error: internal compiler error: compiler\rustc_lint\src\types.rs:859:17: malformed transparent type

[SStarosielec]

// minimal example: each line and derive seems important.

extern "C" {
    pub fn Fg_Init() -> *mut Fg_Struct;
}

#[derive(Debug, Copy, Clone)]
pub struct Fg_Struct_s {
    _unused: [u8; 0],
}

#[repr(transparent)]
pub struct Fg_Struct(pub Fg_Struct_s);

fn main() {
    println!("Hello, world!");
}

Meta

rustc --version --verbose:

rustc 1.56.1 (59eed8a2a 2021-11-01)
binary: rustc
commit-hash: 59eed8a2aac0230a8b53e89d4e99d55912ba6b35
commit-date: 2021-11-01
host: x86_64-pc-windows-msvc
release: 1.56.1
LLVM version: 13.0.0

Error output

error: internal compiler error: compiler\rustc_lint\src\types.rs:859:17: malformed transparent type
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
note: the compiler unexpectedly panicked. this is a bug.

Backtrace

query stack during panic:
#0 [lint_mod] linting top-level module
#1 [analysis] running analysis passes on this crate
end of query stack

[ChrisDenton]

Seems to have been fixed in 1.57.0? Edit: see #87529.

[matthiaskrgr]

Yeah, it seems compile fine on lastest nightly:

warning: type `Fg_Struct_s` should have an upper camel case name
 --> c.rs:8:12
  |
8 | pub struct Fg_Struct_s {
  |            ^^^^^^^^^^^ help: convert the identifier to upper camel case: `FgStructS`
  |
  = note: `#[warn(non_camel_case_types)]` on by default

warning: type `Fg_Struct` should have an upper camel case name
  --> c.rs:13:12
   |
13 | pub struct Fg_Struct(pub Fg_Struct_s);
   |            ^^^^^^^^^ help: convert the identifier to upper camel case: `FgStruct`

warning: `extern` block uses type `Fg_Struct`, which is not FFI-safe
  --> c.rs:4:25
   |
4  |     pub fn Fg_Init() -> *mut Fg_Struct;
   |                         ^^^^^^^^^^^^^^ not FFI-safe
   |
   = note: `#[warn(improper_ctypes)]` on by default
   = note: this struct contains only zero-sized fields
note: the type is defined here
  --> c.rs:13:1
   |
13 | pub struct Fg_Struct(pub Fg_Struct_s);
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: 3 warnings emitted

@SStarosielec please update your rust toolchain if you can 🙂

Closing as fixed.

[SStarosielec]

Thx yes, an update didn't crash rustc anymore.