |
1a4d82fc JJ |
16 | } |
17 | ||
dc9dc135 | 18 | impl<'a, 'tcx> OpportunisticVarResolver<'a, 'tcx> { |
a1dfa0c6 | 19 | #[inline] |
dc9dc135 XL |
20 | pub fn new(infcx: &'a InferCtxt<'a, 'tcx>) -> Self { |
21 | OpportunisticVarResolver { infcx } | |
1a4d82fc JJ |
22 | } |
23 | } | |
24 | ||
dc9dc135 XL |
25 | impl<'a, 'tcx> TypeFolder<'tcx> for OpportunisticVarResolver<'a, 'tcx> { |
26 | fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { | |
1a4d82fc JJ |
27 | self.infcx.tcx |
28 | } | |
29 | ||
30 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
74b04a01 | 31 | if !t.has_infer_types_or_consts() { |
1a4d82fc JJ |
32 | t // micro-optimize -- if there is nothing in this type that this fold affects... |
33 | } else { | |
dc9dc135 XL |
34 | let t = self.infcx.shallow_resolve(t); |
35 | t.super_fold_with(self) | |
36 | } | |
37 | } | |
38 | ||
39 | fn fold_const(&mut self, ct: &'tcx Const<'tcx>) -> &'tcx Const<'tcx> { | |
74b04a01 | 40 | if !ct.has_infer_types_or_consts() { |
dc9dc135 XL |
41 | ct // micro-optimize -- if there is nothing in this const that this fold affects... |
42 | } else { | |
43 | let ct = self.infcx.shallow_resolve(ct); | |
44 | ct.super_fold_with(self) | |
9cc50fc6 SL |
45 | } |
46 | } | |
47 | } | |
48 | ||
f035d41b XL |
49 | /// The opportunistic region resolver opportunistically resolves regions |
50 | /// variables to the variable with the least variable id. It is used when | |
51 | /// normlizing projections to avoid hitting the recursion limit by creating | |
52 | /// many versions of a predicate for types that in the end have to unify. | |
53 | /// | |
54 | /// If you want to resolve type and const variables as well, call | |
55 | /// [InferCtxt::resolve_vars_if_possible] first. | |
56 | pub struct OpportunisticRegionResolver<'a, 'tcx> { | |
dc9dc135 | 57 | infcx: &'a InferCtxt<'a, 'tcx>, |
9cc50fc6 SL |
58 | } |
59 | ||
f035d41b | 60 | impl<'a, 'tcx> OpportunisticRegionResolver<'a, 'tcx> { |
dc9dc135 | 61 | pub fn new(infcx: &'a InferCtxt<'a, 'tcx>) -> Self { |
f035d41b | 62 | OpportunisticRegionResolver { infcx } |
9cc50fc6 SL |
63 | } |
64 | } | |
65 | ||
f035d41b | 66 | impl<'a, 'tcx> TypeFolder<'tcx> for OpportunisticRegionResolver<'a, 'tcx> { |
dc9dc135 | 67 | fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { |
9cc50fc6 SL |
68 | self.infcx.tcx |
69 | } | |
70 | ||
71 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
f035d41b | 72 | if !t.has_infer_regions() { |
9cc50fc6 SL |
73 | t // micro-optimize -- if there is nothing in this type that this fold affects... |
74 | } else { | |
f035d41b | 75 | t.super_fold_with(self) |
9cc50fc6 SL |
76 | } |
77 | } | |
78 | ||
7cac9316 | 79 | fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { |
9e0c209e | 80 | match *r { |
f035d41b XL |
81 | ty::ReVar(rid) => { |
82 | let resolved = self | |
83 | .infcx | |
84 | .inner | |
85 | .borrow_mut() | |
86 | .unwrap_region_constraints() | |
87 | .opportunistic_resolve_var(rid); | |
88 | self.tcx().reuse_or_mk_region(r, ty::ReVar(resolved)) | |
89 | } | |
dfeec247 | 90 | _ => r, |
1a4d82fc JJ |
91 | } |
92 | } | |
48663c56 XL |
93 | |
94 | fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> { | |
f035d41b | 95 | if !ct.has_infer_regions() { |
48663c56 XL |
96 | ct // micro-optimize -- if there is nothing in this const that this fold affects... |
97 | } else { | |
f035d41b | 98 | ct.super_fold_with(self) |
48663c56 XL |
99 | } |
100 | } | |
1a4d82fc JJ |
101 | } |
102 | ||
3b2f2976 XL |
103 | /////////////////////////////////////////////////////////////////////////// |
104 | // UNRESOLVED TYPE FINDER | |
105 | ||
48663c56 XL |
106 | /// The unresolved type **finder** walks a type searching for |
107 | /// type variables that don't yet have a value. The first unresolved type is stored. | |
108 | /// It does not construct the fully resolved type (which might | |
3b2f2976 | 109 | /// involve some hashing and so forth). |
dc9dc135 XL |
110 | pub struct UnresolvedTypeFinder<'a, 'tcx> { |
111 | infcx: &'a InferCtxt<'a, 'tcx>, | |
48663c56 XL |
112 | |
113 | /// Used to find the type parameter name and location for error reporting. | |
dc9dc135 | 114 | pub first_unresolved: Option<(Ty<'tcx>, Option<Span>)>, |
3b2f2976 XL |
115 | } |
116 | ||
dc9dc135 XL |
117 | impl<'a, 'tcx> UnresolvedTypeFinder<'a, 'tcx> { |
118 | pub fn new(infcx: &'a InferCtxt<'a, 'tcx>) -> Self { | |
48663c56 | 119 | UnresolvedTypeFinder { infcx, first_unresolved: None } |
3b2f2976 XL |
120 | } |
121 | } | |
122 | ||
dc9dc135 | 123 | impl<'a, 'tcx> TypeVisitor<'tcx> for UnresolvedTypeFinder<'a, 'tcx> { |
3b2f2976 XL |
124 | fn visit_ty(&mut self, t: Ty<'tcx>) -> bool { |
125 | let t = self.infcx.shallow_resolve(t); | |
126 | if t.has_infer_types() { | |
e74abb32 | 127 | if let ty::Infer(infer_ty) = t.kind { |
3b2f2976 XL |
128 | // Since we called `shallow_resolve` above, this must |
129 | // be an (as yet...) unresolved inference variable. | |
dfeec247 | 130 | let ty_var_span = if let ty::TyVar(ty_vid) = infer_ty { |
f9f354fc XL |
131 | let mut inner = self.infcx.inner.borrow_mut(); |
132 | let ty_vars = &inner.type_variables(); | |
dc9dc135 | 133 | if let TypeVariableOrigin { |
dfeec247 | 134 | kind: TypeVariableOriginKind::TypeParameterDefinition(_, _), |
dc9dc135 XL |
135 | span, |
136 | } = *ty_vars.var_origin(ty_vid) | |
48663c56 XL |
137 | { |
138 | Some(span) | |
139 | } else { | |
140 | None | |
141 | } | |
142 | } else { | |
143 | None | |
144 | }; | |
145 | self.first_unresolved = Some((t, ty_var_span)); | |
dfeec247 | 146 | true // Halt visiting. |
3b2f2976 XL |
147 | } else { |
148 | // Otherwise, visit its contents. | |
149 | t.super_visit_with(self) | |
150 | } | |
151 | } else { | |
48663c56 XL |
152 | // All type variables in inference types must already be resolved, |
153 | // - no need to visit the contents, continue visiting. | |
3b2f2976 XL |
154 | false |
155 | } | |
156 | } | |
157 | } | |
158 | ||
1a4d82fc JJ |
159 | /////////////////////////////////////////////////////////////////////////// |
160 | // FULL TYPE RESOLUTION | |
161 | ||
162 | /// Full type resolution replaces all type and region variables with | |
163 | /// their concrete results. If any variable cannot be replaced (never unified, etc) | |
164 | /// then an `Err` result is returned. | |
dc9dc135 XL |
165 | pub fn fully_resolve<'a, 'tcx, T>(infcx: &InferCtxt<'a, 'tcx>, value: &T) -> FixupResult<'tcx, T> |
166 | where | |
167 | T: TypeFoldable<'tcx>, | |
1a4d82fc | 168 | { |
74b04a01 | 169 | let mut full_resolver = FullTypeResolver { infcx, err: None }; |
1a4d82fc JJ |
170 | let result = value.fold_with(&mut full_resolver); |
171 | match full_resolver.err { | |
172 | None => Ok(result), | |
173 | Some(e) => Err(e), | |
174 | } | |
175 | } | |
176 | ||
177 | // N.B. This type is not public because the protocol around checking the | |
74b04a01 | 178 | // `err` field is not enforceable otherwise. |
dc9dc135 XL |
179 | struct FullTypeResolver<'a, 'tcx> { |
180 | infcx: &'a InferCtxt<'a, 'tcx>, | |
48663c56 | 181 | err: Option<FixupError<'tcx>>, |
1a4d82fc JJ |
182 | } |
183 | ||
dc9dc135 XL |
184 | impl<'a, 'tcx> TypeFolder<'tcx> for FullTypeResolver<'a, 'tcx> { |
185 | fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { | |
1a4d82fc JJ |
186 | self.infcx.tcx |
187 | } | |
188 | ||
189 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
ba9703b0 | 190 | if !t.needs_infer() { |
1a4d82fc JJ |
191 | t // micro-optimize -- if there is nothing in this type that this fold affects... |
192 | } else { | |
193 | let t = self.infcx.shallow_resolve(t); | |
e74abb32 | 194 | match t.kind { |
b7449926 | 195 | ty::Infer(ty::TyVar(vid)) => { |
c1a9b12d | 196 | self.err = Some(FixupError::UnresolvedTy(vid)); |
f035d41b | 197 | self.tcx().ty_error() |
1a4d82fc | 198 | } |
b7449926 | 199 | ty::Infer(ty::IntVar(vid)) => { |
c1a9b12d | 200 | self.err = Some(FixupError::UnresolvedIntTy(vid)); |
f035d41b | 201 | self.tcx().ty_error() |
1a4d82fc | 202 | } |
b7449926 | 203 | ty::Infer(ty::FloatVar(vid)) => { |
c1a9b12d | 204 | self.err = Some(FixupError::UnresolvedFloatTy(vid)); |
f035d41b | 205 | self.tcx().ty_error() |
1a4d82fc | 206 | } |
b7449926 | 207 | ty::Infer(_) => { |
54a0048b | 208 | bug!("Unexpected type in full type resolver: {:?}", t); |
1a4d82fc | 209 | } |
dfeec247 | 210 | _ => t.super_fold_with(self), |
1a4d82fc JJ |
211 | } |
212 | } | |
213 | } | |
214 | ||
7cac9316 | 215 | fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { |
9e0c209e | 216 | match *r { |
dfeec247 XL |
217 | ty::ReVar(rid) => self |
218 | .infcx | |
219 | .lexical_region_resolutions | |
220 | .borrow() | |
221 | .as_ref() | |
222 | .expect("region resolution not performed") | |
223 | .resolve_var(rid), | |
9e0c209e | 224 | _ => r, |
1a4d82fc JJ |
225 | } |
226 | } | |
48663c56 XL |
227 | |
228 | fn fold_const(&mut self, c: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> { | |
ba9703b0 | 229 | if !c.needs_infer() { |
48663c56 | 230 | c // micro-optimize -- if there is nothing in this const that this fold affects... |
48663c56 XL |
231 | } else { |
232 | let c = self.infcx.shallow_resolve(c); | |
233 | match c.val { | |
60c5eb7d | 234 | ty::ConstKind::Infer(InferConst::Var(vid)) => { |
48663c56 | 235 | self.err = Some(FixupError::UnresolvedConst(vid)); |
f035d41b | 236 | return self.tcx().const_error(c.ty); |
48663c56 | 237 | } |
60c5eb7d | 238 | ty::ConstKind::Infer(InferConst::Fresh(_)) => { |
48663c56 XL |
239 | bug!("Unexpected const in full const resolver: {:?}", c); |
240 | } | |
241 | _ => {} | |
242 | } | |
243 | c.super_fold_with(self) | |
244 | } | |
245 | } | |
1a4d82fc | 246 | } |