Use fewer origins when creating type variables.

`InferCtxt::next_{ty,const}_var*` all take an origin, but the
`param_def_id` is almost always `None`. This commit changes them to just
take a `Span` and build the origin within the method, and adds new
methods for the rare cases where `param_def_id` might not be `None`.
This avoids a lot of tedious origin building.

Specifically:
- next_ty_var{,_id_in_universe,_in_universe}: now take `Span` instead of
  `TypeVariableOrigin`
- next_ty_var_with_origin: added

- next_const_var{,_in_universe}: takes Span instead of ConstVariableOrigin
- next_const_var_with_origin: added

- next_region_var, next_region_var_in_universe: these are unchanged,
  still take RegionVariableOrigin

The API inconsistency (ty/const vs region) seems worth it for the
large conciseness improvements.

1 files changed, 1 insertions, 2 deletions

diff --git a/compiler/rustc_lint/src/non_local_def.rs b/compiler/rustc_lint/src/non_local_def.rs
index 7bdf5ef6af4..885c0bb3a89 100644
--- a/compiler/rustc_lint/src/non_local_def.rs
+++ b/compiler/rustc_lint/src/non_local_def.rs
@@ -1,6 +1,5 @@
 use rustc_hir::{def::DefKind, Body, Item, ItemKind, Node, TyKind};
 use rustc_hir::{Path, QPath};
-use rustc_infer::infer::type_variable::TypeVariableOrigin;
 use rustc_infer::infer::InferCtxt;
 use rustc_infer::traits::{Obligation, ObligationCause};
 use rustc_middle::ty::{self, Binder, Ty, TyCtxt, TypeFoldable, TypeFolder};
@@ -337,7 +336,7 @@ impl<'a, 'tcx, F: FnMut(DefId) -> bool> TypeFolder<TyCtxt<'tcx>>
         if let Some(def) = t.ty_adt_def()
             && (self.did_has_local_parent)(def.did())
         {
-            self.infcx.next_ty_var(TypeVariableOrigin { param_def_id: None, span: self.infer_span })
+            self.infcx.next_ty_var(self.infer_span)
         } else {
             t.super_fold_with(self)
         }