thread 'rustc' panicked at rust-nightly/compiler/rustc_errors/src/diagnostic.rs:1006:9:

[wxie7]

I tried this code:

use std::env;
use std::fs::{self, File};
use std::io::{self, Read, Write};
use std::process::{Command, Stdio};
use std::sync::{Arc, Mutex};
use std::thread;
use std::time::{Duration, Instant};
static PROGRAM: &'static str = "ls";
fn main() {
    let args: Vec<String> = env::args().collect();
    let mut list = String::from("");
    if args.len() < 2 {
        list += format!("{}/ \n", env!("PWD")).as_str();
    } else {
        list = get_files(&args[1]);
    };
    println!("The ls: \n{}", list);
}
fn get_files(dir_path: &str) -> String {
    let mut list = {
        print1!("Hello ");
        println1!("Dad!");
        println1!("Rust programming language is one of most famous.");
        println1!("You can click below link to learn more : https://www.rust-lang.org/");
    };
    let f = fs::read_dir(format!("{}", dir_path)).unwrap();
    for d in f {
        let dir = match d {
            Ok(d) => d,
            Err(e) => panic!("{:?}", e),
        };
        list += format!("{}\n", dir.path().display()).as_str();
    }
    return list;
}

I expected to see this happen: explanation

Instead, this happened: explanation

Meta

rustc --version --verbose:

commit-date: unknown
host: x86_64-unknown-linux-gnu
release: 1.85.0-dev
LLVM version: 19.1.4

Backtrace

thread 'rustc' panicked at /data/xieym/workspace/rust/rust-nightly/compiler/rustc_errors/src/diagnostic.rs:1006:9:
Span must not be empty and have no suggestion
stack backtrace:
   0:     0x7f71a9f8bead - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h51e5276f25f67b8a
   1:     0x7f71aa045ea3 - core::fmt::write::h0a73bee6158cdbf1
   2:     0x7f71a9fb2309 - std::io::Write::write_fmt::h206d582822858877
   3:     0x7f71a9f8bd53 - std::sys::backtrace::BacktraceLock::print::h84a9a4c750ade733
   4:     0x7f71a9fc26fc - std::panicking::default_hook::{{closure}}::h216e29259e3d5cff
   5:     0x7f71a9fc24c5 - std::panicking::default_hook::h03ce982d60640bc4
   6:     0x7f71a5869e42 - <alloc[7c2d8435141f8e1e]::boxed::Box<rustc_driver_impl[d7b86d9e63f9aaed]::install_ice_hook::{closure#0}> as core[dcda4f281d996093]::ops::function::Fn<(&dyn for<'a
   7:     0x7f71a9fc2e68 - std::panicking::rust_panic_with_hook::h88b680004200a63a
   8:     0x7f71a9f8c33a - std::panicking::begin_panic_handler::{{closure}}::ha56090df9488ab86
   9:     0x7f71a9f8c169 - std::sys::backtrace::__rust_end_short_backtrace::h8833a10924a5c2d2
  10:     0x7f71a9fc27ed - rust_begin_unwind
  11:     0x7f71aa050a40 - core::panicking::panic_fmt::h57d6d212ea0ce749
  12:     0x7f71a60b734c - <rustc_errors[20cbecb65c2fd5d8]::diagnostic::Diag>::span_suggestion_with_style::<&str, &str>
  13:     0x7f71a5f199c6 - <rustc_hir_typeck[c5136c63f534b988]::fn_ctxt::FnCtxt>::emit_coerce_suggestions
  14:     0x7f71a622abbf - <rustc_hir_typeck[c5136c63f534b988]::coercion::CoerceMany<&rustc_hir[e98c40ff9570e545]::hir::Expr>>::coerce
  15:     0x7f71a5f1e25d - <rustc_hir_typeck[c5136c63f534b988]::fn_ctxt::FnCtxt>::check_return_or_body_tail
  16:     0x7f71a5fb14a4 - <rustc_hir_typeck[c5136c63f534b988]::fn_ctxt::FnCtxt>::check_expr_kind
  17:     0x7f71a5f1cbdf - <rustc_hir_typeck[c5136c63f534b988]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  18:     0x7f71a5faddc5 - <rustc_hir_typeck[c5136c63f534b988]::fn_ctxt::FnCtxt>::check_expr_with_expectation
  19:     0x7f71a5f4f056 - <rustc_hir_typeck[c5136c63f534b988]::fn_ctxt::FnCtxt>::check_expr_block
  20:     0x7f71a5faf982 - <rustc_hir_typeck[c5136c63f534b988]::fn_ctxt::FnCtxt>::check_expr_kind
  21:     0x7f71a5f1cbdf - <rustc_hir_typeck[c5136c63f534b988]::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
  22:     0x7f71a5faddc5 - <rustc_hir_typeck[c5136c63f534b988]::fn_ctxt::FnCtxt>::check_expr_with_expectation
  23:     0x7f71a5f1e1bf - <rustc_hir_typeck[c5136c63f534b988]::fn_ctxt::FnCtxt>::check_return_or_body_tail
  24:     0x7f71a624917b - rustc_hir_typeck[c5136c63f534b988]::check::check_fn
  25:     0x7f71a6241e2f - rustc_hir_typeck[c5136c63f534b988]::typeck
  26:     0x7f71a8045a35 - rustc_query_impl[bec2af351405b693]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[bec2af351405b693]::query_impl::typeck::dynamic_query::{closure#2}::{
  27:     0x7f71a7fb5115 - <rustc_query_impl[bec2af351405b693]::query_impl::typeck::dynamic_query::{closure#2} as core[dcda4f281d996093]::ops::function::FnOnce<(rustc_middle[e6c5fc1c8185df8
  28:     0x7f71a7f12d34 - rustc_query_system[1b6cbf762e62559d]::query::plumbing::try_execute_query::<rustc_query_impl[bec2af351405b693]::DynamicConfig<rustc_data_structures[8c79ebd7d363ac4
  29:     0x7f71a81349fb - rustc_query_impl[bec2af351405b693]::query_impl::typeck::get_query_non_incr::__rust_end_short_backtrace
  30:     0x7f71a64a1e04 - <rustc_middle[e6c5fc1c8185df83]::hir::map::Map>::par_body_owners::<rustc_hir_analysis[beef3382d6061d7f]::check_crate::{closure#4}>::{closure#0}
  31:     0x7f71a649155d - <rustc_data_structures[8c79ebd7d363ac43]::sync::parallel::ParallelGuard>::run::<(), rustc_data_structures[8c79ebd7d363ac43]::sync::parallel::par_for_each_in<&rust
  32:     0x7f71a65098be - rustc_hir_analysis[beef3382d6061d7f]::check_crate
  33:     0x7f71a5b4b3b1 - rustc_interface[3a875bb8a3a01a82]::passes::analysis
  34:     0x7f71a8046053 - rustc_query_impl[bec2af351405b693]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[bec2af351405b693]::query_impl::analysis::dynamic_query::{closure#2}:
  35:     0x7f71a7fb5c41 - <rustc_query_impl[bec2af351405b693]::query_impl::analysis::dynamic_query::{closure#2} as core[dcda4f281d996093]::ops::function::FnOnce<(rustc_middle[e6c5fc1c8185d
  36:     0x7f71a7e608fc - rustc_query_system[1b6cbf762e62559d]::query::plumbing::try_execute_query::<rustc_query_impl[bec2af351405b693]::DynamicConfig<rustc_query_system[1b6cbf762e62559d]:
  37:     0x7f71a8243338 - rustc_query_impl[bec2af351405b693]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  38:     0x7f71a583f8bb - <rustc_middle[e6c5fc1c8185df83]::ty::context::GlobalCtxt>::enter::<rustc_driver_impl[d7b86d9e63f9aaed]::run_compiler::{closure#0}::{closure#1}::{closure#4}, core[
  39:     0x7f71a57f465a - <rustc_interface[3a875bb8a3a01a82]::queries::QueryResult<&rustc_middle[e6c5fc1c8185df83]::ty::context::GlobalCtxt>>::enter::<core[dcda4f281d996093]::result::Resul
  40:     0x7f71a580037c - <rustc_interface[3a875bb8a3a01a82]::interface::Compiler>::enter::<rustc_driver_impl[d7b86d9e63f9aaed]::run_compiler::{closure#0}::{closure#1}, core[dcda4f281d9960
  41:     0x7f71a58301de - <scoped_tls[46415f2badf08390]::ScopedKey<rustc_span[37f46e797e36bb53]::SessionGlobals>>::set::<rustc_interface[3a875bb8a3a01a82]::util::run_in_thread_with_globals
  42:     0x7f71a57e24dc - rustc_span[37f46e797e36bb53]::create_session_globals_then::<core[dcda4f281d996093]::result::Result<(), rustc_span[37f46e797e36bb53]::ErrorGuaranteed>, rustc_intercore[dcda4f281d996093]::result::Result<(), rustc_span[37f46e797e36bb53]::ErrorGuaranteed>, rustc_driver_impl[d7b86d9e63f9aaed]::run_compiler::{closure#0}>::{closure#1}, core[dcda4f281d996093]::result::Result<(), rustc_span[37f46e797e36bb53]::ErrorGuaranteed>>::{closure#0}, core[dcda4f281d996093]::result::Result<(), rustc_span[37f46e797e36bb53]::ErrorGuaranteed>>::{closure#0}::{closure#0}::{closure#0}>
  43:     0x7f71a586d232 - std[31742bae037c253]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[3a875bb8a3a01a82]::util::run_in_thread_with_globals<rustc_interface[3a875bb8a3a01a82]::util::run_in_thread_pool_with_globals<rustc_interface[3a875bb8a3a01a82]::interface::run_compiler<core[dcda4f281d996093]::result::Result<(), rustc_span[37f46e797e36bb53]::ErrorGuaranteed>, rustc_driver_impl[d7b86d9e63f9aaed]::run_compiler::{closure#0}>::{closure#1}, core[dcda4f281d996093]::result::Result<(), rustc_span[37f46e797e36bb53]::ErrorGuaranteed>>::{closure#0}, core[dcda4f281d996093]::result::Result<(), rustc_span[37f46e797e36bb53]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[dcda4f281d996093]::result::Result<(), rustc_span[37f46e797e36bb53]::ErrorGuaranteed>>
  44:     0x7f71a57ee574 - <<std[31742bae037c253]::thread::Builder>::spawn_unchecked_<rustc_interface[3a875bb8a3a01a82]::util::run_in_thread_with_globals<rustc_interface[3a875bb8a3a01a82]::util::run_in_thread_pool_with_globals<rustc_interface[3a875bb8a3a01a82]::interface::run_compiler<core[dcda4f281d996093]::result::Result<(), rustc_span[37f46e797e36bb53]::ErrorGuaranteed>, rustc_driver_impl[d7b86d9e63f9aaed]::run_compiler::{closure#0}>::{closure#1}, core[dcda4f281d996093]::result::Result<(), rustc_span[37f46e797e36bb53]::ErrorGuaranteed>>::{closure#0}, core[dcda4f281d996093]::result::Result<(), rustc_span[37f46e797e36bb53]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[dcda4f281d996093]::result::Result<(), rustc_span[37f46e797e36bb53]::ErrorGuaranteed>>::{closure#1} as core[dcda4f281d996093]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  45:     0x7f71aa00119d - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::hc538cfe9cf5a97c8
  46:     0x7f71a9f903ab - std::sys::pal::unix::thread::Thread::new::thread_start::h7a196e16c036c2e2
  47:     0x7f71a373cac3 - start_thread
                               at ./nptl/pthread_create.c:442:8
  48:     0x7f71a37ce850 - __GI___clone3
                               at ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
  49:                0x0 - <unknown>

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

[jieyouxu]

I can't repro this. @wxie7 how did you invoke rustc? Does it require debug assertions?

[wxie7]

I can't repro this. @wxie7 how did you invoke rustc? Does it require debug assertions?

Yes, I compiled Rust on the latest commit c44b3d5 with assertions and debug-assertions enabled.

[jieyouxu]

@wxie7 thanks for the report. Can you make sure that for future reports, if an ICE needs debug assertions to trigger that you explicitly state that in the issue description? You can also add the label yourself via @/rustbot label +requires-debug-assertions. Also it would be helpful if you can also add which exact commit you compiled rustc from (it's latest now but it won't be several hours later).

[jieyouxu]

@wxie7 also how did you derive this example? This and #133833 looks synthetically generated? Was it through fuzzing?

[wxie7]

@jieyouxu Mutate on the seed provided by the LLM.

[jieyouxu]

@wxie7 ok, so basically fuzzing. Can you make sure for fuzzed examples, that you follow the fuzzing guidelines https://rustc-dev-guide.rust-lang.org/fuzzing.html?highlight=fuzzing#in-a-nutshell, e.g. that you state that the example was fuzzer-produced and include sufficient info like rustc commit hash and debug assertions so we can repro? In particular, it would be very helpful if these examples can be further minimized.

[jieyouxu]

Minimized:

#![crate_type = "lib"]

fn foo() -> String {
    let mut bar = {
        unknown_macro!();
    };
    return bar;
}

requires the block-of-an-undefined-macro.