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Suggest dereferencing boolean reference when used in 'if' or 'while' #65150

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merged 3 commits into from
Oct 8, 2019
Merged

Suggest dereferencing boolean reference when used in 'if' or 'while' #65150

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0b0aeac
Suggest dereferencing boolean reference when used in 'if' or 'while'
XiangQingW Oct 6, 2019
8a164ac
Suggest dereferencing boolean reference when used in 'if' or 'while'
XiangQingW Oct 6, 2019
bbb69d1
Suggest dereferencing boolean reference when used in 'if' or 'while'
XiangQingW Oct 6, 2019
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6 changes: 5 additions & 1 deletion src/librustc_typeck/check/demand.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -349,7 +349,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {

// If the span is from a macro, then it's hard to extract the text
// and make a good suggestion, so don't bother.
let is_macro = sp.from_expansion();
let is_desugaring = match sp.desugaring_kind() {
Some(k) => sp.is_desugaring(k),
None => false
};
let is_macro = sp.from_expansion() && !is_desugaring;

match (&expr.kind, &expected.kind, &checked_ty.kind) {
(_, &ty::Ref(_, exp, _), &ty::Ref(_, check, _)) => match (&exp.kind, &check.kind) {
Expand Down
2 changes: 2 additions & 0 deletions src/librustc_typeck/check/expr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -87,6 +87,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}

if let Some(mut err) = self.demand_suptype_diag(expr.span, expected_ty, ty) {
self.suggest_ref_or_into(&mut err, expr, expected_ty, ty);

let expr = match &expr.kind {
ExprKind::DropTemps(expr) => expr,
_ => expr,
Expand Down
40 changes: 32 additions & 8 deletions src/test/ui/if/if-no-match-bindings.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,10 @@ error[E0308]: mismatched types
--> $DIR/if-no-match-bindings.rs:18:8
|
LL | if b_ref() {}
| ^^^^^^^ expected bool, found &bool
| ^^^^^^^
| |
| expected bool, found &bool
| help: consider dereferencing the borrow: `*b_ref()`
|
= note: expected type `bool`
found type `&bool`
Expand All @@ -11,7 +14,10 @@ error[E0308]: mismatched types
--> $DIR/if-no-match-bindings.rs:19:8
|
LL | if b_mut_ref() {}
| ^^^^^^^^^^^ expected bool, found &mut bool
| ^^^^^^^^^^^
| |
| expected bool, found &mut bool
| help: consider dereferencing the borrow: `*b_mut_ref()`
|
= note: expected type `bool`
found type `&mut bool`
Expand All @@ -20,7 +26,10 @@ error[E0308]: mismatched types
--> $DIR/if-no-match-bindings.rs:20:8
|
LL | if &true {}
| ^^^^^ expected bool, found &bool
| ^^^^^
| |
| expected bool, found &bool
| help: consider dereferencing the borrow: `*&true`
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This tells me that suggest_ref_or_into needs to check for literal borrows before suggesting, but that can be done in a subsequent PR.

|
= note: expected type `bool`
found type `&bool`
Expand All @@ -29,7 +38,10 @@ error[E0308]: mismatched types
--> $DIR/if-no-match-bindings.rs:21:8
|
LL | if &mut true {}
| ^^^^^^^^^ expected bool, found &mut bool
| ^^^^^^^^^
| |
| expected bool, found &mut bool
| help: consider dereferencing the borrow: `*&mut true`
|
= note: expected type `bool`
found type `&mut bool`
Expand All @@ -38,7 +50,10 @@ error[E0308]: mismatched types
--> $DIR/if-no-match-bindings.rs:24:11
|
LL | while b_ref() {}
| ^^^^^^^ expected bool, found &bool
| ^^^^^^^
| |
| expected bool, found &bool
| help: consider dereferencing the borrow: `*b_ref()`
|
= note: expected type `bool`
found type `&bool`
Expand All @@ -47,7 +62,10 @@ error[E0308]: mismatched types
--> $DIR/if-no-match-bindings.rs:25:11
|
LL | while b_mut_ref() {}
| ^^^^^^^^^^^ expected bool, found &mut bool
| ^^^^^^^^^^^
| |
| expected bool, found &mut bool
| help: consider dereferencing the borrow: `*b_mut_ref()`
|
= note: expected type `bool`
found type `&mut bool`
Expand All @@ -56,7 +74,10 @@ error[E0308]: mismatched types
--> $DIR/if-no-match-bindings.rs:26:11
|
LL | while &true {}
| ^^^^^ expected bool, found &bool
| ^^^^^
| |
| expected bool, found &bool
| help: consider dereferencing the borrow: `*&true`
|
= note: expected type `bool`
found type `&bool`
Expand All @@ -65,7 +86,10 @@ error[E0308]: mismatched types
--> $DIR/if-no-match-bindings.rs:27:11
|
LL | while &mut true {}
| ^^^^^^^^^ expected bool, found &mut bool
| ^^^^^^^^^
| |
| expected bool, found &mut bool
| help: consider dereferencing the borrow: `*&mut true`
|
= note: expected type `bool`
found type `&mut bool`
Expand Down
10 changes: 8 additions & 2 deletions src/test/ui/rfc-2497-if-let-chains/disallowed-positions.stderr
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Expand Up @@ -517,7 +517,10 @@ error[E0308]: mismatched types
--> $DIR/disallowed-positions.rs:32:8
|
LL | if &let 0 = 0 {}
| ^^^^^^^^^^ expected bool, found &bool
| ^^^^^^^^^^
| |
| expected bool, found &bool
| help: consider dereferencing the borrow: `*&let 0 = 0`
|
= note: expected type `bool`
found type `&bool`
Expand Down Expand Up @@ -702,7 +705,10 @@ error[E0308]: mismatched types
--> $DIR/disallowed-positions.rs:96:11
|
LL | while &let 0 = 0 {}
| ^^^^^^^^^^ expected bool, found &bool
| ^^^^^^^^^^
| |
| expected bool, found &bool
| help: consider dereferencing the borrow: `*&let 0 = 0`
|
= note: expected type `bool`
found type `&bool`
Expand Down