src/librustc/middle/exported_symbols.rs

   1 use crate::hir::def_id::{DefId, LOCAL_CRATE};
   2 use crate::ich::StableHashingContext;
   3 use rustc_data_structures::stable_hasher::{StableHasher, HashStable,
   4                                            StableHasherResult};
   5 use std::cmp;
   6 use std::mem;
   7 use crate::ty::{self, TyCtxt};
   8 use crate::ty::subst::SubstsRef;
   9
  10 /// The SymbolExportLevel of a symbols specifies from which kinds of crates
  11 /// the symbol will be exported. `C` symbols will be exported from any
  12 /// kind of crate, including cdylibs which export very few things.
  13 /// `Rust` will only be exported if the crate produced is a Rust
  14 /// dylib.
  15 #[derive(Eq, PartialEq, Debug, Copy, Clone, RustcEncodable, RustcDecodable)]
  16 pub enum SymbolExportLevel {
  17     C,
  18     Rust,
  19 }
  20
  21 impl_stable_hash_for!(enum self::SymbolExportLevel {
  22     C,
  23     Rust
  24 });
  25
  26 impl SymbolExportLevel {
  27     pub fn is_below_threshold(self, threshold: SymbolExportLevel) -> bool {
  28         threshold == SymbolExportLevel::Rust // export everything from Rust dylibs
  29           || self == SymbolExportLevel::C
  30     }
  31 }
  32
  33 #[derive(Eq, PartialEq, Debug, Copy, Clone, RustcEncodable, RustcDecodable)]
  34 pub enum ExportedSymbol<'tcx> {
  35     NonGeneric(DefId),
  36     Generic(DefId, SubstsRef<'tcx>),
  37     NoDefId(ty::SymbolName),
  38 }
  39
  40 impl<'tcx> ExportedSymbol<'tcx> {
  41     pub fn symbol_name(&self, tcx: TyCtxt<'tcx, '_>) -> ty::SymbolName {
  42         match *self {
  43             ExportedSymbol::NonGeneric(def_id) => {
  44                 tcx.symbol_name(ty::Instance::mono(tcx, def_id))
  45             }
  46             ExportedSymbol::Generic(def_id, substs) => {
  47                 tcx.symbol_name(ty::Instance::new(def_id, substs))
  48             }
  49             ExportedSymbol::NoDefId(symbol_name) => {
  50                 symbol_name
  51             }
  52         }
  53     }
  54
  55     pub fn compare_stable(
  56         &self,
  57         tcx: TyCtxt<'tcx, '_>,
  58         other: &ExportedSymbol<'tcx>,
  59     ) -> cmp::Ordering {
  60         match *self {
  61             ExportedSymbol::NonGeneric(self_def_id) => match *other {
  62                 ExportedSymbol::NonGeneric(other_def_id) => {
  63                     tcx.def_path_hash(self_def_id).cmp(&tcx.def_path_hash(other_def_id))
  64                 }
  65                 ExportedSymbol::Generic(..) |
  66                 ExportedSymbol::NoDefId(_) => {
  67                     cmp::Ordering::Less
  68                 }
  69             }
  70             ExportedSymbol::Generic(..) => match *other {
  71                 ExportedSymbol::NonGeneric(_) => {
  72                     cmp::Ordering::Greater
  73                 }
  74                 ExportedSymbol::Generic(..) => {
  75                     self.symbol_name(tcx).cmp(&other.symbol_name(tcx))
  76                 }
  77                 ExportedSymbol::NoDefId(_) => {
  78                     cmp::Ordering::Less
  79                 }
  80             }
  81             ExportedSymbol::NoDefId(self_symbol_name) => match *other {
  82                 ExportedSymbol::NonGeneric(_) |
  83                 ExportedSymbol::Generic(..) => {
  84                     cmp::Ordering::Greater
  85                 }
  86                 ExportedSymbol::NoDefId(ref other_symbol_name) => {
  87                     self_symbol_name.cmp(other_symbol_name)
  88                 }
  89             }
  90         }
  91     }
  92 }
  93
  94 pub fn metadata_symbol_name(tcx: TyCtxt<'_, '_>) -> String {
  95     format!("rust_metadata_{}_{}",
  96             tcx.original_crate_name(LOCAL_CRATE),
  97             tcx.crate_disambiguator(LOCAL_CRATE).to_fingerprint().to_hex())
  98 }
  99
 100 impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for ExportedSymbol<'gcx> {
 101     fn hash_stable<W: StableHasherResult>(&self,
 102                                           hcx: &mut StableHashingContext<'a>,
 103                                           hasher: &mut StableHasher<W>) {
 104         mem::discriminant(self).hash_stable(hcx, hasher);
 105         match *self {
 106             ExportedSymbol::NonGeneric(def_id) => {
 107                 def_id.hash_stable(hcx, hasher);
 108             }
 109             ExportedSymbol::Generic(def_id, substs) => {
 110                 def_id.hash_stable(hcx, hasher);
 111                 substs.hash_stable(hcx, hasher);
 112             }
 113             ExportedSymbol::NoDefId(symbol_name) => {
 114                 symbol_name.hash_stable(hcx, hasher);
 115             }
 116         }
 117     }
 118 }