ICE: polonius loan scopes differ from NLL borrow scopes,

[matthiaskrgr]

auto-reduced (treereduce-rust):

use std::io::{self, Read};

pub struct Container<'a> {
    reader: &'a mut dyn Read,
}

impl<'a> Container {
    pub fn wrap<'s>(reader: &'s mut dyn io::Read) -> Container<'s> {
        Container { reader: reader }
    }
}

original:

use std::io::{self, Read};
use std::vec;

pub struct Container<'a> {
    reader: &'a mut dyn Read
}

impl<'a> Container<'local_mac_tt> {
    pub fn wrap<'s>(reader: &'s mut dyn io::Read) -> Container<'s> {
        Container { reader: reader }
    }

    pub fn read_to(&mut self, vec: &mut [u8]) {
        self.reader.read(3, 4);
    }
}

pub fn for_stdin<'a>() -> Container<'dropping_copy_types> {
    let mut r = io::stdin();
    Container::wrap(&mut r as &mut dyn io::Read)
    //~^ ERROR cannot return value referencing local variable
}

fn main() {
    let mut c = for_stdin();
    let (Ok(_x) | Err(!)) = &res;
    c.read_to(v); //~ ERROR E0308
}

Version information

rustc 1.81.0-nightly (bcf1f6db4 2024-07-11)
binary: rustc
commit-hash: bcf1f6db4594ae6132378b179a30cdb3599a863d
commit-date: 2024-07-11
host: x86_64-unknown-linux-gnu
release: 1.81.0-nightly
LLVM version: 18.1.7

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Zpolonius=next

Program output

error[E0726]: implicit elided lifetime not allowed here
 --> /tmp/icemaker_global_tempdir.4feaX3V4ADCu/rustc_testrunner_tmpdir_reporting.ZXhnCcXmdGdv/mvce.rs:7:10
  |
7 | impl<'a> Container {
  |          ^^^^^^^^^ expected lifetime parameter
  |
help: indicate the anonymous lifetime
  |
7 | impl<'a> Container<'_> {
  |                   ++++

error[E0601]: `main` function not found in crate `mvce`
  --> /tmp/icemaker_global_tempdir.4feaX3V4ADCu/rustc_testrunner_tmpdir_reporting.ZXhnCcXmdGdv/mvce.rs:11:2
   |
11 | }
   |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.4feaX3V4ADCu/rustc_testrunner_tmpdir_reporting.ZXhnCcXmdGdv/mvce.rs`

thread 'rustc' panicked at compiler/rustc_borrowck/src/dataflow.rs:418:13:
assertion `left == right` failed: polonius loan scopes differ from NLL borrow scopes, for body /tmp/icemaker_global_tempdir.4feaX3V4ADCu/rustc_testrunner_tmpdir_reporting.ZXhnCcXmdGdv/mvce.rs:8:5: 10:6 (#0)
  left: {bb0[3]: [bw0]}
 right: {bb0[4]: [bw0]}
stack backtrace:
   0:     0x7362c658f655 - std::backtrace_rs::backtrace::libunwind::trace::hcb29af1cb57bcb8d
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/../../backtrace/src/backtrace/libunwind.rs:116:5
   1:     0x7362c658f655 - std::backtrace_rs::backtrace::trace_unsynchronized::he36459e1f5f5e93a
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7362c658f655 - std::sys::backtrace::_print_fmt::heffc99ac4b4675cf
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/sys/backtrace.rs:68:5
   3:     0x7362c658f655 - <std::sys::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hf245997fe8a5daf1
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/sys/backtrace.rs:44:22
   4:     0x7362c65ded3b - core::fmt::rt::Argument::fmt::h0e5779e064dbb7df
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/core/src/fmt/rt.rs:173:76
   5:     0x7362c65ded3b - core::fmt::write::h98cec97192061fdf
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/core/src/fmt/mod.rs:1182:21
   6:     0x7362c658403f - std::io::Write::write_fmt::he6c3afdd93fdc681
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/io/mod.rs:1835:15
   7:     0x7362c658f42e - std::sys::backtrace::_print::h636b421fd7a2e420
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/sys/backtrace.rs:47:5
   8:     0x7362c658f42e - std::sys::backtrace::print::haa02f8c85818b01f
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/sys/backtrace.rs:34:9
   9:     0x7362c6591d79 - std::panicking::default_hook::{{closure}}::h50c9c60844185e9c
  10:     0x7362c6591b1c - std::panicking::default_hook::hde778ca172ded902
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/panicking.rs:292:9
  11:     0x7362c2a21c59 - std[ad414beb854749b5]::panicking::update_hook::<alloc[4dde9fbc2019d87d]::boxed::Box<rustc_driver_impl[7c2f87ab8379164f]::install_ice_hook::{closure#0}>>::{closure#0}
  12:     0x7362c659269f - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h77bec8c01b3205fe
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/alloc/src/boxed.rs:2078:9
  13:     0x7362c659269f - std::panicking::rust_panic_with_hook::h02aa1f3fa26e53db
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/panicking.rs:804:13
  14:     0x7362c65922c7 - std::panicking::begin_panic_handler::{{closure}}::he573aa5eefbb7bfc
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/panicking.rs:670:13
  15:     0x7362c658fb19 - std::sys::backtrace::__rust_end_short_backtrace::ha97f3bba049b4ef0
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/sys/backtrace.rs:171:18
  16:     0x7362c6591f54 - rust_begin_unwind
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/panicking.rs:661:5
  17:     0x7362c65db2f3 - core::panicking::panic_fmt::hd5960ad38e738d13
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/core/src/panicking.rs:74:14
  18:     0x7362c65db8cf - core::panicking::assert_failed_inner::h02724f5e69869174
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/core/src/panicking.rs:405:23
  19:     0x7362c26d1527 - core[5577311df7d42be1]::panicking::assert_failed::<indexmap[5fb9d275e5314e4d]::map::IndexMap<rustc_middle[77b0c22bfadf3e56]::mir::Location, alloc[4dde9fbc2019d87d]::vec::Vec<rustc_borrowck[6a0718d1facf5b73]::dataflow::BorrowIndex>, core[5577311df7d42be1]::hash::BuildHasherDefault<rustc_hash[fad87a7c8a3801b7]::FxHasher>>, indexmap[5fb9d275e5314e4d]::map::IndexMap<rustc_middle[77b0c22bfadf3e56]::mir::Location, alloc[4dde9fbc2019d87d]::vec::Vec<rustc_borrowck[6a0718d1facf5b73]::dataflow::BorrowIndex>, core[5577311df7d42be1]::hash::BuildHasherDefault<rustc_hash[fad87a7c8a3801b7]::FxHasher>>>
  20:     0x7362c504194c - rustc_borrowck[6a0718d1facf5b73]::do_mir_borrowck
  21:     0x7362c5025142 - rustc_query_impl[996ec1e1a9f37899]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[996ec1e1a9f37899]::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[77b0c22bfadf3e56]::query::erase::Erased<[u8; 8usize]>>
  22:     0x7362c43a47b3 - rustc_query_system[f92dbd75fbf471ce]::query::plumbing::try_execute_query::<rustc_query_impl[996ec1e1a9f37899]::DynamicConfig<rustc_query_system[f92dbd75fbf471ce]::query::caches::VecCache<rustc_span[9d9e1055ab85fce3]::def_id::LocalDefId, rustc_middle[77b0c22bfadf3e56]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[996ec1e1a9f37899]::plumbing::QueryCtxt, false>
  23:     0x7362c43a420d - rustc_query_impl[996ec1e1a9f37899]::query_impl::mir_borrowck::get_query_non_incr::__rust_end_short_backtrace
  24:     0x7362c4397a21 - rustc_interface[d8bba0fea4cb4dbe]::passes::analysis
  25:     0x7362c4396c07 - rustc_query_impl[996ec1e1a9f37899]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[996ec1e1a9f37899]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[77b0c22bfadf3e56]::query::erase::Erased<[u8; 1usize]>>
  26:     0x7362c4ef7be5 - rustc_query_system[f92dbd75fbf471ce]::query::plumbing::try_execute_query::<rustc_query_impl[996ec1e1a9f37899]::DynamicConfig<rustc_query_system[f92dbd75fbf471ce]::query::caches::SingleCache<rustc_middle[77b0c22bfadf3e56]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[996ec1e1a9f37899]::plumbing::QueryCtxt, false>
  27:     0x7362c4ef794f - rustc_query_impl[996ec1e1a9f37899]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  28:     0x7362c4df7305 - rustc_interface[d8bba0fea4cb4dbe]::interface::run_compiler::<core[5577311df7d42be1]::result::Result<(), rustc_span[9d9e1055ab85fce3]::ErrorGuaranteed>, rustc_driver_impl[7c2f87ab8379164f]::run_compiler::{closure#0}>::{closure#1}
  29:     0x7362c4dc5509 - std[ad414beb854749b5]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[d8bba0fea4cb4dbe]::util::run_in_thread_with_globals<rustc_interface[d8bba0fea4cb4dbe]::util::run_in_thread_pool_with_globals<rustc_interface[d8bba0fea4cb4dbe]::interface::run_compiler<core[5577311df7d42be1]::result::Result<(), rustc_span[9d9e1055ab85fce3]::ErrorGuaranteed>, rustc_driver_impl[7c2f87ab8379164f]::run_compiler::{closure#0}>::{closure#1}, core[5577311df7d42be1]::result::Result<(), rustc_span[9d9e1055ab85fce3]::ErrorGuaranteed>>::{closure#0}, core[5577311df7d42be1]::result::Result<(), rustc_span[9d9e1055ab85fce3]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[5577311df7d42be1]::result::Result<(), rustc_span[9d9e1055ab85fce3]::ErrorGuaranteed>>
  30:     0x7362c4dc52ba - <<std[ad414beb854749b5]::thread::Builder>::spawn_unchecked_<rustc_interface[d8bba0fea4cb4dbe]::util::run_in_thread_with_globals<rustc_interface[d8bba0fea4cb4dbe]::util::run_in_thread_pool_with_globals<rustc_interface[d8bba0fea4cb4dbe]::interface::run_compiler<core[5577311df7d42be1]::result::Result<(), rustc_span[9d9e1055ab85fce3]::ErrorGuaranteed>, rustc_driver_impl[7c2f87ab8379164f]::run_compiler::{closure#0}>::{closure#1}, core[5577311df7d42be1]::result::Result<(), rustc_span[9d9e1055ab85fce3]::ErrorGuaranteed>>::{closure#0}, core[5577311df7d42be1]::result::Result<(), rustc_span[9d9e1055ab85fce3]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[5577311df7d42be1]::result::Result<(), rustc_span[9d9e1055ab85fce3]::ErrorGuaranteed>>::{closure#2} as core[5577311df7d42be1]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  31:     0x7362c659c4fb - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h4b9d0e9c592a6ae1
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/alloc/src/boxed.rs:2064:9
  32:     0x7362c659c4fb - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h6892ad45769a753a
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/alloc/src/boxed.rs:2064:9
  33:     0x7362c659c4fb - std::sys::pal::unix::thread::Thread::new::thread_start::h4695e9cd59270e16
                               at /rustc/bcf1f6db4594ae6132378b179a30cdb3599a863d/library/std/src/sys/pal/unix/thread.rs:108:17
  34:     0x7362bf4a6ded - <unknown>
  35:     0x7362bf52a0dc - <unknown>
  36:                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.md

note: please make sure that you have updated to the latest nightly

note: rustc 1.81.0-nightly (bcf1f6db4 2024-07-11) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z polonius=next -Z dump-mir-dir=dir

query stack during panic:
#0 [mir_borrowck] borrow-checking `<impl at /tmp/icemaker_global_tempdir.4feaX3V4ADCu/rustc_testrunner_tmpdir_reporting.ZXhnCcXmdGdv/mvce.rs:7:1: 7:19>::wrap`
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 2 previous errors

Some errors have detailed explanations: E0601, E0726.
For more information about an error, try `rustc --explain E0601`.