Outline default query and hook provider function implementations

compiler/rustc_middle/src/hooks/mod.rs

@@ -47,12 +47,7 @@ pub struct Providers {
         impl Default for Providers {
             fn default() -> Self {
                 Providers {
-                    $($name: |_, $($arg,)*| bug!(
+                    $($name: |_, $($arg,)*| default_hook(stringify!($name), &($($arg,)*))),*
-                        "`tcx.{}{:?}` cannot be called as `{}` was never assigned to a provider function.\n",
-                        stringify!($name),
-                        ($($arg,)*),
-                        stringify!($name),
-                    ),)*
                 }
             }
         }
@@ -84,7 +79,6 @@ fn clone(&self) -> Self { *self }
     /// via `mir_built`
     hook build_mir(key: LocalDefId) -> mir::Body<'tcx>;
 
-
     /// Imports all `SourceFile`s from the given crate into the current session.
     /// This normally happens automatically when we decode a `Span` from
     /// that crate's metadata - however, the incr comp cache needs
@@ -103,3 +97,10 @@ fn clone(&self) -> Self { *self }
     /// Will fetch a DefId from a DefPathHash for a foreign crate.
     hook def_path_hash_to_def_id_extern(hash: DefPathHash, stable_crate_id: StableCrateId) -> DefId;
 }
+
+#[cold]
+fn default_hook(name: &str, args: &dyn std::fmt::Debug) -> ! {
+    bug!(
+        "`tcx.{name}{args:?}` cannot be called as `{name}` was never assigned to a provider function"
+    )
+}

compiler/rustc_middle/src/query/plumbing.rs

@@ -266,13 +266,7 @@ macro_rules! separate_provide_extern_default {
         ()
     };
     ([(separate_provide_extern) $($rest:tt)*][$name:ident]) => {
-        |_, key| bug!(
+        |_, key| $crate::query::plumbing::default_extern_query(stringify!($name), &key)
-            "`tcx.{}({:?})` unsupported by its crate; \
-             perhaps the `{}` query was never assigned a provider function",
-            stringify!($name),
-            key,
-            stringify!($name),
-        )
     };
     ([$other:tt $($modifiers:tt)*][$($args:tt)*]) => {
         separate_provide_extern_default!([$($modifiers)*][$($args)*])
@@ -462,15 +456,7 @@ pub struct ExternProviders {
         impl Default for Providers {
             fn default() -> Self {
                 Providers {
-                    $($name: |_, key| bug!(
+                    $($name: |_, key| $crate::query::plumbing::default_query(stringify!($name), &key)),*
-                        "`tcx.{}({:?})` is not supported for this key;\n\
-                        hint: Queries can be either made to the local crate, or the external crate. \
-                        This error means you tried to use it for one that's not supported.\n\
-                        If that's not the case, {} was likely never assigned to a provider function.\n",
-                        stringify!($name),
-                        key,
-                        stringify!($name),
-                    ),)*
                 }
             }
         }
@@ -661,3 +647,21 @@ fn into_query_param(self) -> LocalDefId {
 
 #[derive(Copy, Clone, Debug, HashStable)]
 pub struct CyclePlaceholder(pub ErrorGuaranteed);
+
+#[cold]
+pub(crate) fn default_query(name: &str, key: &dyn std::fmt::Debug) -> ! {
+    bug!(
+        "`tcx.{name}({key:?})` is not supported for this key;\n\
+        hint: Queries can be either made to the local crate, or the external crate. \
+        This error means you tried to use it for one that's not supported.\n\
+        If that's not the case, {name} was likely never assigned to a provider function.\n",
+    )
+}
+
+#[cold]
+pub(crate) fn default_extern_query(name: &str, key: &dyn std::fmt::Debug) -> ! {
+    bug!(
+        "`tcx.{name}({key:?})` unsupported by its crate; \
+         perhaps the `{name}` query was never assigned a provider function",
+    )
+}