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chenyukangchenyukang
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suggest unwrap/expect for let binding type mismatch
1 parent a483969 commit 4e9d93f

9 files changed

Lines changed: 326 additions & 1 deletion

‎compiler/rustc_hir_typeck/src/demand.rs‎

Lines changed: 81 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -58,7 +58,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
5858
|| self.suggest_into(err, expr, expr_ty, expected)
5959
|| self.suggest_floating_point_literal(err, expr, expected)
6060
|| self.suggest_null_ptr_for_literal_zero_given_to_ptr_arg(err, expr, expected)
61-
|| self.suggest_coercing_result_via_try_operator(err, expr, expected, expr_ty);
61+
|| self.suggest_coercing_result_via_try_operator(err, expr, expected, expr_ty)
62+
|| self.suggest_missing_unwrap_expect(err, expr, expected, expr_ty);
6263

6364
if !suggested {
6465
self.note_source_of_type_mismatch_constraint(
@@ -954,6 +955,85 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
954955
);
955956
}
956957

958+
pub(crate) fn suggest_missing_unwrap_expect(
959+
&self,
960+
err: &mut Diagnostic,
961+
expr: &hir::Expr<'tcx>,
962+
expected: Ty<'tcx>,
963+
found: Ty<'tcx>,
964+
) -> bool {
965+
let ty::Adt(adt, args) = found.kind() else { return false };
966+
let ret_ty_matches = |diagnostic_item| {
967+
if let Some(ret_ty) = self
968+
.ret_coercion
969+
.as_ref()
970+
.map(|c| self.resolve_vars_if_possible(c.borrow().expected_ty()))
971+
&& let ty::Adt(kind, _) = ret_ty.kind()
972+
&& self.tcx.get_diagnostic_item(diagnostic_item) == Some(kind.did())
973+
{
974+
true
975+
} else {
976+
false
977+
}
978+
};
979+
980+
// don't suggest anything like `Ok(ok_val).unwrap()` , `Some(some_val).unwrap()`,
981+
// `None.unwrap()` etc.
982+
let is_ctor = matches!(
983+
expr.kind,
984+
hir::ExprKind::Call(
985+
hir::Expr {
986+
kind: hir::ExprKind::Path(hir::QPath::Resolved(
987+
None,
988+
hir::Path { res: Res::Def(hir::def::DefKind::Ctor(_, _), _), .. },
989+
)),
990+
..
991+
},
992+
..,
993+
) | hir::ExprKind::Path(hir::QPath::Resolved(
994+
None,
995+
hir::Path { res: Res::Def(hir::def::DefKind::Ctor(_, _), _), .. },
996+
)),
997+
);
998+
999+
let (article, kind, variant, sugg_operator) =
1000+
if self.tcx.is_diagnostic_item(sym::Result, adt.did()) {
1001+
("a", "Result", "Err", ret_ty_matches(sym::Result))
1002+
} else if self.tcx.is_diagnostic_item(sym::Option, adt.did()) {
1003+
("an", "Option", "None", ret_ty_matches(sym::Option))
1004+
} else {
1005+
return false;
1006+
};
1007+
if is_ctor || !self.can_coerce(args.type_at(0), expected) {
1008+
return false;
1009+
}
1010+
1011+
let (msg, sugg) = if sugg_operator {
1012+
(
1013+
format!(
1014+
"use the `?` operator to extract the `{found}` value, propagating \
1015+
{article} `{kind}::{variant}` value to the caller"
1016+
),
1017+
"?",
1018+
)
1019+
} else {
1020+
(
1021+
format!(
1022+
"consider using `{kind}::expect` to unwrap the `{found}` value, \
1023+
panicking if the value is {article} `{kind}::{variant}`"
1024+
),
1025+
".expect(\"REASON\")",
1026+
)
1027+
};
1028+
err.span_suggestion_verbose(
1029+
expr.span.shrink_to_hi(),
1030+
msg,
1031+
sugg,
1032+
Applicability::HasPlaceholders,
1033+
);
1034+
return true;
1035+
}
1036+
9571037
pub(crate) fn suggest_coercing_result_via_try_operator(
9581038
&self,
9591039
err: &mut Diagnostic,

‎tests/ui/lifetimes/issue-26638.stderr‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -44,6 +44,10 @@ LL | fn parse_type(iter: Box<dyn Iterator<Item=&str>+'static>) -> &str { iter.ne
4444
|
4545
= note: expected reference `&str`
4646
found enum `Option<&str>`
47+
help: consider using `Option::expect` to unwrap the `Option<&str>` value, panicking if the value is an `Option::None`
48+
|
49+
LL | fn parse_type(iter: Box<dyn Iterator<Item=&str>+'static>) -> &str { iter.next().expect("REASON") }
50+
| +++++++++++++++++
4751

4852
error[E0061]: this function takes 1 argument but 0 arguments were supplied
4953
--> $DIR/issue-26638.rs:5:47

‎tests/ui/mismatched_types/mismatch-ty-dont-suggest.rs‎

Lines changed: 23 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,23 @@
1+
#![allow(unused, dead_code)]
2+
3+
fn test_unwrap() -> Option<i32> {
4+
let b: Result<i32, ()> = Ok(1);
5+
let v: i32 = b; // return type is not `Result`, we don't suggest ? here
6+
//~^ ERROR mismatched types
7+
Some(v)
8+
}
9+
10+
fn test_unwrap_option() -> Result<i32, ()> {
11+
let b = Some(1);
12+
let v: i32 = b; // return type is not `Option`, we don't suggest ? here
13+
//~^ ERROR mismatched types
14+
Ok(v)
15+
}
16+
17+
fn main() {
18+
let v: i32 = Some(0); //~ ERROR mismatched types
19+
20+
let c = Ok(false);
21+
let v: i32 = c; //~ ERROR mismatched types
22+
23+
}

‎tests/ui/mismatched_types/mismatch-ty-dont-suggest.stderr‎

Lines changed: 55 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,55 @@
1+
error[E0308]: mismatched types
2+
--> $DIR/mismatch-ty-dont-suggest.rs:5:18
3+
|
4+
LL | let v: i32 = b; // return type is not `Result`, we don't suggest ? here
5+
| --- ^ expected `i32`, found `Result<i32, ()>`
6+
| |
7+
| expected due to this
8+
|
9+
= note: expected type `i32`
10+
found enum `Result<i32, ()>`
11+
help: consider using `Result::expect` to unwrap the `Result<i32, ()>` value, panicking if the value is a `Result::Err`
12+
|
13+
LL | let v: i32 = b.expect("REASON"); // return type is not `Result`, we don't suggest ? here
14+
| +++++++++++++++++
15+
16+
error[E0308]: mismatched types
17+
--> $DIR/mismatch-ty-dont-suggest.rs:12:18
18+
|
19+
LL | let v: i32 = b; // return type is not `Option`, we don't suggest ? here
20+
| --- ^ expected `i32`, found `Option<{integer}>`
21+
| |
22+
| expected due to this
23+
|
24+
= note: expected type `i32`
25+
found enum `Option<{integer}>`
26+
help: consider using `Option::expect` to unwrap the `Option<{integer}>` value, panicking if the value is an `Option::None`
27+
|
28+
LL | let v: i32 = b.expect("REASON"); // return type is not `Option`, we don't suggest ? here
29+
| +++++++++++++++++
30+
31+
error[E0308]: mismatched types
32+
--> $DIR/mismatch-ty-dont-suggest.rs:18:18
33+
|
34+
LL | let v: i32 = Some(0);
35+
| --- ^^^^^^^ expected `i32`, found `Option<{integer}>`
36+
| |
37+
| expected due to this
38+
|
39+
= note: expected type `i32`
40+
found enum `Option<{integer}>`
41+
42+
error[E0308]: mismatched types
43+
--> $DIR/mismatch-ty-dont-suggest.rs:21:18
44+
|
45+
LL | let v: i32 = c;
46+
| --- ^ expected `i32`, found `Result<bool, _>`
47+
| |
48+
| expected due to this
49+
|
50+
= note: expected type `i32`
51+
found enum `Result<bool, _>`
52+
53+
error: aborting due to 4 previous errors
54+
55+
For more information about this error, try `rustc --explain E0308`.

‎tests/ui/mismatched_types/mismatch-ty-unwrap-expect.fixed‎

Lines changed: 31 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,31 @@
1+
// run-rustfix
2+
#![allow(unused, dead_code)]
3+
4+
fn func() -> Option<i32> {
5+
Some(1)
6+
}
7+
8+
fn test_unwrap() -> Result<i32, ()> {
9+
let b: Result<i32, ()> = Ok(1);
10+
let v: i32 = b?; //~ ERROR mismatched types
11+
Ok(v)
12+
}
13+
14+
fn test_unwrap_option() -> Option<i32> {
15+
let b = Some(1);
16+
let v: i32 = b?; //~ ERROR mismatched types
17+
Some(v)
18+
}
19+
20+
fn main() {
21+
let a = Some(1);
22+
let v: i32 = a.expect("REASON"); //~ ERROR mismatched types
23+
24+
let b: Result<i32, ()> = Ok(1);
25+
let v: i32 = b.expect("REASON"); //~ ERROR mismatched types
26+
27+
let v: i32 = func().expect("REASON"); //~ ERROR mismatched types
28+
29+
let a = None;
30+
let v: i32 = a.expect("REASON"); //~ ERROR mismatched types
31+
}

‎tests/ui/mismatched_types/mismatch-ty-unwrap-expect.rs‎

Lines changed: 31 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,31 @@
1+
// run-rustfix
2+
#![allow(unused, dead_code)]
3+
4+
fn func() -> Option<i32> {
5+
Some(1)
6+
}
7+
8+
fn test_unwrap() -> Result<i32, ()> {
9+
let b: Result<i32, ()> = Ok(1);
10+
let v: i32 = b; //~ ERROR mismatched types
11+
Ok(v)
12+
}
13+
14+
fn test_unwrap_option() -> Option<i32> {
15+
let b = Some(1);
16+
let v: i32 = b; //~ ERROR mismatched types
17+
Some(v)
18+
}
19+
20+
fn main() {
21+
let a = Some(1);
22+
let v: i32 = a; //~ ERROR mismatched types
23+
24+
let b: Result<i32, ()> = Ok(1);
25+
let v: i32 = b; //~ ERROR mismatched types
26+
27+
let v: i32 = func(); //~ ERROR mismatched types
28+
29+
let a = None;
30+
let v: i32 = a; //~ ERROR mismatched types
31+
}

‎tests/ui/mismatched_types/mismatch-ty-unwrap-expect.stderr‎

Lines changed: 93 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,93 @@
1+
error[E0308]: mismatched types
2+
--> $DIR/mismatch-ty-unwrap-expect.rs:10:18
3+
|
4+
LL | let v: i32 = b;
5+
| --- ^ expected `i32`, found `Result<i32, ()>`
6+
| |
7+
| expected due to this
8+
|
9+
= note: expected type `i32`
10+
found enum `Result<i32, ()>`
11+
help: use the `?` operator to extract the `Result<i32, ()>` value, propagating a `Result::Err` value to the caller
12+
|
13+
LL | let v: i32 = b?;
14+
| +
15+
16+
error[E0308]: mismatched types
17+
--> $DIR/mismatch-ty-unwrap-expect.rs:16:18
18+
|
19+
LL | let v: i32 = b;
20+
| --- ^ expected `i32`, found `Option<{integer}>`
21+
| |
22+
| expected due to this
23+
|
24+
= note: expected type `i32`
25+
found enum `Option<{integer}>`
26+
help: use the `?` operator to extract the `Option<{integer}>` value, propagating an `Option::None` value to the caller
27+
|
28+
LL | let v: i32 = b?;
29+
| +
30+
31+
error[E0308]: mismatched types
32+
--> $DIR/mismatch-ty-unwrap-expect.rs:22:18
33+
|
34+
LL | let v: i32 = a;
35+
| --- ^ expected `i32`, found `Option<{integer}>`
36+
| |
37+
| expected due to this
38+
|
39+
= note: expected type `i32`
40+
found enum `Option<{integer}>`
41+
help: consider using `Option::expect` to unwrap the `Option<{integer}>` value, panicking if the value is an `Option::None`
42+
|
43+
LL | let v: i32 = a.expect("REASON");
44+
| +++++++++++++++++
45+
46+
error[E0308]: mismatched types
47+
--> $DIR/mismatch-ty-unwrap-expect.rs:25:18
48+
|
49+
LL | let v: i32 = b;
50+
| --- ^ expected `i32`, found `Result<i32, ()>`
51+
| |
52+
| expected due to this
53+
|
54+
= note: expected type `i32`
55+
found enum `Result<i32, ()>`
56+
help: consider using `Result::expect` to unwrap the `Result<i32, ()>` value, panicking if the value is a `Result::Err`
57+
|
58+
LL | let v: i32 = b.expect("REASON");
59+
| +++++++++++++++++
60+
61+
error[E0308]: mismatched types
62+
--> $DIR/mismatch-ty-unwrap-expect.rs:27:18
63+
|
64+
LL | let v: i32 = func();
65+
| --- ^^^^^^ expected `i32`, found `Option<i32>`
66+
| |
67+
| expected due to this
68+
|
69+
= note: expected type `i32`
70+
found enum `Option<i32>`
71+
help: consider using `Option::expect` to unwrap the `Option<i32>` value, panicking if the value is an `Option::None`
72+
|
73+
LL | let v: i32 = func().expect("REASON");
74+
| +++++++++++++++++
75+
76+
error[E0308]: mismatched types
77+
--> $DIR/mismatch-ty-unwrap-expect.rs:30:18
78+
|
79+
LL | let v: i32 = a;
80+
| --- ^ expected `i32`, found `Option<_>`
81+
| |
82+
| expected due to this
83+
|
84+
= note: expected type `i32`
85+
found enum `Option<_>`
86+
help: consider using `Option::expect` to unwrap the `Option<_>` value, panicking if the value is an `Option::None`
87+
|
88+
LL | let v: i32 = a.expect("REASON");
89+
| +++++++++++++++++
90+
91+
error: aborting due to 6 previous errors
92+
93+
For more information about this error, try `rustc --explain E0308`.

‎tests/ui/noexporttypeexe.stderr‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -8,6 +8,10 @@ LL | let x: isize = noexporttypelib::foo();
88
|
99
= note: expected type `isize`
1010
found enum `Option<isize>`
11+
help: consider using `Option::expect` to unwrap the `Option<isize>` value, panicking if the value is an `Option::None`
12+
|
13+
LL | let x: isize = noexporttypelib::foo().expect("REASON");
14+
| +++++++++++++++++
1115

1216
error: aborting due to previous error
1317

‎tests/ui/typeck/tag-that-dare-not-speak-its-name.stderr‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -8,6 +8,10 @@ LL | let x : char = last(y);
88
|
99
= note: expected type `char`
1010
found enum `Option<_>`
11+
help: consider using `Option::expect` to unwrap the `Option<_>` value, panicking if the value is an `Option::None`
12+
|
13+
LL | let x : char = last(y).expect("REASON");
14+
| +++++++++++++++++
1115

1216
error: aborting due to previous error
1317

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