Fix ICE on --print=... i/o errors

[dtolnay]

rustc --print=cfg > /dev/full

Before: ICE (see below)

After: exits quietly with code 1.

thread 'rustc' panicked at 'failed printing to stdout: No space left on device (os error 28)', library/std/src/io/stdio.rs:1019:9stack backtrace: 0: 0x7ffa84d68f33 - std::backtrace_rs::backtrace::libunwind::trace::h527d8d64d53ade2d at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5 1: 0x7ffa84d68f33 - std::backtrace_rs::backtrace::trace_unsynchronized::hfb55b01517dd6379 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5 2: 0x7ffa84d68f33 - std::sys_common::backtrace::_print_fmt::hd134e914eea0bd97 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/sys_common/backtrace.rs:65:5 3: 0x7ffa84d68f33 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h1480db11ec399d77 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/sys_common/backtrace.rs:44:22 4: 0x7ffa84dc9d4f - core::fmt::write::h67ec4c4171c92b26 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/core/src/fmt/mod.rs:1247:17 5: 0x7ffa84d5bed1 - std::io::Write::write_fmt::h3b12aef0fff2463b at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/io/mod.rs:1712:15 6: 0x7ffa84d68d45 - std::sys_common::backtrace::_print::h584400135abdbd51 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/sys_common/backtrace.rs:47:5 7: 0x7ffa84d68d45 - std::sys_common::backtrace::print::hce41d3c8bd91096b at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/sys_common/backtrace.rs:34:9 8: 0x7ffa84d6b84f - std::panicking::default_hook::{{closure}}::h2043b657a3791225 9: 0x7ffa84d6b507 - std::panicking::default_hook::h99252b8d3dd5719c at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/panicking.rs:293:9 10: 0x7ffa87fdf915 - <rustc_driver_impl[d30cd2737d9d343a]::DEFAULT_HOOK::{closure#0}::{closure#0} as core[cc19a662f3570270]::ops::function::FnOnce<(&core[cc19a662f3570270]::panic::panic_info::PanicInfo,)>>::call_once::{shim:vtable#0} 11: 0x7ffa84d6c005 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h222a2b674b9f4762 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/alloc/src/boxed.rs:1976:9 12: 0x7ffa84d6c005 - std::panicking::rust_panic_with_hook::h7f49b36bf7f8ff77 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/panicking.rs:704:13 13: 0x7ffa84d6bd73 - std::panicking::begin_panic_handler::{{closure}}::haa23a7352589e31e at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/panicking.rs:595:13 14: 0x7ffa84d69376 - std::sys_common::backtrace::__rust_end_short_backtrace::h3d0cf6e3c96e3fe9 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/sys_common/backtrace.rs:150:18 15: 0x7ffa84d6ba72 - rust_begin_unwind at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/panicking.rs:584:5 16: 0x7ffa84dc5fe3 - core::panicking::panic_fmt::hf4b4ea11e3fdb110 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/core/src/panicking.rs:67:14 17: 0x7ffa84d5aa07 - std::io::stdio::print_to::h55760b9ede306280 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/io/stdio.rs:1019:9 18: 0x7ffa84d5aa07 - std::io::stdio::_print::h93deb6099db33eab at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/io/stdio.rs:1095:5 19: 0x7ffa871e163b - rustc_driver_impl[d30cd2737d9d343a]::print_crate_info 20: 0x7ffa87fb8e01 - rustc_span[9551eaa044f53f4f]::set_source_map::<(), rustc_interface[c2b70c9b1dae0906]::interface::run_compiler<(), rustc_driver_impl[d30cd2737d9d343a]::run_compiler::{closure#0}>::{closure#0}::{closure#0}> 21: 0x7ffa87fb6d59 - std[71a32ca0600a6a04]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[c2b70c9b1dae0906]::util::run_in_thread_pool_with_globals<rustc_interface[c2b70c9b1dae0906]::interface::run_compiler<(), rustc_driver_impl[d30cd2737d9d343a]::run_compiler::{closure#0}>::{closure#0}, ()>::{closure#0}::{closure#0}, ()> 22: 0x7ffa87fe25b4 - std[71a32ca0600a6a04]::panicking::try::<(), core[cc19a662f3570270]::panic::unwind_safe::AssertUnwindSafe<<std[71a32ca0600a6a04]::thread::Builder>::spawn_unchecked_<rustc_interface[c2b70c9b1dae0906]::util::run_in_thread_pool_with_globals<rustc_interface[c2b70c9b1dae0906]::interface::run_compiler<(), rustc_driver_impl[d30cd2737d9d343a]::run_compiler::{closure#0}>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1}::{closure#0}>> 23: 0x7ffa87fb0cf1 - <<std[71a32ca0600a6a04]::thread::Builder>::spawn_unchecked_<rustc_interface[c2b70c9b1dae0906]::util::run_in_thread_pool_with_globals<rustc_interface[c2b70c9b1dae0906]::interface::run_compiler<(), rustc_driver_impl[d30cd2737d9d343a]::run_compiler::{closure#0}>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[cc19a662f3570270]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0} 24: 0x7ffa84d763e5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hf15d802f31f86225 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/alloc/src/boxed.rs:1962:9 25: 0x7ffa84d763e5 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hac564355b46c52d6 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/alloc/src/boxed.rs:1962:9 26: 0x7ffa84d763e5 - std::sys::unix::thread::Thread::new::thread_start::h86fb3aedb7811f07 at /rustc/7f94b314cead7059a71a265a8b64905ef2511796/library/std/src/sys/unix/thread.rs:108:17 27: 0x7ffa84a94b43 - start_thread at ./nptl/pthread_create.c:442:8 28: 0x7ffa84b26a00 - clone3 at ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81 29: 0x0 - <unknown>error: 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.mdnote: rustc 1.71.0-nightly (7f94b314c 2023-04-23) running on x86_64-unknown-linux-gnuquery stack during panic:end of query stack

[rustbot]

r? @petrochenkov

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[petrochenkov]

These imports need a comment about their purpose, anybody could remove them and the removal will pass CI.

[petrochenkov]

r=me with the comment #110783 (comment) added.

[dtolnay]

@bors r=petrochenkov

[bors]

📌 Commit 040e1b6 has been approved by petrochenkov

It is now in the queue for this repository.