Split CrateNum into an enum instead of having magic constants

src/librustc/hir/def_id.rs

@@ -18,23 +18,51 @@ use std::u32;
 newtype_index! {
     pub struct CrateNum {
         ENCODABLE = custom
-        DEBUG_FORMAT = "crate{}",
+    }
+}
 
-        /// Item definitions in the currently-compiled crate would have the CrateNum
-        /// LOCAL_CRATE in their DefId.
-        const LOCAL_CRATE = 0,
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub enum CrateNum {
+    /// Virtual crate for builtin macros
+    // FIXME(jseyfried): this is also used for custom derives until proc-macro crates get
+    // `CrateNum`s.
+    BuiltinMacros,
+    /// A CrateNum value that indicates that something is wrong.
+    Invalid,
+    /// A special CrateNum that we use for the tcx.rcache when decoding from
+    /// the incr. comp. cache.
+    ReservedForIncrCompCache,
+    Index(CrateId),
+}
 
-        /// Virtual crate for builtin macros
-        // FIXME(jseyfried): this is also used for custom derives until proc-macro crates get
-        // `CrateNum`s.
-        const BUILTIN_MACROS_CRATE = CrateNum::MAX_AS_U32,
+impl ::std::fmt::Debug for CrateNum {
+    fn fmt(&self, fmt: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+        match self {
+            CrateNum::Index(id) => write!(fmt, "crate{}", id.0),
+            CrateNum::Invalid => write!(fmt, "invalid crate"),
+            CrateNum::BuiltinMacros => write!(fmt, "bultin macros crate"),
+            CrateNum::ReservedForIncrCompCache => write!(fmt, "crate for decoding incr comp cache"),
+        }
+    }
+}
 
-        /// A CrateNum value that indicates that something is wrong.
-        const INVALID_CRATE = CrateNum::MAX_AS_U32 - 1,
+/// Item definitions in the currently-compiled crate would have the CrateNum
+/// LOCAL_CRATE in their DefId.
+pub const LOCAL_CRATE: CrateNum = CrateNum::Index(CrateId(0));
 
-        /// A special CrateNum that we use for the tcx.rcache when decoding from
-        /// the incr. comp. cache.
-        const RESERVED_FOR_INCR_COMP_CACHE = CrateNum::MAX_AS_U32 - 2,
+
+impl Idx for CrateNum {
+    #[inline]
+    fn new(value: usize) -> Self {
+        CrateNum::Index(Idx::new(value))
+    }
+
+    #[inline]
+    fn index(self) -> usize {
+        match self {
+            CrateNum::Index(idx) => Idx::index(idx),
+            _ => bug!("Tried to get crate index of {:?}", self),
+        }
     }
 }
 
@@ -48,7 +76,12 @@ impl CrateNum {
 
 impl fmt::Display for CrateNum {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Display::fmt(&self.as_u32(), f)
+        match self {
+            CrateNum::Index(id) => fmt::Display::fmt(&id.0, f),
+            CrateNum::Invalid => write!(f, "invalid crate"),
+            CrateNum::BuiltinMacros => write!(f, "bultin macros crate"),
+            CrateNum::ReservedForIncrCompCache => write!(f, "crate for decoding incr comp cache"),
+        }
     }
 }
 

src/librustc/ty/context.rs

@@ -829,9 +829,9 @@ impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for TypeckTables<'gcx> {
 impl<'tcx> CommonTypes<'tcx> {
     fn new(interners: &CtxtInterners<'tcx>) -> CommonTypes<'tcx> {
         // Ensure our type representation does not grow
-        #[cfg(target_pointer_width = "64")]
+        #[cfg(all(not(stage0), target_pointer_width = "64"))]
         assert!(mem::size_of::<ty::TyKind>() <= 24);
-        #[cfg(target_pointer_width = "64")]
+        #[cfg(all(not(stage0), target_pointer_width = "64"))]
         assert!(mem::size_of::<ty::TyS>() <= 32);
 
         let mk = |sty| CtxtInterners::intern_ty(interners, interners, sty);

src/librustc/ty/query/on_disk_cache.rs

@@ -11,8 +11,7 @@
 use dep_graph::{DepNodeIndex, SerializedDepNodeIndex};
 use errors::Diagnostic;
 use hir;
-use hir::def_id::{CrateNum, DefIndex, DefId, LocalDefId,
-                  RESERVED_FOR_INCR_COMP_CACHE, LOCAL_CRATE};
+use hir::def_id::{CrateNum, DefIndex, DefId, LocalDefId, LOCAL_CRATE};
 use hir::map::definitions::DefPathHash;
 use ich::{CachingSourceMapView, Fingerprint};
 use mir::{self, interpret};
@@ -566,7 +565,7 @@ impl<'a, 'tcx: 'a, 'x> ty_codec::TyDecoder<'a, 'tcx> for CacheDecoder<'a, 'tcx,
         let tcx = self.tcx();
 
         let cache_key = ty::CReaderCacheKey {
-            cnum: RESERVED_FOR_INCR_COMP_CACHE,
+            cnum: CrateNum::ReservedForIncrCompCache,
             pos: shorthand,
         };
 

src/librustc_resolve/build_reduced_graph.rs

@@ -22,7 +22,7 @@ use Namespace::{self, TypeNS, ValueNS, MacroNS};
 use {resolve_error, resolve_struct_error, ResolutionError};
 
 use rustc::hir::def::*;
-use rustc::hir::def_id::{BUILTIN_MACROS_CRATE, CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
+use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, LOCAL_CRATE, DefId};
 use rustc::ty;
 use rustc::middle::cstore::CrateStore;
 use rustc_metadata::cstore::LoadedMacro;
@@ -768,7 +768,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
         let def_id = self.macro_defs[&expansion];
         if let Some(id) = self.definitions.as_local_node_id(def_id) {
             self.local_macro_def_scopes[&id]
-        } else if def_id.krate == BUILTIN_MACROS_CRATE {
+        } else if def_id.krate == CrateNum::BuiltinMacros {
             self.injected_crate.unwrap_or(self.graph_root)
         } else {
             let module_def_id = ty::DefIdTree::parent(&*self, def_id).unwrap();

src/librustc_resolve/macros.rs

@@ -14,8 +14,8 @@ use ModuleOrUniformRoot;
 use Namespace::{self, TypeNS, MacroNS};
 use build_reduced_graph::{BuildReducedGraphVisitor, IsMacroExport};
 use resolve_imports::ImportResolver;
-use rustc::hir::def_id::{DefId, BUILTIN_MACROS_CRATE, CRATE_DEF_INDEX, DefIndex,
-                         DefIndexAddressSpace};
+use rustc::hir::def_id::{DefId, CRATE_DEF_INDEX, DefIndex,
+                         CrateNum, DefIndexAddressSpace};
 use rustc::hir::def::{Def, NonMacroAttrKind};
 use rustc::hir::map::{self, DefCollector};
 use rustc::{ty, lint};
@@ -202,7 +202,7 @@ impl<'a, 'crateloader: 'a> base::Resolver for Resolver<'a, 'crateloader> {
 
     fn add_builtin(&mut self, ident: ast::Ident, ext: Lrc<SyntaxExtension>) {
         let def_id = DefId {
-            krate: BUILTIN_MACROS_CRATE,
+            krate: CrateNum::BuiltinMacros,
             index: DefIndex::from_array_index(self.macro_map.len(),
                                               DefIndexAddressSpace::Low),
         };
@@ -335,7 +335,7 @@ impl<'a, 'crateloader: 'a> base::Resolver for Resolver<'a, 'crateloader> {
             self.definitions.add_parent_module_of_macro_def(invoc.expansion_data.mark,
                                                             normal_module_def_id);
             invoc.expansion_data.mark.set_default_transparency(ext.default_transparency());
-            invoc.expansion_data.mark.set_is_builtin(def_id.krate == BUILTIN_MACROS_CRATE);
+            invoc.expansion_data.mark.set_is_builtin(def_id.krate == CrateNum::BuiltinMacros);
         }
 
         Ok(Some(ext))
@@ -1087,7 +1087,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
         };
 
         // Plugin-based syntax extensions are exempt from this check
-        if krate == BUILTIN_MACROS_CRATE { return; }
+        if krate == CrateNum::BuiltinMacros { return; }
 
         let ext = binding.get_macro(self);