Rollup merge of #129738 - nnethercote:rustc_mir_transform-cleanups, r=cjgillot

`rustc_mir_transform` cleanups

A bunch of small improvements I made while looking closely at this code.

r? `@saethlin`

Author: matthiaskrgr

compiler/rustc_mir_transform/src/add_moves_for_packed_drops.rs

@@ -86,7 +86,7 @@ fn add_move_for_packed_drop<'tcx>(
 
     let source_info = terminator.source_info;
     let ty = place.ty(body, tcx).ty;
-    let temp = patch.new_temp(ty, terminator.source_info.span);
+    let temp = patch.new_temp(ty, source_info.span);
 
     let storage_dead_block = patch.new_block(BasicBlockData {
         statements: vec![Statement { source_info, kind: StatementKind::StorageDead(temp) }],

compiler/rustc_mir_transform/src/check_packed_ref.rs

@@ -37,24 +37,17 @@ impl<'tcx> Visitor<'tcx> for PackedRefChecker<'_, 'tcx> {
     }
 
     fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, _location: Location) {
-        if context.is_borrow() {
-            if util::is_disaligned(self.tcx, self.body, self.param_env, *place) {
-                let def_id = self.body.source.instance.def_id();
-                if let Some(impl_def_id) = self.tcx.impl_of_method(def_id)
-                    && self.tcx.is_builtin_derived(impl_def_id)
-                {
-                    // If we ever reach here it means that the generated derive
-                    // code is somehow doing an unaligned reference, which it
-                    // shouldn't do.
-                    span_bug!(
-                        self.source_info.span,
-                        "builtin derive created an unaligned reference"
-                    );
-                } else {
-                    self.tcx
-                        .dcx()
-                        .emit_err(errors::UnalignedPackedRef { span: self.source_info.span });
-                }
+        if context.is_borrow() && util::is_disaligned(self.tcx, self.body, self.param_env, *place) {
+            let def_id = self.body.source.instance.def_id();
+            if let Some(impl_def_id) = self.tcx.impl_of_method(def_id)
+                && self.tcx.is_builtin_derived(impl_def_id)
+            {
+                // If we ever reach here it means that the generated derive
+                // code is somehow doing an unaligned reference, which it
+                // shouldn't do.
+                span_bug!(self.source_info.span, "builtin derive created an unaligned reference");
+            } else {
+                self.tcx.dcx().emit_err(errors::UnalignedPackedRef { span: self.source_info.span });
             }
         }
     }