Auto merge of #33602 - eddyb:no-trans--check, r=michaelwoerister

Save metadata even with -Z no-trans (e.g. for multi-crate cargo check).

Removes the item symbol map in metadata, as we can now generate them in a deterministic manner.
The `-Z no-trans` change lets the LLVM passes and linking run, but with just metadata and no code.
It fails while trying to link a binary because there's no `main` function, which is correct but not good UX.

There's also no way to easily throw away all of the artifacts to rebuild with actual code generation.
We might want `cargo check` to do that using cargo-internal information and then it would just work.

cc @alexcrichton @nikomatsakis @Aatch @michaelwoerister

src/librustc/middle/cstore.rs

@@ -34,8 +34,7 @@ use mir::mir_map::MirMap;
 use session::Session;
 use session::config::PanicStrategy;
 use session::search_paths::PathKind;
-use util::nodemap::{FnvHashMap, NodeMap, NodeSet, DefIdMap};
-use std::cell::RefCell;
+use util::nodemap::{FnvHashMap, NodeSet, DefIdMap};
 use std::rc::Rc;
 use std::path::PathBuf;
 use syntax::ast;
@@ -169,7 +168,6 @@ pub trait CrateStore<'tcx> {
     fn item_super_predicates<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
                                  -> ty::GenericPredicates<'tcx>;
     fn item_attrs(&self, def_id: DefId) -> Vec<ast::Attribute>;
-    fn item_symbol(&self, def: DefId) -> String;
     fn trait_def<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)-> ty::TraitDef<'tcx>;
     fn adt_def<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId) -> ty::AdtDefMaster<'tcx>;
     fn method_arg_names(&self, did: DefId) -> Vec<String>;
@@ -205,6 +203,7 @@ pub trait CrateStore<'tcx> {
     fn is_impl(&self, did: DefId) -> bool;
     fn is_default_impl(&self, impl_did: DefId) -> bool;
     fn is_extern_item<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, did: DefId) -> bool;
+    fn is_foreign_item(&self, did: DefId) -> bool;
     fn is_static_method(&self, did: DefId) -> bool;
     fn is_statically_included_foreign_item(&self, id: ast::NodeId) -> bool;
     fn is_typedef(&self, did: DefId) -> bool;
@@ -274,7 +273,6 @@ pub trait CrateStore<'tcx> {
     fn extern_mod_stmt_cnum(&self, emod_id: ast::NodeId) -> Option<ast::CrateNum>;
     fn encode_metadata<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
                            reexports: &def::ExportMap,
-                           item_symbols: &RefCell<NodeMap<String>>,
                            link_meta: &LinkMeta,
                            reachable: &NodeSet,
                            mir_map: &MirMap<'tcx>,
@@ -352,7 +350,6 @@ impl<'tcx> CrateStore<'tcx> for DummyCrateStore {
     fn item_super_predicates<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
                                  -> ty::GenericPredicates<'tcx> { bug!("item_super_predicates") }
     fn item_attrs(&self, def_id: DefId) -> Vec<ast::Attribute> { bug!("item_attrs") }
-    fn item_symbol(&self, def: DefId) -> String { bug!("item_symbol") }
     fn trait_def<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)-> ty::TraitDef<'tcx>
         { bug!("trait_def") }
     fn adt_def<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId) -> ty::AdtDefMaster<'tcx>
@@ -399,6 +396,7 @@ impl<'tcx> CrateStore<'tcx> for DummyCrateStore {
     fn is_default_impl(&self, impl_did: DefId) -> bool { bug!("is_default_impl") }
     fn is_extern_item<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, did: DefId) -> bool
         { bug!("is_extern_item") }
+    fn is_foreign_item(&self, did: DefId) -> bool { bug!("is_foreign_item") }
     fn is_static_method(&self, did: DefId) -> bool { bug!("is_static_method") }
     fn is_statically_included_foreign_item(&self, id: ast::NodeId) -> bool { false }
     fn is_typedef(&self, did: DefId) -> bool { bug!("is_typedef") }
@@ -481,7 +479,6 @@ impl<'tcx> CrateStore<'tcx> for DummyCrateStore {
     fn extern_mod_stmt_cnum(&self, emod_id: ast::NodeId) -> Option<ast::CrateNum> { None }
     fn encode_metadata<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
                            reexports: &def::ExportMap,
-                           item_symbols: &RefCell<NodeMap<String>>,
                            link_meta: &LinkMeta,
                            reachable: &NodeSet,
                            mir_map: &MirMap<'tcx>,

src/librustc/session/config.rs

@@ -1104,7 +1104,7 @@ pub fn build_session_options(matches: &getopts::Matches) -> Options {
     let no_analysis = debugging_opts.no_analysis;
 
     let mut output_types = HashMap::new();
-    if !debugging_opts.parse_only && !no_trans {
+    if !debugging_opts.parse_only {
         for list in matches.opt_strs("emit") {
             for output_type in list.split(',') {
                 let mut parts = output_type.splitn(2, '=');

src/librustc/session/mod.rs

@@ -9,6 +9,8 @@
 // except according to those terms.
 
 use dep_graph::DepGraph;
+use hir::def_id::DefIndex;
+use hir::svh::Svh;
 use lint;
 use middle::cstore::CrateStore;
 use middle::dependency_format;
@@ -312,6 +314,14 @@ impl Session {
     pub fn nonzeroing_move_hints(&self) -> bool {
         self.opts.debugging_opts.enable_nonzeroing_move_hints
     }
+
+    /// Returns the symbol name for the registrar function,
+    /// given the crate Svh and the function DefIndex.
+    pub fn generate_plugin_registrar_symbol(&self, svh: &Svh, index: DefIndex)
+                                            -> String {
+        format!("__rustc_plugin_registrar__{}_{}", svh, index.as_usize())
+    }
+
     pub fn sysroot<'a>(&'a self) -> &'a Path {
         match self.opts.maybe_sysroot {
             Some (ref sysroot) => sysroot,

src/librustc/ty/item_path.rs

@@ -14,12 +14,38 @@ use hir::def_id::{DefId, CRATE_DEF_INDEX};
 use ty::{self, Ty, TyCtxt};
 use syntax::ast;
 
+use std::cell::Cell;
+
+thread_local! {
+    static FORCE_ABSOLUTE: Cell<bool> = Cell::new(false)
+}
+
+/// Enforces that item_path_str always returns an absolute path.
+/// This is useful when building symbols that contain types,
+/// where we want the crate name to be part of the symbol.
+pub fn with_forced_absolute_paths<F: FnOnce() -> R, R>(f: F) -> R {
+    FORCE_ABSOLUTE.with(|force| {
+        let old = force.get();
+        force.set(true);
+        let result = f();
+        force.set(old);
+        result
+    })
+}
+
 impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
     /// Returns a string identifying this def-id. This string is
     /// suitable for user output. It is relative to the current crate
-    /// root.
+    /// root, unless with_forced_absolute_paths was used.
     pub fn item_path_str(self, def_id: DefId) -> String {
-        let mut buffer = LocalPathBuffer::new(RootMode::Local);
+        let mode = FORCE_ABSOLUTE.with(|force| {
+            if force.get() {
+                RootMode::Absolute
+            } else {
+                RootMode::Local
+            }
+        });
+        let mut buffer = LocalPathBuffer::new(mode);
         self.push_item_path(&mut buffer, def_id);
         buffer.into_string()
     }
@@ -75,7 +101,11 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
             RootMode::Absolute => {
                 // In absolute mode, just write the crate name
                 // unconditionally.
-                buffer.push(&self.crate_name(cnum));
+                if cnum == LOCAL_CRATE {
+                    buffer.push(&self.crate_name(cnum));
+                } else {
+                    buffer.push(&self.sess.cstore.original_crate_name(cnum));
+                }
             }
         }
     }

src/librustc_driver/lib.rs

@@ -511,10 +511,6 @@ impl<'a> CompilerCalls<'a> for RustcDefaultCalls {
             control.after_write_deps.stop = Compilation::Stop;
         }
 
-        if sess.opts.no_trans {
-            control.after_analysis.stop = Compilation::Stop;
-        }
-
         if !sess.opts.output_types.keys().any(|&i| i == OutputType::Exe) {
             control.after_llvm.stop = Compilation::Stop;
         }

src/librustc_metadata/common.rs

@@ -33,7 +33,7 @@ pub const tag_items_data_item_family: usize = 0x24;
 
 pub const tag_items_data_item_type: usize = 0x25;
 
-pub const tag_items_data_item_symbol: usize = 0x26;
+// GAP 0x26
 
 pub const tag_items_data_item_variant: usize = 0x27;
 

src/librustc_metadata/creader.rs

@@ -17,6 +17,7 @@ use cstore::{self, CStore, CrateSource, MetadataBlob};
 use decoder;
 use loader::{self, CratePaths};
 
+use rustc::hir::def_id::DefIndex;
 use rustc::hir::svh::Svh;
 use rustc::dep_graph::{DepGraph, DepNode};
 use rustc::session::{config, Session};
@@ -610,9 +611,10 @@ impl<'a> CrateReader<'a> {
         macros
     }
 
-    /// Look for a plugin registrar. Returns library path and symbol name.
+    /// Look for a plugin registrar. Returns library path, crate
+    /// SVH and DefIndex of the registrar function.
     pub fn find_plugin_registrar(&mut self, span: Span, name: &str)
-                                 -> Option<(PathBuf, String)> {
+                                 -> Option<(PathBuf, Svh, DefIndex)> {
         let ekrate = self.read_extension_crate(span, &CrateInfo {
              name: name.to_string(),
              ident: name.to_string(),
@@ -630,12 +632,14 @@ impl<'a> CrateReader<'a> {
             span_fatal!(self.sess, span, E0456, "{}", &message[..]);
         }
 
+        let svh = decoder::get_crate_hash(ekrate.metadata.as_slice());
         let registrar =
-            decoder::get_plugin_registrar_fn(ekrate.metadata.as_slice())
-            .map(|id| decoder::get_symbol_from_buf(ekrate.metadata.as_slice(), id));
+            decoder::get_plugin_registrar_fn(ekrate.metadata.as_slice());
 
         match (ekrate.dylib.as_ref(), registrar) {
-            (Some(dylib), Some(reg)) => Some((dylib.to_path_buf(), reg)),
+            (Some(dylib), Some(reg)) => {
+                Some((dylib.to_path_buf(), svh, reg))
+            }
             (None, Some(_)) => {
                 span_err!(self.sess, span, E0457,
                           "plugin `{}` only found in rlib format, but must be available \

src/librustc_metadata/csearch.rs

@@ -25,7 +25,7 @@ use rustc::hir::map as hir_map;
 use rustc::hir::map::DefKey;
 use rustc::mir::repr::Mir;
 use rustc::mir::mir_map::MirMap;
-use rustc::util::nodemap::{FnvHashMap, NodeMap, NodeSet, DefIdMap};
+use rustc::util::nodemap::{FnvHashMap, NodeSet, DefIdMap};
 use rustc::session::config::PanicStrategy;
 
 use std::cell::RefCell;
@@ -115,13 +115,6 @@ impl<'tcx> CrateStore<'tcx> for cstore::CStore {
         decoder::get_item_attrs(&cdata, def_id.index)
     }
 
-    fn item_symbol(&self, def: DefId) -> String
-    {
-        self.dep_graph.read(DepNode::MetaData(def));
-        let cdata = self.get_crate_data(def.krate);
-        decoder::get_symbol(&cdata, def.index)
-    }
-
     fn trait_def<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId) -> ty::TraitDef<'tcx>
     {
         self.dep_graph.read(DepNode::MetaData(def));
@@ -284,6 +277,11 @@ impl<'tcx> CrateStore<'tcx> for cstore::CStore {
         decoder::is_extern_item(&cdata, did.index, tcx)
     }
 
+    fn is_foreign_item(&self, did: DefId) -> bool {
+        let cdata = self.get_crate_data(did.krate);
+        decoder::is_foreign_item(&cdata, did.index)
+    }
+
     fn is_static_method(&self, def: DefId) -> bool
     {
         self.dep_graph.read(DepNode::MetaData(def));
@@ -564,7 +562,6 @@ impl<'tcx> CrateStore<'tcx> for cstore::CStore {
 
     fn encode_metadata<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
                            reexports: &def::ExportMap,
-                           item_symbols: &RefCell<NodeMap<String>>,
                            link_meta: &LinkMeta,
                            reachable: &NodeSet,
                            mir_map: &MirMap<'tcx>,
@@ -574,7 +571,6 @@ impl<'tcx> CrateStore<'tcx> for cstore::CStore {
             diag: tcx.sess.diagnostic(),
             tcx: tcx,
             reexports: reexports,
-            item_symbols: item_symbols,
             link_meta: link_meta,
             cstore: self,
             reachable: reachable,

src/librustc_metadata/decoder.rs

@@ -213,10 +213,6 @@ fn item_sort(item: rbml::Doc) -> Option<char> {
     })
 }
 
-fn item_symbol(item: rbml::Doc) -> String {
-    reader::get_doc(item, tag_items_data_item_symbol).as_str().to_string()
-}
-
 fn untranslated_def_id(d: rbml::Doc) -> DefId {
     let id = reader::doc_as_u64(d);
     let index = DefIndex::new((id & 0xFFFF_FFFF) as usize);
@@ -640,18 +636,6 @@ pub fn get_impl_trait<'a, 'tcx>(cdata: Cmd,
     }
 }
 
-pub fn get_symbol(cdata: Cmd, id: DefIndex) -> String {
-    return item_symbol(cdata.lookup_item(id));
-}
-
-/// If you have a crate_metadata, call get_symbol instead
-pub fn get_symbol_from_buf(data: &[u8], id: DefIndex) -> String {
-    let index = load_index(data);
-    let pos = index.lookup_item(data, id).unwrap();
-    let doc = reader::doc_at(data, pos as usize).unwrap().doc;
-    item_symbol(doc)
-}
-
 /// Iterates over the language items in the given crate.
 pub fn each_lang_item<F>(cdata: Cmd, mut f: F) -> bool where
     F: FnMut(DefIndex, usize) -> bool,
@@ -1642,6 +1626,16 @@ pub fn is_extern_item<'a, 'tcx>(cdata: Cmd,
     }
 }
 
+pub fn is_foreign_item(cdata: Cmd, id: DefIndex) -> bool {
+    let item_doc = cdata.lookup_item(id);
+    let parent_item_id = match item_parent_item(cdata, item_doc) {
+        None => return false,
+        Some(item_id) => item_id,
+    };
+    let parent_item_doc = cdata.lookup_item(parent_item_id.index);
+    item_family(parent_item_doc) == ForeignMod
+}
+
 pub fn is_impl(cdata: Cmd, id: DefIndex) -> bool {
     let item_doc = cdata.lookup_item(id);
     match item_family(item_doc) {