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Broken LLVM function when pushing dyn* item to Vec. #102141

Closed
Tracked by #102425
mejrs opened this issue Sep 22, 2022 · 2 comments · Fixed by #104338
Closed
Tracked by #102425

Broken LLVM function when pushing dyn* item to Vec. #102141

mejrs opened this issue Sep 22, 2022 · 2 comments · Fixed by #104338
Labels
A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. C-bug Category: This is a bug. F-dyn_star `#![feature(dyn_star)]` requires-nightly This issue requires a nightly compiler in some way.

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@mejrs
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mejrs commented Sep 22, 2022

Playground

Code

#![feature(dyn_star)]
#![allow(incomplete_features)]

use core::fmt::Debug;

fn main() {
    let mut v = vec![];
    let i = 42_u8 as dyn* Debug;
    v.push(i);
}

Result:

Call parameter type does not match function signature!
i8 42
 i64  invoke void @"_ZN5alloc3vec16Vec$LT$T$C$A$GT$4push17h57979dab0e1643c2E"(ptr align 8 %3, i8 42, ptr align 8 @6)
          to label  unwind label %8, !dbg !2675
in function _ZN10playground4main17h68903ee09fbec9bcE
LLVM ERROR: Broken function found, compilation aborted!

Meta

1.66.0-nightly (2022-09-21 9062b780b32d2eab060b)

@rustbot label: F-dyn_star requires-nightly A-LLVM
@mejrs mejrs added the C-bug Category: This is a bug. label Sep 22, 2022
@rustbot rustbot added A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. F-dyn_star `#![feature(dyn_star)]` requires-nightly This issue requires a nightly compiler in some way. labels Sep 22, 2022
@matthiaskrgr
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Miri actually reports this as a bug :)

error: Undefined Behavior: scalar size mismatch: expected 8 bytes but got 1 bytes instead
 --> src/main.rs:8:13
  |
8 |     let i = 42_u8 as dyn* Debug;
  |             ^^^^^^^^^^^^^^^^^^^ scalar size mismatch: expected 8 bytes but got 1 bytes instead
  |
  = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
  = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
  = note: BACKTRACE:
  = note: inside `main` at src/main.rs:8:13

@compiler-errors
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FYI: We currently have 0 checks that dyn* actually fit their size requirement currently.

@eholk eholk mentioned this issue Sep 28, 2022
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@compiler-errors compiler-errors mentioned this issue Nov 12, 2022
Merged
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Nov 16, 2022
@matthiaskrgr
Rollup merge of rust-lang#104338 - compiler-errors:pointer-sized, r=e…
9cd06e6 
…holk

Enforce that `dyn*` coercions are actually pointer-sized

Implement a perma-unstable, rudimentary `PointerSized` trait to enforce `dyn*` casts are `usize`-sized for now, at least to prevent ICEs and weird codegen issues from cropping up after monomorphization since currently we enforce *nothing*.

This probably can/should be removed in favor of a more sophisticated trait for handling `dyn*` conversions when we decide on one, but I just want to get something up for discussion and experimentation for now.

r? `@eholk` cc `@tmandry` (though feel free to claim/reassign)

Fixes rust-lang#102141
Fixes rust-lang#102173
Manishearth added a commit to Manishearth/rust that referenced this issue Nov 18, 2022
@Manishearth
Rollup merge of rust-lang#104338 - compiler-errors:pointer-sized, r=e…
6520fdc 
…holk

Enforce that `dyn*` coercions are actually pointer-sized

Implement a perma-unstable, rudimentary `PointerSized` trait to enforce `dyn*` casts are `usize`-sized for now, at least to prevent ICEs and weird codegen issues from cropping up after monomorphization since currently we enforce *nothing*.

This probably can/should be removed in favor of a more sophisticated trait for handling `dyn*` conversions when we decide on one, but I just want to get something up for discussion and experimentation for now.

r? `@eholk` cc `@tmandry` (though feel free to claim/reassign)

Fixes rust-lang#102141
Fixes rust-lang#102173
Manishearth added a commit to Manishearth/rust that referenced this issue Nov 18, 2022
@Manishearth
Rollup merge of rust-lang#104338 - compiler-errors:pointer-sized, r=e…
171b519 
…holk

Enforce that `dyn*` coercions are actually pointer-sized

Implement a perma-unstable, rudimentary `PointerSized` trait to enforce `dyn*` casts are `usize`-sized for now, at least to prevent ICEs and weird codegen issues from cropping up after monomorphization since currently we enforce *nothing*.

This probably can/should be removed in favor of a more sophisticated trait for handling `dyn*` conversions when we decide on one, but I just want to get something up for discussion and experimentation for now.

r? ``@eholk`` cc ``@tmandry`` (though feel free to claim/reassign)

Fixes rust-lang#102141
Fixes rust-lang#102173
@bors bors closed this as completed in 24ee599 Nov 19, 2022
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A-LLVM Area: Code generation parts specific to LLVM. Both correctness bugs and optimization-related issues. C-bug Category: This is a bug. F-dyn_star `#![feature(dyn_star)]` requires-nightly This issue requires a nightly compiler in some way.
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Enforce that dyn* coercions are actually pointer-sized compiler-errors/rust
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@matthiaskrgr @compiler-errors @rustbot @mejrs