Auto merge of #111913 - oli-obk:valtrees2, r=lcnr

Only rewrite valtree-constants to patterns and keep other constants opaque

Now that we can reliably fall back to comparing constants with `PartialEq::eq` to the match scrutinee, we can

1. eagerly try to convert constants to valtrees
2. then deeply convert the valtree to a pattern
3. if the to-valtree conversion failed, create an "opaque constant" pattern.

This PR specifically avoids any behavioral changes or major cleanups. What we can now do as follow ups is

* move the two remaining call sites to `destructure_mir_constant` off that query
* make valtree to pattern conversion infallible
    * this needs to be done after careful analysis of the effects. There may be user visible changes from that.

based on https://github.com/rust-lang/rust/pull/111768

1 files changed, 2 insertions, 2 deletions

diff --git a/compiler/rustc_span/src/hygiene.rs b/compiler/rustc_span/src/hygiene.rs
index b219fde4da9..0c7e36b3bef 100644
--- a/compiler/rustc_span/src/hygiene.rs
+++ b/compiler/rustc_span/src/hygiene.rs
@@ -1288,7 +1288,7 @@ pub fn decode_expn_id(
     decode_data: impl FnOnce(ExpnId) -> (ExpnData, ExpnHash),
 ) -> ExpnId {
     if index == 0 {
-        debug!("decode_expn_id: deserialized root");
+        trace!("decode_expn_id: deserialized root");
         return ExpnId::root();
     }
 
@@ -1321,7 +1321,7 @@ pub fn decode_syntax_context<D: Decoder, F: FnOnce(&mut D, u32) -> SyntaxContext
 ) -> SyntaxContext {
     let raw_id: u32 = Decodable::decode(d);
     if raw_id == 0 {
-        debug!("decode_syntax_context: deserialized root");
+        trace!("decode_syntax_context: deserialized root");
         // The root is special
         return SyntaxContext::root();
     }