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Allow const parameters in array sizes to be unified #60742

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Merged
merged 17 commits into from
May 29, 2019
Merged

Allow const parameters in array sizes to be unified #60742

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73f7e42
Relate identical parameters in array lengths
varkor May 11, 2019
5a585fe
Add a test for a function taking a const param array as an argument
varkor May 11, 2019
4ad5c62
Resolve consts in OpportunisticTypeResolver
varkor May 11, 2019
55dcc20
Add tests for uninferred consts during codegen
varkor May 11, 2019
c94ba63
Rename `OpportunisticTypeResolver` to `OpportunisticVarResolver`
varkor May 11, 2019
908d97d
Update test output
varkor May 12, 2019
d5c6cb8
Eagerly evaluate in `super_relate_consts`
varkor May 13, 2019
193b748
Remove FixedArraySize error
varkor May 13, 2019
57ff589
Add broken MIR regression tests
varkor May 20, 2019
cfa1f80
Fix test after rebase
varkor May 21, 2019
f865b7d
Update tests after pretty printing
varkor May 25, 2019
f13317c
Use Display rather than Debug printing for const mismatch
varkor May 25, 2019
8549953
Reintroduce `TypeError::FixedArraySize`
varkor May 27, 2019
56181cf
Correct pluralisation of tuple/array/associated type binding mismatch…
varkor May 27, 2019
b3a13fd
Make sure array length diagnostic doesn't regress
varkor May 27, 2019
2949160
Fix nits
varkor May 28, 2019
6233d1f
Use assert_eq! instead of println! in tests
varkor May 28, 2019
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Use Display rather than Debug printing for const mismatch
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@varkor
varkor committed May 28, 2019
commit f13317ca2ee16163ee121fbdf28eb2184840b6dd
2 changes: 1 addition & 1 deletion src/librustc/ty/error.rs
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Expand Up @@ -159,7 +159,7 @@ impl<'tcx> fmt::Display for TypeError<'tcx> {
&format!("trait `{}`", values.found))
}
ConstMismatch(ref values) => {
write!(f, "expected `{:?}`, found `{:?}`", values.expected, values.found)
write!(f, "expected `{}`, found `{}`", values.expected, values.found)
}
}
}
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2 changes: 1 addition & 1 deletion src/test/ui/const-generics/cannot-infer-type-for-const-param.stderr
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Expand Up @@ -14,7 +14,7 @@ error[E0308]: mismatched types
--> $DIR/cannot-infer-type-for-const-param.rs:10:22
|
LL | let _ = Foo::<3>([1, 2, 3]);
| ^^^^^^^^^ expected `Const { ty: usize, val: Unevaluated(DefId(0:18 ~ cannot_infer_type_for_const_param[317d]::main[0]::{{constant}}[0]), []) }`, found `Const { ty: usize, val: Scalar(0x0000000000000003) }`
| ^^^^^^^^^ expected `3`, found `3usize`
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This... is really weird? I assume the 3 is @oli-obk's printing of same-crate anon consts?

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I think it's because it can't infer the specific type, rather than an issue with printing. This is a bug, though, which should be fixed by #60839. (Which is ready to go as soon as this one is.)

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I mean that the printing output is from Unevaluated for the 3 in Foo::<3> and not the value 3.

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ugh, ok I did not envision user facing effects from that. So.... should I just do _ or {{unevaluated}} or sth?

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I don't think we need to jump to something else here, but we should consider it carefully.
_ is clearly the conservative choice, as for "unevaluated" - I don't like that name too much, it just happened to be useful in ty::Const (and we could/should pick another name).

|
= note: expected type `[u8; _]`
found type `[u8; 3]`
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4 changes: 2 additions & 2 deletions src/test/ui/consts/const-array-oob-arith.stderr
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Expand Up @@ -2,7 +2,7 @@ error[E0308]: mismatched types
--> $DIR/const-array-oob-arith.rs:7:45
|
LL | const BLUB: [i32; (ARR[0] - 40) as usize] = [5];
| ^^^ expected `Const { ty: usize, val: Scalar(0x0000000000000002) }`, found `Const { ty: usize, val: Scalar(0x0000000000000001) }`
| ^^^ expected `2usize`, found `1usize`
|
= note: expected type `[i32; 2]`
found type `[i32; 1]`
Expand All @@ -11,7 +11,7 @@ error[E0308]: mismatched types
--> $DIR/const-array-oob-arith.rs:8:44
|
LL | const BOO: [i32; (ARR[0] - 41) as usize] = [5, 99];
| ^^^^^^^ expected `Const { ty: usize, val: Scalar(0x0000000000000001) }`, found `Const { ty: usize, val: Scalar(0x0000000000000002) }`
| ^^^^^^^ expected `1usize`, found `2usize`
|
= note: expected type `[i32; 1]`
found type `[i32; 2]`
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