compiler/rustc_middle/src/middle/exported_symbols.rs

   1 use crate::ty::subst::SubstsRef;
   2 use crate::ty::{self, Ty, TyCtxt};
   3 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
   4 use rustc_macros::HashStable;
   5
   6 /// The SymbolExportLevel of a symbols specifies from which kinds of crates
   7 /// the symbol will be exported. `C` symbols will be exported from any
   8 /// kind of crate, including cdylibs which export very few things.
   9 /// `Rust` will only be exported if the crate produced is a Rust
  10 /// dylib.
  11 #[derive(Eq, PartialEq, Debug, Copy, Clone, TyEncodable, TyDecodable, HashStable)]
  12 pub enum SymbolExportLevel {
  13     C,
  14     Rust,
  15 }
  16
  17 impl SymbolExportLevel {
  18     pub fn is_below_threshold(self, threshold: SymbolExportLevel) -> bool {
  19         threshold == SymbolExportLevel::Rust // export everything from Rust dylibs
  20           || self == SymbolExportLevel::C
  21     }
  22 }
  23
  24 #[derive(Eq, PartialEq, Debug, Copy, Clone, TyEncodable, TyDecodable, HashStable)]
  25 pub enum ExportedSymbol<'tcx> {
  26     NonGeneric(DefId),
  27     Generic(DefId, SubstsRef<'tcx>),
  28     DropGlue(Ty<'tcx>),
  29     NoDefId(ty::SymbolName<'tcx>),
  30 }
  31
  32 impl<'tcx> ExportedSymbol<'tcx> {
  33     /// This is the symbol name of an instance if it is instantiated in the
  34     /// local crate.
  35     pub fn symbol_name_for_local_instance(&self, tcx: TyCtxt<'tcx>) -> ty::SymbolName<'tcx> {
  36         match *self {
  37             ExportedSymbol::NonGeneric(def_id) => tcx.symbol_name(ty::Instance::mono(tcx, def_id)),
  38             ExportedSymbol::Generic(def_id, substs) => {
  39                 tcx.symbol_name(ty::Instance::new(def_id, substs))
  40             }
  41             ExportedSymbol::DropGlue(ty) => {
  42                 tcx.symbol_name(ty::Instance::resolve_drop_in_place(tcx, ty))
  43             }
  44             ExportedSymbol::NoDefId(symbol_name) => symbol_name,
  45         }
  46     }
  47 }
  48
  49 pub fn metadata_symbol_name(tcx: TyCtxt<'_>) -> String {
  50     format!(
  51         "rust_metadata_{}_{:08x}",
  52         tcx.crate_name(LOCAL_CRATE),
  53         tcx.sess.local_stable_crate_id().to_u64(),
  54     )
  55 }