Auto merge of rust-lang#107421 - cjgillot:drop-tracking-mir, r=oli-obk

Enable -Zdrop-tracking-mir by default

This PR enables the `drop-tracking-mir` flag by default. This flag was initially implemented in rust-lang#101692.

This flag computes auto-traits on generators based on their analysis MIR, instead of trying to compute on the HIR body. This removes the need for HIR-based drop-tracking, as we can now reuse the same code to compute generator witness types and to compute generator interior fields.

Author: bors

compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs

@@ -426,7 +426,6 @@ fn push_debuginfo_type_name<'tcx>(
         | ty::Placeholder(..)
         | ty::Alias(..)
         | ty::Bound(..)
-        | ty::GeneratorWitnessMIR(..)
         | ty::GeneratorWitness(..) => {
             bug!(
                 "debuginfo: Trying to create type name for \

compiler/rustc_const_eval/src/const_eval/valtrees.rs

@@ -152,7 +152,7 @@ pub(crate) fn const_to_valtree_inner<'tcx>(
         // FIXME(oli-obk): we can probably encode closures just like structs
         | ty::Closure(..)
         | ty::Generator(..)
-        | ty::GeneratorWitness(..) |ty::GeneratorWitnessMIR(..)=> Err(ValTreeCreationError::NonSupportedType),
+        | ty::GeneratorWitness(..) => Err(ValTreeCreationError::NonSupportedType),
     }
 }
 
@@ -280,7 +280,6 @@ pub fn valtree_to_const_value<'tcx>(
         | ty::Closure(..)
         | ty::Generator(..)
         | ty::GeneratorWitness(..)
-        | ty::GeneratorWitnessMIR(..)
         | ty::FnPtr(_)
         | ty::RawPtr(_)
         | ty::Str