Print a backtrace in const eval if interrupted

compiler/rustc_const_eval/messages.ftl

@@ -146,6 +146,8 @@ const_eval_intern_kind = {$kind ->
     *[other] {""}
 }
 
+const_eval_interrupted = compilation was interrupted
+
 const_eval_invalid_align_details =
     invalid align passed to `{$name}`: {$align} is {$err_kind ->
         [not_power_of_two] not a power of 2

compiler/rustc_const_eval/src/const_eval/eval_queries.rs

@@ -1,3 +1,5 @@
+use std::sync::atomic::Ordering::Relaxed;
+
 use either::{Left, Right};
 
 use rustc_hir::def::DefKind;
@@ -22,6 +24,7 @@ use crate::interpret::{
     InternKind, InterpCx, InterpError, InterpResult, MPlaceTy, MemoryKind, OpTy, RefTracking,
     StackPopCleanup,
 };
+use crate::CTRL_C_RECEIVED;
 
 // Returns a pointer to where the result lives
 #[instrument(level = "trace", skip(ecx, body))]
@@ -79,7 +82,11 @@ fn eval_body_using_ecx<'mir, 'tcx, R: InterpretationResult<'tcx>>(
     ecx.storage_live_for_always_live_locals()?;
 
     // The main interpreter loop.
-    while ecx.step()? {}
+    while ecx.step()? {
+        if CTRL_C_RECEIVED.load(Relaxed) {
+            throw_exhaust!(Interrupted);
+        }
+    }
 
     // Intern the result
     intern_const_alloc_recursive(ecx, intern_kind, &ret)?;

compiler/rustc_const_eval/src/errors.rs

@@ -884,6 +884,7 @@ impl ReportErrorExt for ResourceExhaustionInfo {
             ResourceExhaustionInfo::StackFrameLimitReached => const_eval_stack_frame_limit_reached,
             ResourceExhaustionInfo::MemoryExhausted => const_eval_memory_exhausted,
             ResourceExhaustionInfo::AddressSpaceFull => const_eval_address_space_full,
+            ResourceExhaustionInfo::Interrupted => const_eval_interrupted,
         }
     }
     fn add_args<G: EmissionGuarantee>(self, _: &mut Diag<'_, G>) {}

compiler/rustc_const_eval/src/lib.rs

@@ -32,6 +32,8 @@ pub mod interpret;
 pub mod transform;
 pub mod util;
 
+use std::sync::atomic::AtomicBool;
+
 pub use errors::ReportErrorExt;
 
 use rustc_middle::{ty, util::Providers};
@@ -57,3 +59,8 @@ pub fn provide(providers: &mut Providers) {
         util::check_validity_requirement(tcx, init_kind, param_env_and_ty)
     };
 }
+
+/// `rustc_driver::main` installs a handler that will set this to `true` if
+/// the compiler has been sent a request to shut down, such as by a Ctrl-C.
+/// This static lives here because it is only read by the interpreter.
+pub static CTRL_C_RECEIVED: AtomicBool = AtomicBool::new(false);