Rollup merge of #92191 - jackh726:issue-89352, r=nikomatsakis

Prefer projection candidates instead of param_env candidates for Sized predicates

Fixes #89352

Also includes some drive by logging and verbose printing changes that I found useful when debugging this, but I can remove this if needed.

This is a little hacky - but imo no more than the rest of `candidate_should_be_dropped_in_favor_of`. Importantly, in a Chalk-like world, both candidates should be completely compatible.

r? ```@nikomatsakis```

compiler/rustc_typeck/src/astconv/mod.rs

@@ -288,7 +288,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
     /// Given the type/lifetime/const arguments provided to some path (along with
     /// an implicit `Self`, if this is a trait reference), returns the complete
     /// set of substitutions. This may involve applying defaulted type parameters.
-    /// Also returns back constraints on associated types.
+    /// Constraints on associated typess are created from `create_assoc_bindings_for_generic_args`.
     ///
     /// Example:
     ///
@@ -302,7 +302,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
     ///    which will have been resolved to a `def_id`
     /// 3. The `generic_args` contains info on the `<...>` contents. The `usize` type
     ///    parameters are returned in the `SubstsRef`, the associated type bindings like
-    ///    `Output = u32` are returned in the `Vec<ConvertedBinding...>` result.
+    ///    `Output = u32` are returned from `create_assoc_bindings_for_generic_args`.
     ///
     /// Note that the type listing given here is *exactly* what the user provided.
     ///

compiler/rustc_typeck/src/check/method/mod.rs

@@ -359,6 +359,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let (obligation, substs) =
             self.obligation_for_method(span, trait_def_id, self_ty, opt_input_types);
 
+        debug!(?obligation);
+
         // Now we want to know if this can be matched
         if !self.predicate_may_hold(&obligation) {
             debug!("--> Cannot match obligation");