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Commit | Line | Data |
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dc9dc135 | 1 | use super::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; |
dfeec247 | 2 | use super::{FixupError, FixupResult, InferCtxt, Span}; |
cdc7bbd5 | 3 | use rustc_middle::mir; |
a2a8927a | 4 | use rustc_middle::ty::fold::{FallibleTypeFolder, TypeFolder, TypeVisitor}; |
ba9703b0 | 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 | ||
5099ac24 | 42 | fn fold_const(&mut self, ct: Const<'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 | 100 | |
5099ac24 | 101 | fn fold_const(&mut self, ct: ty::Const<'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 XL |
128 | type BreakTy = (Ty<'tcx>, Option<Span>); |
129 | fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> { | |
3b2f2976 XL |
130 | let t = self.infcx.shallow_resolve(t); |
131 | if t.has_infer_types() { | |
1b1a35ee | 132 | if let ty::Infer(infer_ty) = *t.kind() { |
3b2f2976 XL |
133 | // Since we called `shallow_resolve` above, this must |
134 | // be an (as yet...) unresolved inference variable. | |
dfeec247 | 135 | let ty_var_span = if let ty::TyVar(ty_vid) = infer_ty { |
f9f354fc XL |
136 | let mut inner = self.infcx.inner.borrow_mut(); |
137 | let ty_vars = &inner.type_variables(); | |
dc9dc135 | 138 | if let TypeVariableOrigin { |
dfeec247 | 139 | kind: TypeVariableOriginKind::TypeParameterDefinition(_, _), |
dc9dc135 XL |
140 | span, |
141 | } = *ty_vars.var_origin(ty_vid) | |
48663c56 XL |
142 | { |
143 | Some(span) | |
144 | } else { | |
145 | None | |
146 | } | |
147 | } else { | |
148 | None | |
149 | }; | |
fc512014 | 150 | ControlFlow::Break((t, ty_var_span)) |
3b2f2976 XL |
151 | } else { |
152 | // Otherwise, visit its contents. | |
153 | t.super_visit_with(self) | |
154 | } | |
155 | } else { | |
48663c56 XL |
156 | // All type variables in inference types must already be resolved, |
157 | // - no need to visit the contents, continue visiting. | |
29967ef6 | 158 | ControlFlow::CONTINUE |
3b2f2976 XL |
159 | } |
160 | } | |
161 | } | |
162 | ||
1a4d82fc JJ |
163 | /////////////////////////////////////////////////////////////////////////// |
164 | // FULL TYPE RESOLUTION | |
165 | ||
166 | /// Full type resolution replaces all type and region variables with | |
167 | /// their concrete results. If any variable cannot be replaced (never unified, etc) | |
168 | /// then an `Err` result is returned. | |
fc512014 | 169 | pub fn fully_resolve<'a, 'tcx, T>(infcx: &InferCtxt<'a, 'tcx>, value: T) -> FixupResult<'tcx, T> |
dc9dc135 XL |
170 | where |
171 | T: TypeFoldable<'tcx>, | |
1a4d82fc | 172 | { |
a2a8927a | 173 | value.try_fold_with(&mut FullTypeResolver { infcx }) |
1a4d82fc JJ |
174 | } |
175 | ||
176 | // N.B. This type is not public because the protocol around checking the | |
74b04a01 | 177 | // `err` field is not enforceable otherwise. |
dc9dc135 XL |
178 | struct FullTypeResolver<'a, 'tcx> { |
179 | infcx: &'a InferCtxt<'a, 'tcx>, | |
1a4d82fc JJ |
180 | } |
181 | ||
dc9dc135 | 182 | impl<'a, 'tcx> TypeFolder<'tcx> for FullTypeResolver<'a, 'tcx> { |
a2a8927a XL |
183 | type Error = FixupError<'tcx>; |
184 | ||
dc9dc135 | 185 | fn tcx<'b>(&'b self) -> TyCtxt<'tcx> { |
1a4d82fc JJ |
186 | self.infcx.tcx |
187 | } | |
a2a8927a | 188 | } |
1a4d82fc | 189 | |
a2a8927a XL |
190 | impl<'a, 'tcx> FallibleTypeFolder<'tcx> for FullTypeResolver<'a, 'tcx> { |
191 | fn try_fold_ty(&mut self, t: Ty<'tcx>) -> Result<Ty<'tcx>, Self::Error> { | |
ba9703b0 | 192 | if !t.needs_infer() { |
a2a8927a | 193 | Ok(t) // micro-optimize -- if there is nothing in this type that this fold affects... |
1a4d82fc JJ |
194 | } else { |
195 | let t = self.infcx.shallow_resolve(t); | |
1b1a35ee | 196 | match *t.kind() { |
a2a8927a XL |
197 | ty::Infer(ty::TyVar(vid)) => Err(FixupError::UnresolvedTy(vid)), |
198 | ty::Infer(ty::IntVar(vid)) => Err(FixupError::UnresolvedIntTy(vid)), | |
199 | ty::Infer(ty::FloatVar(vid)) => Err(FixupError::UnresolvedFloatTy(vid)), | |
b7449926 | 200 | ty::Infer(_) => { |
54a0048b | 201 | bug!("Unexpected type in full type resolver: {:?}", t); |
1a4d82fc | 202 | } |
a2a8927a | 203 | _ => t.try_super_fold_with(self), |
1a4d82fc JJ |
204 | } |
205 | } | |
206 | } | |
207 | ||
a2a8927a | 208 | fn try_fold_region(&mut self, r: ty::Region<'tcx>) -> Result<ty::Region<'tcx>, Self::Error> { |
9e0c209e | 209 | match *r { |
a2a8927a | 210 | ty::ReVar(rid) => Ok(self |
dfeec247 XL |
211 | .infcx |
212 | .lexical_region_resolutions | |
213 | .borrow() | |
214 | .as_ref() | |
215 | .expect("region resolution not performed") | |
a2a8927a XL |
216 | .resolve_var(rid)), |
217 | _ => Ok(r), | |
1a4d82fc JJ |
218 | } |
219 | } | |
48663c56 | 220 | |
5099ac24 | 221 | fn try_fold_const(&mut self, c: ty::Const<'tcx>) -> Result<ty::Const<'tcx>, Self::Error> { |
ba9703b0 | 222 | if !c.needs_infer() { |
a2a8927a | 223 | Ok(c) // micro-optimize -- if there is nothing in this const that this fold affects... |
48663c56 XL |
224 | } else { |
225 | let c = self.infcx.shallow_resolve(c); | |
5099ac24 | 226 | match c.val() { |
60c5eb7d | 227 | ty::ConstKind::Infer(InferConst::Var(vid)) => { |
a2a8927a | 228 | return Err(FixupError::UnresolvedConst(vid)); |
48663c56 | 229 | } |
60c5eb7d | 230 | ty::ConstKind::Infer(InferConst::Fresh(_)) => { |
48663c56 XL |
231 | bug!("Unexpected const in full const resolver: {:?}", c); |
232 | } | |
233 | _ => {} | |
234 | } | |
a2a8927a | 235 | c.try_super_fold_with(self) |
48663c56 XL |
236 | } |
237 | } | |
1a4d82fc | 238 | } |