LLVM assertion error for #[deriving(PartialEq)] on an unsized type

[SimonSapin]

Test case:

#[deriving(PartialEq)]
pub struct Wtf8Slice {
    bytes: [u8]
}

Output of rustc nigthly 45cbdec 2014-11-07:

rustc: /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/llvm/lib/IR/Instructions.cpp:1086: void llvm::StoreInst::AssertOK(): Assertion `getOperand(0)->getType() == cast<PointerType>(getOperand(1)->getType())->getElementType() && "Ptr must be a pointer to Val type!"' failed.

[SimonSapin]

Output of rustc --pretty expanded:

#![feature(phase)]
#![no_std]
#![feature(globs)]
#[phase(plugin, link)]
extern crate "std" as std;
extern crate "native" as rt;
#[prelude_import]
use std::prelude::*;
pub struct Wtf8Slice {
    bytes: [u8],
}
#[automatically_derived]
impl ::std::cmp::PartialEq for Wtf8Slice {
    #[inline]
    fn eq(&self, __arg_0: &Wtf8Slice) -> ::bool {
        match *__arg_0 {
            Wtf8Slice { bytes: ref __self_1_0 } =>
            match *self {
                Wtf8Slice { bytes: ref __self_0_0 } =>
                true && (*__self_0_0) == (*__self_1_0),
            },
        }
    }
    #[inline]
    fn ne(&self, __arg_0: &Wtf8Slice) -> ::bool {
        match *__arg_0 {
            Wtf8Slice { bytes: ref __self_1_0 } =>
            match *self {
                Wtf8Slice { bytes: ref __self_0_0 } =>
                false || (*__self_0_0) != (*__self_1_0),
            },
        }
    }
}

[apasel422]

A similar problem, with a different error:

struct Foo {
    bytes: [u8],
}

fn bar(&Foo { ref bytes }: &Foo) {}

Output of rustc 0.13.0-nightly (770378a31 2014-11-20 23:02:01 +0000):

rustc: /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/llvm/include/llvm/Support/Casting.h:237: typename llvm::cast_retty<X, Y*>::ret_type llvm::cast(Y*) [with X = llvm::PointerType; Y = const llvm::Type; typename llvm::cast_retty<X, Y*>::ret_type = const llvm::PointerType*]: Assertion `isa<X>(Val) && "cast<Ty>() argument of incompatible type!"' failed.

This also applies to tuple structs with an unsized field.

[japaric]

@apasel422 That looks like #19064

[steveklabnik]

This still ICEs for me.

[XMPPwocky]

It still ICEs. Looks like the core issue is trying to store a %struct.Wtf8Slice** in an alloca for {i8*, i64} .

[tamird]

This is now a segfault:

#![crate_type="lib"]

#[derive(PartialEq)]
pub struct Wtf8Slice {
    bytes: [u8]
}

$ rustc main.rs
Segmentation fault: 11

[arielb1]

Does not seem to be an issue on 1.2+

[SimonSapin]

Indeed, I can’t reproduce this anymore.