ICE - trying to take the sizing type of <core::iter::Iterator + 'static as core::iter::Iterator>::Item, an unsized type

[shepmaster]

Code

fn changer<'a>(mut things: Box<Iterator<Item=&'a mut u8>>) {
    for item in *things { *item = 0 }
}

fn main() {
}

Error

error: internal compiler error: trying to take the sizing type of <core::iter::Iterator + 'static as core::iter::Iterator>::Item, an unsized type
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<Any>', /Users/shep/Projects/rust/src/libsyntax/diagnostic.rs:182

stack backtrace:
   1:        0x110a80d05 - sys::backtrace::write::h57cb71e45a6ad05bARs
   2:        0x110aa667f - failure::on_fail::h1e60313e5a552ea32Ty
   3:        0x110a0bb6a - rt::unwind::begin_unwind_inner::h591d6980cb1eb9bb2By
   4:        0x10e753937 - rt::unwind::begin_unwind::h15926596774839260564
   5:        0x10e7542a8 - diagnostic::Handler::bug::h4055c4ca2e17f0c6DLF
   6:        0x10dd63cb8 - session::Session::bug::h5d1941c792f1e4caroq
   7:        0x10d326a23 - trans::type_of::sizing_type_of::hded88082b54ddc4bgSo
   8:        0x10d4422eb - trans::adt::represent_type_uncached::h5d90b81a92acc1b47xH
   9:        0x10d320cd3 - trans::adt::represent_type::hdeb853742a302b7fHuH
  10:        0x10d30c662 - trans::type_of::type_of::h0a1f71fc9850898aYYo
  11:        0x10d30c34c - trans::type_of::type_of::h0a1f71fc9850898aYYo
  12:        0x10d3b803f - trans::type_of::type_of_rust_fn::hf6b24d412c4c9582xOo
  13:        0x10d41665c - trans::meth::trans_trait_callee_from_llval::h2aa4e324f7a786d6kwz
  14:        0x10d413a56 - trans::meth::trans_object_shim::hfa24eaa4bec56008jBz
  15:        0x10d31eb5f - trans::meth::trans_method_callee::hce96e8ac9be0c90eq6y
  16:        0x10d385573 - trans::callee::trans_call_inner::h12246188759747685167
  17:        0x10d354691 - trans::expr::trans_rvalue_stmt_unadjusted::hd58bf8791601bef4kQi
  18:        0x10d306c8d - trans::expr::trans_into::h8bab20af1840b0a57xh
  19:        0x10d307605 - trans::controlflow::trans_block::h051994b75eb2405cS1d
  20:        0x10d3d0f44 - trans::base::trans_closure::hb694bfd51133ec9fMSt
  21:        0x10d2f2a2b - trans::base::trans_fn::h816a9b6a32db67faj3t
  22:        0x10d2ee086 - trans::base::trans_item::h223cbaffa1a561c6aqu
  23:        0x10d3d8718 - trans::base::trans_crate::h7f75c26047f82847vlv
  24:        0x10d19064e - driver::phase_4_translate_to_llvm::h17f0f28873e0c2d6uFa
  25:        0x10d172501 - driver::compile_input::h059943f6c48c38c7vba
  26:        0x10d239173 - thunk::F.Invoke<A, R>::invoke::h17305763774885229909
  27:        0x10d2362d0 - rt::unwind::try::try_fn::h8419390306595151514
  28:        0x110b0dba9 - rust_try_inner
  29:        0x110b0db96 - rust_try
  30:        0x10d236a16 - thunk::F.Invoke<A, R>::invoke::h8115208835806211442
  31:        0x110a92154 - sys::thread::thread_start::hf32c2ee467ccc238CEv
  32:     0x7fff9663c2fc - _pthread_body
  33:     0x7fff9663c279 - _pthread_body

Version

rustc 0.13.0-dev (5773bdeff 2015-01-04 21:36:41 +0000)
binary: rustc
commit-hash: 5773bdefff2e47cc007f5cc2af3f80b30303d45a
commit-date: 2015-01-04 21:36:41 +0000
host: x86_64-apple-darwin
release: 0.13.0-dev

[Sgeo]

The following also ICEs on Rust playpen:

fn changer<'a>(things: &mut Iterator) {
    for item in *things {  }
}

fn main() {
}

[skurmedel]

I am getting this as well for a function:

fn write_ppm16(
    out: &mut Writer, 
    dims: (u16, u16), 
    pixels: &mut iter::Iterator<Item = RGB16>,
    opt_conf: Option<PPMConfig>) -> IoResult<u32> {
// ...
for p in *pixels {
        try!(out.write_be_u16(p.r));
        try!(out.write_be_u16(p.g));
        try!(out.write_be_u16(p.b));

        bytes_written += 6;
    }
// ...
}

Is there a work-around?

Error

error: internal compiler error: trying to take the sizing type of <core::iter::Iterator + 'static as core::iter::Iterator>::Item, an unsized type
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', C:\bot\slave\nightly-dist-rustc-win-64\build\src\libsyntax\diagnostic.rs:182

stack backtrace:
1: 0x69bee9cd - sys::backtrace::write::hd40c6de25ef01e0bfjt
2: 0x69c01a32 - rt::unwind::register::hcb202fda23aef97aw7y
3: 0x69b834a7 - rt::unwind::begin_unwind_inner::h43ca250f1ae88b3e64y
4: 0x6f89cbf6 - diagnostic::SpanHandler::span_bug::hb66e4bdba79bcb62uGF
5: 0x6f89d4a5 - diagnostic::Handler::bug::h85a78a072de1c70cuMF
6: 0x902ba2 - session::Session::bug::h67201db2df2c561edcq
7: 0x1184508 - trans::common::u32.AsU64::as_u64::hb09c0f9cedc2afe9Vml
8: 0x129bd66 - trans::adt::Struct<'tcx>...std..cmp..Eq::assert_receiver_is_total_eq::ha4043fc1c68313ebebH
9: 0x117deca - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::pop_and_trans_custom_cleanup_scope::he19b59ee6fbbbdabvoK
10: 0x11698b8 - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::push_custom_cleanup_scope::h8a436d69fac4a20bveK
11: 0x1169588 - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::push_custom_cleanup_scope::h8a436d69fac4a20bveK
12: 0x121591f - trans::context::CrateContext<'b, 'tcx>::report_overbig_object::h7fa55c84f4a7e14cxDm
13: 0x1272821 - trans::closure::ClosureKind<'tcx>...std..cmp..PartialEq::eq::h22627d35aff317eamOx
14: 0x126fb19 - trans::closure::ClosureKind<'tcx>...std..cmp..PartialEq::eq::h22627d35aff317eamOx
15: 0x117bda3 - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::pop_and_trans_custom_cleanup_scope::he19b59ee6fbbbdabvoK
16: 0x11e43ca - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::schedule_free_value::h59b3033bcd53c94bkBK
17: 0x11b4b1b - trans::type_::Type...std..cmp..PartialEq::ne::hc5732761018813b3ckJ
18: 0x11644a6 - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::pop_and_trans_ast_cleanup_scope::h001d1bfc7990d7c63hK
19: 0x116338b - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::push_ast_cleanup_scope::hb0e55269a2ff9d34l9J
20: 0x1164aef - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::pop_and_trans_ast_cleanup_scope::h001d1bfc7990d7c63hK
21: 0x122d3de - trans::base::IsUnboxedClosureFlag...std..clone..Clone::clone::h8d9b5221c757fe7fbLt
22: 0x114fea0 - trans::context::CrateContext<'b, 'tcx>::sess::h0c92734bae2bfb65wmm
23: 0x114b63d - trans::context::CrateContext<'b, 'tcx>::stats::hfdf50b198e5f7592qzm
24: 0x122fc48 - trans::cleanup::FunctionContext<'blk, 'tcx>.CleanupMethods<'blk, 'tcx>::push_custom_cleanup_scope_with_debug_loc::hc8a6918f1c87a4b9ngK
25: 0x114b857 - trans::context::CrateContext<'b, 'tcx>::stats::hfdf50b198e5f7592qzm
26: 0x1234728 - trans::base::trans_crate::ha9ad2d2ee040c191Udv
27: 0x70b2543a - driver::phase_4_translate_to_llvm::h9dcbc7c0b9c8c65bJFa
28: 0x70b03243 - driver::compile_input::h45b30318e07c4cf6vba
29: 0x70bcaa1e - run::heefafb1ff7869308B4b
30: 0x70bc786a - run::heefafb1ff7869308B4b
31: 0x69c288fc - rust_try
32: 0x69c288d9 - rust_try
33: 0x70bc7fa9 - run::heefafb1ff7869308B4b
34: 0x69bf3457 - sys::tcp::TcpListener::bind::hfcf283b88d14d24bfTv
35: 0x775659ed - BaseThreadInitThunk

Version

rustc 1.0.0-nightly (ea6f65c 2015-01-06 19:47:08 +0000)
binary: rustc
commit-hash: ea6f65c
commit-date: 2015-01-06 19:47:08 +0000
host: x86_64-pc-windows-gnu
release: 1.0.0-nightly

[japaric]

Updated error message is an LLVM assertion:

rustc: /home/rustbuild/src/rust-buildbot/slave/nightly-dist-rustc-linux/build/src/llvm/lib/IR/Instructions.cpp:550: void llvm::InvokeInst::init(llvm::Value*, llvm::BasicBlock*, llvm::BasicBlock*, llvm::ArrayRef<llvm::Value*>, const llvm::Twine&): Assertion `(i >= FTy->getNumParams() || FTy->getParamType(i) == Args[i]->getType()) && "Invoking a function with a bad signature!"' failed.
[1]    8065 abort (core dumped)  rustc 20605.rs

To workaround the bug, simply don't dereference the iterator, this doesn't crash:

fn changer<'a>(mut things: Box<Iterator<Item=&'a mut u8>>) {
    for item in things { *item = 0 }
}

fn main() {
}

[japaric]

FWIW, the new for loops (#20790) report a compiler error in this case, instead of ICEing:

fn changer<'a>(mut things: Box<Iterator<Item=&'a mut u8>>) {
    for item in *things { *item = 0 }
}

fn main() {
}

Output:

20605.rs:2:5: 3:2 error: the trait `core::marker::Sized` is not implemented for the type `core::iter::Iterator` [E0277]
20605.rs:2     for item in *things { *item = 0 }
20605.rs:3 }
20605.rs:2:5: 3:2 note: `core::iter::Iterator` does not have a constant size known at compile-time
20605.rs:2     for item in *things { *item = 0 }
20605.rs:3 }
20605.rs:2:5: 3:2 error: the trait `core::marker::Sized` is not implemented for the type `core::iter::Iterator` [E0277]
20605.rs:2     for item in *things { *item = 0 }
20605.rs:3 }
20605.rs:2:5: 3:2 note: `core::iter::Iterator` does not have a constant size known at compile-time
20605.rs:2     for item in *things { *item = 0 }
20605.rs:3 }
20605.rs:2:5: 3:2 error: the trait `core::marker::Sized` is not implemented for the type `core::iter::Iterator` [E0277]
20605.rs:2     for item in *things { *item = 0 }
20605.rs:3 }
20605.rs:2:5: 3:2 note: `core::iter::Iterator` does not have a constant size known at compile-time
20605.rs:2     for item in *things { *item = 0 }
20605.rs:3 }
error: aborting due to 3 previous errors

cc @nikomatsakis