Use `empty()` instead of a special const

src/librustc/middle/check_const.rs

@@ -45,8 +45,6 @@
 bitflags! {
     #[derive(RustcEncodable, RustcDecodable)]
     flags ConstQualif: u8 {
-        // Const rvalue which can be placed behind a reference.
-        const PURE_CONST         = 0,
         // Inner mutability (can not be placed behind a reference) or behind
         // &mut in a non-global expression. Can be copied from static memory.
         const MUTABLE_MEM        = 1 << 0,
@@ -104,7 +102,7 @@ fn with_mode<F, R>(&mut self, mode: Mode, f: F) -> R where
     {
         let (old_mode, old_qualif) = (self.mode, self.qualif);
         self.mode = mode;
-        self.qualif = ConstQualif::PURE_CONST;
+        self.qualif = ConstQualif::empty();
         let r = f(self);
         self.mode = old_mode;
         self.qualif = old_qualif;
@@ -128,7 +126,7 @@ fn global_expr(&mut self, mode: Mode, expr: &ast::Expr) -> ConstQualif {
             Entry::Occupied(entry) => return *entry.get(),
             Entry::Vacant(entry) => {
                 // Prevent infinite recursion on re-entry.
-                entry.insert(ConstQualif::PURE_CONST);
+                entry.insert(ConstQualif::empty());
             }
         }
         self.with_mode(mode, |this| {
@@ -273,7 +271,7 @@ fn visit_pat(&mut self, p: &ast::Pat) {
 
     fn visit_expr(&mut self, ex: &ast::Expr) {
         let mut outer = self.qualif;
-        self.qualif = ConstQualif::PURE_CONST;
+        self.qualif = ConstQualif::empty();
 
         let node_ty = ty::node_id_to_type(self.tcx, ex.id);
         check_expr(self, ex, node_ty);

src/librustc/middle/mem_categorization.rs

@@ -850,9 +850,10 @@ pub fn cat_rvalue_node(&self,
         // Compute maximum lifetime of this rvalue. This is 'static if
         // we can promote to a constant, otherwise equal to enclosing temp
         // lifetime.
-        let re = match qualif & check_const::ConstQualif::NON_STATIC_BORROWS {
-            check_const::ConstQualif::PURE_CONST => ty::ReStatic,
-            _ => self.temporary_scope(id),
+        let re = if qualif.intersects(check_const::ConstQualif::NON_STATIC_BORROWS) {
+            self.temporary_scope(id)
+        } else {
+            ty::ReStatic
         };
         let ret = self.cat_rvalue(id, span, re, expr_ty);
         debug!("cat_rvalue_node ret {}", ret.repr(self.tcx()));

src/librustc/middle/ty.rs

@@ -849,7 +849,6 @@ pub fn free_region_map(&self, id: NodeId) -> FreeRegionMap {
 // recursing over the type itself.
 bitflags! {
     flags TypeFlags: u32 {
-        const NO_TYPE_FLAGS     = 0,
         const HAS_PARAMS        = 1 << 0,
         const HAS_SELF          = 1 << 1,
         const HAS_TY_INFER      = 1 << 2,
@@ -2925,7 +2924,7 @@ struct FlagComputation {
 
 impl FlagComputation {
     fn new() -> FlagComputation {
-        FlagComputation { flags: TypeFlags::NO_TYPE_FLAGS, depth: 0 }
+        FlagComputation { flags: TypeFlags::empty(), depth: 0 }
     }
 
     fn for_sty(st: &sty) -> FlagComputation {

src/librustc_trans/trans/consts.rs

@@ -186,7 +186,7 @@ fn get_const_val(ccx: &CrateContext,
                  ref_expr: &ast::Expr) -> ValueRef {
     let expr = get_const_expr(ccx, def_id, ref_expr);
     let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
-    get_const_expr_as_global(ccx, expr, check_const::ConstQualif::PURE_CONST, empty_substs)
+    get_const_expr_as_global(ccx, expr, check_const::ConstQualif::empty(), empty_substs)
 }
 
 pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,

src/libsyntax/parse/parser.rs

@@ -88,7 +88,6 @@
 
 bitflags! {
     flags Restrictions: u8 {
-        const UNRESTRICTED                  = 0,
         const RESTRICTION_STMT_EXPR         = 1 << 0,
         const RESTRICTION_NO_STRUCT_LITERAL = 1 << 1,
     }
@@ -339,7 +338,7 @@ pub fn new(sess: &'a ParseSess,
             buffer_start: 0,
             buffer_end: 0,
             tokens_consumed: 0,
-            restrictions: Restrictions::UNRESTRICTED,
+            restrictions: Restrictions::empty(),
             quote_depth: 0,
             obsolete_set: HashSet::new(),
             mod_path_stack: Vec::new(),
@@ -2991,7 +2990,7 @@ pub fn parse_arm_nopanic(&mut self) -> PResult<Arm> {
 
     /// Parse an expression
     pub fn parse_expr_nopanic(&mut self) -> PResult<P<Expr>> {
-        return self.parse_expr_res(Restrictions::UNRESTRICTED);
+        self.parse_expr_res(Restrictions::empty())
     }
 
     /// Parse an expression, subject to the given restrictions