adding mir::StaticKind enum for static and promoted

Author: Saleem Jaffer

src/librustc/mir/mod.rs

@@ -1915,19 +1915,22 @@ pub enum PlaceBase<'tcx> {
     Static(Box<Static<'tcx>>),
 }
 
-/// The `DefId` of a static, along with its normalized type (which is
-/// stored to avoid requiring normalization when reading MIR).
+/// We store the normalized type to avoid requiring normalization when reading MIR
 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
 pub struct Static<'tcx> {
-    pub def_id: DefId,
     pub ty: Ty<'tcx>,
-    pub promoted: Option<Promoted>,
+    pub kind: StaticKind,
+}
+
+#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable, RustcEncodable, RustcDecodable)]
+pub enum StaticKind {
+    Promoted(Promoted),
+    Static(DefId),
 }
 
 impl_stable_hash_for!(struct Static<'tcx> {
-    def_id,
     ty,
-    promoted
+    kind
 });
 
 /// The `Projection` data structure defines things of the form `B.x`
@@ -2058,21 +2061,23 @@ impl<'tcx> Debug for Place<'tcx> {
 
         match *self {
             Base(PlaceBase::Local(id)) => write!(fmt, "{:?}", id),
-            Base(PlaceBase::Static(box self::Static { def_id, ty, promoted })) => {
-                match promoted {
-                    None => write!(
-                        fmt,
-                        "({}: {:?})",
-                        ty::tls::with(|tcx| tcx.def_path_str(def_id)),
-                        ty
-                    ),
-                    Some(pr) => write!(
-                        fmt,
-                        "({:?}: {:?})",
-                        pr,
-                        ty
-                    ),
-                }
+            Base(PlaceBase::Static(box self::Static { ty, kind: StaticKind::Static(def_id) })) => {
+                write!(
+                    fmt,
+                    "({}: {:?})",
+                    ty::tls::with(|tcx| tcx.def_path_str(def_id)),
+                    ty
+                )
+            },
+            Base(PlaceBase::Static(
+                box self::Static { ty, kind: StaticKind::Promoted(promoted) })
+            ) => {
+                write!(
+                    fmt,
+                    "({:?}: {:?})",
+                    promoted,
+                    ty
+                )
             },
             Projection(ref data) => match data.elem {
                 ProjectionElem::Downcast(ref adt_def, index) => {

src/librustc/mir/visit.rs

@@ -725,15 +725,18 @@ macro_rules! make_mir_visitor {
                             place: & $($mutability)? Place<'tcx>,
                             context: PlaceContext<'tcx>,
                             location: Location) {
+                use crate::mir::{Static, StaticKind};
                 match place {
                     Place::Base(PlaceBase::Local(local)) => {
                         self.visit_local(local, context, location);
                     }
-                    Place::Base(PlaceBase::Static(static_)) => {
-                        if static_.promoted.is_none() {
-                            self.visit_def_id(& $($mutability)? static_.def_id, location);
-                        }
-                        self.visit_ty(& $($mutability)? static_.ty, TyContext::Location(location));
+                    Place::Base(
+                        PlaceBase::Static(box Static{kind: StaticKind::Static(def_id), ..})
+                    ) => {
+                        self.visit_def_id(& $($mutability)? *def_id, location)
+                    }
+                    Place::Base(PlaceBase::Static(box Static{ty, ..})) => {
+                        self.visit_ty(& $($mutability)? *ty, TyContext::Location(location));
                     }
                     Place::Projection(proj) => {
                         self.visit_projection(proj, context, location);

src/librustc_codegen_ssa/mir/block.rs

@@ -1,7 +1,7 @@
 use rustc::middle::lang_items;
 use rustc::ty::{self, Ty, TypeFoldable};
 use rustc::ty::layout::{self, LayoutOf, HasTyCtxt};
-use rustc::mir::{self, Place, PlaceBase};
+use rustc::mir::{self, Place, PlaceBase, Static, StaticKind};
 use rustc::mir::interpret::EvalErrorKind;
 use rustc_target::abi::call::{ArgType, FnType, PassMode, IgnoreMode};
 use rustc_target::spec::abi::Abi;
@@ -621,14 +621,18 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                         // but specified directly in the code. This means it gets promoted
                         // and we can then extract the value by evaluating the promoted.
                         mir::Operand::Copy(
-                            Place::Base(PlaceBase::Static(
-                                box mir::Static {promoted: Some(promoted), ty, ..}
-                            ))
+                            Place::Base(
+                                PlaceBase::Static(
+                                    box Static { kind: StaticKind::Promoted(promoted), ty }
+                                )
+                            )
                         ) |
                         mir::Operand::Move(
-                            Place::Base(PlaceBase::Static(
-                                box mir::Static {promoted: Some(promoted), ty, ..}
-                            ))
+                            Place::Base(
+                                PlaceBase::Static(
+                                    box Static { kind: StaticKind::Promoted(promoted), ty }
+                                )
+                            )
                         ) => {
                             let param_env = ty::ParamEnv::reveal_all();
                             let cid = mir::interpret::GlobalId {

src/librustc_codegen_ssa/mir/place.rs

@@ -409,7 +409,9 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
         let result = match *place {
             mir::Place::Base(mir::PlaceBase::Local(_)) => bug!(), // handled above
             mir::Place::Base(
-                mir::PlaceBase::Static(box mir::Static { def_id: _, ty, promoted: Some(promoted) })
+                mir::PlaceBase::Static(
+                    box mir::Static { ty, kind: mir::StaticKind::Promoted(promoted) }
+                )
             ) => {
                 let param_env = ty::ParamEnv::reveal_all();
                 let cid = mir::interpret::GlobalId {
@@ -438,7 +440,9 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 }
             }
             mir::Place::Base(
-                mir::PlaceBase::Static(box mir::Static { def_id, ty, promoted: None })
+                mir::PlaceBase::Static(
+                    box mir::Static { ty, kind: mir::StaticKind::Static(def_id) }
+                )
             ) => {
                 // NB: The layout of a static may be unsized as is the case when working
                 // with a static that is an extern_type.

src/librustc_mir/borrow_check/error_reporting.rs

@@ -10,7 +10,7 @@ use rustc::mir::{
     self, AggregateKind, BindingForm, BorrowKind, ClearCrossCrate, Constant,
     ConstraintCategory, Field, Local, LocalDecl, LocalKind, Location, Operand,
     Place, PlaceBase, PlaceProjection, ProjectionElem, Rvalue, Statement, StatementKind,
-    TerminatorKind, VarBindingForm,
+    Static, StaticKind, TerminatorKind, VarBindingForm,
 };
 use rustc::ty::{self, DefIdTree};
 use rustc::ty::print::Print;
@@ -1601,12 +1601,11 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
             Place::Base(PlaceBase::Local(local)) => {
                 self.append_local_to_string(local, buf)?;
             }
-            Place::Base(PlaceBase::Static(ref static_)) => {
-                if static_.promoted.is_some() {
-                    buf.push_str("promoted");
-                } else {
-                    buf.push_str(&self.infcx.tcx.item_name(static_.def_id).to_string());
-                }
+            Place::Base(PlaceBase::Static(box Static{ kind: StaticKind::Promoted(_), .. })) => {
+                buf.push_str("promoted");
+            }
+            Place::Base(PlaceBase::Static(box Static{ kind: StaticKind::Static(def_id), .. })) => {
+                buf.push_str(&self.infcx.tcx.item_name(def_id).to_string());
             }
             Place::Projection(ref proj) => {
                 match proj.elem {
@@ -1808,8 +1807,10 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
 
     /// Checks if a place is a thread-local static.
     pub fn is_place_thread_local(&self, place: &Place<'tcx>) -> bool {
-        if let Place::Base(PlaceBase::Static(statik)) = place {
-            let attrs = self.infcx.tcx.get_attrs(statik.def_id);
+        if let Place::Base(
+            PlaceBase::Static(box Static{ kind: StaticKind::Static(def_id), .. })
+        ) = place {
+            let attrs = self.infcx.tcx.get_attrs(*def_id);
             let is_thread_local = attrs.iter().any(|attr| attr.check_name("thread_local"));
 
             debug!(

src/librustc_mir/borrow_check/mod.rs

@@ -8,7 +8,9 @@ use rustc::infer::InferCtxt;
 use rustc::lint::builtin::UNUSED_MUT;
 use rustc::middle::borrowck::SignalledError;
 use rustc::mir::{AggregateKind, BasicBlock, BorrowCheckResult, BorrowKind};
-use rustc::mir::{ClearCrossCrate, Local, Location, Mir, Mutability, Operand, Place, PlaceBase};
+use rustc::mir::{
+    ClearCrossCrate, Local, Location, Mir, Mutability, Operand, Place, PlaceBase, Static, StaticKind
+};
 use rustc::mir::{Field, Projection, ProjectionElem, Rvalue, Statement, StatementKind};
 use rustc::mir::{Terminator, TerminatorKind};
 use rustc::ty::query::Providers;
@@ -1308,8 +1310,13 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
         //
         // FIXME: allow thread-locals to borrow other thread locals?
         let (might_be_alive, will_be_dropped) = match root_place {
-            Place::Base(PlaceBase::Static(st)) => {
-                (true, st.promoted.is_none() && self.is_place_thread_local(&root_place))
+            Place::Base(PlaceBase::Static(box Static{ kind: StaticKind::Promoted(_), .. })) => {
+                (true, false)
+            }
+            Place::Base(PlaceBase::Static(box Static{ kind: _, .. })) => {
+                // Thread-locals might be dropped after the function exits, but
+                // "true" statics will never be.
+                (true, self.is_place_thread_local(&root_place))
             }
             Place::Base(PlaceBase::Local(_)) => {
                 // Locals are always dropped at function exit, and if they
@@ -1982,18 +1989,19 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
             }
             // The rules for promotion are made by `qualify_consts`, there wouldn't even be a
             // `Place::Promoted` if the promotion weren't 100% legal. So we just forward this
-            Place::Base(PlaceBase::Static(ref static_)) => {
-                if static_.promoted.is_some() ||
-                    (static_.promoted.is_none() &&
-                        self.infcx.tcx.is_static(static_.def_id)
-                            == Some(hir::Mutability::MutMutable)
-                    ){
+            Place::Base(PlaceBase::Static(box Static{kind: StaticKind::Promoted(_), ..})) =>
+                Ok(RootPlace {
+                    place,
+                    is_local_mutation_allowed,
+                }),
+            Place::Base(PlaceBase::Static(box Static{ kind: StaticKind::Static(def_id), .. })) => {
+                if self.infcx.tcx.is_static(def_id) != Some(hir::Mutability::MutMutable) {
+                    Err(place)
+                } else {
                     Ok(RootPlace {
                         place,
                         is_local_mutation_allowed,
                     })
-                } else {
-                    Err(place)
                 }
             }
             Place::Projection(ref proj) => {

src/librustc_mir/borrow_check/mutability_errors.rs

@@ -1,7 +1,9 @@
 use rustc::hir;
 use rustc::hir::Node;
 use rustc::mir::{self, BindingForm, Constant, ClearCrossCrate, Local, Location, Mir};
-use rustc::mir::{Mutability, Operand, Place, PlaceBase, Projection, ProjectionElem, Static};
+use rustc::mir::{
+    Mutability, Operand, Place, PlaceBase, Projection, ProjectionElem, Static, StaticKind,
+};
 use rustc::mir::{Terminator, TerminatorKind};
 use rustc::ty::{self, Const, DefIdTree, TyS, TyKind, TyCtxt};
 use rustc_data_structures::indexed_vec::Idx;
@@ -129,8 +131,10 @@ impl<'a, 'gcx, 'tcx> MirBorrowckCtxt<'a, 'gcx, 'tcx> {
                 }
             }
 
-            Place::Base(PlaceBase::Static(box Static { def_id, ty: _, promoted })) => {
-                assert!(promoted.is_none());
+            Place::Base(PlaceBase::Static(box Static { kind: StaticKind::Promoted(_), .. })) =>
+                unreachable!(),
+
+            Place::Base(PlaceBase::Static(box Static { kind: StaticKind::Static(def_id), .. })) => {
                 if let Place::Base(PlaceBase::Static(_)) = access_place {
                     item_msg = format!("immutable static item `{}`", access_place_desc.unwrap());
                     reason = String::new();

src/librustc_mir/borrow_check/nll/type_check/mod.rs

@@ -453,45 +453,53 @@ impl<'a, 'b, 'gcx, 'tcx> TypeVerifier<'a, 'b, 'gcx, 'tcx> {
             Place::Base(PlaceBase::Local(index)) => PlaceTy::Ty {
                 ty: self.mir.local_decls[index].ty,
             },
-            Place::Base(PlaceBase::Static(box Static { def_id, ty: sty, promoted })) => {
+            Place::Base(
+                PlaceBase::Static(box Static { kind: StaticKind::Promoted(promoted), ty: sty })
+            ) => {
                 let sty = self.sanitize_type(place, sty);
-                let check_err =
-                    |verifier: &mut TypeVerifier<'a, 'b, 'gcx, 'tcx> ,
-                     place: &Place<'tcx>,
-                     ty,
-                     sty| {
-                    if let Err(terr) = verifier.cx.eq_types(
+
+                if !self.errors_reported {
+                    let promoted_mir = &self.mir.promoted[promoted];
+                    self.sanitize_promoted(promoted_mir, location);
+
+                    let promoted_ty = promoted_mir.return_ty();
+
+                    if let Err(terr) = self.cx.eq_types(
                         sty,
-                        ty,
+                        promoted_ty,
                         location.to_locations(),
                         ConstraintCategory::Boring,
                     ) {
                         span_mirbug!(
-                            verifier,
+                            self,
                             place,
                             "bad promoted type ({:?}: {:?}): {:?}",
-                            ty,
+                            promoted_ty,
                             sty,
                             terr
                         );
                     };
-                };
-                match promoted {
-                    Some(pr) => {
-                        if !self.errors_reported {
-                            let promoted_mir = &self.mir.promoted[pr];
-                            self.sanitize_promoted(promoted_mir, location);
-
-                            let promoted_ty = promoted_mir.return_ty();
-                            check_err(self, place, promoted_ty, sty);
-                        }
-                    }
-                    None => {
-                        let ty = self.tcx().type_of(def_id);
-                        let ty = self.cx.normalize(ty, location);
-
-                        check_err(self, place, ty, sty);
-                    }
+                }
+                PlaceTy::Ty { ty: sty }
+            }
+            Place::Base(
+                PlaceBase::Static(box Static { kind: StaticKind::Static(def_id), ty: sty })
+            ) => {
+                let sty = self.sanitize_type(place, sty);
+                let ty = self.tcx().type_of(def_id);
+                let ty = self.cx.normalize(ty, location);
+                if let Err(terr) =
+                    self.cx
+                        .eq_types(ty, sty, location.to_locations(), ConstraintCategory::Boring)
+                {
+                    span_mirbug!(
+                        self,
+                        place,
+                        "bad static type ({:?}: {:?}): {:?}",
+                        ty,
+                        sty,
+                        terr
+                    );
                 }
                 PlaceTy::Ty { ty: sty }
             }

src/librustc_mir/borrow_check/place_ext.rs

@@ -1,6 +1,6 @@
 use rustc::hir;
 use rustc::mir::ProjectionElem;
-use rustc::mir::{Local, Mir, Place, PlaceBase, Mutability};
+use rustc::mir::{Local, Mir, Place, PlaceBase, Mutability, Static, StaticKind};
 use rustc::ty::{self, TyCtxt};
 use crate::borrow_check::borrow_set::LocalsStateAtExit;
 
@@ -49,9 +49,10 @@ impl<'tcx> PlaceExt<'tcx> for Place<'tcx> {
                     }
                 }
             }
-            Place::Base(PlaceBase::Static(static_)) => {
-                static_.promoted.is_none() &&
-                    (tcx.is_static(static_.def_id) == Some(hir::Mutability::MutMutable))
+            Place::Base(PlaceBase::Static(box Static{ kind: StaticKind::Promoted(_), .. })) =>
+                false,
+            Place::Base(PlaceBase::Static(box Static{ kind: StaticKind::Static(def_id), .. })) => {
+                tcx.is_static(*def_id) == Some(hir::Mutability::MutMutable)
             }
             Place::Projection(proj) => match proj.elem {
                 ProjectionElem::Field(..)