Make HandleCycleError an enum instead of a macro-generated closure

- Add a `HandleCycleError` enum to rustc_query_system, along with a `handle_cycle_error` function
- Move `Value` to rustc_query_system, so `handle_cycle_error` can use it
- Move the `Value` impls from rustc_query_impl to rustc_middle. This is necessary due to orphan rules.

compiler/rustc_query_impl/src/lib.rs

@@ -34,9 +34,6 @@ pub use rustc_query_system::query::{deadlock, QueryContext};
 mod keys;
 use keys::Key;
 
-mod values;
-use self::values::Value;
-
 pub use rustc_query_system::query::QueryConfig;
 pub(crate) use rustc_query_system::query::{QueryDescription, QueryVTable};
 

compiler/rustc_query_impl/src/plumbing.rs

@@ -18,6 +18,7 @@ use rustc_query_system::query::{
     force_query, QueryConfig, QueryContext, QueryDescription, QueryJobId, QueryMap,
     QuerySideEffects, QueryStackFrame,
 };
+use rustc_query_system::Value;
 use std::any::Any;
 use std::num::NonZeroU64;
 use thin_vec::ThinVec;
@@ -174,21 +175,17 @@ impl<'tcx> QueryCtxt<'tcx> {
 }
 
 macro_rules! handle_cycle_error {
-    ([][$tcx: expr, $error:expr]) => {{
-        $error.emit();
-        Value::from_cycle_error($tcx)
+    ([]) => {{
+        rustc_query_system::HandleCycleError::Error
     }};
-    ([(fatal_cycle) $($rest:tt)*][$tcx:expr, $error:expr]) => {{
-        $error.emit();
-        $tcx.sess.abort_if_errors();
-        unreachable!()
+    ([(fatal_cycle) $($rest:tt)*]) => {{
+        rustc_query_system::HandleCycleError::Fatal
     }};
-    ([(cycle_delay_bug) $($rest:tt)*][$tcx:expr, $error:expr]) => {{
-        $error.delay_as_bug();
-        Value::from_cycle_error($tcx)
+    ([(cycle_delay_bug) $($rest:tt)*]) => {{
+        rustc_query_system::HandleCycleError::DelayBug
     }};
-    ([$other:tt $($modifiers:tt)*][$($args:tt)*]) => {
-        handle_cycle_error!([$($modifiers)*][$($args)*])
+    ([$other:tt $($modifiers:tt)*]) => {
+        handle_cycle_error!([$($modifiers)*])
     };
 }
 
@@ -320,6 +317,7 @@ fn force_from_dep_node<'tcx, Q>(tcx: TyCtxt<'tcx>, dep_node: DepNode) -> bool
 where
     Q: QueryDescription<QueryCtxt<'tcx>>,
     Q::Key: DepNodeParams<TyCtxt<'tcx>>,
+    Q::Value: Value<TyCtxt<'tcx>>,
 {
     if let Some(key) = Q::Key::recover(tcx, &dep_node) {
         #[cfg(debug_assertions)]
@@ -418,7 +416,7 @@ macro_rules! define_queries {
                     depth_limit: depth_limit!([$($modifiers)*]),
                     dep_kind: dep_graph::DepKind::$name,
                     hash_result: hash_result!([$($modifiers)*]),
-                    handle_cycle_error: |tcx, mut error| handle_cycle_error!([$($modifiers)*][tcx, error]),
+                    handle_cycle_error: handle_cycle_error!([$($modifiers)*]),
                     compute,
                     cache_on_disk,
                     try_load_from_disk: Self::TRY_LOAD_FROM_DISK,

compiler/rustc_query_impl/src/values.rs

@@ -1,65 +0,0 @@
-use super::QueryCtxt;
-use rustc_middle::ty::{self, AdtSizedConstraint, Ty};
-
-pub(super) trait Value<'tcx>: Sized {
-    fn from_cycle_error(tcx: QueryCtxt<'tcx>) -> Self;
-}
-
-impl<'tcx, T> Value<'tcx> for T {
-    default fn from_cycle_error(tcx: QueryCtxt<'tcx>) -> T {
-        tcx.sess.abort_if_errors();
-        bug!("Value::from_cycle_error called without errors");
-    }
-}
-
-impl<'tcx> Value<'tcx> for Ty<'_> {
-    fn from_cycle_error(tcx: QueryCtxt<'tcx>) -> Self {
-        // SAFETY: This is never called when `Self` is not `Ty<'tcx>`.
-        // FIXME: Represent the above fact in the trait system somehow.
-        unsafe { std::mem::transmute::<Ty<'tcx>, Ty<'_>>(tcx.ty_error()) }
-    }
-}
-
-impl<'tcx> Value<'tcx> for ty::SymbolName<'_> {
-    fn from_cycle_error(tcx: QueryCtxt<'tcx>) -> Self {
-        // SAFETY: This is never called when `Self` is not `SymbolName<'tcx>`.
-        // FIXME: Represent the above fact in the trait system somehow.
-        unsafe {
-            std::mem::transmute::<ty::SymbolName<'tcx>, ty::SymbolName<'_>>(ty::SymbolName::new(
-                *tcx, "<error>",
-            ))
-        }
-    }
-}
-
-impl<'tcx> Value<'tcx> for AdtSizedConstraint<'_> {
-    fn from_cycle_error(tcx: QueryCtxt<'tcx>) -> Self {
-        // SAFETY: This is never called when `Self` is not `AdtSizedConstraint<'tcx>`.
-        // FIXME: Represent the above fact in the trait system somehow.
-        unsafe {
-            std::mem::transmute::<AdtSizedConstraint<'tcx>, AdtSizedConstraint<'_>>(
-                AdtSizedConstraint(tcx.intern_type_list(&[tcx.ty_error()])),
-            )
-        }
-    }
-}
-
-impl<'tcx> Value<'tcx> for ty::Binder<'_, ty::FnSig<'_>> {
-    fn from_cycle_error(tcx: QueryCtxt<'tcx>) -> Self {
-        let err = tcx.ty_error();
-        // FIXME(compiler-errors): It would be nice if we could get the
-        // query key, so we could at least generate a fn signature that
-        // has the right arity.
-        let fn_sig = ty::Binder::dummy(tcx.mk_fn_sig(
-            [].into_iter(),
-            err,
-            false,
-            rustc_hir::Unsafety::Normal,
-            rustc_target::spec::abi::Abi::Rust,
-        ));
-
-        // SAFETY: This is never called when `Self` is not `ty::Binder<'tcx, ty::FnSig<'tcx>>`.
-        // FIXME: Represent the above fact in the trait system somehow.
-        unsafe { std::mem::transmute::<ty::PolyFnSig<'tcx>, ty::Binder<'_, ty::FnSig<'_>>>(fn_sig) }
-    }
-}