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Rollup merge of #74991 - JulianKnodt:74199, r=lcnr

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Fix Const-Generic Cycle ICE #74199

This PR intends to fix the bug in Issue #74199 by following the suggestion provided of ignoring the error that causes the ICE.

This does not fix the underlying cycle detection issue, but fixes the ICE.
Also adds a test to check that it doesn't causes an ICE but returns a valid error for now.

r? @lcnr

Edit: Also it's funny how this PR number is an anagram of the issue number
This commit is contained in:
Yuki Okushi 2020-08-01 08:02:12 +09:00 committed by GitHub
commit 3ad6feda56
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3 changed files with 178 additions and 0 deletions
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1
src/librustc_typeck/variance/constraints.rs
View File

@ -161,6 +161,7 @@ impl<'a, 'tcx> ConstraintContext<'a, 'tcx> {
self.add_constraints_from_sig(current_item, tcx.fn_sig(def_id), self.covariant);
}
ty::Error(_) => {}
_ => {
span_bug!(
tcx.def_span(def_id),

18
src/test/ui/const-generics/nested-type.rs Normal file
View File

@ -0,0 +1,18 @@
#![feature(const_generics)]
#![allow(incomplete_features)]
struct Foo<const N: [u8; {
//~^ ERROR cycle detected
//~| ERROR cycle detected
struct Foo<const N: usize>;
impl<const N: usize> Foo<N> {
fn value() -> usize {
N
}
}
Foo::<17>::value()
}]>;
fn main() {}

159
src/test/ui/const-generics/nested-type.stderr Normal file
View File

@ -0,0 +1,159 @@
error[E0391]: cycle detected when computing type of `Foo`
--> $DIR/nested-type.rs:4:1
|
LL | struct Foo<const N: [u8; {
| ^^^^^^^^^^^^^^^^^^^^^^^^
|
note: ...which requires computing type of `Foo::N`...
--> $DIR/nested-type.rs:4:18
|
LL | struct Foo<const N: [u8; {
| ^
note: ...which requires const-evaluating + checking `Foo::{{constant}}#0`...
--> $DIR/nested-type.rs:4:26
|
LL | struct Foo<const N: [u8; {
| __________________________^
LL | |
LL | |
LL | | struct Foo<const N: usize>;
... |
LL | | Foo::<17>::value()
LL | | }]>;
| |_^
note: ...which requires const-evaluating + checking `Foo::{{constant}}#0`...
--> $DIR/nested-type.rs:4:26
|
LL | struct Foo<const N: [u8; {
| __________________________^
LL | |
LL | |
LL | | struct Foo<const N: usize>;
... |
LL | | Foo::<17>::value()
LL | | }]>;
| |_^
note: ...which requires const-evaluating `Foo::{{constant}}#0`...
--> $DIR/nested-type.rs:4:26
|
LL | struct Foo<const N: [u8; {
| __________________________^
LL | |
LL | |
LL | | struct Foo<const N: usize>;
... |
LL | | Foo::<17>::value()
LL | | }]>;
| |_^
note: ...which requires type-checking `Foo::{{constant}}#0`...
--> $DIR/nested-type.rs:4:26
|
LL | struct Foo<const N: [u8; {
| __________________________^
LL | |
LL | |
LL | | struct Foo<const N: usize>;
... |
LL | | Foo::<17>::value()
LL | | }]>;
| |_^
note: ...which requires computing the variances of `Foo::{{constant}}#0::Foo`...
--> $DIR/nested-type.rs:7:5
|
LL | struct Foo<const N: usize>;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: ...which requires computing the variances for items in this crate...
= note: ...which again requires computing type of `Foo`, completing the cycle
note: cycle used when collecting item types in top-level module
--> $DIR/nested-type.rs:1:1
|
LL | / #![feature(const_generics)]
LL | | #![allow(incomplete_features)]
LL | |
LL | | struct Foo<const N: [u8; {
... |
LL | |
LL | | fn main() {}
| |____________^
error[E0391]: cycle detected when computing type of `Foo`
--> $DIR/nested-type.rs:4:1
|
LL | struct Foo<const N: [u8; {
| ^^^^^^^^^^^^^^^^^^^^^^^^
|
note: ...which requires computing type of `Foo::N`...
--> $DIR/nested-type.rs:4:18
|
LL | struct Foo<const N: [u8; {
| ^
note: ...which requires const-evaluating + checking `Foo::{{constant}}#0`...
--> $DIR/nested-type.rs:4:26
|
LL | struct Foo<const N: [u8; {
| __________________________^
LL | |
LL | |
LL | | struct Foo<const N: usize>;
... |
LL | | Foo::<17>::value()
LL | | }]>;
| |_^
note: ...which requires const-evaluating + checking `Foo::{{constant}}#0`...
--> $DIR/nested-type.rs:4:26
|
LL | struct Foo<const N: [u8; {
| __________________________^
LL | |
LL | |
LL | | struct Foo<const N: usize>;
... |
LL | | Foo::<17>::value()
LL | | }]>;
| |_^
note: ...which requires const-evaluating `Foo::{{constant}}#0`...
--> $DIR/nested-type.rs:4:26
|
LL | struct Foo<const N: [u8; {
| __________________________^
LL | |
LL | |
LL | | struct Foo<const N: usize>;
... |
LL | | Foo::<17>::value()
LL | | }]>;
| |_^
note: ...which requires type-checking `Foo::{{constant}}#0`...
--> $DIR/nested-type.rs:4:26
|
LL | struct Foo<const N: [u8; {
| __________________________^
LL | |
LL | |
LL | | struct Foo<const N: usize>;
... |
LL | | Foo::<17>::value()
LL | | }]>;
| |_^
note: ...which requires computing the variances of `Foo::{{constant}}#0::Foo`...
--> $DIR/nested-type.rs:7:5
|
LL | struct Foo<const N: usize>;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: ...which requires computing the variances for items in this crate...
= note: ...which again requires computing type of `Foo`, completing the cycle
note: cycle used when collecting item types in top-level module
--> $DIR/nested-type.rs:1:1
|
LL | / #![feature(const_generics)]
LL | | #![allow(incomplete_features)]
LL | |
LL | | struct Foo<const N: [u8; {
... |
LL | |
LL | | fn main() {}
| |____________^
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0391`.