add dynamic for smir

[ericmarkmartin]

r? spastorino

[bors]

☔ The latest upstream changes (presumably #113943) made this pull request unmergeable. Please resolve the merge conflicts.

[spastorino]

Can you rename the T here to V. I think it will be clearer because we won't have the T param and the T associated type and won't have this T = T thing that looks weird :).

[spastorino]

Unsure what's the preferred way here, if having Copy as bound, if using Deref and calling as_deref() and then implement stable for what's returned or if calling clone.
cc @oli-obk

[ericmarkmartin]

I considered using a Clone bound but I thought it might be too weak?

If there's a type with an expensive clone, I'm not sure I wanted to implicitly derive an expensive implementation of stable

[ericmarkmartin]

Also, isn't as_deref just an Option thing? I thought the method you get from Deref is just deref

[spastorino]

If I'm not wrong, this works ...

diff --git a/compiler/rustc_smir/src/rustc_smir/mod.rs b/compiler/rustc_smir/src/rustc_smir/mod.rs
index dd0d7df9ecf..b7e827dced0 100644
--- a/compiler/rustc_smir/src/rustc_smir/mod.rs
+++ b/compiler/rustc_smir/src/rustc_smir/mod.rs
@@ -581,13 +581,13 @@ fn stable(&self, tables: &mut Tables<'tcx>) -> Self::T {

 impl<'tcx, S, T> Stable<'tcx> for ty::Binder<'tcx, S>
 where
-    S: Stable<'tcx, T = T> + Copy,
+    S: Stable<'tcx, T = T>,
 {
     type T = stable_mir::ty::Binder<T>;

     fn stable(&self, tables: &mut Tables<'tcx>) -> Self::T {
         stable_mir::ty::Binder {
-            value: self.skip_binder().stable(tables),
+            value: self.as_ref().skip_binder().stable(tables),
             bound_vars: self
                 .bound_vars()
                 .iter()

[ericmarkmartin]

Oh as_ref not as_deref

[ericmarkmartin]

Oh ignore me I'm being dumb--binder has both

[spastorino]

This looks good to me, please squash the commits. Maybe you can make a first commit with the Binder change and then the one that adds Dynamic.

[ericmarkmartin]

Sure I can squash as such. I'm actually not done though, hence the PR being a draft. In particular, I think I want to handle Term properly rather than as an opaque.

[rustbot]

This PR changes Stable MIR

cc @oli-obk, @celinval, @spastorino

[spastorino]

@bors r+ rollup

[bors]

📌 Commit badb617 has been approved by spastorino

It is now in the queue for this repository.