Auto merge of #111769 - saethlin:ctfe-backtrace-ctrlc, r=RalfJung

Print a backtrace in const eval if interrupted

Demo:
```rust
#![feature(const_eval_limit)]
#![const_eval_limit = "0"]

const OW: u64 = {
    let mut res: u64 = 0;
    let mut i = 0;
    while i < u64::MAX {
        res = res.wrapping_add(i);
        i += 1;
    }
    res
};

fn main() {
    println!("{}", OW);
}
```
```
╭ ➜ ben@archlinux:~/rust
╰ ➤ rustc +stage1 spin.rs
^Cerror[E0080]: evaluation of constant value failed
 --> spin.rs:8:33
  |
8 |         res = res.wrapping_add(i);
  |                                 ^ Compilation was interrupted

note: erroneous constant used
  --> spin.rs:15:20
   |
15 |     println!("{}", OW);
   |                    ^^

note: erroneous constant used
  --> spin.rs:15:20
   |
15 |     println!("{}", OW);
   |                    ^^
   |
   = note: this note originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to previous error

For more information about this error, try `rustc --explain E0080`.
```

2 files changed, 20 insertions, 0 deletions

diff --git a/compiler/rustc_driver_impl/Cargo.toml b/compiler/rustc_driver_impl/Cargo.toml
index fcc0afd3488..e4fb13822f8 100644
--- a/compiler/rustc_driver_impl/Cargo.toml
+++ b/compiler/rustc_driver_impl/Cargo.toml
@@ -5,6 +5,7 @@ edition = "2021"
 
 [dependencies]
 # tidy-alphabetical-start
+ctrlc = "3.4.4"
 rustc_ast = { path = "../rustc_ast" }
 rustc_ast_lowering = { path = "../rustc_ast_lowering" }
 rustc_ast_passes = { path = "../rustc_ast_passes" }
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index 716e31080dd..b4007aeb8d7 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -19,6 +19,7 @@ extern crate tracing;
 
 use rustc_ast as ast;
 use rustc_codegen_ssa::{traits::CodegenBackend, CodegenErrors, CodegenResults};
+use rustc_const_eval::CTRL_C_RECEIVED;
 use rustc_data_structures::profiling::{
     get_resident_set_size, print_time_passes_entry, TimePassesFormat,
 };
@@ -1518,6 +1519,22 @@ pub fn init_logger(early_dcx: &EarlyDiagCtxt, cfg: rustc_log::LoggerConfig) {
     }
 }
 
+/// Install our usual `ctrlc` handler, which sets [`rustc_const_eval::CTRL_C_RECEIVED`].
+/// Making this handler optional lets tools can install a different handler, if they wish.
+pub fn install_ctrlc_handler() {
+    ctrlc::set_handler(move || {
+        // Indicate that we have been signaled to stop. If we were already signaled, exit
+        // immediately. In our interpreter loop we try to consult this value often, but if for
+        // whatever reason we don't get to that check or the cleanup we do upon finding that
+        // this bool has become true takes a long time, the exit here will promptly exit the
+        // process on the second Ctrl-C.
+        if CTRL_C_RECEIVED.swap(true, Ordering::Relaxed) {
+            std::process::exit(1);
+        }
+    })
+    .expect("Unable to install ctrlc handler");
+}
+
 pub fn main() -> ! {
     let start_time = Instant::now();
     let start_rss = get_resident_set_size();
@@ -1528,6 +1545,8 @@ pub fn main() -> ! {
     signal_handler::install();
     let mut callbacks = TimePassesCallbacks::default();
     let using_internal_features = install_ice_hook(DEFAULT_BUG_REPORT_URL, |_| ());
+    install_ctrlc_handler();
+
     let exit_code = catch_with_exit_code(|| {
         RunCompiler::new(&args::raw_args(&early_dcx)?, &mut callbacks)
             .set_using_internal_features(using_internal_features)