ICE: translating unsupported cast: *const str (cast_other) -> *const u8 (cast_pointer)

[antekone]

The code is probably invalid, but still generates an ICE.

$ rustc src/ice.rs
src/ice.rs:3:9: 3:12 warning: unused variable: `ptr`, #[warn(unused_variables)] on by default
src/ice.rs:3     let ptr = string as *const _ as *const u8;
                     ^~~
error: internal compiler error: translating unsupported cast: *const str (cast_other) -> *const u8     (cast_pointer)
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
task 'rustc' panicked at 'Box<Any>', /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/libsyntax/diagnostic.rs:180

The code is very short:

fn main() {
    let string: &str = "test1";
    let ptr = string as *const _ as *const u8;
}

Backtrace:

$ gdb --args rustc src/ice.rs       
Reading symbols from rustc...(no debugging symbols found)...done.
(gdb) b rust_panic
Function "rust_panic" not defined.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (rust_panic) pending.
(gdb) r
src/ice.rs:3:9: 3:12 warning: unused variable: `ptr`, #[warn(unused_variables)] on by default
src/ice.rs:3     let ptr = string as *const _ as *const u8;
                 ^~~
error: internal compiler error: translating unsupported cast: *const str (cast_other) -> *const u8 (cast_pointer)

Breakpoint 1, 0x00007ffff7111440 in rust_panic () from /usr/local/lib/librustrt-4e7c5e5c.so
(gdb) bt
#0  0x00007ffff7111440 in rust_panic () from /usr/local/lib/librustrt-4e7c5e5c.so
#1  0x00007ffff7111b06 in unwind::begin_unwind_inner::hf044c6d185c5aca3tad () from /usr/local/lib/librustrt-4e7c5e5c.so
#2  0x00007ffff4e51529 in unwind::begin_unwind::h5761018185178914378 () from /usr/local/lib/libsyntax-4e7c5e5c.so
#3  0x00007ffff4e51c84 in diagnostic::Handler::bug::hfb9fa81ad3c3172cL3F () from /usr/local/lib/libsyntax-4e7c5e5c.so
#4  0x00007ffff5e5c935 in session::Session::bug::h176dff5b0ea34ba0Lt1 () from /usr/local/lib/librustc-4e7c5e5c.so
#5  0x00007ffff7932899 in trans::expr::trans_imm_cast::ha29135b513d0179aTLk () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#6  0x00007ffff7925c63 in trans::expr::trans_unadjusted::h4dd3a502f0c61d18iJi () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#7  0x00007ffff78e6287 in trans::expr::trans_into::h9ab7d00213095796hQh () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#8  0x00007ffff79de1bd in trans::_match::store_local::closure.49047 () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#9  0x00007ffff79dd5a4 in trans::_match::mk_binding_alloca::h3960520261142917360 () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#10 0x00007ffff7990094 in trans::_match::store_local::he5f9566f16d0e035w9x () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#11 0x00007ffff78e582e in trans::base::init_local::h305f837109a50408MIt () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#12 0x00007ffff78e4e42 in trans::controlflow::trans_stmt::h8e6bafcdf7128142cXd () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#13 0x00007ffff78e64f9 in trans::controlflow::trans_block::h7ed275868dcb5977k2d () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#14 0x00007ffff7998c40 in trans::base::trans_closure::h45d1af6bd984feb85Au () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#15 0x00007ffff78d9587 in trans::base::trans_fn::he30b79362e00aa4eVMu () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#16 0x00007ffff78d679e in trans::base::trans_item::hd3d39cc929783f51F8u () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#17 0x00007ffff79a21f8 in trans::base::trans_crate::h9cc619fc129272e2Z6v () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#18 0x00007ffff7a4cc45 in driver::driver::phase_4_translate_to_llvm::he2f0cbfd547d4bd4UtS () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#19 0x00007ffff7a3c4b5 in driver::driver::compile_input::h3764e7506ecf962760R () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#20 0x00007ffff7abfa87 in driver::run_compiler::hd5386abc6d794eaceZT () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#21 0x00007ffff7abe0ac in driver::run::closure.59712 () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#22 0x00007ffff78cbdfb in task::TaskBuilder::try_future::closure.38971 () from /usr/local/lib/librustc_trans-4e7c5e5c.so
#23 0x00007ffff743d43d in task::TaskBuilder::spawn_internal::closure.24316 () from /usr/local/lib/libstd-4e7c5e5c.so
#24 0x00007ffff710f4d2 in task::Task::spawn::closure.6079 () from /usr/local/lib/librustrt-4e7c5e5c.so
#25 0x00007ffff7169e3c in rust_try_inner () from /usr/local/lib/librustrt-4e7c5e5c.so
#26 0x00007ffff7169e26 in rust_try () from /usr/local/lib/librustrt-4e7c5e5c.so
#27 0x00007ffff710f583 in unwind::try::hc6a5679abcd17f59OYc () from /usr/local/lib/librustrt-4e7c5e5c.so
#28 0x00007ffff710f37c in task::Task::run::h56429f146a5c97ecX5b () from /usr/local/lib/librustrt-4e7c5e5c.so
#29 0x00007ffff710efc8 in task::Task::spawn::closure.6055 () from /usr/local/lib/librustrt-4e7c5e5c.so
#30 0x00007ffff7110d25 in thread::thread_start::hce41c81aad9e2f16Kpc () from /usr/local/lib/librustrt-4e7c5e5c.so
#31 0x00007ffff1c2c314 in start_thread () from /usr/lib/libpthread.so.0
#32 0x00007ffff6de63ed in clone () from /usr/lib/libc.so.6

Version info:

$ rustc --version=verbose
rustc 0.13.0-nightly (395901393 2014-11-24 00:46:30 +0000)
binary: rustc
commit-hash: 395901393c369c910a8ae36ace71402cb206d217
commit-date: 2014-11-24 00:46:30 +0000
host: x86_64-unknown-linux-gnu
release: 0.13.0-nightly

Happens also in:

$ rustc --version=verbose                                 
rustc 0.13.0-nightly (fac5a0767 2014-11-26 22:37:06 +0000)
binary: rustc
commit-hash: fac5a07679cac21a580badc84b755b8df0f975cf
commit-date: 2014-11-26 22:37:06 +0000
host: x86_64-unknown-linux-gnu
release: 0.13.0-nightly

[japaric]

Duplicate of #18396

[flaper87]

Another case was reported in #18396 which is basically the same example:

fn main() {
    let foo: &mut [u8] = &mut [1,2,3];
    foo as *mut [u8] as *mut u8;
}

error: internal compiler error: translating unsupported cast: *mut [u8] (cast_other) -> *mut u8 (cast_pointer)
note: the compiler hit an unexpected failure path. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with `RUST_BACKTRACE=1` for a backtrace
task 'rustc' failed at 'Box<Any>', /build/rust-git/src/rust/src/libsyntax/diagnostic.rs:175

[Blei]

Possible duplicate of #15355

[Hansyperman]

Another one, probably also invalid code. It rusn on a nightly of last week or so.

pub trait Trait{
fn something();
}

static mut staticvar:*mut u8=0 as *mut u8;

pub fn func(env:&mut Trait){
unsafe{
let env2:*mut Trait=env;
staticvar=env2 as *mut u8;

}

}

pub fn main(){}
/*
$ RUST_BACKTRACE=1 rustc src/testje.rs
error: internal compiler error: translating unsupported cast: *mut Trait + 'static (cast_other) -> *mut u8 (cast_pointer)
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: http://doc.rust-lang.org/complement-bugreport.html
note: run with RUST_BACKTRACE=1 for a backtrace
thread 'rustc' panicked at 'Box', /home/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/libsyntax/diagnostic.rs:189

stack backtrace:
1: 0x7f79b28d05b0 - sys::backtrace::write::h0cbfc88baae43aa021y
2: 0x7f79b28f49b0 - failure::on_fail::h0a7ead13585065c0rcH
3: 0x7f79b2852970 - rt::unwind::begin_unwind_inner::h5389a239af7b06eeMQG
4: 0x7f79afc28d80 - rt::unwind::begin_unwind::h6290790253480038265
5: 0x7f79afc29540 - diagnostic::Handler::bug::he11a02ced7d59aaaq9E
6: 0x7f79b091c550 - session::Session::bug::h882451eebbf062afXcr
7: 0x7f79b15edf40 - trans::expr::trans_imm_cast::h14ef54f0be458053Ljk
8: 0x7f79b15d4ee0 - trans::expr::trans_unadjusted::hf6315b53521e627beqi
9: 0x7f79b158dcb0 - trans::expr::trans::h4aa11cd527e88cd0dIh
10: 0x7f79b15d4ee0 - trans::expr::trans_unadjusted::hf6315b53521e627beqi
11: 0x7f79b158dcb0 - trans::expr::trans::h4aa11cd527e88cd0dIh
12: 0x7f79b15db050 - trans::expr::trans_rvalue_stmt_unadjusted::hdb847b98cb6a7ecaRSi
13: 0x7f79b158cb20 - trans::expr::trans_into::h792bd9b430d8f7dfJEh
14: 0x7f79b158bfc0 - trans::controlflow::trans_stmt_semi::hf566cf4106125cabKce
15: 0x7f79b158d130 - trans::controlflow::trans_block::hd445a33426df7637Bde
16: 0x7f79b15d5ac0 - trans::expr::trans_rvalue_dps_unadjusted::he15e3ebaa41399dfJYi
17: 0x7f79b158cb20 - trans::expr::trans_into::h792bd9b430d8f7dfJEh
18: 0x7f79b158d130 - trans::controlflow::trans_block::hd445a33426df7637Bde
19: 0x7f79b1658530 - trans::base::trans_closure::h899ff1df83d7583b9du
20: 0x7f79b15795e0 - trans::base::trans_fn::hc2298bc13eeb8cfappu
21: 0x7f79b1574570 - trans::base::trans_item::h03200b520668f12feOu
22: 0x7f79b165f990 - trans::base::trans_crate::ha94cd7a9cd13cad4yLv
23: 0x7f79b2ee6210 - driver::phase_4_translate_to_llvm::he09ab588c39cf70ewPa
24: 0x7f79b2ebf200 - driver::compile_input::h0eb7a1103ff8aba2Eba
25: 0x7f79b2f906e0 - run_compiler::ha9d14025fcb8e9fc5bc
26: 0x7f79b2f8ed40 - thunk::F.Invoke<A, R>::invoke::h5646167225587318028
27: 0x7f79b2f8dc30 - rt::unwind::try::try_fn::h4383208440922308355
28: 0x7f79b2960d40 - rust_try_inner
29: 0x7f79b2960d30 - rust_try
30: 0x7f79b2f8dee0 - thunk::F.Invoke<A, R>::invoke::h10387639015308431532
31: 0x7f79b28e0ea0 - sys::thread::thread_start::h5a97a888379df6e9FQC
32: 0x7f79ac906a80 - start_thread
33: 0x0 -

*/

$ rustc --version
rustc 1.0.0-nightly (a954663 2015-02-10 22:08:30 +0000)

[tamird]

No longer ICEs.

$ rustc main.rs
main.rs:3:15: 3:46 error: illegal cast; cast from fat pointer: `*const str` as `*const u8`
main.rs:3     let ptr = string as *const _ as *const u8;
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
error: aborting due to previous error