-
Notifications
You must be signed in to change notification settings - Fork 12.5k
/
need_type_info.rs
227 lines (208 loc) · 7.86 KB
/
need_type_info.rs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
use crate::hir::def::Namespace;
use crate::hir::{self, Local, Pat, Body, HirId};
use crate::hir::intravisit::{self, Visitor, NestedVisitorMap};
use crate::infer::InferCtxt;
use crate::infer::type_variable::TypeVariableOrigin;
use crate::ty::{self, Ty, Infer, TyVar};
use crate::ty::print::Print;
use syntax::source_map::CompilerDesugaringKind;
use syntax_pos::Span;
use errors::DiagnosticBuilder;
struct FindLocalByTypeVisitor<'a, 'gcx: 'a + 'tcx, 'tcx: 'a> {
infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
target_ty: Ty<'tcx>,
hir_map: &'a hir::map::Map<'gcx>,
found_local_pattern: Option<&'gcx Pat>,
found_arg_pattern: Option<&'gcx Pat>,
found_ty: Option<Ty<'tcx>>,
}
impl<'a, 'gcx, 'tcx> FindLocalByTypeVisitor<'a, 'gcx, 'tcx> {
fn node_matches_type(&mut self, hir_id: HirId) -> Option<Ty<'tcx>> {
let ty_opt = self.infcx.in_progress_tables.and_then(|tables| {
tables.borrow().node_type_opt(hir_id)
});
match ty_opt {
Some(ty) => {
let ty = self.infcx.resolve_vars_if_possible(&ty);
if ty.walk().any(|inner_ty| {
inner_ty == self.target_ty || match (&inner_ty.sty, &self.target_ty.sty) {
(&Infer(TyVar(a_vid)), &Infer(TyVar(b_vid))) => {
self.infcx
.type_variables
.borrow_mut()
.sub_unified(a_vid, b_vid)
}
_ => false,
}
}) {
Some(ty)
} else {
None
}
}
None => None,
}
}
}
impl<'a, 'gcx, 'tcx> Visitor<'gcx> for FindLocalByTypeVisitor<'a, 'gcx, 'tcx> {
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'gcx> {
NestedVisitorMap::OnlyBodies(&self.hir_map)
}
fn visit_local(&mut self, local: &'gcx Local) {
if let (None, Some(ty)) = (self.found_local_pattern, self.node_matches_type(local.hir_id)) {
self.found_local_pattern = Some(&*local.pat);
self.found_ty = Some(ty);
}
intravisit::walk_local(self, local);
}
fn visit_body(&mut self, body: &'gcx Body) {
for argument in &body.arguments {
if let (None, Some(ty)) = (
self.found_arg_pattern,
self.node_matches_type(argument.hir_id),
) {
self.found_arg_pattern = Some(&*argument.pat);
self.found_ty = Some(ty);
}
}
intravisit::walk_body(self, body);
}
}
impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
pub fn extract_type_name(
&self,
ty: Ty<'tcx>,
highlight: Option<ty::print::RegionHighlightMode>,
) -> String {
if let ty::Infer(ty::TyVar(ty_vid)) = ty.sty {
let ty_vars = self.type_variables.borrow();
if let TypeVariableOrigin::TypeParameterDefinition(_, name) =
*ty_vars.var_origin(ty_vid) {
return name.to_string();
}
}
let mut s = String::new();
let mut printer = ty::print::FmtPrinter::new(self.tcx, &mut s, Namespace::TypeNS);
if let Some(highlight) = highlight {
printer.region_highlight_mode = highlight;
}
let _ = ty.print(printer);
s
}
pub fn need_type_info_err(
&self,
body_id: Option<hir::BodyId>,
span: Span,
ty: Ty<'tcx>
) -> DiagnosticBuilder<'gcx> {
let ty = self.resolve_vars_if_possible(&ty);
let name = self.extract_type_name(&ty, None);
let mut err_span = span;
let mut labels = vec![(span, InferCtxt::missing_type_msg(&name))];
let mut local_visitor = FindLocalByTypeVisitor {
infcx: &self,
target_ty: ty,
hir_map: &self.tcx.hir(),
found_local_pattern: None,
found_arg_pattern: None,
found_ty: None,
};
if let Some(body_id) = body_id {
let expr = self.tcx.hir().expect_expr_by_hir_id(body_id.hir_id);
local_visitor.visit_expr(expr);
}
let ty_msg = match local_visitor.found_ty {
Some(ty) if &ty.to_string() != "_" => format!(" for `{}`", ty),
_ => String::new(),
};
if let Some(pattern) = local_visitor.found_arg_pattern {
err_span = pattern.span;
// We don't want to show the default label for closures.
//
// So, before clearing, the output would look something like this:
// ```
// let x = |_| { };
// - ^^^^ cannot infer type for `[_; 0]`
// |
// consider giving this closure parameter a type
// ```
//
// After clearing, it looks something like this:
// ```
// let x = |_| { };
// ^ consider giving this closure parameter a type
// ```
labels.clear();
labels.push((pattern.span, format!(
"consider giving this closure parameter {}",
match local_visitor.found_ty {
Some(ty) if &ty.to_string() != "_" => format!(
"the type `{}` with the type parameter `{}` specified",
ty,
name,
),
_ => "a type".to_owned(),
},
)));
} else if let Some(pattern) = local_visitor.found_local_pattern {
if let Some(simple_ident) = pattern.simple_ident() {
match pattern.span.compiler_desugaring_kind() {
None => labels.push((
pattern.span,
format!(
"consider giving `{}` {}",
simple_ident,
match local_visitor.found_ty {
Some(ty) if &ty.to_string() != "_" => format!(
"the type `{}` with the type parameter `{}` specified",
ty,
name,
),
_ => "a type".to_owned(),
},
),
)),
Some(CompilerDesugaringKind::ForLoop) => labels.push((
pattern.span,
"the element type for this iterator is not specified".to_owned(),
)),
_ => {}
}
} else {
labels.push((pattern.span, "consider giving the pattern a type".to_owned()));
}
};
let mut err = struct_span_err!(
self.tcx.sess,
err_span,
E0282,
"type annotations needed{}",
ty_msg,
);
for (target_span, label_message) in labels {
err.span_label(target_span, label_message);
}
err
}
pub fn need_type_info_err_in_generator(
&self,
span: Span,
ty: Ty<'tcx>
) -> DiagnosticBuilder<'gcx> {
let ty = self.resolve_vars_if_possible(&ty);
let name = self.extract_type_name(&ty, None);
let mut err = struct_span_err!(self.tcx.sess,
span,
E0698,
"type inside generator must be known in this context");
err.span_label(span, InferCtxt::missing_type_msg(&name));
err
}
fn missing_type_msg(type_name: &str) -> String {
if type_name == "_" {
"cannot infer type".to_owned()
} else {
format!("cannot infer type for `{}`", type_name)
}
}
}