store the normalized types of statics in MIR Lvalues

The types of statics, like all other items, are stored in the tcx
unnormalized. This is necessarily so, because
    a) Item types other than statics have generics, which can't be
normalized.
    b) Eager normalization causes undesirable on-demand dependencies.

Keeping with the principle that MIR lvalues require no normalization in
order to interpret, this patch stores the normalized type of the statics
in the Lvalue and reads it to get the lvalue type.

Fixes #39367.

2 files changed, 13 insertions, 3 deletions

diff --git a/src/librustc_mir/build/expr/as_lvalue.rs b/src/librustc_mir/build/expr/as_lvalue.rs
index 5abfe084f22..ec412d4e9c6 100644
--- a/src/librustc_mir/build/expr/as_lvalue.rs
+++ b/src/librustc_mir/build/expr/as_lvalue.rs
@@ -84,7 +84,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 block.and(Lvalue::Local(index))
             }
             ExprKind::StaticRef { id } => {
-                block.and(Lvalue::Static(id))
+                block.and(Lvalue::Static(Box::new(Static { def_id: id, ty: expr.ty })))
             }
 
             ExprKind::Array { .. } |
diff --git a/src/librustc_mir/transform/type_check.rs b/src/librustc_mir/transform/type_check.rs
index af4a4a53905..c2faf27412c 100644
--- a/src/librustc_mir/transform/type_check.rs
+++ b/src/librustc_mir/transform/type_check.rs
@@ -126,8 +126,18 @@ impl<'a, 'b, 'gcx, 'tcx> TypeVerifier<'a, 'b, 'gcx, 'tcx> {
         debug!("sanitize_lvalue: {:?}", lvalue);
         match *lvalue {
             Lvalue::Local(index) => LvalueTy::Ty { ty: self.mir.local_decls[index].ty },
-            Lvalue::Static(def_id) =>
-                LvalueTy::Ty { ty: self.tcx().item_type(def_id) },
+            Lvalue::Static(box Static { def_id, ty: sty }) => {
+                let sty = self.sanitize_type(lvalue, sty);
+                let ty = self.tcx().item_type(def_id);
+                let ty = self.cx.normalize(&ty);
+                if let Err(terr) = self.cx.eq_types(self.last_span, ty, sty) {
+                    span_mirbug!(
+                        self, lvalue, "bad static type ({:?}: {:?}): {:?}",
+                        ty, sty, terr);
+                }
+                LvalueTy::Ty { ty: sty }
+
+            },
             Lvalue::Projection(ref proj) => {
                 let base_ty = self.sanitize_lvalue(&proj.base, location);
                 if let LvalueTy::Ty { ty } = base_ty {