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typeck: note other end-point when checking range pats #67287

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merged 1 commit into from
Dec 30, 2019
Merged

typeck: note other end-point when checking range pats #67287

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31 changes: 21 additions & 10 deletions src/librustc_typeck/check/pat.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -353,21 +353,21 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
fn check_pat_range(
&self,
span: Span,
begin: &'tcx hir::Expr<'tcx>,
end: &'tcx hir::Expr<'tcx>,
lhs: &'tcx hir::Expr<'tcx>,
rhs: &'tcx hir::Expr<'tcx>,
expected: Ty<'tcx>,
discrim_span: Option<Span>,
) -> Option<Ty<'tcx>> {
let lhs_ty = self.check_expr(begin);
let rhs_ty = self.check_expr(end);
let lhs_ty = self.check_expr(lhs);
let rhs_ty = self.check_expr(rhs);

// Check that both end-points are of numeric or char type.
let numeric_or_char = |ty: Ty<'_>| ty.is_numeric() || ty.is_char() || ty.references_error();
let lhs_fail = !numeric_or_char(lhs_ty);
let rhs_fail = !numeric_or_char(rhs_ty);

if lhs_fail || rhs_fail {
self.emit_err_pat_range(span, begin.span, end.span, lhs_fail, rhs_fail, lhs_ty, rhs_ty);
self.emit_err_pat_range(span, lhs.span, rhs.span, lhs_fail, rhs_fail, lhs_ty, rhs_ty);
return None;
}

Expand All @@ -376,11 +376,24 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let common_type = self.resolve_vars_if_possible(&lhs_ty);

// Subtyping doesn't matter here, as the value is some kind of scalar.
self.demand_eqtype_pat(span, expected, lhs_ty, discrim_span);
self.demand_eqtype_pat(span, expected, rhs_ty, discrim_span);
let demand_eqtype = |x_span, y_span, x_ty, y_ty| {
self.demand_eqtype_pat_diag(x_span, expected, x_ty, discrim_span).map(|mut err| {
self.endpoint_has_type(&mut err, y_span, y_ty);
err.emit();
});
};
demand_eqtype(lhs.span, rhs.span, lhs_ty, rhs_ty);
demand_eqtype(rhs.span, lhs.span, rhs_ty, lhs_ty);

Some(common_type)
}

fn endpoint_has_type(&self, err: &mut DiagnosticBuilder<'_>, span: Span, ty: Ty<'_>) {
if !ty.references_error() {
err.span_label(span, &format!("this is of type `{}`", ty));
}
}

fn emit_err_pat_range(
&self,
span: Span,
Expand Down Expand Up @@ -408,9 +421,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
let msg = |ty| format!("this is of type `{}` but it should be `char` or numeric", ty);
let mut one_side_err = |first_span, first_ty, second_span, second_ty: Ty<'_>| {
err.span_label(first_span, &msg(first_ty));
if !second_ty.references_error() {
err.span_label(second_span, &format!("this is of type `{}`", second_ty));
}
self.endpoint_has_type(&mut err, second_span, second_ty);
};
if lhs_fail && rhs_fail {
err.span_label(begin_span, &msg(lhs_ty));
Expand Down
6 changes: 4 additions & 2 deletions src/test/ui/error-codes/E0308-4.stderr
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Original file line number Diff line number Diff line change
@@ -1,10 +1,12 @@
error[E0308]: mismatched types
--> $DIR/E0308-4.rs:4:9
--> $DIR/E0308-4.rs:4:15
|
LL | match x {
| - this match expression has type `u8`
LL | 0u8..=3i8 => (),
| ^^^^^^^^^ expected `u8`, found `i8`
| --- ^^^ expected `u8`, found `i8`
| |
| this is of type `u8`

error: aborting due to previous error

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/exclusive-range/exclusive_range_pattern_syntax_collision.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@ error[E0308]: mismatched types
LL | match [5..4, 99..105, 43..44] {
| ----------------------- this match expression has type `std::ops::Range<{integer}>`
LL | [_, 99.., _] => {},
| ^^^^ expected struct `std::ops::Range`, found integer
| ^^ expected struct `std::ops::Range`, found integer
|
= note: expected struct `std::ops::Range<{integer}>`
found type `{integer}`
Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/exclusive-range/exclusive_range_pattern_syntax_collision2.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ error[E0308]: mismatched types
LL | match [5..4, 99..105, 43..44] {
| ----------------------- this match expression has type `std::ops::Range<{integer}>`
LL | [_, 99..] => {},
| ^^^^ expected struct `std::ops::Range`, found integer
| ^^ expected struct `std::ops::Range`, found integer
|
= note: expected struct `std::ops::Range<{integer}>`
found type `{integer}`
Expand Down
1 change: 1 addition & 0 deletions src/test/ui/exclusive-range/exclusive_range_pattern_syntax_collision3.rs
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Expand Up @@ -6,6 +6,7 @@ fn main() {
//~^ ERROR `..X` range patterns are not supported
//~| ERROR mismatched types
//~| ERROR mismatched types
//~| ERROR mismatched types
_ => {},
}
}
23 changes: 19 additions & 4 deletions src/test/ui/exclusive-range/exclusive_range_pattern_syntax_collision3.stderr
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Expand Up @@ -5,12 +5,12 @@ LL | [..9, 99..100, _] => {},
| ^^^ help: try using the minimum value for the type: `MIN..9`

error[E0308]: mismatched types
--> $DIR/exclusive_range_pattern_syntax_collision3.rs:5:10
--> $DIR/exclusive_range_pattern_syntax_collision3.rs:5:12
|
LL | match [5..4, 99..105, 43..44] {
| ----------------------- this match expression has type `std::ops::Range<{integer}>`
LL | [..9, 99..100, _] => {},
| ^^^ expected struct `std::ops::Range`, found integer
| ^ expected struct `std::ops::Range`, found integer
|
= note: expected struct `std::ops::Range<{integer}>`
found type `{integer}`
Expand All @@ -21,11 +21,26 @@ error[E0308]: mismatched types
LL | match [5..4, 99..105, 43..44] {
| ----------------------- this match expression has type `std::ops::Range<{integer}>`
LL | [..9, 99..100, _] => {},
| ^^^^^^^ expected struct `std::ops::Range`, found integer
| ^^ --- this is of type `{integer}`
| |
| expected struct `std::ops::Range`, found integer
|
= note: expected struct `std::ops::Range<{integer}>`
found type `{integer}`

error[E0308]: mismatched types
--> $DIR/exclusive_range_pattern_syntax_collision3.rs:5:19
|
LL | match [5..4, 99..105, 43..44] {
| ----------------------- this match expression has type `std::ops::Range<{integer}>`
LL | [..9, 99..100, _] => {},
| -- ^^^ expected struct `std::ops::Range`, found integer
| |
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I still don't understand what's happening here

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The first error above is for 99 and the other one is for 100. They now occur twice because the spans are different and so there's no de-duplication. The type error happens because 99..105 is at type Range<{integer}> whereas 99..100 is a range pattern at type {integer}.

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In my version I tried changing "this match expression has" to "this match expression requires" in an attempt to clarify these errors

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It's fine to change that, but that can be in a different PR than this (e.g. yours).

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@estebank estebank Dec 14, 2019 •
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The problem I have with this wording is "expected struct std::ops::Range, found integer", but now I see that the thing being matched is [5..4, 99..105, 43..44] and not [5, 99, 43], which accounts for the weirdness.

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Right, and that part hasn't changed as you can see from the diff. :)

| this is of type `{integer}`
|
= note: expected struct `std::ops::Range<{integer}>`
found type `{integer}`

error: aborting due to 3 previous errors
error: aborting due to 4 previous errors

For more information about this error, try `rustc --explain E0308`.
4 changes: 3 additions & 1 deletion src/test/ui/match/match-range-fail.stderr
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Expand Up @@ -28,7 +28,9 @@ error[E0308]: mismatched types
--> $DIR/match-range-fail.rs:18:9
|
LL | 'c' ..= 100 => { }
| ^^^^^^^^^^^ expected integer, found `char`
| ^^^ --- this is of type `{integer}`
| |
| expected integer, found `char`

error: aborting due to 4 previous errors

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/parser/pat-tuple-5.stderr
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Expand Up @@ -19,7 +19,7 @@ error[E0308]: mismatched types
LL | match (0, 1) {
| ------ this match expression has type `({integer}, {integer})`
LL | (PAT ..) => {}
| ^^^^^^ expected tuple, found `u8`
| ^^^ expected tuple, found `u8`
|
= note: expected tuple `({integer}, {integer})`
found type `u8`
Expand Down
48 changes: 30 additions & 18 deletions src/test/ui/parser/recover-range-pats.stderr
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Expand Up @@ -417,13 +417,17 @@ error[E0308]: mismatched types
--> $DIR/recover-range-pats.rs:21:12
|
LL | if let .0..Y = 0 {}
| ^^^^^ expected integer, found floating-point number
| ^^ - this is of type `u8`
| |
| expected integer, found floating-point number

error[E0308]: mismatched types
--> $DIR/recover-range-pats.rs:23:12
--> $DIR/recover-range-pats.rs:23:16
|
LL | if let X.. .0 = 0 {}
| ^^^^^^ expected integer, found floating-point number
| - ^^ expected integer, found floating-point number
| |
| this is of type `u8`

error[E0029]: only char and numeric types are allowed in range patterns
--> $DIR/recover-range-pats.rs:32:12
Expand All @@ -445,13 +449,17 @@ error[E0308]: mismatched types
--> $DIR/recover-range-pats.rs:34:12
|
LL | if let .0..=Y = 0 {}
| ^^^^^^ expected integer, found floating-point number
| ^^ - this is of type `u8`
| |
| expected integer, found floating-point number

error[E0308]: mismatched types
--> $DIR/recover-range-pats.rs:36:12
--> $DIR/recover-range-pats.rs:36:16
|
LL | if let X..=.0 = 0 {}
| ^^^^^^ expected integer, found floating-point number
| - ^^ expected integer, found floating-point number
| |
| this is of type `u8`

error[E0029]: only char and numeric types are allowed in range patterns
--> $DIR/recover-range-pats.rs:45:12
Expand All @@ -473,13 +481,17 @@ error[E0308]: mismatched types
--> $DIR/recover-range-pats.rs:49:12
|
LL | if let .0...Y = 0 {}
| ^^^^^^ expected integer, found floating-point number
| ^^ - this is of type `u8`
| |
| expected integer, found floating-point number

error[E0308]: mismatched types
--> $DIR/recover-range-pats.rs:52:12
--> $DIR/recover-range-pats.rs:52:17
|
LL | if let X... .0 = 0 {}
| ^^^^^^^ expected integer, found floating-point number
| - ^^ expected integer, found floating-point number
| |
| this is of type `u8`

error[E0029]: only char and numeric types are allowed in range patterns
--> $DIR/recover-range-pats.rs:60:12
Expand All @@ -491,7 +503,7 @@ error[E0308]: mismatched types
--> $DIR/recover-range-pats.rs:62:12
|
LL | if let .0.. = 0 {}
| ^^^^ expected integer, found floating-point number
| ^^ expected integer, found floating-point number

error[E0029]: only char and numeric types are allowed in range patterns
--> $DIR/recover-range-pats.rs:70:12
Expand All @@ -503,7 +515,7 @@ error[E0308]: mismatched types
--> $DIR/recover-range-pats.rs:72:12
|
LL | if let .0..= = 0 {}
| ^^^^^ expected integer, found floating-point number
| ^^ expected integer, found floating-point number

error[E0029]: only char and numeric types are allowed in range patterns
--> $DIR/recover-range-pats.rs:82:12
Expand All @@ -515,7 +527,7 @@ error[E0308]: mismatched types
--> $DIR/recover-range-pats.rs:85:12
|
LL | if let .0... = 0 {}
| ^^^^^ expected integer, found floating-point number
| ^^ expected integer, found floating-point number

error[E0029]: only char and numeric types are allowed in range patterns
--> $DIR/recover-range-pats.rs:94:14
Expand All @@ -524,10 +536,10 @@ LL | if let ..true = 0 {}
| ^^^^ this is of type `bool` but it should be `char` or numeric

error[E0308]: mismatched types
--> $DIR/recover-range-pats.rs:96:12
--> $DIR/recover-range-pats.rs:96:15
|
LL | if let .. .0 = 0 {}
| ^^^^^ expected integer, found floating-point number
| ^^ expected integer, found floating-point number

error[E0029]: only char and numeric types are allowed in range patterns
--> $DIR/recover-range-pats.rs:104:15
Expand All @@ -536,10 +548,10 @@ LL | if let ..=true = 0 {}
| ^^^^ this is of type `bool` but it should be `char` or numeric

error[E0308]: mismatched types
--> $DIR/recover-range-pats.rs:106:12
--> $DIR/recover-range-pats.rs:106:15
|
LL | if let ..=.0 = 0 {}
| ^^^^^ expected integer, found floating-point number
| ^^ expected integer, found floating-point number

error[E0029]: only char and numeric types are allowed in range patterns
--> $DIR/recover-range-pats.rs:116:15
Expand All @@ -548,10 +560,10 @@ LL | if let ...true = 0 {}
| ^^^^ this is of type `bool` but it should be `char` or numeric

error[E0308]: mismatched types
--> $DIR/recover-range-pats.rs:119:12
--> $DIR/recover-range-pats.rs:119:15
|
LL | if let ....3 = 0 {}
| ^^^^^ expected integer, found floating-point number
| ^^ expected integer, found floating-point number

error: aborting due to 85 previous errors

Expand Down