`-Zthreads` breaks the single-threaded assumption made by the format args collector

[y21]

Summary

With -Zthreads being a thing now, maybe we shouldn't rely on TLS anymore like we're doing right now? I can reliably hit this assertion

rust-clippy/clippy_utils/src/macros.rs

Line 393 in 5ba6480

"incorrect assumption: `AST_FORMAT_ARGS` should only be accessed by a single thread",

This is a debug assert, so the ICE won't be reproducible with the cargo clippy that is shipped as a component.

Reproducer

// y.rs
fn main() {
    println!("1");
}

$ ./target/debug/clippy-driver y.rs -Zno-codegen -Zthreads=10

Version

commit f30a859ae32c97668a1a8473fc95b72857073e37

Error output

Backtrace

thread 'rustc' panicked at clippy_utils/src/macros.rs:391:9:
incorrect assumption: `AST_FORMAT_ARGS` should only be accessed by a single thread
stack backtrace:
 0:     0x7f6775df889c - std::backtrace_rs::backtrace::libunwind::trace::hc8ce14f1f51b19f3
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
 1:     0x7f6775df889c - std::backtrace_rs::backtrace::trace_unsynchronized::h31756ac1c596273b
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
 2:     0x7f6775df889c - std::sys_common::backtrace::_print_fmt::h40f31fb4d7056540
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/sys_common/backtrace.rs:67:5
 3:     0x7f6775df889c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hcd6ddd3255a8e554
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/sys_common/backtrace.rs:44:22
 4:     0x7f6775e4b8a0 - core::fmt::rt::Argument::fmt::haa38531ef8752652
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/core/src/fmt/rt.rs:142:9
 5:     0x7f6775e4b8a0 - core::fmt::write::ha0f782bd1ecfc2dc
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/core/src/fmt/mod.rs:1120:17
 6:     0x7f6775dec7bf - std::io::Write::write_fmt::h5f37f3e5a0e4b544
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/io/mod.rs:1762:15
 7:     0x7f6775df8684 - std::sys_common::backtrace::_print::h166370b298d5569f
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/sys_common/backtrace.rs:47:5
 8:     0x7f6775df8684 - std::sys_common::backtrace::print::hab8f751e46216a08
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/sys_common/backtrace.rs:34:9
 9:     0x7f6775dfb317 - std::panicking::default_hook::{{closure}}::h058a18801f9aa311
10:     0x7f6775dfb07f - std::panicking::default_hook::h21798126b0cefb30
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/panicking.rs:292:9
11:     0x7f6772ae4660 - std[ee38bba0a237925c]::panicking::update_hook::<alloc[a43fc757b277f94f]::boxed::Box<rustc_driver_impl[4cf9e24b9673574]::install_ice_hook::{closure#0}>>::{closure#0}
12:     0x7f6775dfba58 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hae78327b43bc7d35
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/alloc/src/boxed.rs:2021:9
13:     0x7f6775dfba58 - std::panicking::rust_panic_with_hook::h394983fd1617103f
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/panicking.rs:783:13
14:     0x7f6775dfb779 - std::panicking::begin_panic_handler::{{closure}}::hd49ee216b5583372
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/panicking.rs:649:13
15:     0x7f6775df8d66 - std::sys_common::backtrace::__rust_end_short_backtrace::h29c7582710951d8d
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/sys_common/backtrace.rs:170:18
16:     0x7f6775dfb512 - rust_begin_unwind
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/panicking.rs:645:5
17:     0x7f6775e47f85 - core::panicking::panic_fmt::h1ab6d174ce586fe3
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/core/src/panicking.rs:72:14
18:     0x5572633c761e - clippy_utils::macros::AST_FORMAT_ARGS::__init::h54adb8261143af00
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/core/src/panic.rs:106:9
19:     0x55726320c8d4 - clippy_utils::macros::AST_FORMAT_ARGS::__getit::{{closure}}::hb43e469d96715dbc
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/sys/common/thread_local/fast_local.rs:99:25
20:     0x557263117b31 - std::sys::common::thread_local::lazy::LazyKeyInner<T>::initialize::h70a0e9f33a1c05f8
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/sys/common/thread_local/mod.rs:54:25
21:     0x557263251602 - std::sys::common::thread_local::fast_local::Key<T>::try_initialize::hd222f65d0e36c777
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/sys/common/thread_local/fast_local.rs:190:27
22:     0x557263251870 - std::sys::common::thread_local::fast_local::Key<T>::get::hb43b1876ea5aafa7
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/sys/common/thread_local/fast_local.rs:173:25
23:     0x5572633c7665 - clippy_utils::macros::AST_FORMAT_ARGS::__getit::h80c8efd0c1c63629
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/sys/common/thread_local/fast_local.rs:91:21
24:     0x55726332b7b4 - std::thread::local::LocalKey<T>::try_with::hda287d5dbe8b5f4d
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/thread/local.rs:269:32
25:     0x55726332a7ad - std::thread::local::LocalKey<T>::with::ha72d176466541b1f
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/thread/local.rs:246:9
26:     0x5572633c6c37 - clippy_utils::macros::find_format_args::h836040932b2da5f6
                             at /home/timo/rust-clippy/clippy_utils/src/macros.rs:419:5
27:     0x557262beecbf - <clippy_lints::format_args::FormatArgs as rustc_lint::passes::LateLintPass>::check_expr::he7f74ba4c7a752b2
                             at /home/timo/rust-clippy/clippy_lints/src/format_args.rs:190:40
28:     0x7f6772e8cf50 - <rustc_lint[6b16f16878f0609a]::late::LateContextAndPass<rustc_lint[6b16f16878f0609a]::late::RuntimeCombinedLateLintPass> as rustc_hir[bfecebe82f70b3af]::intravisit::Visitor>::visit_expr::{closure#0}
29:     0x7f6772e8cdd8 - <rustc_lint[6b16f16878f0609a]::late::LateContextAndPass<rustc_lint[6b16f16878f0609a]::late::RuntimeCombinedLateLintPass> as rustc_hir[bfecebe82f70b3af]::intravisit::Visitor>::visit_expr
30:     0x7f6772e8de6e - <rustc_lint[6b16f16878f0609a]::late::LateContextAndPass<rustc_lint[6b16f16878f0609a]::late::RuntimeCombinedLateLintPass> as rustc_hir[bfecebe82f70b3af]::intravisit::Visitor>::visit_block
31:     0x7f6772e8d5a8 - <rustc_lint[6b16f16878f0609a]::late::LateContextAndPass<rustc_lint[6b16f16878f0609a]::late::RuntimeCombinedLateLintPass> as rustc_hir[bfecebe82f70b3af]::intravisit::Visitor>::visit_expr::{closure#0}
32:     0x7f6772e8cdd8 - <rustc_lint[6b16f16878f0609a]::late::LateContextAndPass<rustc_lint[6b16f16878f0609a]::late::RuntimeCombinedLateLintPass> as rustc_hir[bfecebe82f70b3af]::intravisit::Visitor>::visit_expr
33:     0x7f6772e8b7aa - <rustc_lint[6b16f16878f0609a]::late::LateContextAndPass<rustc_lint[6b16f16878f0609a]::late::RuntimeCombinedLateLintPass> as rustc_hir[bfecebe82f70b3af]::intravisit::Visitor>::visit_nested_body
34:     0x7f6772e8d944 - <rustc_lint[6b16f16878f0609a]::late::LateContextAndPass<rustc_lint[6b16f16878f0609a]::late::RuntimeCombinedLateLintPass> as rustc_hir[bfecebe82f70b3af]::intravisit::Visitor>::visit_fn
35:     0x7f6772e8bff5 - <rustc_lint[6b16f16878f0609a]::late::LateContextAndPass<rustc_lint[6b16f16878f0609a]::late::RuntimeCombinedLateLintPass> as rustc_hir[bfecebe82f70b3af]::intravisit::Visitor>::visit_item
36:     0x7f6772e8dc7a - <rustc_lint[6b16f16878f0609a]::late::LateContextAndPass<rustc_lint[6b16f16878f0609a]::late::RuntimeCombinedLateLintPass> as rustc_hir[bfecebe82f70b3af]::intravisit::Visitor>::visit_mod
37:     0x7f6774817ba7 - rustc_lint[6b16f16878f0609a]::late::check_crate::{closure#0}
38:     0x7f6772e6d842 - rayon_core[4fd33d6976072015]::join::join_context::<rayon_core[4fd33d6976072015]::join::join::call<core[8f41822517f550cc]::option::Option<rustc_data_structures[74d3a12135b02663]::marker::FromDyn<()>>, rustc_data_structures[74d3a12135b02663]::sync::parallel::enabled::join<rustc_lint[6b16f16878f0609a]::late::check_crate::{closure#0}, rustc_lint[6b16f16878f0609a]::late::check_crate::{closure#1}, (), ()>::{closure#0}::{closure#0}>::{closure#0}, rayon_core[4fd33d6976072015]::join::join::call<core[8f41822517f550cc]::option::Option<rustc_data_structures[74d3a12135b02663]::marker::FromDyn<()>>, rustc_data_structures[74d3a12135b02663]::sync::parallel::enabled::join<rustc_lint[6b16f16878f0609a]::late::check_crate::{closure#0}, rustc_lint[6b16f16878f0609a]::late::check_crate::{closure#1}, (), ()>::{closure#0}::{closure#1}>::{closure#0}, core[8f41822517f550cc]::option::Option<rustc_data_structures[74d3a12135b02663]::marker::FromDyn<()>>, core[8f41822517f550cc]::option::Option<rustc_data_structures[74d3a12135b02663]::marker::FromDyn<()>>>::{closure#0}
39:     0x7f6774817e55 - rustc_lint[6b16f16878f0609a]::late::check_crate
40:     0x7f6772e3af3a - <rayon_core[4fd33d6976072015]::job::HeapJob<<rayon_core[4fd33d6976072015]::scope::Scope>::spawn<rustc_interface[bcd40bc45d5d0754]::passes::analysis::{closure#6}::{closure#2}::{closure#0}::{closure#2}::{closure#1}::{closure#0}::{closure#3}>::{closure#0}> as rayon_core[4fd33d6976072015]::job::Job>::execute
41:     0x7f67726d9ed5 - <rayon_core[4fd33d6976072015]::registry::WorkerThread>::wait_until_cold
42:     0x7f67726d6da3 - <rayon_core[4fd33d6976072015]::registry::ThreadBuilder>::run
43:     0x7f6772ae6697 - <<crossbeam_utils[6d482fbb41000f9]::thread::ScopedThreadBuilder>::spawn<<rayon_core[4fd33d6976072015]::ThreadPoolBuilder>::build_scoped<rustc_interface[bcd40bc45d5d0754]::util::run_in_thread_pool_with_globals<rustc_interface[bcd40bc45d5d0754]::interface::run_compiler<core[8f41822517f550cc]::result::Result<(), rustc_span[74aab3a68d021777]::ErrorGuaranteed>, rustc_driver_impl[4cf9e24b9673574]::run_compiler::{closure#1}>::{closure#0}, core[8f41822517f550cc]::result::Result<(), rustc_span[74aab3a68d021777]::ErrorGuaranteed>>::{closure#3}::{closure#0}::{closure#0}, rustc_interface[bcd40bc45d5d0754]::util::run_in_thread_pool_with_globals<rustc_interface[bcd40bc45d5d0754]::interface::run_compiler<core[8f41822517f550cc]::result::Result<(), rustc_span[74aab3a68d021777]::ErrorGuaranteed>, rustc_driver_impl[4cf9e24b9673574]::run_compiler::{closure#1}>::{closure#0}, core[8f41822517f550cc]::result::Result<(), rustc_span[74aab3a68d021777]::ErrorGuaranteed>>::{closure#3}::{closure#0}::{closure#1}, core[8f41822517f550cc]::result::Result<(), rustc_span[74aab3a68d021777]::ErrorGuaranteed>>::{closure#0}::{closure#0}::{closure#0}, ()>::{closure#0} as core[8f41822517f550cc]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
44:     0x7f6772adf3ce - std[ee38bba0a237925c]::sys_common::backtrace::__rust_begin_short_backtrace::<alloc[a43fc757b277f94f]::boxed::Box<dyn core[8f41822517f550cc]::ops::function::FnOnce<(), Output = ()> + core[8f41822517f550cc]::marker::Send>, ()>
45:     0x7f6772ae6323 - <<std[ee38bba0a237925c]::thread::Builder>::spawn_unchecked_<alloc[a43fc757b277f94f]::boxed::Box<dyn core[8f41822517f550cc]::ops::function::FnOnce<(), Output = ()> + core[8f41822517f550cc]::marker::Send>, ()>::{closure#1} as core[8f41822517f550cc]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
46:     0x7f6775e05915 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::he32d1cc72bddfec8
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/alloc/src/boxed.rs:2007:9
47:     0x7f6775e05915 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hfc224f9cd2e7edd6
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/alloc/src/boxed.rs:2007:9
48:     0x7f6775e05915 - std::sys::unix::thread::Thread::new::thread_start::h1b679b756cd6878e
                             at /rustc/6b771f6b5a6c8b03b6322a9c77ac77cb346148f0/library/std/src/sys/unix/thread.rs:108:17
49:     0x7f676826cb43 - start_thread
                             at ./nptl/pthread_create.c:442:8
50:     0x7f67682fea00 - clone3
                             at ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
51:                0x0 - <unknown>

error: the compiler unexpectedly panicked. this is a bug.

[flip1995]

#10275 (comment)

Damn, I kinda predicted that... But back then I didn't expect that we'll get parallel compilation this soon.

@Alexendoo I think we'll have to think about a different solution...

[Alexendoo]

Ahh I thought we'd have longer since whole crate passes aren't run in parallel even with -Zthreads, however the early lint passes may have happened on a different thread when parallel is enabled

I've been thinking about how to fix it when working on the module pass stuff and have a pretty good idea of how to go about it