compiler internal error: subtype error

[GuillaumeGomez]

Hey,

Here's the bug description :

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>', /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/libsyntax/ast_util.rs:784

stack backtrace:
   1:     0x7f0af2d49120 - rt::backtrace::imp::write::h3c0523c13636656fOLq
   2:     0x7f0af2d4c310 - failure::on_fail::h9a355b0a53be785cw7q
   3:     0x7f0af3534740 - unwind::begin_unwind_inner::h0ab5484e74ee0101rje
   4:     0x7f0aeef8d310 - unwind::begin_unwind::h13307728250319235624
   5:     0x7f0aeef8d260 - diagnostic::SpanHandler::span_bug::hd3a5390ca4771f82c7E
   6:     0x7f0af3ad09c0 - driver::session::Session::span_bug::h0a5e146c6cf2b5d6z5C
   7:     0x7f0af3ec0d90 - middle::typeck::check::method::LookupContext<'a>::bug::h9a33b4d07f69923cE7T
   8:     0x7f0af3ec0e10 - middle::typeck::check::method::LookupContext<'a>::consider_candidates::hd71b17fb2347b67bAhT
   9:     0x7f0af3ebeb70 - middle::typeck::check::method::LookupContext<'a>::search_for_method::h120681b24b4af1c9ZbT
  10:     0x7f0af3eb86f0 - middle::typeck::check::method::LookupContext<'a>::search_for_autoderefd_method::hd5035f1a55ee2f7b0GS
  11:     0x7f0af3eb75e0 - middle::typeck::check::method::LookupContext<'a>::search_step::hd82b82931d4ce8fbDUR
  12:     0x7f0af3eb50c0 - middle::typeck::check::method::LookupContext<'a>::search::h493a1bb3adffef68hTR
  13:     0x7f0af3eb5b40 - middle::typeck::check::method::lookup_in_trait::h07cf77d528545225dIR
  14:     0x7f0af3f14600 - middle::typeck::check::try_overloaded_call::he76080159aee37b6C3W
  15:     0x7f0af3f1a3a0 - middle::typeck::check::check_expr_with_unifier::hf0af3bf6d346d9a50UX
  16:     0x7f0af3f234d0 - middle::typeck::check::check_expr_with_unifier::check_binop::hdbfd9cf45432c1f0dcY
  17:     0x7f0af3f1a3a0 - middle::typeck::check::check_expr_with_unifier::hf0af3bf6d346d9a50UX
  18:     0x7f0af3ed8e90 - middle::typeck::check::check_block_with_expected::ha3382383e0174a72c2Z
  19:     0x7f0af3ed3c90 - middle::typeck::check::check_fn::hd8d96b66c3c25771wDU
  20:     0x7f0af3ed3a60 - middle::typeck::check::check_bare_fn::h2aaf5a27582ba014hsU
  21:     0x7f0af3ecc4c0 - middle::typeck::check::check_item::h0d35a108b1e2219207U
  22:     0x7f0af3ece420 - visit::walk_item::h4994048128054535781
  23:     0x7f0af3ece420 - visit::walk_item::h4994048128054535781
  24:     0x7f0af3ed3790 - middle::typeck::check::check_item_types::hc4d314b34aa4fa7fgrU
  25:     0x7f0af3915260 - util::common::time::h14172350515681977473
  26:     0x7f0af410de80 - middle::typeck::check_crate::hbe9ce24801a7cbd7vSm
  27:     0x7f0af41cf500 - driver::driver::phase_3_run_analysis_passes::hc7abcc76bf622eafiyB
  28:     0x7f0af41cabf0 - driver::driver::compile_input::ha48623fcead7bd7e5jB
  29:     0x7f0af425e890 - driver::run_compiler::h0b258b9c360b66ddjRE
  30:     0x7f0af425e7a0 - driver::main_args::closure.141085
  31:     0x7f0af4272dc0 - task::TaskBuilder<S>::try_future::closure.142270
  32:     0x7f0af4272bc0 - task::TaskBuilder<S>::spawn_internal::closure.142247
  33:     0x7f0af4cdd0b0 - task::spawn_opts::closure.8370
  34:     0x7f0af358d490 - rust_try_inner
  35:     0x7f0af358d480 - rust_try
  36:     0x7f0af3531cf0 - unwind::try::hea1640d217ab7457H7d
  37:     0x7f0af3531a90 - task::Task::run::hb52aad40b24ebf23Ndd
  38:     0x7f0af4cdce10 - task::spawn_opts::closure.8316
  39:     0x7f0af3533930 - thread::thread_start::h741158bbfb282555MCd
  40:     0x7f0af27dd0c0 - start_thread
  41:     0x7f0af31faf89 - __clone
  42:                0x0 - <unknown>

And here is my rust compiler version :

> rustc -v
rustc 0.12.0-pre-nightly (5419b2ca2 2014-08-29 22:16:20 +0000)

You can redo this bug with this project on the bug branch.

[mdinger]

I shrunk this to a much smaller test case.

rgsl.rs:

use std::intrinsics::sinf64;

pub type function<T> = fn(x: f64, p: &mut T) -> f64;

struct InternParam<'r, T:'r> {
    func: ::function<T>,
    param: &'r mut T,
    p2: f64
}

struct fn_fourier_params<'r, T:'r> {
    omega: f64,
    function: &'r mut ::function<T>,
    arg: &'r mut T
}

unsafe fn fn_sin<T>(x: f64, p: &mut fn_fourier_params<T>) -> f64 {
    let f = p.function;
    let w = p.omega;
    let wx = w * x;
    let sinwx = sinf64(wx);

    f(x, p.arg) * sinwx
}

Build output:

$ cargo build
   Compiling rust-GSL v0.4.9 (file:///home/mdinger/Programs/gsl/rust-GSL)
src/rgsl.rs:23:5: 23:16 error: internal compiler error: &mut fn(f64, &mut T) -> f64 was a subtype of &mut fn(<generic #15>, <generic #16>) -> <generic #14> but now is not?
src/rgsl.rs:23     f(x, p.arg) * sinwx
                   ^~~~~~~~~~~
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>', /home/rustbuild/src/rust-buildbot/slave/nightly-linux/build/src/libsyntax/ast_util.rs:776


Could not compile `rust-GSL`.

To learn more, run the command again with --verbose.

[EDIT]
I've edited this to be up to date with my repository.
Removed the branch after he got minimum testcase.

[GuillaumeGomez]

It's a lot better like that, thanks !

Minimal:

fn f<'r>(p: &'r mut fn(p: &mut ())) {
    p(())
}

fn main() {}

[nikomatsakis]

cc me

[cakey]

Hey,
Wasn't sure where else to put this, but I came across a bug that seems similar:

Code:

use std::iter::AdditiveIterator;

fn adder(args: [f64]) -> f64 {
    args.sum()
}

fn main() {

}

Report:

/Users/b.shaw/Projects/rust/bug.rs:4:5: 4:15 error: internal compiler error: &mut [f64] was a subtype of &mut <generic #38> but now is not?
/Users/b.shaw/Projects/rust/bug.rs:4     args.sum()
                                             ^~~~~~~~~~
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>', /Users/rustbuild/src/rust-buildbot/slave/nightly-mac/build/src/libsyntax/diagnostic.rs:116

(On Mac 10.10 nightly installer)

[nikomatsakis]

@cakey I don't see that error when checking with a local build (at least not anymore). You may want to upgrade. Note also that the code is illegal. A working version looks something like this (maybe there's a nicer way to do it, not sure):

use std::iter::AdditiveIterator;

fn adder(args: &[f64]) -> f64 {
    args.iter().map(|x| *x).sum()
}

fn main() {

}

UPDATE: fixed code example