ICE: translating unsupported cast

[swizard0]

Example code:

let mem: &[u8] = &[48, 49];
let ptr = mem.as_ptr() as *const str;
let s = unsafe { &*ptr };

Error message:

error: internal compiler error: translating unsupported cast: *const u8 (cast_pointer) -> *const str (cast_other)
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'Box<Any>', /Users/swizard/distr/rust/src/libsyntax/diagnostic.rs:190
stack backtrace:
   1:        0x105f01957 - sys::backtrace::write::h49bc1af3bff4a6e3DJC
   2:        0x105f2f873 - panicking::on_panic::h22918d2e20ddf008PxI
   3:        0x105e53cbe - rt::unwind::begin_unwind_inner::hb0f5c720a6629d10qfI
   4:        0x10563b19e - rt::unwind::begin_unwind::h13792904101880946349
   5:        0x10563b9e9 - diagnostic::Handler::bug::h8d018cb8efa3e647EsB
   6:        0x102f32627 - session::Session::bug::he24b74119a1174bbFPq
   7:        0x1029c1358 - trans::expr::trans_imm_cast::h0dc669e5f6c002d8nKj
   8:        0x1029a82e6 - trans::expr::trans_unadjusted::h86976c6745580e14TXh
   9:        0x10295a53c - trans::expr::trans_into::hefe6c24c6801eb34gfh
  10:        0x102a7ad1a - trans::_match::mk_binding_alloca::h16979327121447448331
  11:        0x10295977f - trans::base::init_local::h45ac8135c05a5146NMs
  12:        0x10295b342 - trans::controlflow::trans_block::h8c650fbe27085d2cH6d
  13:        0x102a3b4f5 - trans::base::trans_closure::h46864fd94aa01bc0Qtt
  14:        0x102942c83 - trans::base::trans_fn::h2ca708b7c163d918zEt
  15:        0x10294463e - trans::monomorphize::monomorphic_fn::h95fbd095b702f0baYtd
  16:        0x102989b81 - trans::callee::trans_fn_ref_with_substs::h1994bdb61afbe636Zbg
  17:        0x102988a2e - trans::meth::trans_static_method_callee::hf8b89488d2117b8dNAy
  18:        0x1029859ca - trans::callee::trans::hbb34a5eec289d1c9jPf
  19:        0x10299c33b - trans::callee::trans_call_inner::h8192340426532286712
  20:        0x1029aa770 - trans::expr::trans_rvalue_dps_unadjusted::h27b9d0cd52a394f1mti
  21:        0x10295a51c - trans::expr::trans_into::hefe6c24c6801eb34gfh
  22:        0x102a7ad1a - trans::_match::mk_binding_alloca::h16979327121447448331
  23:        0x10295977f - trans::base::init_local::h45ac8135c05a5146NMs
  24:        0x10295b342 - trans::controlflow::trans_block::h8c650fbe27085d2cH6d
  25:        0x102a3b4f5 - trans::base::trans_closure::h46864fd94aa01bc0Qtt
  26:        0x102942c83 - trans::base::trans_fn::h2ca708b7c163d918zEt
  27:        0x102944592 - trans::monomorphize::monomorphic_fn::h95fbd095b702f0baYtd
  28:        0x102989b81 - trans::callee::trans_fn_ref_with_substs::h1994bdb61afbe636Zbg
  29:        0x102987f57 - trans::callee::trans_fn_ref::h63f04e40db0908572Zf
  30:        0x102985bd0 - trans::callee::trans::hbb34a5eec289d1c9jPf
  31:        0x10299c33b - trans::callee::trans_call_inner::h8192340426532286712
  32:        0x1029aa770 - trans::expr::trans_rvalue_dps_unadjusted::h27b9d0cd52a394f1mti
  33:        0x10295a51c - trans::expr::trans_into::hefe6c24c6801eb34gfh
  34:        0x102959492 - trans::controlflow::trans_stmt_semi::he0a71a03e8e22f97L5d
  35:        0x10295b317 - trans::controlflow::trans_block::h8c650fbe27085d2cH6d
  36:        0x1029a9bad - trans::expr::trans_rvalue_dps_unadjusted::h27b9d0cd52a394f1mti
  37:        0x10295a51c - trans::expr::trans_into::hefe6c24c6801eb34gfh
  38:        0x10295b6a0 - trans::controlflow::trans_block::h8c650fbe27085d2cH6d
  39:        0x102a3b4f5 - trans::base::trans_closure::h46864fd94aa01bc0Qtt
  40:        0x102942c83 - trans::base::trans_fn::h2ca708b7c163d918zEt
  41:        0x10293d4bd - trans::base::trans_item::h46b9d96ec061ef10P2t
  42:        0x102a43fc7 - trans::base::trans_crate::h2a7f765e28da6987lZu
  43:        0x10236a82c - driver::phase_4_translate_to_llvm::hb12845c52d9d2a39aOa
  44:        0x10234217e - driver::compile_input::hf700a572a1239378Qba
  45:        0x1023ffd35 - run_compiler::h2254195776d5d4d5S4b
  46:        0x1023fd502 - boxed::F.FnBox<A>::call_box::h6405845031818806926
  47:        0x1023fc9f7 - rt::unwind::try::try_fn::h692286709647191617
  48:        0x105fbc4b8 - rust_try_inner
  49:        0x105fbc4a5 - rust_try
  50:        0x1023fccea - boxed::F.FnBox<A>::call_box::h15513867904557068020
  51:        0x105f18d5d - sys::thread::create::thread_start::h320d70da47133ff2weH
  52:     0x7fff8f86f267 - _pthread_body
  53:     0x7fff8f86f1e4 - _pthread_start

Rust:

rustc 1.0.0-dev (b3c5507f3 2015-04-05) (built 2015-04-05)

OS:

Darwin pair 14.1.0 Darwin Kernel Version 14.1.0: Thu Feb 26 19:26:47 PST 2015; root:xnu-2782.10.73~1/RELEASE_X86_64 x86_64

[goertzenator]

Me too:

Crate: https://github.com/goertzenator/liblrust

Output: https://gist.github.com/goertzenator/912f010da6f2ae243336

Rust:

rustc 1.0.0-beta (9854143cb 2015-04-02) (built 2015-04-02)

OS:

Linux goertzen-G550JK 3.16.0-33-generic #44-Ubuntu SMP Thu Mar 12 12:19:35 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

[robn]

Me three, with this trivial program:

#[derive(Debug)]
struct S {
    v: String,
}

fn main() {
    let x = S { v: "hello".to_string() };
    println!("{:?}", x as S);
}

$ RUST_BACKTRACE=1 rustc test.rs 
error: internal compiler error: translating unsupported cast: S (cast_other) -> S (cast_other)
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'Box<Any>', /home/robn/code/rust/rust/src/libsyntax/diagnostic.rs:190

stack backtrace:
   1:     0x7f9ef6fdb0b8 - sys::backtrace::write::hc7bf68ee23aa2a47IJC
   2:     0x7f9ef7006460 - panicking::on_panic::hae54fd167ccd0c87sXI
   3:     0x7f9ef6f3e193 - rt::unwind::begin_unwind_inner::h04b19af4046d9402ACI
   4:     0x7f9ef430657d - rt::unwind::begin_unwind::h14358179414781977900
   5:     0x7f9ef4306cd2 - diagnostic::Handler::bug::h6b05bef8ecda0ec4ZsB
   6:     0x7f9ef4d1980b - session::Session::bug::h7677b9d1b16c63a2oYq
   7:     0x7f9ef668358a - trans::expr::trans_imm_cast::h3c51f5e7bab523a6nKj
   8:     0x7f9ef666b3b9 - trans::expr::trans_unadjusted::h50be0c1e615b9b53TXh
   9:     0x7f9ef6622944 - trans::expr::trans::h5fac271f51fcff39Blh
  10:     0x7f9ef6682347 - trans::expr::trans_addr_of::h6ef6c8160ed58d06fij
  11:     0x7f9ef666b67f - trans::expr::trans_unadjusted::h50be0c1e615b9b53TXh
  12:     0x7f9ef6620ff9 - trans::expr::trans_into::h03dc3dcf7bddc72dgfh
  13:     0x7f9ef669e4bd - trans::expr::trans_adt::h390328ce7ac619d86Yi
  14:     0x7f9ef666ee4e - trans::expr::trans_rvalue_dps_unadjusted::ha57d2ad1e4a3199amti
  15:     0x7f9ef666b1e0 - trans::expr::trans_unadjusted::h50be0c1e615b9b53TXh
  16:     0x7f9ef6622944 - trans::expr::trans::h5fac271f51fcff39Blh
  17:     0x7f9ef6719a60 - trans::_match::trans_match_inner::hc4bc6db15d8e6ce3gUw
  18:     0x7f9ef666ca8c - trans::expr::trans_rvalue_dps_unadjusted::ha57d2ad1e4a3199amti
  19:     0x7f9ef666b1e0 - trans::expr::trans_unadjusted::h50be0c1e615b9b53TXh
  20:     0x7f9ef6622944 - trans::expr::trans::h5fac271f51fcff39Blh
  21:     0x7f9ef6682347 - trans::expr::trans_addr_of::h6ef6c8160ed58d06fij
  22:     0x7f9ef666b67f - trans::expr::trans_unadjusted::h50be0c1e615b9b53TXh
  23:     0x7f9ef6622944 - trans::expr::trans::h5fac271f51fcff39Blh
  24:     0x7f9ef665a28f - trans::callee::trans_args::hea46cd98019ae23d9Rg
  25:     0x7f9ef6660d24 - trans::callee::trans_call_inner::h8036123679852670048
  26:     0x7f9ef666d583 - trans::expr::trans_rvalue_dps_unadjusted::ha57d2ad1e4a3199amti
  27:     0x7f9ef666b1e0 - trans::expr::trans_unadjusted::h50be0c1e615b9b53TXh
  28:     0x7f9ef6622944 - trans::expr::trans::h5fac271f51fcff39Blh
  29:     0x7f9ef665a28f - trans::callee::trans_args::hea46cd98019ae23d9Rg
  30:     0x7f9ef6660d24 - trans::callee::trans_call_inner::h8036123679852670048
  31:     0x7f9ef666d583 - trans::expr::trans_rvalue_dps_unadjusted::ha57d2ad1e4a3199amti
  32:     0x7f9ef6620fd8 - trans::expr::trans_into::h03dc3dcf7bddc72dgfh
  33:     0x7f9ef6620056 - trans::controlflow::trans_stmt_semi::hd76f97e4ff316b93L5d
  34:     0x7f9ef6621ca5 - trans::controlflow::trans_block::h2574d0aaf248b2a2H6d
  35:     0x7f9ef66f8d2f - trans::base::trans_closure::h4bbbebda4a6a2eaeQtt
  36:     0x7f9ef660ac76 - trans::base::trans_fn::hc59e1e3af67fd20dzEt
  37:     0x7f9ef660590f - trans::base::trans_item::h0c811983fce37f04P2t
  38:     0x7f9ef670126c - trans::base::trans_crate::h84a63b946dfd0dd2lZu
  39:     0x7f9ef766e84f - driver::phase_4_translate_to_llvm::h0f768fc8e75d0e95aOa
  40:     0x7f9ef764629b - driver::compile_input::h154756c108de519fQba
  41:     0x7f9ef76fd675 - run_compiler::hd45ff49ff4db7f9fV4b
  42:     0x7f9ef76faf8d - boxed::F.FnBox<A>::call_box::h998211653744645471
  43:     0x7f9ef76fa4c9 - rt::unwind::try::try_fn::h5486996895865591730
  44:     0x7f9ef708b748 - rust_try_inner
  45:     0x7f9ef708b735 - rust_try
  46:     0x7f9ef76fa79b - boxed::F.FnBox<A>::call_box::h4941640570998788665
  47:     0x7f9ef6ff1471 - sys::thread::create::thread_start::haf7c3f703308e235ExH
  48:     0x7f9ef0f480a3 - start_thread
  49:     0x7f9ef6ba804c - __clone
  50:                0x0 - <unknown>

Self-built rustc from the 1.0.0-beta commit:

$ rustc --version --verbose
rustc 1.0.0-dev (9854143cb 2015-04-02) (built 2015-04-07)
binary: rustc
commit-hash: 9854143cba679834bc4ef932858cd5303f015a0e
commit-date: 2015-04-02
build-date: 2015-04-07
host: x86_64-unknown-linux-gnu
release: 1.0.0-dev

[polyfractal]

Adding another report, with a similar setup. Encountered this in my code, boiled it down to this test...looks very similar to @robn's ICE, since it is trying to cast "same" -> "same".

Seems to only happen when trying to cast a struct to itself with as. If you use primitive types, there is no ICE. I tried deriving Copy/Clone to see if that was the problem, but it still threw an ICE.

error: internal compiler error: translating unsupported cast: TestStruct (cast_other) -> TestStruct (cast_other)
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'Box<Any>', /Users/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-mac/build/src/libsyntax/diagnostic.rs:230

stack backtrace:
   1:        0x10dd99b3f - sys::backtrace::write::h7c4b7b31b5a98994KVr
   2:        0x10dda2242 - panicking::on_panic::h130becb52f065864NVv
   3:        0x10dd5e985 - rt::unwind::begin_unwind_inner::hf2ec506d50a3ea22wDv
   4:        0x10d5692de - rt::unwind::begin_unwind::h10963008848674724601
   5:        0x10d569a82 - diagnostic::Handler::bug::h7f6411f5b5710a68VxB
   6:        0x10af2d887 - session::Session::bug::h67c3e63982ede886xWp
   7:        0x10a767a0c - trans::expr::trans_imm_cast::h56c659d7a3aa3946OkC
   8:        0x10a75bbde - trans::expr::trans_unadjusted::h16ccd3176676f118vxA
   9:        0x10a72fdf7 - trans::expr::trans_into::hb0f7fdd5a2a9abdbj4z
  10:        0x10a6b1109 - trans::controlflow::trans_block::h12567c1fc6ee8337H1u
  11:        0x10a6afa06 - trans::base::trans_closure::ha53aa9eb2a9bf670gEh
  12:        0x10a6b173e - trans::base::trans_fn::h8f58e16c0621df33YOh
  13:        0x10a6f2f25 - trans::monomorphize::monomorphic_fn::h9b2fe76155400f16iAJ
  14:        0x10a6e33b7 - trans::callee::trans_fn_ref_with_substs::ha369033cd198b04eBGn
  15:        0x10a6e1e52 - trans::callee::trans_fn_ref::h20eb8b04123e4545Gun
  16:        0x10a6f6feb - trans::meth::trans_method_callee::h0e2799d89ca0fda9jxI
  17:        0x10a6f5533 - trans::callee::trans_call_inner::h2848324853079840396
  18:        0x10a75c79b - trans::expr::trans_rvalue_dps_unadjusted::hadab5746c39f5e9fY2A
  19:        0x10a72fdd7 - trans::expr::trans_into::hb0f7fdd5a2a9abdbj4z
  20:        0x10a7b0c61 - trans::_match::mk_binding_alloca::h3749212929604063812
  21:        0x10a6a0b39 - trans::base::init_local::hcee21b7a4917a72djXg
  22:        0x10a6b0df3 - trans::controlflow::trans_block::h12567c1fc6ee8337H1u
  23:        0x10a6afa06 - trans::base::trans_closure::ha53aa9eb2a9bf670gEh
  24:        0x10a6b173e - trans::base::trans_fn::h8f58e16c0621df33YOh
  25:        0x10a6b4d38 - trans::base::trans_item::he86179308be326c4adi
  26:        0x10a6c3b80 - trans::base::trans_crate::h350105e1ee0f6a06a2i
  27:        0x10a531c2e - driver::phase_4_translate_to_llvm::h7039638042d67b1enOa
  28:        0x10a50a7a9 - driver::compile_input::h65cad254ac62afa6Qba
  29:        0x10a5c9613 - run_compiler::hbd6a992aacaf1248F4b
  30:        0x10a5c6d7a - boxed::F.FnBox<A>::call_box::h9480122591250505076
  31:        0x10a5c62c7 - rt::unwind::try::try_fn::h5956310425634165804
  32:        0x10de24618 - rust_try_inner
  33:        0x10de24605 - rust_try
  34:        0x10a5c659e - boxed::F.FnBox<A>::call_box::h8195565033996650298
  35:        0x10dda0c3d - sys::thread::Thread::new::thread_start::h8efe8b1c3780385fvYu
  36:     0x7fff92e872fb - _pthread_body
  37:     0x7fff92e87278 - _pthread_start

rustc 1.1.0-nightly (5fb0259ed 2015-04-26) (built 2015-04-26)
binary: rustc
commit-hash: 5fb0259edfbc4034cfbcf827ab91d6118b7ae848
commit-date: 2015-04-26
build-date: 2015-04-26
host: x86_64-apple-darwin
release: 1.1.0-nightly

pub struct Consumer<T> {
    vec: Vec<T>
}

impl<T> Consumer<T> {
    pub fn pop(&mut self) -> T {
        self.vec.pop().unwrap() as T // <--- Removing "as T" fixes the ICE
    }
}

// #[derive(Copy, Clone)]  // <-- tried to add Copy/Clone, does not fix ICE
struct TestStruct {
    a: u32
}

impl TestStruct {
    pub fn new() -> TestStruct {
        TestStruct { a: 19 }
    }
}


#[test]
fn test_struct() {
    let mut c = Consumer {
        vec: vec![TestStruct::new(), TestStruct::new()]
        //vec: vec![0,1,2,3]        // <-- works fine
    };

    let t: TestStruct = c.pop();
}