ICE: errors resolving bounds after type-checking for fmt::Display #65774
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Labels
A-associated-items
Area: Associated items (types, constants & functions)
A-trait-system
Area: Trait system
C-bug
Category: This is a bug.
F-associated_type_defaults
`#![feature(associated_type_defaults)]`
glacier
ICE tracked in rust-lang/glacier.
I-ICE
Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️
P-medium
Medium priority
requires-nightly
This issue requires a nightly compiler in some way.
T-compiler
Relevant to the compiler team, which will review and decide on the PR/issue.
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2 tasks
Centril
added
I-ICE
|
If possible, could you please provide a self-contained example that ICEs on e.g. the playground? |
Mark-Simulacrum
added
the
E-needs-mcve
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Hmm...I tried creating a small example, but I can't seem to replicate the behavior. I'm not really sure what is happening to cause it. I have found that the error occurs even though I'm not actually creating an object of type let _ = writer.write_fmt(format_args!("{}", config));from a different crate which is where the fmt function would get used if I did create something of the type then the error does not occur. |
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triage: P-high, removing I-nominated label |
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I cannot reproduce this locally: Please do try to come up with an MCVE. I recommend taking the original code and paring it down, rather than trying to jump straight to a minimal bit of code. |
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closing as not reproducible in absence of MCVE |
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Thank you for being willing to try to reproduce! Would you mind trying
again with the "mpu-print" branch checked out? Tock for RISCV compiles
correctly (and has for a while) on master, but the issue has creeped in
when making the change for tock/tock#1428.
Also, I have been periodically checking new nightlies and have gotten the
same error.
…On Thu, Nov 14, 2019, 7:42 AM Felix S Klock II ***@***.***> wrote:
Closed #65774 <#65774>.
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Ah, okay, I overlooked that detail earlier. Now I can reproduce it. Reopening (and will try to minimize, if only as fodder for a blog post on reducing i am planning) |
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Okay I've narrowed it down. I don't have the test case into a state where I'm ready to post it yet (I need to clean it up a little more) But if you want to fix your problem, its this: pub trait MPU {
type MpuConfig: Default + Display = ();
...
}Namely, you are using the (feature-gated) Specifically in this case, But instead of nicely reporting that to you at the trait definition site, or even at a trait implementation site, you are instead seeing an error far far downstream, unfortunately. (As for how to work around this, I suspect your best bet is to make your own unit-struct that implements |
pnkfelix
added
the
requires-nightly
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Okay here is the reduction (play): #![feature(associated_type_defaults)]
trait MyDisplay { fn method(&self) { } }
impl<'a, T: MyDisplay> MyDisplay for &'a mut T { }
struct T;
trait MPU {
type MpuConfig: MyDisplay = T;
}
struct S;
impl MPU for S { }
trait MyWrite {
fn my_write(&self, _: &dyn MyDisplay) { }
}
trait ProcessType {
fn process_detail_fmt(&self, _: &mut dyn MyWrite);
}
struct Process;
impl ProcessType for Process {
fn process_detail_fmt(&self, writer: &mut dyn MyWrite)
{
let mut val: Option<<S as MPU>::MpuConfig> = None;
let valref: &mut <S as MPU>::MpuConfig = val.as_mut().unwrap();
// // This causes a different ICE (but its similar if you squint right):
// //
// // `Unimplemented` selecting `Binder(<T as MyDisplay>)` during codegen
//
// writer.my_write(valref)
// This one causes the ICE:
// FulfillmentError(Obligation(predicate=Binder(TraitPredicate(<T as MyDisplay>)), depth=1),Unimplemented)
let closure = |config: &mut <S as MPU>::MpuConfig| writer.my_write(&config);
closure(valref);
}
}
fn create() -> &'static dyn ProcessType {
let input: Option<&mut Process> = None;
let process: &mut Process = input.unwrap();
process
}
pub fn main() {
create();
} |
pnkfelix
added
A-associated-items
|
I'm going to downgrade this from P-high to P-medium, based on:
(it may or may not be fixed by #61812; I haven't checked that.) |
bradjc
added a commit
to tock/tock
that referenced
this issue
Nov 15, 2019
This is needed to workaround a compiler error. If rust-lang/rust#65774 is fixed then we should be able to revert this commit.
|
cc @jonas-schievink re. #61812. |
bors bot
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to tock/tock
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Nov 18, 2019
1428: Add MPU information to panic!() print r=ppannuto a=bradjc ### Pull Request Overview This pull request changes the `MpuConfig` type to require that it implement the `fmt::Display` trait so that the process.rs panic printout can display the MPU information. This fixes #925. ### Testing Strategy This pull request was tested by running `crash_dummy` on Hail and verifying that the MPU display looks ok. ### TODO or Help Wanted 1. The output looks like: ``` Cortex-M MPU Region 0: base: 20004000, length: 8192 bytes; ReadWrite (0x3) Region 1: base: 30000, length: 1024 bytes; ReadOnly (0x6) Region 2: Unused Region 3: Unused Region 4: Unused Region 5: Unused Region 6: Unused Region 7: Unused ``` I'm not sure how to get the `0x` to display on the base address. The format string looks like `Region {}: base:{:>width$x}` and sticking a `#` in there to make it print the `0x` gives me errors. 2. The rust compiler generates an error when linking for risc-v. rust-lang/rust#65774 I have no idea what to do about that. ### Documentation Updated I added a new copy of the panic!() output to the docs to keep that up to date. - [x] Updated the relevant files in `/docs`, or no updates are required. ### Formatting - [x] Ran `make formatall`. Co-authored-by: Brad Campbell <bradjc5@gmail.com> Co-authored-by: Pat Pannuto <pat.pannuto@gmail.com>
|
#61812 will currently reject this trait due to the unfulfilled trait bound. I've added a test. |
bradjc
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Sep 17, 2021
Clean up comment now that rust-lang/rust#65774 has been closed.
2 tasks
bors bot
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Sep 17, 2021
2829: kernel: mpu: Cleanup the comment for the default config type r=hudson-ayers a=bradjc Clean up comment now that rust-lang/rust#65774 has been closed. ### Testing Strategy I tried just using `()` and I got a compiler error this time. ### TODO or Help Wanted n/a ### Documentation Updated - [x] Updated the relevant files in `/docs`, or no updates are required. ### Formatting - [x] Ran `make prepush`. Co-authored-by: Brad Campbell <bradjc5@gmail.com>
lschuermann
pushed a commit
to lschuermann/tock-registers
that referenced
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Dec 18, 2021
1428: Add MPU information to panic!() print r=ppannuto a=bradjc
### Pull Request Overview
This pull request changes the `MpuConfig` type to require that it implement the `fmt::Display` trait so that the process.rs panic printout can display the MPU information.
This fixes #925.
### Testing Strategy
This pull request was tested by running `crash_dummy` on Hail and verifying that the MPU display looks ok.
### TODO or Help Wanted
1. The output looks like:
```
Cortex-M MPU
Region 0: base: 20004000, length: 8192 bytes; ReadWrite (0x3)
Region 1: base: 30000, length: 1024 bytes; ReadOnly (0x6)
Region 2: Unused
Region 3: Unused
Region 4: Unused
Region 5: Unused
Region 6: Unused
Region 7: Unused
```
I'm not sure how to get the `0x` to display on the base address. The format string looks like `Region {}: base:{:>width$x}` and sticking a `#` in there to make it print the `0x` gives me errors.
2. The rust compiler generates an error when linking for risc-v. rust-lang/rust#65774 I have no idea what to do about that.
### Documentation Updated
I added a new copy of the panic!() output to the docs to keep that up to date.
- [x] Updated the relevant files in `/docs`, or no updates are required.
### Formatting
- [x] Ran `make formatall`.
Co-authored-by: Brad Campbell <bradjc5@gmail.com>
Co-authored-by: Pat Pannuto <pat.pannuto@gmail.com>
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pnkfelix: here is the reduced test case (play):
(Sadly I have not been able to reduce it further. But this should serve us well enough.)
Original bug report follows:
I'm getting a compiler error when trying to compile:
I'm compiling for the
riscv32imac-unknown-none-elftarget.Full branch here:
https://github.com/tock/tock/blob/f29f8aa9bf9925893e905feb1aa42db2ce57d36f/arch/rv32i/src/pmp.rs#L26
or with full backtrace:
and more debug output on my build:
Travis also seems to agree that it will not compile: https://travis-ci.org/tock/tock/builds/602484885
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