Closed
Description
I have a crate that statically checks the size of a type by instantiating an invalid array if the types size is incorrect. Running cargo doc on the crate panics on the location of the array length expression.
#![feature(const_size_of)]
use std::cell::Cell;
use std::mem;
pub struct S {
s: Cell<usize>
}
type _S = [usize; 0 - (mem::size_of::<S>() != 4) as usize];causes this error:
thread 'rustc' panicked at 'called `Result::unwrap()` on an `Err` value: ConstEvalErr { span: src/main.rs:10:19: 10:58, kind: Math(Overflow(Sub)) }', libcore/result.rs:945:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.
error: internal compiler error: unexpected panic
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: rustc 1.25.0-nightly (21882aad7 2018-01-28) running on x86_64-unknown-linux-gnu
rustc --version --verbose:
use std::cell::Cell;
use std::mem;
struct S {
s: Cell<usize>,
}
type _S = [u8; 0 - (mem::size_of::<S>() != 4) as usize];
backtrace:
thread 'rustc' panicked at 'called `Result::unwrap()` on an `Err` value: ConstEvalErr { span: src/main.rs:10:19: 10:58, kind: Math(Overflow(Sub)) }', libcore/result.rs:945:5
stack backtrace:
0: 0x7f4f4fee5e2b - std::sys::unix::backtrace::tracing::imp::unwind_backtrace::h279fd5fd9f05345b
at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
1: 0x7f4f4feb1530 - std::sys_common::backtrace::print::h6e90012f267bcd2d
at libstd/sys_common/backtrace.rs:71
at libstd/sys_common/backtrace.rs:59
2: 0x7f4f4feb7550 - std::panicking::default_hook::{{closure}}::h073ace7ec685c21b
at libstd/panicking.rs:380
3: 0x7f4f4feb72a7 - std::panicking::default_hook::he7b56ddcad2e358c
at libstd/panicking.rs:396
4: 0x7f4f4feb7a5b - std::panicking::rust_panic_with_hook::hb4d0f8287add03b2
at libstd/panicking.rs:576
5: 0x7f4f4feb791e - std::panicking::begin_panic::hc91952597c81491c
at libstd/panicking.rs:537
6: 0x7f4f4feb781a - std::panicking::begin_panic_fmt::h00f630be4e5e5d35
at libstd/panicking.rs:521
7: 0x7f4f4feb77b2 - rust_begin_unwind
at libstd/panicking.rs:497
8: 0x7f4f4ff57850 - core::panicking::panic_fmt::h848bc35221bffff5
at libcore/panicking.rs:71
9: 0x5574958285ed - core::result::unwrap_failed::hfa99739ec53d72eb
at /checkout/src/libcore/macros.rs:23
10: 0x557495a5ee6f - <rustc::hir::Ty as rustdoc::clean::Clean<rustdoc::clean::Type>>::clean::hb7815fc1d916d5e9
at /checkout/src/libcore/result.rs:782
at librustdoc/clean/mod.rs:2450
11: 0x5574958e333f - <rustdoc::doctree::Typedef as rustdoc::clean::Clean<rustdoc::clean::Item>>::clean::hfee5104da271a11c
at librustdoc/clean/mod.rs:86
at librustdoc/clean/mod.rs:3110
12: 0x5574959b66e9 - <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T, I>>::spec_extend::h9473d0f48b25c183
at librustdoc/clean/mod.rs:501
at /checkout/src/libcore/ops/function.rs:271
at /checkout/src/libcore/option.rs:404
at /checkout/src/libcore/iter/mod.rs:1251
at /checkout/src/liballoc/vec.rs:1844
13: 0x5574958de5da - <rustdoc::doctree::Module as rustdoc::clean::Clean<rustdoc::clean::Item>>::clean::hfd00e08b6fc7742f
at /checkout/src/liballoc/vec.rs:1782
at librustdoc/clean/mod.rs:501
14: 0x557495a59914 - <rustdoc::visit_ast::RustdocVisitor<'a, 'tcx, 'rcx> as rustdoc::clean::Clean<rustdoc::clean::Crate>>::clean::h9d810f68e4f5903c
at librustdoc/clean/mod.rs:150
15: 0x5574958c0c84 - rustdoc::core::run_core::{{closure}}::hc9c6b1c50e2bfa6c
at librustdoc/core.rs:255
16: 0x5574958b1e22 - <std::thread::local::LocalKey<T>>::with::hc3ec3303cd604207
at /checkout/src/librustc_driver/driver.rs:1071
at /checkout/src/librustc/ty/context.rs:1573
at /checkout/src/libstd/thread/local.rs:377
at /checkout/src/libstd/thread/local.rs:288
17: 0x5574958b1034 - <std::thread::local::LocalKey<T>>::with::hab3e16cdb2729852
at /checkout/src/librustc/ty/context.rs:1570
at /checkout/src/librustc/ty/context.rs:1557
at /checkout/src/libstd/thread/local.rs:377
at /checkout/src/libstd/thread/local.rs:288
18: 0x55749595d493 - rustc::ty::context::TyCtxt::create_and_enter::ha6230dfc8beb1281
at /checkout/src/librustc/ty/context.rs:1554
at /checkout/src/librustc/ty/context.rs:1197
19: 0x5574958c1624 - rustc_driver::driver::phase_3_run_analysis_passes::hccc7b178d7dc9ce3
at /checkout/src/librustc_driver/driver.rs:984
20: 0x557495a6403a - rustdoc::core::run_core::h31dbfe5815dc3d35
at librustdoc/core.rs:213
21: 0x5574958ea549 - std::sys_common::backtrace::__rust_begin_short_backtrace::h1c6f4b8920eaed47
at librustdoc/lib.rs:537
at /checkout/src/librustc_driver/lib.rs:1426
at /checkout/src/libstd/sys_common/backtrace.rs:136
22: 0x557495a25d6d - std::panicking::try::do_call::h14a7c45cc34b9968
at /checkout/src/libstd/thread/mod.rs:406
at /checkout/src/libstd/panic.rs:293
at /checkout/src/libstd/panicking.rs:479
23: 0x7f4f4fefb11e - __rust_maybe_catch_panic
at libpanic_unwind/lib.rs:102
24: 0x557495a48873 - <F as alloc::boxed::FnBox<A>>::call_box::h1785f7be69232ab0
at /checkout/src/libstd/panicking.rs:458
at /checkout/src/libstd/panic.rs:358
at /checkout/src/libstd/thread/mod.rs:405
at /checkout/src/liballoc/boxed.rs:788
25: 0x7f4f4fee9f07 - std::sys_common::thread::start_thread::h52f16600cce7c01e
at /checkout/src/liballoc/boxed.rs:798
at libstd/sys_common/thread.rs:24
26: 0x7f4f4feb82a8 - std::sys::unix::thread::Thread::new::thread_start::h0ab1c0a2f78d344a
at libstd/sys/unix/thread.rs:90
27: 0x7f4f4fc4d08b - start_thread
28: 0x7f4f4f76de1e - __GI___clone
29: 0x0 - <unknown>