Rollup merge of rust-lang#121120 - nnethercote:LitKind-Err-guar, r=fmease

Add `ErrorGuaranteed` to `ast::LitKind::Err`, `token::LitKind::Err`.

Similar to recent work doing the same for `ExprKind::Err` (rust-lang#120586) and `TyKind::Err` (rust-lang#121109).

r? `@oli-obk`

Author: GuillaumeGomez

proc_macro/src/bridge/mod.rs

@@ -337,7 +337,11 @@ pub enum LitKind {
     ByteStrRaw(u8),
     CStr,
     CStrRaw(u8),
-    Err,
+    // This should have an `ErrorGuaranteed`, except that type isn't available
+    // in this crate. (Imagine it is there.) Hence the `WithGuar` suffix. Must
+    // only be constructed in `LitKind::from_internal`, where an
+    // `ErrorGuaranteed` is available.
+    ErrWithGuar,
 }
 
 rpc_encode_decode!(
@@ -352,7 +356,7 @@ rpc_encode_decode!(
         ByteStrRaw(n),
         CStr,
         CStrRaw(n),
-        Err,
+        ErrWithGuar,
     }
 );
 

proc_macro/src/lib.rs

@@ -1451,7 +1451,7 @@ impl Literal {
                 f(&["cr", hashes, "\"", symbol, "\"", hashes, suffix])
             }
 
-            bridge::LitKind::Integer | bridge::LitKind::Float | bridge::LitKind::Err => {
+            bridge::LitKind::Integer | bridge::LitKind::Float | bridge::LitKind::ErrWithGuar => {
                 f(&[symbol, suffix])
             }
         })