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.

8 files changed, 100 insertions, 16 deletions

diff --git a/src/librustc/mir/mod.rs b/src/librustc/mir/mod.rs
index 40ebc97a78a..a7e89e77f34 100644
--- a/src/librustc/mir/mod.rs
+++ b/src/librustc/mir/mod.rs
@@ -816,12 +816,20 @@ pub enum Lvalue<'tcx> {
     Local(Local),
 
     /// static or static mut variable
-    Static(DefId),
+    Static(Box<Static<'tcx>>),
 
     /// projection out of an lvalue (access a field, deref a pointer, etc)
     Projection(Box<LvalueProjection<'tcx>>),
 }
 
+/// The def-id of a static, along with its normalized type (which is
+/// stored to avoid requiring normalization when reading MIR).
+#[derive(Clone, PartialEq, RustcEncodable, RustcDecodable)]
+pub struct Static<'tcx> {
+    pub def_id: DefId,
+    pub ty: Ty<'tcx>,
+}
+
 /// The `Projection` data structure defines things of the form `B.x`
 /// or `*B` or `B[index]`. Note that it is parameterized because it is
 /// shared between `Constant` and `Lvalue`. See the aliases
@@ -911,8 +919,8 @@ impl<'tcx> Debug for Lvalue<'tcx> {
 
         match *self {
             Local(id) => write!(fmt, "{:?}", id),
-            Static(def_id) =>
-                write!(fmt, "{}", ty::tls::with(|tcx| tcx.item_path_str(def_id))),
+            Static(box self::Static { def_id, ty }) =>
+                write!(fmt, "({}: {:?})", ty::tls::with(|tcx| tcx.item_path_str(def_id)), ty),
             Projection(ref data) =>
                 match data.elem {
                     ProjectionElem::Downcast(ref adt_def, index) =>
diff --git a/src/librustc/mir/tcx.rs b/src/librustc/mir/tcx.rs
index 50a80305bee..638655aee15 100644
--- a/src/librustc/mir/tcx.rs
+++ b/src/librustc/mir/tcx.rs
@@ -125,8 +125,8 @@ impl<'tcx> Lvalue<'tcx> {
         match *self {
             Lvalue::Local(index) =>
                 LvalueTy::Ty { ty: mir.local_decls[index].ty },
-            Lvalue::Static(def_id) =>
-                LvalueTy::Ty { ty: tcx.item_type(def_id) },
+            Lvalue::Static(ref data) =>
+                LvalueTy::Ty { ty: data.ty },
             Lvalue::Projection(ref proj) =>
                 proj.base.ty(mir, tcx).projection_ty(tcx, &proj.elem),
         }
diff --git a/src/librustc/mir/visit.rs b/src/librustc/mir/visit.rs
index 7cdbd5cae06..1172172a845 100644
--- a/src/librustc/mir/visit.rs
+++ b/src/librustc/mir/visit.rs
@@ -154,6 +154,13 @@ macro_rules! make_mir_visitor {
                 self.super_lvalue(lvalue, context, location);
             }
 
+            fn visit_static(&mut self,
+                            static_: & $($mutability)* Static<'tcx>,
+                            context: LvalueContext<'tcx>,
+                            location: Location) {
+                self.super_static(static_, context, location);
+            }
+
             fn visit_projection(&mut self,
                                 lvalue: & $($mutability)* LvalueProjection<'tcx>,
                                 context: LvalueContext<'tcx>,
@@ -559,8 +566,8 @@ macro_rules! make_mir_visitor {
                 match *lvalue {
                     Lvalue::Local(_) => {
                     }
-                    Lvalue::Static(ref $($mutability)* def_id) => {
-                        self.visit_def_id(def_id, location);
+                    Lvalue::Static(ref $($mutability)* static_) => {
+                        self.visit_static(static_, context, location);
                     }
                     Lvalue::Projection(ref $($mutability)* proj) => {
                         self.visit_projection(proj, context, location);
@@ -568,6 +575,18 @@ macro_rules! make_mir_visitor {
                 }
             }
 
+            fn super_static(&mut self,
+                            static_: & $($mutability)* Static<'tcx>,
+                            _context: LvalueContext<'tcx>,
+                            location: Location) {
+                let Static {
+                    ref $($mutability)* def_id,
+                    ref $($mutability)* ty,
+                } = *static_;
+                self.visit_def_id(def_id, location);
+                self.visit_ty(ty);
+            }
+
             fn super_projection(&mut self,
                                 proj: & $($mutability)* LvalueProjection<'tcx>,
                                 context: LvalueContext<'tcx>,
@@ -837,4 +856,3 @@ impl<'tcx> LvalueContext<'tcx> {
         self.is_mutating_use() || self.is_nonmutating_use()
     }
 }
-
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 {
diff --git a/src/librustc_trans/mir/constant.rs b/src/librustc_trans/mir/constant.rs
index 771a5b7f366..fb2ef8f60c4 100644
--- a/src/librustc_trans/mir/constant.rs
+++ b/src/librustc_trans/mir/constant.rs
@@ -382,11 +382,11 @@ impl<'a, 'tcx> MirConstContext<'a, 'tcx> {
 
         let lvalue = match *lvalue {
             mir::Lvalue::Local(_)  => bug!(), // handled above
-            mir::Lvalue::Static(def_id) => {
+            mir::Lvalue::Static(box mir::Static { def_id, ty }) => {
                 ConstLvalue {
                     base: Base::Static(consts::get_static(self.ccx, def_id)),
                     llextra: ptr::null_mut(),
-                    ty: lvalue.ty(self.mir, tcx).to_ty(tcx)
+                    ty: self.monomorphize(&ty),
                 }
             }
             mir::Lvalue::Projection(ref projection) => {
diff --git a/src/librustc_trans/mir/lvalue.rs b/src/librustc_trans/mir/lvalue.rs
index 2538f32031f..49e1e385557 100644
--- a/src/librustc_trans/mir/lvalue.rs
+++ b/src/librustc_trans/mir/lvalue.rs
@@ -304,10 +304,9 @@ impl<'a, 'tcx> MirContext<'a, 'tcx> {
 
         let result = match *lvalue {
             mir::Lvalue::Local(_) => bug!(), // handled above
-            mir::Lvalue::Static(def_id) => {
-                let const_ty = self.monomorphized_lvalue_ty(lvalue);
+            mir::Lvalue::Static(box mir::Static { def_id, ty }) => {
                 LvalueRef::new_sized(consts::get_static(ccx, def_id),
-                                     LvalueTy::from_ty(const_ty),
+                                     LvalueTy::from_ty(self.monomorphize(&ty)),
                                      Alignment::AbiAligned)
             },
             mir::Lvalue::Projection(box mir::Projection {
diff --git a/src/test/run-pass/issue-39367.rs b/src/test/run-pass/issue-39367.rs
new file mode 100644
index 00000000000..3e72efada84
--- /dev/null
+++ b/src/test/run-pass/issue-39367.rs
@@ -0,0 +1,49 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::ops::Deref;
+
+struct ArenaSet<U: Deref, V=<U as Deref>::Target>(U, &'static V)
+    where V: 'static + ?Sized;
+
+static Z: [u8; 4] = [1,2,3,4];
+
+fn arena() -> &'static ArenaSet<Vec<u8>> {
+    fn __static_ref_initialize() -> ArenaSet<Vec<u8>> {
+        ArenaSet(vec![], &Z)
+    }
+    unsafe {
+        use std::sync::{Once, ONCE_INIT};
+        fn require_sync<T: Sync>(_: &T) { }
+        unsafe fn __stability() -> &'static ArenaSet<Vec<u8>> {
+            use std::mem::transmute;
+            use std::boxed::Box;
+            static mut DATA: *const ArenaSet<Vec<u8>> = 0 as *const ArenaSet<Vec<u8>>;
+
+            static mut ONCE: Once = ONCE_INIT;
+            ONCE.call_once(|| {
+                DATA = transmute
+                    ::<Box<ArenaSet<Vec<u8>>>, *const ArenaSet<Vec<u8>>>
+                    (Box::new(__static_ref_initialize()));
+            });
+
+            &*DATA
+        }
+        let static_ref = __stability();
+        require_sync(static_ref);
+        static_ref
+    }
+}
+
+fn main() {
+    let &ArenaSet(ref u, v) = arena();
+    assert!(u.is_empty());
+    assert_eq!(v, Z);
+}