LLVM assert failure with struct pointers and foreign functions

[brandonson]

Say we have a crate file A.rc which includes mod A and mod B, file B is a module that defines an extern function that takes a pointer to a struct, and file C is a module that uses file B using mod B.

I get the following error:

rust/src/llvm/include/llvm/Support/Casting.h:231: typename llvm::enable_if<llvm::is_same<Y, typename llvm::simplify_type<From>::SimpleType>, typename llvm::cast_retty<X, Y*>::ret_type>::type llvm::cast(Y*) [with X = llvm::Function; Y = llvm::Value; typename llvm::enable_if<llvm::is_same<Y, typename llvm::simplify_type<From>::SimpleType>, typename llvm::cast_retty<X, Y*>::ret_type>::type = llvm::Function*]: Assertion `isa<X>(Val) && "cast<Ty>() argument of incompatible type!"' failed.

I managed to bring it down to a simple example that reproduces the problem:

crate.rc

#[crate_type = "lib"];
mod other;
mod other2;

other.rs

struct Foo{
  bar: libc::c_int
}

#[link_args = "-lSDL2"]
extern{
  fn externFunc(param:&Foo) -> libc::c_int;
}

other2.rs

mod other;

Note that this does not happen when the parameters to the extern fn are not pointers to a struct. It also does not happen when compiling just other.rs, or without crate.rc depending on other2.rs.

I'm running ubuntu 13.04 with gcc 4.7.3, and I've had this occur with rust builds from both the master and auto branches, and also with rust 0.6.

[bblum]

Thanks for reporting this. I confirm that it crashes, and that it can't be minimized smaller than 3 files.

Here's a slightly more minimal version of other.rs that reproduces:

struct Foo;

extern{
      fn externFunc(param:&Foo);
}

Nominating well-covered milestone.

[catamorphism]

Accepted for production-ready

[luqmana]

I can't seem to reproduce this. @singingboyo, @bblum is this still an issue?

[thestinger]

I might have fixed this with f504461.

[luqmana]

In that case, I'll close this now but feel free to reopen if this is still an issue.