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Rollup merge of rust-lang#59455 - estebank:borrow-sugg-shorthand-field, r=davidtwco
Account for short-hand field syntax when suggesting borrow Fix rust-lang#52965.
2 parents c07b227 + ddfa47f commit 22c267d

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3 files changed

+125
-20
lines changed

3 files changed

+125
-20
lines changed

‎src/librustc_typeck/check/demand.rs

+55-16
Original file line numberDiff line numberDiff line change
@@ -270,6 +270,26 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
270270
None
271271
}
272272

273+
fn is_hir_id_from_struct_pattern_shorthand_field(&self, hir_id: hir::HirId, sp: Span) -> bool {
274+
let cm = self.sess().source_map();
275+
let parent_id = self.tcx.hir().get_parent_node_by_hir_id(hir_id);
276+
if let Some(parent) = self.tcx.hir().find_by_hir_id(parent_id) {
277+
// Account for fields
278+
if let Node::Expr(hir::Expr {
279+
node: hir::ExprKind::Struct(_, fields, ..), ..
280+
}) = parent {
281+
if let Ok(src) = cm.span_to_snippet(sp) {
282+
for field in fields {
283+
if field.ident.as_str() == src.as_str() && field.is_shorthand {
284+
return true;
285+
}
286+
}
287+
}
288+
}
289+
}
290+
false
291+
}
292+
273293
/// This function is used to determine potential "simple" improvements or users' errors and
274294
/// provide them useful help. For example:
275295
///
@@ -299,6 +319,11 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
299319
return None;
300320
}
301321

322+
let is_struct_pat_shorthand_field = self.is_hir_id_from_struct_pattern_shorthand_field(
323+
expr.hir_id,
324+
sp,
325+
);
326+
302327
match (&expected.sty, &checked_ty.sty) {
303328
(&ty::Ref(_, exp, _), &ty::Ref(_, check, _)) => match (&exp.sty, &check.sty) {
304329
(&ty::Str, &ty::Array(arr, _)) |
@@ -337,12 +362,12 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
337362
// bar(&x); // error, expected &mut
338363
// ```
339364
let ref_ty = match mutability {
340-
hir::Mutability::MutMutable => self.tcx.mk_mut_ref(
341-
self.tcx.mk_region(ty::ReStatic),
342-
checked_ty),
343-
hir::Mutability::MutImmutable => self.tcx.mk_imm_ref(
344-
self.tcx.mk_region(ty::ReStatic),
345-
checked_ty),
365+
hir::Mutability::MutMutable => {
366+
self.tcx.mk_mut_ref(self.tcx.mk_region(ty::ReStatic), checked_ty)
367+
}
368+
hir::Mutability::MutImmutable => {
369+
self.tcx.mk_imm_ref(self.tcx.mk_region(ty::ReStatic), checked_ty)
370+
}
346371
};
347372
if self.can_coerce(ref_ty, expected) {
348373
if let Ok(src) = cm.span_to_snippet(sp) {
@@ -363,14 +388,22 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
363388
if let Some(sugg) = self.can_use_as_ref(expr) {
364389
return Some(sugg);
365390
}
391+
let field_name = if is_struct_pat_shorthand_field {
392+
format!("{}: ", sugg_expr)
393+
} else {
394+
String::new()
395+
};
366396
return Some(match mutability {
367-
hir::Mutability::MutMutable => {
368-
(sp, "consider mutably borrowing here", format!("&mut {}",
369-
sugg_expr))
370-
}
371-
hir::Mutability::MutImmutable => {
372-
(sp, "consider borrowing here", format!("&{}", sugg_expr))
373-
}
397+
hir::Mutability::MutMutable => (
398+
sp,
399+
"consider mutably borrowing here",
400+
format!("{}&mut {}", field_name, sugg_expr),
401+
),
402+
hir::Mutability::MutImmutable => (
403+
sp,
404+
"consider borrowing here",
405+
format!("{}&{}", field_name, sugg_expr),
406+
),
374407
});
375408
}
376409
}
@@ -411,12 +444,18 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
411444
checked,
412445
sp) {
413446
// do not suggest if the span comes from a macro (#52783)
414-
if let (Ok(code),
415-
true) = (cm.span_to_snippet(sp), sp == expr.span) {
447+
if let (Ok(code), true) = (
448+
cm.span_to_snippet(sp),
449+
sp == expr.span,
450+
) {
416451
return Some((
417452
sp,
418453
"consider dereferencing the borrow",
419-
format!("*{}", code),
454+
if is_struct_pat_shorthand_field {
455+
format!("{}: *{}", code, code)
456+
} else {
457+
format!("*{}", code)
458+
},
420459
));
421460
}
422461
}

‎src/test/ui/deref-suggestion.rs

+18
Original file line numberDiff line numberDiff line change
@@ -15,6 +15,14 @@ fn foo4(u: &u32) {
1515
//~^ ERROR mismatched types
1616
}
1717

18+
struct S<'a> {
19+
u: &'a u32,
20+
}
21+
22+
struct R {
23+
i: u32,
24+
}
25+
1826
fn main() {
1927
let s = String::new();
2028
let r_s = &s;
@@ -27,4 +35,14 @@ fn main() {
2735
foo4(&0);
2836
assert_eq!(3i32, &3i32);
2937
//~^ ERROR mismatched types
38+
let u = 3;
39+
let s = S { u };
40+
//~^ ERROR mismatched types
41+
let s = S { u: u };
42+
//~^ ERROR mismatched types
43+
let i = &4;
44+
let r = R { i };
45+
//~^ ERROR mismatched types
46+
let r = R { i: i };
47+
//~^ ERROR mismatched types
3048
}

‎src/test/ui/deref-suggestion.stderr

+52-4
Original file line numberDiff line numberDiff line change
@@ -23,7 +23,7 @@ LL | foo3(u);
2323
found type `&u32`
2424

2525
error[E0308]: mismatched types
26-
--> $DIR/deref-suggestion.rs:22:9
26+
--> $DIR/deref-suggestion.rs:30:9
2727
|
2828
LL | foo(&"aaa".to_owned());
2929
| ^^^^^^^^^^^^^^^^^
@@ -35,7 +35,7 @@ LL | foo(&"aaa".to_owned());
3535
found type `&std::string::String`
3636

3737
error[E0308]: mismatched types
38-
--> $DIR/deref-suggestion.rs:24:9
38+
--> $DIR/deref-suggestion.rs:32:9
3939
|
4040
LL | foo(&mut "aaa".to_owned());
4141
| ^^^^^^^^^^^^^^^^^^^^^
@@ -59,7 +59,7 @@ LL | foo3(borrow!(0));
5959
found type `&{integer}`
6060

6161
error[E0308]: mismatched types
62-
--> $DIR/deref-suggestion.rs:28:5
62+
--> $DIR/deref-suggestion.rs:36:5
6363
|
6464
LL | assert_eq!(3i32, &3i32);
6565
| ^^^^^^^^^^^^^^^^^^^^^^^^ expected i32, found &i32
@@ -68,6 +68,54 @@ LL | assert_eq!(3i32, &3i32);
6868
found type `&i32`
6969
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
7070

71-
error: aborting due to 6 previous errors
71+
error[E0308]: mismatched types
72+
--> $DIR/deref-suggestion.rs:39:17
73+
|
74+
LL | let s = S { u };
75+
| ^
76+
| |
77+
| expected &u32, found integer
78+
| help: consider borrowing here: `u: &u`
79+
|
80+
= note: expected type `&u32`
81+
found type `{integer}`
82+
83+
error[E0308]: mismatched types
84+
--> $DIR/deref-suggestion.rs:41:20
85+
|
86+
LL | let s = S { u: u };
87+
| ^
88+
| |
89+
| expected &u32, found integer
90+
| help: consider borrowing here: `&u`
91+
|
92+
= note: expected type `&u32`
93+
found type `{integer}`
94+
95+
error[E0308]: mismatched types
96+
--> $DIR/deref-suggestion.rs:44:17
97+
|
98+
LL | let r = R { i };
99+
| ^
100+
| |
101+
| expected u32, found &{integer}
102+
| help: consider dereferencing the borrow: `i: *i`
103+
|
104+
= note: expected type `u32`
105+
found type `&{integer}`
106+
107+
error[E0308]: mismatched types
108+
--> $DIR/deref-suggestion.rs:46:20
109+
|
110+
LL | let r = R { i: i };
111+
| ^
112+
| |
113+
| expected u32, found &{integer}
114+
| help: consider dereferencing the borrow: `*i`
115+
|
116+
= note: expected type `u32`
117+
found type `&{integer}`
118+
119+
error: aborting due to 10 previous errors
72120

73121
For more information about this error, try `rustc --explain E0308`.

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