Auto merge of #101467 - nnethercote:shrink-hir-Ty-Pat, r=spastorino

Shrink `hir::Ty` and `hir::Pat`

r? `@ghost`

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -338,7 +338,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
         &mut self,
         pats: &'tcx [hir::Pat<'tcx>],
         expected_len: usize,
-        gap_pos: Option<usize>,
+        gap_pos: hir::DotDotPos,
     ) -> Vec<FieldPat<'tcx>> {
         pats.iter()
             .enumerate_and_adjust(expected_len, gap_pos)