Fix const eval bug breaking run-pass tests in Miri

PR #63580 broke miri's ability to run the run-pass test suite with MIR optimizations enabled. The issue was that we weren't properly handling the substs and DefId associated with a Promoted value. This didn't break anything in rustc because in rustc this code runs before the Inliner pass which is where the DefId and substs can diverge from their initial values. It broke Miri though because it ran this code again after running the optimization pass.
rust-lang · bors · Sep 5, 2019 · Aug 21, 2019 · Aug 27, 2019 · Aug 27, 2019
commit 46877e289087c67d03572019fca9792d95e55e0c
diff --git a/src/librustc_mir/interpret/place.rs b/src/librustc_mir/interpret/place.rs
@@ -585,8 +585,9 @@ where
         use rustc::mir::StaticKind;
 
         Ok(match place_static.kind {
-            StaticKind::Promoted(promoted, _) => {
-                let instance = self.frame().instance;
+            StaticKind::Promoted(promoted, promoted_substs) => {
+                let substs = self.subst_from_frame_and_normalize_erasing_regions(promoted_substs);
+                let instance = ty::Instance::new(place_static.def_id, substs);
                 self.const_eval_raw(GlobalId {
                     instance,
                     promoted: Some(promoted),