ICE: cannot convert ReErased to a region vid
#81857
Labels
A-borrow-checker
Area: The borrow checker
A-lifetimes
Area: Lifetimes / regions
C-bug
Category: This is a bug.
F-inline_const
Inline constants (aka: const blocks, const expressions, anonymous constants)
I-ICE
Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️
T-compiler
Relevant to the compiler team, which will review and decide on the PR/issue.
Comments
ZhangZhuoSJTU
added
C-bug
jonas-schievink
added
A-borrow-checker
|
searched nightlies: from nightly-2020-10-11 to nightly-2021-02-08 bisected with cargo-bisect-rustc v0.6.0Host triple: aarch64-unknown-linux-gnu cargo bisect-rustc --regress ice |
|
Another test-case. fn main() {
const {
""
}
} |
|
This seems to be a bad interaction between constant evaluation and region erasing. It's not specific to string literals, same thing happens with e.g. #![feature(inline_const)]
#![allow(incomplete_features)]
fn main() {
const { &[1usize] };
}Basically returning a I'd like to debug this but I'm not sure where to start. Where can I learn more about the handling of regions in constant evaluation? |
|
This example used to ICE but is now picked up by E308, at least on x86_64/aarch64-unknown-linux-gnu |
matthiaskrgr
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Nov 8, 2021
Type inference for inline consts Fixes rust-lang#78132 Fixes rust-lang#78174 Fixes rust-lang#81857 Fixes rust-lang#89964 Perform type checking/inference of inline consts in the same context as the outer def, similar to what is currently done to closure. Doing so would require `closure_base_def_id` of the inline const to return the outer def, and since `closure_base_def_id` can be called on non-local crate (and thus have no HIR available), a new `DefKind` is created for inline consts. The type of the generated anon const can capture lifetime of outer def, so we couldn't just use the typeck result as the type of the inline const's def. Closure has a similar issue, and it uses extra type params `CK, CS, U` to capture closure kind, input/output signature and upvars. I use a similar approach for inline consts, letting it have an extra type param `R`, and then `typeof(InlineConst<[paremt generics], R>)` would just be `R`. In borrowck region requirements are also propagated to the outer MIR body just like it's currently done for closure. With this PR, inline consts in expression position are quitely usable now; however the usage in pattern position is still incomplete -- since those does not remain in the MIR borrowck couldn't verify the lifetime there. I have left an ignored test as a FIXME. Some disucssions can be found on [this Zulip thread](https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/inline.20consts.20typeck). cc `@spastorino` `@lcnr` r? `@nikomatsakis` `@rustbot` label A-inference F-inline_const T-compiler
matthiaskrgr
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Nov 8, 2021
Type inference for inline consts Fixes rust-lang#78132 Fixes rust-lang#78174 Fixes rust-lang#81857 Fixes rust-lang#89964 Perform type checking/inference of inline consts in the same context as the outer def, similar to what is currently done to closure. Doing so would require `closure_base_def_id` of the inline const to return the outer def, and since `closure_base_def_id` can be called on non-local crate (and thus have no HIR available), a new `DefKind` is created for inline consts. The type of the generated anon const can capture lifetime of outer def, so we couldn't just use the typeck result as the type of the inline const's def. Closure has a similar issue, and it uses extra type params `CK, CS, U` to capture closure kind, input/output signature and upvars. I use a similar approach for inline consts, letting it have an extra type param `R`, and then `typeof(InlineConst<[paremt generics], R>)` would just be `R`. In borrowck region requirements are also propagated to the outer MIR body just like it's currently done for closure. With this PR, inline consts in expression position are quitely usable now; however the usage in pattern position is still incomplete -- since those does not remain in the MIR borrowck couldn't verify the lifetime there. I have left an ignored test as a FIXME. Some disucssions can be found on [this Zulip thread](https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/inline.20consts.20typeck). cc ``@spastorino`` ``@lcnr`` r? ``@nikomatsakis`` ``@rustbot`` label A-inference F-inline_const T-compiler
matthiaskrgr
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to matthiaskrgr/rust
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Nov 8, 2021
Type inference for inline consts Fixes rust-lang#78132 Fixes rust-lang#78174 Fixes rust-lang#81857 Fixes rust-lang#89964 Perform type checking/inference of inline consts in the same context as the outer def, similar to what is currently done to closure. Doing so would require `closure_base_def_id` of the inline const to return the outer def, and since `closure_base_def_id` can be called on non-local crate (and thus have no HIR available), a new `DefKind` is created for inline consts. The type of the generated anon const can capture lifetime of outer def, so we couldn't just use the typeck result as the type of the inline const's def. Closure has a similar issue, and it uses extra type params `CK, CS, U` to capture closure kind, input/output signature and upvars. I use a similar approach for inline consts, letting it have an extra type param `R`, and then `typeof(InlineConst<[paremt generics], R>)` would just be `R`. In borrowck region requirements are also propagated to the outer MIR body just like it's currently done for closure. With this PR, inline consts in expression position are quitely usable now; however the usage in pattern position is still incomplete -- since those does not remain in the MIR borrowck couldn't verify the lifetime there. I have left an ignored test as a FIXME. Some disucssions can be found on [this Zulip thread](https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/inline.20consts.20typeck). cc ```@spastorino``` ```@lcnr``` r? ```@nikomatsakis``` ```@rustbot``` label A-inference F-inline_const T-compiler
matthiaskrgr
added a commit
to matthiaskrgr/rust
that referenced
this issue
Nov 8, 2021
Type inference for inline consts Fixes rust-lang#78132 Fixes rust-lang#78174 Fixes rust-lang#81857 Fixes rust-lang#89964 Perform type checking/inference of inline consts in the same context as the outer def, similar to what is currently done to closure. Doing so would require `closure_base_def_id` of the inline const to return the outer def, and since `closure_base_def_id` can be called on non-local crate (and thus have no HIR available), a new `DefKind` is created for inline consts. The type of the generated anon const can capture lifetime of outer def, so we couldn't just use the typeck result as the type of the inline const's def. Closure has a similar issue, and it uses extra type params `CK, CS, U` to capture closure kind, input/output signature and upvars. I use a similar approach for inline consts, letting it have an extra type param `R`, and then `typeof(InlineConst<[paremt generics], R>)` would just be `R`. In borrowck region requirements are also propagated to the outer MIR body just like it's currently done for closure. With this PR, inline consts in expression position are quitely usable now; however the usage in pattern position is still incomplete -- since those does not remain in the MIR borrowck couldn't verify the lifetime there. I have left an ignored test as a FIXME. Some disucssions can be found on [this Zulip thread](https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/inline.20consts.20typeck). cc ````@spastorino```` ````@lcnr```` r? ````@nikomatsakis```` ````@rustbot```` label A-inference F-inline_const T-compiler
flip1995
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Nov 23, 2021
Type inference for inline consts Fixes rust-lang#78132 Fixes rust-lang#78174 Fixes rust-lang#81857 Fixes rust-lang#89964 Perform type checking/inference of inline consts in the same context as the outer def, similar to what is currently done to closure. Doing so would require `closure_base_def_id` of the inline const to return the outer def, and since `closure_base_def_id` can be called on non-local crate (and thus have no HIR available), a new `DefKind` is created for inline consts. The type of the generated anon const can capture lifetime of outer def, so we couldn't just use the typeck result as the type of the inline const's def. Closure has a similar issue, and it uses extra type params `CK, CS, U` to capture closure kind, input/output signature and upvars. I use a similar approach for inline consts, letting it have an extra type param `R`, and then `typeof(InlineConst<[paremt generics], R>)` would just be `R`. In borrowck region requirements are also propagated to the outer MIR body just like it's currently done for closure. With this PR, inline consts in expression position are quitely usable now; however the usage in pattern position is still incomplete -- since those does not remain in the MIR borrowck couldn't verify the lifetime there. I have left an ignored test as a FIXME. Some disucssions can be found on [this Zulip thread](https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/inline.20consts.20typeck). cc `````@spastorino````` `````@lcnr````` r? `````@nikomatsakis````` `````@rustbot````` label A-inference F-inline_const T-compiler
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It seems like a duplicate of #78174. But it is, on the other hand, an invalid statements instead of a nightly-only feature (inline_const). So I open this issue.
I will try to understand whether it is indeed a duplicate. But it would be very appreciated if someone can figure it out, so that we do not bother so much. Thanks!
Code
md5: fef99e2b36eeaaa4fe32447f7ff03c9c
Meta
It is on nightly, beta, and stable versions.
rustc --version --verbose:Error output
The output is from nightly.
Backtrace
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