src/librustc/middle/cstore.rs - third_party/rust - Git at Google

 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.

 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.

 //! the rustc crate store interface. This also includes types that
 //! are *mostly* used as a part of that interface, but these should
 //! probably get a better home if someone can find one.

 use hir;
 use hir::def;
 use hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
 use hir::map as hir_map;
 use hir::map::definitions::{Definitions, DefKey, DefPathTable};
 use hir::svh::Svh;
 use ich;
 use ty::{self, TyCtxt};
 use session::{Session, CrateDisambiguator};
 use session::search_paths::PathKind;

 use std::any::Any;
 use std::collections::BTreeMap;
 use std::path::{Path, PathBuf};
 use syntax::ast;
 use syntax::ext::base::SyntaxExtension;
 use syntax::symbol::Symbol;
 use syntax_pos::Span;
 use rustc_back::target::Target;
 use rustc_data_structures::sync::{MetadataRef, Lrc};

 pub use self::NativeLibraryKind::*;

 // lonely orphan structs and enums looking for a better home

 #[derive(Clone, Debug, Copy)]
 pub struct LinkMeta {
     pub crate_hash: Svh,
 }

 /// Where a crate came from on the local filesystem. One of these three options
 /// must be non-None.
 #[derive(PartialEq, Clone, Debug)]
 pub struct CrateSource {
     pub dylib: Option<(PathBuf, PathKind)>,
     pub rlib: Option<(PathBuf, PathKind)>,
     pub rmeta: Option<(PathBuf, PathKind)>,
 }

 #[derive(RustcEncodable, RustcDecodable, Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Debug)]
 pub enum DepKind {
     /// A dependency that is only used for its macros, none of which are visible from other crates.
     /// These are included in the metadata only as placeholders and are ignored when decoding.
     UnexportedMacrosOnly,
     /// A dependency that is only used for its macros.
     MacrosOnly,
     /// A dependency that is always injected into the dependency list and so
     /// doesn't need to be linked to an rlib, e.g. the injected allocator.
     Implicit,
     /// A dependency that is required by an rlib version of this crate.
     /// Ordinary `extern crate`s result in `Explicit` dependencies.
     Explicit,
 }

 impl DepKind {
     pub fn macros_only(self) -> bool {
         match self {
             DepKind::UnexportedMacrosOnly | DepKind::MacrosOnly => true,
             DepKind::Implicit | DepKind::Explicit => false,
         }
     }
 }

 #[derive(PartialEq, Clone, Debug)]
 pub enum LibSource {
     Some(PathBuf),
     MetadataOnly,
     None,
 }

 impl LibSource {
     pub fn is_some(&self) -> bool {
         if let LibSource::Some(_) = *self {
             true
         } else {
             false
         }
     }

     pub fn option(&self) -> Option<PathBuf> {
         match *self {
             LibSource::Some(ref p) => Some(p.clone()),
             LibSource::MetadataOnly | LibSource::None => None,
         }
     }
 }

 #[derive(Copy, Debug, PartialEq, Clone, RustcEncodable, RustcDecodable)]
 pub enum LinkagePreference {
     RequireDynamic,
     RequireStatic,
 }

 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
 pub enum NativeLibraryKind {
     /// native static library (.a archive)
     NativeStatic,
     /// native static library, which doesn't get bundled into .rlibs
     NativeStaticNobundle,
     /// macOS-specific
     NativeFramework,
     /// default way to specify a dynamic library
     NativeUnknown,
 }

 #[derive(Clone, Hash, RustcEncodable, RustcDecodable)]
 pub struct NativeLibrary {
     pub kind: NativeLibraryKind,
     pub name: Symbol,
     pub cfg: Option<ast::MetaItem>,
     pub foreign_module: Option<DefId>,
 }

 #[derive(Clone, Hash, RustcEncodable, RustcDecodable)]
 pub struct ForeignModule {
     pub foreign_items: Vec<DefId>,
     pub def_id: DefId,
 }

 pub enum LoadedMacro {
     MacroDef(ast::Item),
     ProcMacro(Lrc<SyntaxExtension>),
 }

 #[derive(Copy, Clone, Debug)]
 pub struct ExternCrate {
     pub src: ExternCrateSource,

     /// span of the extern crate that caused this to be loaded
     pub span: Span,

     /// Number of links to reach the extern;
     /// used to select the extern with the shortest path
     pub path_len: usize,

     /// If true, then this crate is the crate named by the extern
     /// crate referenced above. If false, then this crate is a dep
     /// of the crate.
     pub direct: bool,
 }

 #[derive(Copy, Clone, Debug)]
 pub enum ExternCrateSource {
     /// Crate is loaded by `extern crate`.
     Extern(
         /// def_id of the item in the current crate that caused
         /// this crate to be loaded; note that there could be multiple
         /// such ids
         DefId,
     ),
     // Crate is loaded by `use`.
     Use,
     /// Crate is implicitly loaded by an absolute or an `extern::` path.
     Path,
 }

 pub struct EncodedMetadata {
     pub raw_data: Vec<u8>
 }

 impl EncodedMetadata {
     pub fn new() -> EncodedMetadata {
         EncodedMetadata {
             raw_data: Vec::new(),
         }
     }
 }

 /// The backend's way to give the crate store access to the metadata in a library.
 /// Note that it returns the raw metadata bytes stored in the library file, whether
 /// it is compressed, uncompressed, some weird mix, etc.
 /// rmeta files are backend independent and not handled here.
 ///
 /// At the time of this writing, there is only one backend and one way to store
 /// metadata in library -- this trait just serves to decouple rustc_metadata from
 /// the archive reader, which depends on LLVM.
 pub trait MetadataLoader {
     fn get_rlib_metadata(&self,
                          target: &Target,
                          filename: &Path)
                          -> Result<MetadataRef, String>;
     fn get_dylib_metadata(&self,
                           target: &Target,
                           filename: &Path)
                           -> Result<MetadataRef, String>;
 }

 #[derive(Clone)]
 pub struct ExternConstBody<'tcx> {
     pub body: &'tcx hir::Body,

     // It would require a lot of infrastructure to enable stable-hashing Bodies
     // from other crates, so we hash on export and just store the fingerprint
     // with them.
     pub fingerprint: ich::Fingerprint,
 }

 #[derive(Clone)]
 pub struct ExternBodyNestedBodies {
     pub nested_bodies: Lrc<BTreeMap<hir::BodyId, hir::Body>>,

     // It would require a lot of infrastructure to enable stable-hashing Bodies
     // from other crates, so we hash on export and just store the fingerprint
     // with them.
     pub fingerprint: ich::Fingerprint,
 }

 /// A store of Rust crates, through with their metadata
 /// can be accessed.
 ///
 /// Note that this trait should probably not be expanding today. All new
 /// functionality should be driven through queries instead!
 ///
 /// If you find a method on this trait named `{name}_untracked` it signifies
 /// that it's *not* tracked for dependency information throughout compilation
 /// (it'd break incremental compilation) and should only be called pre-HIR (e.g.
 /// during resolve)
 pub trait CrateStore {
     fn crate_data_as_rc_any(&self, krate: CrateNum) -> Lrc<dyn Any>;

     // access to the metadata loader
     fn metadata_loader(&self) -> &dyn MetadataLoader;

     // resolve
     fn def_key(&self, def: DefId) -> DefKey;
     fn def_path(&self, def: DefId) -> hir_map::DefPath;
     fn def_path_hash(&self, def: DefId) -> hir_map::DefPathHash;
     fn def_path_table(&self, cnum: CrateNum) -> Lrc<DefPathTable>;

     // "queries" used in resolve that aren't tracked for incremental compilation
     fn visibility_untracked(&self, def: DefId) -> ty::Visibility;
     fn export_macros_untracked(&self, cnum: CrateNum);
     fn dep_kind_untracked(&self, cnum: CrateNum) -> DepKind;
     fn crate_name_untracked(&self, cnum: CrateNum) -> Symbol;
     fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> CrateDisambiguator;
     fn crate_hash_untracked(&self, cnum: CrateNum) -> Svh;
     fn struct_field_names_untracked(&self, def: DefId) -> Vec<ast::Name>;
     fn item_children_untracked(&self, did: DefId, sess: &Session) -> Vec<def::Export>;
     fn load_macro_untracked(&self, did: DefId, sess: &Session) -> LoadedMacro;
     fn extern_mod_stmt_cnum_untracked(&self, emod_id: ast::NodeId) -> Option<CrateNum>;
     fn item_generics_cloned_untracked(&self, def: DefId, sess: &Session) -> ty::Generics;
     fn associated_item_cloned_untracked(&self, def: DefId) -> ty::AssociatedItem;
     fn postorder_cnums_untracked(&self) -> Vec<CrateNum>;

     // This is basically a 1-based range of ints, which is a little
     // silly - I may fix that.
     fn crates_untracked(&self) -> Vec<CrateNum>;

     // utility functions
     fn encode_metadata<'a, 'tcx>(&self,
                                  tcx: TyCtxt<'a, 'tcx, 'tcx>,
                                  link_meta: &LinkMeta)
                                  -> EncodedMetadata;
     fn metadata_encoding_version(&self) -> &[u8];
 }

 // FIXME: find a better place for this?
 pub fn validate_crate_name(sess: Option<&Session>, s: &str, sp: Option<Span>) {
     let mut err_count = 0;
     {
         let mut say = |s: &str| {
             match (sp, sess) {
                 (_, None) => bug!("{}", s),
                 (Some(sp), Some(sess)) => sess.span_err(sp, s),
                 (None, Some(sess)) => sess.err(s),
             }
             err_count += 1;
         };
         if s.is_empty() {
             say("crate name must not be empty");
         }
         for c in s.chars() {
             if c.is_alphanumeric() { continue }
             if c == '_'  { continue }
             say(&format!("invalid character `{}` in crate name: `{}`", c, s));
         }
     }

     if err_count > 0 {
         sess.unwrap().abort_if_errors();
     }
 }

 /// A dummy crate store that does not support any non-local crates,
 /// for test purposes.
 pub struct DummyCrateStore;

 #[allow(unused_variables)]
 impl CrateStore for DummyCrateStore {
     fn crate_data_as_rc_any(&self, krate: CrateNum) -> Lrc<dyn Any>
         { bug!("crate_data_as_rc_any") }
     // item info
     fn visibility_untracked(&self, def: DefId) -> ty::Visibility { bug!("visibility") }
     fn item_generics_cloned_untracked(&self, def: DefId, sess: &Session) -> ty::Generics
         { bug!("item_generics_cloned") }

     // trait/impl-item info
     fn associated_item_cloned_untracked(&self, def: DefId) -> ty::AssociatedItem
         { bug!("associated_item_cloned") }

     // crate metadata
     fn dep_kind_untracked(&self, cnum: CrateNum) -> DepKind { bug!("is_explicitly_linked") }
     fn export_macros_untracked(&self, cnum: CrateNum) { bug!("export_macros") }
     fn crate_name_untracked(&self, cnum: CrateNum) -> Symbol { bug!("crate_name") }
     fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> CrateDisambiguator {
         bug!("crate_disambiguator")
     }
     fn crate_hash_untracked(&self, cnum: CrateNum) -> Svh { bug!("crate_hash") }

     // resolve
     fn def_key(&self, def: DefId) -> DefKey { bug!("def_key") }
     fn def_path(&self, def: DefId) -> hir_map::DefPath {
         bug!("relative_def_path")
     }
     fn def_path_hash(&self, def: DefId) -> hir_map::DefPathHash {
         bug!("def_path_hash")
     }
     fn def_path_table(&self, cnum: CrateNum) -> Lrc<DefPathTable> {
         bug!("def_path_table")
     }
     fn struct_field_names_untracked(&self, def: DefId) -> Vec<ast::Name> {
         bug!("struct_field_names")
     }
     fn item_children_untracked(&self, did: DefId, sess: &Session) -> Vec<def::Export> {
         bug!("item_children")
     }
     fn load_macro_untracked(&self, did: DefId, sess: &Session) -> LoadedMacro { bug!("load_macro") }

     fn crates_untracked(&self) -> Vec<CrateNum> { vec![] }

     // utility functions
     fn extern_mod_stmt_cnum_untracked(&self, emod_id: ast::NodeId) -> Option<CrateNum> { None }
     fn encode_metadata<'a, 'tcx>(&self,
                                  tcx: TyCtxt<'a, 'tcx, 'tcx>,
                                  link_meta: &LinkMeta)
                                  -> EncodedMetadata {
         bug!("encode_metadata")
     }
     fn metadata_encoding_version(&self) -> &[u8] { bug!("metadata_encoding_version") }
     fn postorder_cnums_untracked(&self) -> Vec<CrateNum> { bug!("postorder_cnums_untracked") }

     // access to the metadata loader
     fn metadata_loader(&self) -> &dyn MetadataLoader { bug!("metadata_loader") }
 }

 pub trait CrateLoader {
     fn process_extern_crate(&mut self, item: &ast::Item, defs: &Definitions) -> CrateNum;

     fn process_path_extern(
         &mut self,
         name: Symbol,
         span: Span,
     ) -> CrateNum;

     fn process_use_extern(
         &mut self,
         name: Symbol,
         span: Span,
         id: ast::NodeId,
         defs: &Definitions,
     ) -> CrateNum;

     fn postprocess(&mut self, krate: &ast::Crate);
 }

 // This method is used when generating the command line to pass through to
 // system linker. The linker expects undefined symbols on the left of the
 // command line to be defined in libraries on the right, not the other way
 // around. For more info, see some comments in the add_used_library function
 // below.
 //
 // In order to get this left-to-right dependency ordering, we perform a
 // topological sort of all crates putting the leaves at the right-most
 // positions.
 pub fn used_crates(tcx: TyCtxt, prefer: LinkagePreference)
     -> Vec<(CrateNum, LibSource)>
 {
     let mut libs = tcx.crates()
         .iter()
         .cloned()
         .filter_map(|cnum| {
             if tcx.dep_kind(cnum).macros_only() {
                 return None
             }
             let source = tcx.used_crate_source(cnum);
             let path = match prefer {
                 LinkagePreference::RequireDynamic => source.dylib.clone().map(|p| p.0),
                 LinkagePreference::RequireStatic => source.rlib.clone().map(|p| p.0),
             };
             let path = match path {
                 Some(p) => LibSource::Some(p),
                 None => {
                     if source.rmeta.is_some() {
                         LibSource::MetadataOnly
                     } else {
                         LibSource::None
                     }
                 }
             };
             Some((cnum, path))
         })
         .collect::<Vec<_>>();
     let mut ordering = tcx.postorder_cnums(LOCAL_CRATE);
     Lrc::make_mut(&mut ordering).reverse();
     libs.sort_by_cached_key(|&(a, _)| {
         ordering.iter().position(|x| *x == a)
     });
     libs
 }
	// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
	// file at the top-level directory of this distribution and at
	// http://rust-lang.org/COPYRIGHT.
	//
	// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	// option. This file may not be copied, modified, or distributed
	// except according to those terms.

	// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
	// file at the top-level directory of this distribution and at
	// http://rust-lang.org/COPYRIGHT.
	//
	// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	// option. This file may not be copied, modified, or distributed
	// except according to those terms.

	//! the rustc crate store interface. This also includes types that
	//! are mostly used as a part of that interface, but these should
	//! probably get a better home if someone can find one.

	use hir;
	use hir::def;
	use hir::def_id::{CrateNum, DefId, LOCAL_CRATE};
	use hir::map as hir_map;
	use hir::map::definitions::{Definitions, DefKey, DefPathTable};
	use hir::svh::Svh;
	use ich;
	use ty::{self, TyCtxt};
	use session::{Session, CrateDisambiguator};
	use session::search_paths::PathKind;

	use std::any::Any;
	use std::collections::BTreeMap;
	use std::path::{Path, PathBuf};
	use syntax::ast;
	use syntax::ext::base::SyntaxExtension;
	use syntax::symbol::Symbol;
	use syntax_pos::Span;
	use rustc_back::target::Target;
	use rustc_data_structures::sync::{MetadataRef, Lrc};

	pub use self::NativeLibraryKind::*;

	// lonely orphan structs and enums looking for a better home

	#[derive(Clone, Debug, Copy)]
	pub struct LinkMeta {
	pub crate_hash: Svh,
	}

	/// Where a crate came from on the local filesystem. One of these three options
	/// must be non-None.
	#[derive(PartialEq, Clone, Debug)]
	pub struct CrateSource {
	pub dylib: Option<(PathBuf, PathKind)>,
	pub rlib: Option<(PathBuf, PathKind)>,
	pub rmeta: Option<(PathBuf, PathKind)>,
	}

	#[derive(RustcEncodable, RustcDecodable, Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Debug)]
	pub enum DepKind {
	/// A dependency that is only used for its macros, none of which are visible from other crates.
	/// These are included in the metadata only as placeholders and are ignored when decoding.
	UnexportedMacrosOnly,
	/// A dependency that is only used for its macros.
	MacrosOnly,
	/// A dependency that is always injected into the dependency list and so
	/// doesn't need to be linked to an rlib, e.g. the injected allocator.
	Implicit,
	/// A dependency that is required by an rlib version of this crate.
	/// Ordinary `extern crate`s result in `Explicit` dependencies.
	Explicit,
	}

	impl DepKind {
	pub fn macros_only(self) -> bool {
	match self {
	DepKind::UnexportedMacrosOnly \| DepKind::MacrosOnly => true,
	DepKind::Implicit \| DepKind::Explicit => false,
	}
	}
	}

	#[derive(PartialEq, Clone, Debug)]
	pub enum LibSource {
	Some(PathBuf),
	MetadataOnly,
	None,
	}

	impl LibSource {
	pub fn is_some(&self) -> bool {
	if let LibSource::Some(_) = *self {
	true
	} else {
	false
	}
	}

	pub fn option(&self) -> Option<PathBuf> {
	match *self {
	LibSource::Some(ref p) => Some(p.clone()),
	LibSource::MetadataOnly \| LibSource::None => None,
	}
	}
	}

	#[derive(Copy, Debug, PartialEq, Clone, RustcEncodable, RustcDecodable)]
	pub enum LinkagePreference {
	RequireDynamic,
	RequireStatic,
	}

	#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable)]
	pub enum NativeLibraryKind {
	/// native static library (.a archive)
	NativeStatic,
	/// native static library, which doesn't get bundled into .rlibs
	NativeStaticNobundle,
	/// macOS-specific
	NativeFramework,
	/// default way to specify a dynamic library
	NativeUnknown,
	}

	#[derive(Clone, Hash, RustcEncodable, RustcDecodable)]
	pub struct NativeLibrary {
	pub kind: NativeLibraryKind,
	pub name: Symbol,
	pub cfg: Option<ast::MetaItem>,
	pub foreign_module: Option<DefId>,
	}

	#[derive(Clone, Hash, RustcEncodable, RustcDecodable)]
	pub struct ForeignModule {
	pub foreign_items: Vec<DefId>,
	pub def_id: DefId,
	}

	pub enum LoadedMacro {
	MacroDef(ast::Item),
	ProcMacro(Lrc<SyntaxExtension>),
	}

	#[derive(Copy, Clone, Debug)]
	pub struct ExternCrate {
	pub src: ExternCrateSource,

	/// span of the extern crate that caused this to be loaded
	pub span: Span,

	/// Number of links to reach the extern;
	/// used to select the extern with the shortest path
	pub path_len: usize,

	/// If true, then this crate is the crate named by the extern
	/// crate referenced above. If false, then this crate is a dep
	/// of the crate.
	pub direct: bool,
	}

	#[derive(Copy, Clone, Debug)]
	pub enum ExternCrateSource {
	/// Crate is loaded by `extern crate`.
	Extern(
	/// def_id of the item in the current crate that caused
	/// this crate to be loaded; note that there could be multiple
	/// such ids
	DefId,
	),
	// Crate is loaded by `use`.
	Use,
	/// Crate is implicitly loaded by an absolute or an `extern::` path.
	Path,
	}

	pub struct EncodedMetadata {
	pub raw_data: Vec<u8>
	}

	impl EncodedMetadata {
	pub fn new() -> EncodedMetadata {
	EncodedMetadata {
	raw_data: Vec::new(),
	}
	}
	}

	/// The backend's way to give the crate store access to the metadata in a library.
	/// Note that it returns the raw metadata bytes stored in the library file, whether
	/// it is compressed, uncompressed, some weird mix, etc.
	/// rmeta files are backend independent and not handled here.
	///
	/// At the time of this writing, there is only one backend and one way to store
	/// metadata in library -- this trait just serves to decouple rustc_metadata from
	/// the archive reader, which depends on LLVM.
	pub trait MetadataLoader {
	fn get_rlib_metadata(&self,
	target: &Target,
	filename: &Path)
	-> Result<MetadataRef, String>;
	fn get_dylib_metadata(&self,
	target: &Target,
	filename: &Path)
	-> Result<MetadataRef, String>;
	}

	#[derive(Clone)]
	pub struct ExternConstBody<'tcx> {
	pub body: &'tcx hir::Body,

	// It would require a lot of infrastructure to enable stable-hashing Bodies
	// from other crates, so we hash on export and just store the fingerprint
	// with them.
	pub fingerprint: ich::Fingerprint,
	}

	#[derive(Clone)]
	pub struct ExternBodyNestedBodies {
	pub nested_bodies: Lrc<BTreeMap<hir::BodyId, hir::Body>>,

	// It would require a lot of infrastructure to enable stable-hashing Bodies
	// from other crates, so we hash on export and just store the fingerprint
	// with them.
	pub fingerprint: ich::Fingerprint,
	}

	/// A store of Rust crates, through with their metadata
	/// can be accessed.
	///
	/// Note that this trait should probably not be expanding today. All new
	/// functionality should be driven through queries instead!
	///
	/// If you find a method on this trait named `{name}_untracked` it signifies
	/// that it's not tracked for dependency information throughout compilation
	/// (it'd break incremental compilation) and should only be called pre-HIR (e.g.
	/// during resolve)
	pub trait CrateStore {
	fn crate_data_as_rc_any(&self, krate: CrateNum) -> Lrc<dyn Any>;

	// access to the metadata loader
	fn metadata_loader(&self) -> &dyn MetadataLoader;

	// resolve
	fn def_key(&self, def: DefId) -> DefKey;
	fn def_path(&self, def: DefId) -> hir_map::DefPath;
	fn def_path_hash(&self, def: DefId) -> hir_map::DefPathHash;
	fn def_path_table(&self, cnum: CrateNum) -> Lrc<DefPathTable>;

	// "queries" used in resolve that aren't tracked for incremental compilation
	fn visibility_untracked(&self, def: DefId) -> ty::Visibility;
	fn export_macros_untracked(&self, cnum: CrateNum);
	fn dep_kind_untracked(&self, cnum: CrateNum) -> DepKind;
	fn crate_name_untracked(&self, cnum: CrateNum) -> Symbol;
	fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> CrateDisambiguator;
	fn crate_hash_untracked(&self, cnum: CrateNum) -> Svh;
	fn struct_field_names_untracked(&self, def: DefId) -> Vec<ast::Name>;
	fn item_children_untracked(&self, did: DefId, sess: &Session) -> Vec<def::Export>;
	fn load_macro_untracked(&self, did: DefId, sess: &Session) -> LoadedMacro;
	fn extern_mod_stmt_cnum_untracked(&self, emod_id: ast::NodeId) -> Option<CrateNum>;
	fn item_generics_cloned_untracked(&self, def: DefId, sess: &Session) -> ty::Generics;
	fn associated_item_cloned_untracked(&self, def: DefId) -> ty::AssociatedItem;
	fn postorder_cnums_untracked(&self) -> Vec<CrateNum>;

	// This is basically a 1-based range of ints, which is a little
	// silly - I may fix that.
	fn crates_untracked(&self) -> Vec<CrateNum>;

	// utility functions
	fn encode_metadata<'a, 'tcx>(&self,
	tcx: TyCtxt<'a, 'tcx, 'tcx>,
	link_meta: &LinkMeta)
	-> EncodedMetadata;
	fn metadata_encoding_version(&self) -> &[u8];
	}

	// FIXME: find a better place for this?
	pub fn validate_crate_name(sess: Option<&Session>, s: &str, sp: Option<Span>) {
	let mut err_count = 0;
	{
	let mut say = \|s: &str\| {
	match (sp, sess) {
	(_, None) => bug!("{}", s),
	(Some(sp), Some(sess)) => sess.span_err(sp, s),
	(None, Some(sess)) => sess.err(s),
	}
	err_count += 1;
	};
	if s.is_empty() {
	say("crate name must not be empty");
	}
	for c in s.chars() {
	if c.is_alphanumeric() { continue }
	if c == '_' { continue }
	say(&format!("invalid character `{}` in crate name: `{}`", c, s));
	}
	}

	if err_count > 0 {
	sess.unwrap().abort_if_errors();
	}
	}

	/// A dummy crate store that does not support any non-local crates,
	/// for test purposes.
	pub struct DummyCrateStore;

	#[allow(unused_variables)]
	impl CrateStore for DummyCrateStore {
	fn crate_data_as_rc_any(&self, krate: CrateNum) -> Lrc<dyn Any>
	{ bug!("crate_data_as_rc_any") }
	// item info
	fn visibility_untracked(&self, def: DefId) -> ty::Visibility { bug!("visibility") }
	fn item_generics_cloned_untracked(&self, def: DefId, sess: &Session) -> ty::Generics
	{ bug!("item_generics_cloned") }

	// trait/impl-item info
	fn associated_item_cloned_untracked(&self, def: DefId) -> ty::AssociatedItem
	{ bug!("associated_item_cloned") }

	// crate metadata
	fn dep_kind_untracked(&self, cnum: CrateNum) -> DepKind { bug!("is_explicitly_linked") }
	fn export_macros_untracked(&self, cnum: CrateNum) { bug!("export_macros") }
	fn crate_name_untracked(&self, cnum: CrateNum) -> Symbol { bug!("crate_name") }
	fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> CrateDisambiguator {
	bug!("crate_disambiguator")
	}
	fn crate_hash_untracked(&self, cnum: CrateNum) -> Svh { bug!("crate_hash") }

	// resolve
	fn def_key(&self, def: DefId) -> DefKey { bug!("def_key") }
	fn def_path(&self, def: DefId) -> hir_map::DefPath {
	bug!("relative_def_path")
	}
	fn def_path_hash(&self, def: DefId) -> hir_map::DefPathHash {
	bug!("def_path_hash")
	}
	fn def_path_table(&self, cnum: CrateNum) -> Lrc<DefPathTable> {
	bug!("def_path_table")
	}
	fn struct_field_names_untracked(&self, def: DefId) -> Vec<ast::Name> {
	bug!("struct_field_names")
	}
	fn item_children_untracked(&self, did: DefId, sess: &Session) -> Vec<def::Export> {
	bug!("item_children")
	}
	fn load_macro_untracked(&self, did: DefId, sess: &Session) -> LoadedMacro { bug!("load_macro") }

	fn crates_untracked(&self) -> Vec<CrateNum> { vec![] }

	// utility functions
	fn extern_mod_stmt_cnum_untracked(&self, emod_id: ast::NodeId) -> Option<CrateNum> { None }
	fn encode_metadata<'a, 'tcx>(&self,
	tcx: TyCtxt<'a, 'tcx, 'tcx>,
	link_meta: &LinkMeta)
	-> EncodedMetadata {
	bug!("encode_metadata")
	}
	fn metadata_encoding_version(&self) -> &[u8] { bug!("metadata_encoding_version") }
	fn postorder_cnums_untracked(&self) -> Vec<CrateNum> { bug!("postorder_cnums_untracked") }

	// access to the metadata loader
	fn metadata_loader(&self) -> &dyn MetadataLoader { bug!("metadata_loader") }
	}

	pub trait CrateLoader {
	fn process_extern_crate(&mut self, item: &ast::Item, defs: &Definitions) -> CrateNum;

	fn process_path_extern(
	&mut self,
	name: Symbol,
	span: Span,
	) -> CrateNum;

	fn process_use_extern(
	&mut self,
	name: Symbol,
	span: Span,
	id: ast::NodeId,
	defs: &Definitions,
	) -> CrateNum;

	fn postprocess(&mut self, krate: &ast::Crate);
	}

	// This method is used when generating the command line to pass through to
	// system linker. The linker expects undefined symbols on the left of the
	// command line to be defined in libraries on the right, not the other way
	// around. For more info, see some comments in the add_used_library function
	// below.
	//
	// In order to get this left-to-right dependency ordering, we perform a
	// topological sort of all crates putting the leaves at the right-most
	// positions.
	pub fn used_crates(tcx: TyCtxt, prefer: LinkagePreference)
	-> Vec<(CrateNum, LibSource)>
	{
	let mut libs = tcx.crates()
	.iter()
	.cloned()
	.filter_map(\|cnum\| {
	if tcx.dep_kind(cnum).macros_only() {
	return None
	}
	let source = tcx.used_crate_source(cnum);
	let path = match prefer {
	LinkagePreference::RequireDynamic => source.dylib.clone().map(\|p\| p.0),
	LinkagePreference::RequireStatic => source.rlib.clone().map(\|p\| p.0),
	};
	let path = match path {
	Some(p) => LibSource::Some(p),
	None => {
	if source.rmeta.is_some() {
	LibSource::MetadataOnly
	} else {
	LibSource::None
	}
	}
	};
	Some((cnum, path))
	})
	.collect::<Vec<_>>();
	let mut ordering = tcx.postorder_cnums(LOCAL_CRATE);
	Lrc::make_mut(&mut ordering).reverse();
	libs.sort_by_cached_key(\|&(a, _)\| {
	ordering.iter().position(\|x\| *x == a)
	});
	libs
	}