]>
Commit | Line | Data |
---|---|---|
dc9dc135 | 1 | use super::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; |
dfeec247 | 2 | use super::{FixupError, FixupResult, InferCtxt, Span}; |
cdc7bbd5 | 3 | use rustc_middle::mir; |
ba9703b0 XL |
4 | use rustc_middle::ty::fold::{TypeFolder, TypeVisitor}; |
5 | use rustc_middle::ty::{self, Const, InferConst, Ty, TyCtxt, TypeFoldable}; | |
1a4d82fc | 6 | |
29967ef6 XL |
7 | use std::ops::ControlFlow; |
8 | ||
1a4d82fc | 9 | /////////////////////////////////////////////////////////////////////////// |
dc9dc135 | 10 | // OPPORTUNISTIC VAR RESOLVER |
1a4d82fc | 11 | |
dc9dc135 XL |
12 | /// The opportunistic resolver can be used at any time. It simply replaces |
13 | /// type/const variables that have been unified with the things they have | |
1a4d82fc JJ |
14 | /// been unified with (similar to `shallow_resolve`, but deep). This is |
15 | /// useful for printing messages etc but also required at various | |
16 | /// points for correctness. | |
dc9dc135 XL |
17 | pub struct OpportunisticVarResolver<'a, 'tcx> { |
18 | infcx: &'a InferCtxt<'a, 'tcx>, | |
1a4d82fc JJ |
19 | } |
20 | ||
dc9dc135 | 21 | impl<'a, 'tcx> OpportunisticVarResolver<'a, 'tcx> { |
a1dfa0c6 | 22 | #[inline] |
dc9dc135 XL |
23 | pub fn new(infcx: &'a InferCtxt<'a, 'tcx>) -> Self { |
24 | OpportunisticVarResolver { infcx } | |
1a4d82fc JJ |
25 | } |
26 | } | |
27 | ||
dc9dc135 XL |
28 | impl<'a, 'tcx> TypeFolder<'tcx> for OpportunisticVarResolver<'a, 'tcx> { |
29 | fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { | |
1a4d82fc JJ |
30 | self.infcx.tcx |
31 | } | |
32 | ||
33 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
74b04a01 | 34 | if !t.has_infer_types_or_consts() { |
1a4d82fc JJ |
35 | t // micro-optimize -- if there is nothing in this type that this fold affects... |
36 | } else { | |
dc9dc135 XL |
37 | let t = self.infcx.shallow_resolve(t); |
38 | t.super_fold_with(self) | |
39 | } | |
40 | } | |
41 | ||
42 | fn fold_const(&mut self, ct: &'tcx Const<'tcx>) -> &'tcx Const<'tcx> { | |
74b04a01 | 43 | if !ct.has_infer_types_or_consts() { |
dc9dc135 XL |
44 | ct // micro-optimize -- if there is nothing in this const that this fold affects... |
45 | } else { | |
46 | let ct = self.infcx.shallow_resolve(ct); | |
47 | ct.super_fold_with(self) | |
9cc50fc6 SL |
48 | } |
49 | } | |
cdc7bbd5 XL |
50 | |
51 | fn fold_mir_const(&mut self, constant: mir::ConstantKind<'tcx>) -> mir::ConstantKind<'tcx> { | |
52 | constant.super_fold_with(self) | |
53 | } | |
9cc50fc6 SL |
54 | } |
55 | ||
f035d41b XL |
56 | /// The opportunistic region resolver opportunistically resolves regions |
57 | /// variables to the variable with the least variable id. It is used when | |
58 | /// normlizing projections to avoid hitting the recursion limit by creating | |
59 | /// many versions of a predicate for types that in the end have to unify. | |
60 | /// | |
61 | /// If you want to resolve type and const variables as well, call | |
62 | /// [InferCtxt::resolve_vars_if_possible] first. | |
63 | pub struct OpportunisticRegionResolver<'a, 'tcx> { | |
dc9dc135 | 64 | infcx: &'a InferCtxt<'a, 'tcx>, |
9cc50fc6 SL |
65 | } |
66 | ||
f035d41b | 67 | impl<'a, 'tcx> OpportunisticRegionResolver<'a, 'tcx> { |
dc9dc135 | 68 | pub fn new(infcx: &'a InferCtxt<'a, 'tcx>) -> Self { |
f035d41b | 69 | OpportunisticRegionResolver { infcx } |
9cc50fc6 SL |
70 | } |
71 | } | |
72 | ||
f035d41b | 73 | impl<'a, 'tcx> TypeFolder<'tcx> for OpportunisticRegionResolver<'a, 'tcx> { |
dc9dc135 | 74 | fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { |
9cc50fc6 SL |
75 | self.infcx.tcx |
76 | } | |
77 | ||
78 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
f035d41b | 79 | if !t.has_infer_regions() { |
9cc50fc6 SL |
80 | t // micro-optimize -- if there is nothing in this type that this fold affects... |
81 | } else { | |
f035d41b | 82 | t.super_fold_with(self) |
9cc50fc6 SL |
83 | } |
84 | } | |
85 | ||
7cac9316 | 86 | fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { |
9e0c209e | 87 | match *r { |
f035d41b XL |
88 | ty::ReVar(rid) => { |
89 | let resolved = self | |
90 | .infcx | |
91 | .inner | |
92 | .borrow_mut() | |
93 | .unwrap_region_constraints() | |
94 | .opportunistic_resolve_var(rid); | |
95 | self.tcx().reuse_or_mk_region(r, ty::ReVar(resolved)) | |
96 | } | |
dfeec247 | 97 | _ => r, |
1a4d82fc JJ |
98 | } |
99 | } | |
48663c56 XL |
100 | |
101 | fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> { | |
f035d41b | 102 | if !ct.has_infer_regions() { |
48663c56 XL |
103 | ct // micro-optimize -- if there is nothing in this const that this fold affects... |
104 | } else { | |
f035d41b | 105 | ct.super_fold_with(self) |
48663c56 XL |
106 | } |
107 | } | |
1a4d82fc JJ |
108 | } |
109 | ||
3b2f2976 XL |
110 | /////////////////////////////////////////////////////////////////////////// |
111 | // UNRESOLVED TYPE FINDER | |
112 | ||
48663c56 XL |
113 | /// The unresolved type **finder** walks a type searching for |
114 | /// type variables that don't yet have a value. The first unresolved type is stored. | |
115 | /// It does not construct the fully resolved type (which might | |
3b2f2976 | 116 | /// involve some hashing and so forth). |
dc9dc135 XL |
117 | pub struct UnresolvedTypeFinder<'a, 'tcx> { |
118 | infcx: &'a InferCtxt<'a, 'tcx>, | |
3b2f2976 XL |
119 | } |
120 | ||
dc9dc135 XL |
121 | impl<'a, 'tcx> UnresolvedTypeFinder<'a, 'tcx> { |
122 | pub fn new(infcx: &'a InferCtxt<'a, 'tcx>) -> Self { | |
fc512014 | 123 | UnresolvedTypeFinder { infcx } |
3b2f2976 XL |
124 | } |
125 | } | |
126 | ||
dc9dc135 | 127 | impl<'a, 'tcx> TypeVisitor<'tcx> for UnresolvedTypeFinder<'a, 'tcx> { |
fc512014 | 128 | type BreakTy = (Ty<'tcx>, Option<Span>); |
94222f64 XL |
129 | |
130 | fn tcx_for_anon_const_substs(&self) -> Option<TyCtxt<'tcx>> { | |
131 | Some(self.infcx.tcx) | |
132 | } | |
133 | ||
fc512014 | 134 | fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> { |
3b2f2976 XL |
135 | let t = self.infcx.shallow_resolve(t); |
136 | if t.has_infer_types() { | |
1b1a35ee | 137 | if let ty::Infer(infer_ty) = *t.kind() { |
3b2f2976 XL |
138 | // Since we called `shallow_resolve` above, this must |
139 | // be an (as yet...) unresolved inference variable. | |
dfeec247 | 140 | let ty_var_span = if let ty::TyVar(ty_vid) = infer_ty { |
f9f354fc XL |
141 | let mut inner = self.infcx.inner.borrow_mut(); |
142 | let ty_vars = &inner.type_variables(); | |
dc9dc135 | 143 | if let TypeVariableOrigin { |
dfeec247 | 144 | kind: TypeVariableOriginKind::TypeParameterDefinition(_, _), |
dc9dc135 XL |
145 | span, |
146 | } = *ty_vars.var_origin(ty_vid) | |
48663c56 XL |
147 | { |
148 | Some(span) | |
149 | } else { | |
150 | None | |
151 | } | |
152 | } else { | |
153 | None | |
154 | }; | |
fc512014 | 155 | ControlFlow::Break((t, ty_var_span)) |
3b2f2976 XL |
156 | } else { |
157 | // Otherwise, visit its contents. | |
158 | t.super_visit_with(self) | |
159 | } | |
160 | } else { | |
48663c56 XL |
161 | // All type variables in inference types must already be resolved, |
162 | // - no need to visit the contents, continue visiting. | |
29967ef6 | 163 | ControlFlow::CONTINUE |
3b2f2976 XL |
164 | } |
165 | } | |
166 | } | |
167 | ||
1a4d82fc JJ |
168 | /////////////////////////////////////////////////////////////////////////// |
169 | // FULL TYPE RESOLUTION | |
170 | ||
171 | /// Full type resolution replaces all type and region variables with | |
172 | /// their concrete results. If any variable cannot be replaced (never unified, etc) | |
173 | /// then an `Err` result is returned. | |
fc512014 | 174 | pub fn fully_resolve<'a, 'tcx, T>(infcx: &InferCtxt<'a, 'tcx>, value: T) -> FixupResult<'tcx, T> |
dc9dc135 XL |
175 | where |
176 | T: TypeFoldable<'tcx>, | |
1a4d82fc | 177 | { |
74b04a01 | 178 | let mut full_resolver = FullTypeResolver { infcx, err: None }; |
1a4d82fc JJ |
179 | let result = value.fold_with(&mut full_resolver); |
180 | match full_resolver.err { | |
181 | None => Ok(result), | |
182 | Some(e) => Err(e), | |
183 | } | |
184 | } | |
185 | ||
186 | // N.B. This type is not public because the protocol around checking the | |
74b04a01 | 187 | // `err` field is not enforceable otherwise. |
dc9dc135 XL |
188 | struct FullTypeResolver<'a, 'tcx> { |
189 | infcx: &'a InferCtxt<'a, 'tcx>, | |
48663c56 | 190 | err: Option<FixupError<'tcx>>, |
1a4d82fc JJ |
191 | } |
192 | ||
dc9dc135 XL |
193 | impl<'a, 'tcx> TypeFolder<'tcx> for FullTypeResolver<'a, 'tcx> { |
194 | fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { | |
1a4d82fc JJ |
195 | self.infcx.tcx |
196 | } | |
197 | ||
198 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
ba9703b0 | 199 | if !t.needs_infer() { |
1a4d82fc JJ |
200 | t // micro-optimize -- if there is nothing in this type that this fold affects... |
201 | } else { | |
202 | let t = self.infcx.shallow_resolve(t); | |
1b1a35ee | 203 | match *t.kind() { |
b7449926 | 204 | ty::Infer(ty::TyVar(vid)) => { |
c1a9b12d | 205 | self.err = Some(FixupError::UnresolvedTy(vid)); |
f035d41b | 206 | self.tcx().ty_error() |
1a4d82fc | 207 | } |
b7449926 | 208 | ty::Infer(ty::IntVar(vid)) => { |
c1a9b12d | 209 | self.err = Some(FixupError::UnresolvedIntTy(vid)); |
f035d41b | 210 | self.tcx().ty_error() |
1a4d82fc | 211 | } |
b7449926 | 212 | ty::Infer(ty::FloatVar(vid)) => { |
c1a9b12d | 213 | self.err = Some(FixupError::UnresolvedFloatTy(vid)); |
f035d41b | 214 | self.tcx().ty_error() |
1a4d82fc | 215 | } |
b7449926 | 216 | ty::Infer(_) => { |
54a0048b | 217 | bug!("Unexpected type in full type resolver: {:?}", t); |
1a4d82fc | 218 | } |
dfeec247 | 219 | _ => t.super_fold_with(self), |
1a4d82fc JJ |
220 | } |
221 | } | |
222 | } | |
223 | ||
7cac9316 | 224 | fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { |
9e0c209e | 225 | match *r { |
dfeec247 XL |
226 | ty::ReVar(rid) => self |
227 | .infcx | |
228 | .lexical_region_resolutions | |
229 | .borrow() | |
230 | .as_ref() | |
231 | .expect("region resolution not performed") | |
232 | .resolve_var(rid), | |
9e0c209e | 233 | _ => r, |
1a4d82fc JJ |
234 | } |
235 | } | |
48663c56 XL |
236 | |
237 | fn fold_const(&mut self, c: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> { | |
ba9703b0 | 238 | if !c.needs_infer() { |
48663c56 | 239 | c // micro-optimize -- if there is nothing in this const that this fold affects... |
48663c56 XL |
240 | } else { |
241 | let c = self.infcx.shallow_resolve(c); | |
242 | match c.val { | |
60c5eb7d | 243 | ty::ConstKind::Infer(InferConst::Var(vid)) => { |
48663c56 | 244 | self.err = Some(FixupError::UnresolvedConst(vid)); |
f035d41b | 245 | return self.tcx().const_error(c.ty); |
48663c56 | 246 | } |
60c5eb7d | 247 | ty::ConstKind::Infer(InferConst::Fresh(_)) => { |
48663c56 XL |
248 | bug!("Unexpected const in full const resolver: {:?}", c); |
249 | } | |
250 | _ => {} | |
251 | } | |
252 | c.super_fold_with(self) | |
253 | } | |
254 | } | |
1a4d82fc | 255 | } |