Rustc panics when piped into other commands

[ms747]

rustc panics when its output is being piped into other commands.

I tried this code:

$ rustc | grep
$ rustc | rg
$ rustc | echo

Meta

Bug exists on both stable and nightly builds.

rustc 1.62.1 (e092d0b6b 2022-07-16)
binary: rustc
commit-hash: e092d0b6b43f2de967af0887873151bb1c0b18d3
commit-date: 2022-07-16
host: x86_64-pc-windows-gnu
release: 1.62.1
LLVM version: 14.0.5

Backtrace

$ rustc | echo

thread 'main' panicked at 'failed printing to stdout: The pipe is being closed. (os error 232)', library\std\src\io\stdio.rs:1016:9
stack backtrace:
   0:         0x66a0b6e0 - std::backtrace_rs::backtrace::dbghelp::trace::hcf1edc4340169add
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src\..\..\backtrace\src\backtrace/dbghelp.rs:98:5
   1:         0x66a0b6e0 - std::backtrace_rs::backtrace::trace_unsynchronized::h667c1c2dcc656354
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src\..\..\backtrace\src\backtrace/mod.rs:66:5
   2:         0x66a0b6e0 - std::sys_common::backtrace::_print_fmt::hfb7bace0584ade55
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src\sys_common/backtrace.rs:66:5
   3:         0x66a0b6e0 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hb33b4e98d0091546
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src\sys_common/backtrace.rs:45:22
   4:         0x66a70e4a - core::fmt::write::h6c05da133b140855
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\core\src\fmt/mod.rs:1196:17
   5:         0x669fd373 - std::io::Write::write_fmt::h9b6cb30f5a3cd549
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src\io/mod.rs:1654:15
   6:         0x66a0eb09 - std::sys_common::backtrace::_print::hc9d14608fb2479ef
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src\sys_common/backtrace.rs:48:5
   7:         0x66a0eb09 - std::sys_common::backtrace::print::hbd6a7f88953bf46c
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src\sys_common/backtrace.rs:35:9
   8:         0x66a0eb09 - std::panicking::default_hook::{{closure}}::h9cbf1d70d95153f7
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/panicking.rs:295:22
   9:         0x66a0e78d - std::panicking::default_hook::h6361d2e804ad32c1
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/panicking.rs:314:9
  10:         0x673df389 - rustc_driver[4502434ebcdcaeba]::DEFAULT_HOOK::{closure#0}::{closure#0}
  11:         0x66a0f3db - std::panicking::rust_panic_with_hook::h9759101d5af84392
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/panicking.rs:702:17
  12:         0x66a0f125 - std::panicking::begin_panic_handler::{{closure}}::h3400764062bd15ad
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/panicking.rs:588:13
  13:         0x66a0c2e7 - std::sys_common::backtrace::__rust_end_short_backtrace::h199fe7c55d65b172
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src\sys_common/backtrace.rs:138:18
  14:         0x66a0ee59 - rust_begin_unwind
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/panicking.rs:584:5
  15:         0x66a6d6f5 - core::panicking::panic_fmt::haf27162bd71f9b2c
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\core\src/panicking.rs:142:14
  16:         0x669fac0b - std::io::stdio::print_to::h67a6ba4112d4d800
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src\io/stdio.rs:1016:9
  17:         0x669fac0b - std::io::stdio::_print::h4f77d1fb452cb5a1
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src\io/stdio.rs:1028:5
  18:         0x673dc2f3 - rustc_driver[4502434ebcdcaeba]::usage
  19:         0x673de2b1 - rustc_driver[4502434ebcdcaeba]::handle_options
  20:         0x673d7d5b - <rustc_driver[4502434ebcdcaeba]::RunCompiler>::run
  21:         0x673715ca - <core[be4d9e6022649537]::panic::unwind_safe::AssertUnwindSafe<rustc_driver[4502434ebcdcaeba]::main::{closure#0}> as core[be4d9e6022649537]::ops::function::FnOnce<()>>::call_once
  22:         0x673e064d - rustc_driver[4502434ebcdcaeba]::main
  23:           0x40164e - rustc_main[80d93e91ab353e27]::main
  24:           0x4015b6 - std[c1538c24ed0124a6]::sys_common::backtrace::__rust_begin_short_backtrace::<fn(), ()>
  25:           0x40160c - std[c1538c24ed0124a6]::rt::lang_start::<()>::{closure#0}
  26:         0x669ed75a - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once::h392d7cb81e6352b4
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3\library\core\src\ops/function.rs:280:13
  27:         0x669ed75a - std::panicking::try::do_call::h131f29fc06b4f4bb
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/panicking.rs:492:40
  28:         0x669ed75a - std::panicking::try::h2b4cdc89938fcb7d
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/panicking.rs:456:19
  29:         0x669ed75a - std::panic::catch_unwind::h327f69bb8fe3e3f9
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/panic.rs:137:14
  30:         0x669ed75a - std::rt::lang_start_internal::{{closure}}::h050c0e344fae99eb
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/rt.rs:128:48
  31:         0x669ed75a - std::panicking::try::do_call::hf5df717773459fcf
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/panicking.rs:492:40
  32:         0x669ed75a - std::panicking::try::h724c59bb637e9cac
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/panicking.rs:456:19
  33:         0x669ed75a - std::panic::catch_unwind::h2c5424824164171e
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/panic.rs:137:14
  34:         0x669ed75a - std::rt::lang_start_internal::h71b2fce70fe28f35
                               at /rustc/e092d0b6b43f2de967af0887873151bb1c0b18d3/library\std\src/rt.rs:128:20
  35:           0x401688 - main
  36:           0x4013f8 - __tmainCRTStartup
  37:           0x40151b - mainCRTStartup
  38:     0x7ffec8a354e0 - <unknown>
  39:     0x7ffec9c2485b - <unknown>

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/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: rustc 1.62.1 (e092d0b6b 2022-07-16) running on x86_64-pc-windows-gnu

[ChrisDenton]

The issue is that grep, rg and echo without arguments will exit without reading input and some shells are aggressive about closing the pipe immediately afterward.

Consider these commands:

$ echo "hello" | grep
Usage: grep [OPTION]... PATTERN [FILE]...
Try 'grep --help' for more information.

Here we see that grep doesn't wait for stdin and instead exits immediately.

The fix for rustc is to either:

a) not use the println! macro (which panics on all errors)
b) change the println! macro in std to ignore pipe closing errors (this would require the libs-api team to agree with the change)

[ehuss]

Thanks for the report! Closing as a duplicate of #98700.