Switch crate_extern_paths to a query, and tweak wording.

src/librustc_metadata/rmeta/decoder/cstore_impl.rs

@@ -27,7 +27,6 @@ use rustc_span::symbol::{Ident, Symbol};
 use rustc_data_structures::sync::Lrc;
 use smallvec::SmallVec;
 use std::any::Any;
-use std::path::PathBuf;
 
 macro_rules! provide {
     (<$lt:tt> $tcx:ident, $def_id:ident, $other:ident, $cdata:ident,
@@ -240,6 +239,8 @@ provide! { <'tcx> tcx, def_id, other, cdata,
 
         syms
     }
+
+    crate_extern_paths => { cdata.source().paths().cloned().collect() }
 }
 
 pub fn provide(providers: &mut Providers<'_>) {
@@ -514,8 +515,4 @@ impl CrateStore for CStore {
     fn allocator_kind(&self) -> Option<AllocatorKind> {
         self.allocator_kind()
     }
-
-    fn crate_extern_paths(&self, cnum: CrateNum) -> Vec<PathBuf> {
-        self.get_crate_data(cnum).source().paths().cloned().collect()
-    }
 }

src/librustc_middle/middle/cstore.rs

@@ -203,7 +203,6 @@ pub trait CrateStore {
     fn encode_metadata(&self, tcx: TyCtxt<'_>) -> EncodedMetadata;
     fn metadata_encoding_version(&self) -> &[u8];
     fn allocator_kind(&self) -> Option<AllocatorKind>;
-    fn crate_extern_paths(&self, cnum: CrateNum) -> Vec<PathBuf>;
 }
 
 pub type CrateStoreDyn = dyn CrateStore + sync::Sync;

src/librustc_middle/query/mod.rs

@@ -1042,6 +1042,10 @@ rustc_queries! {
             eval_always
             desc { "looking up the extra filename for a crate" }
         }
+        query crate_extern_paths(_: CrateNum) -> Vec<PathBuf> {
+            eval_always
+            desc { "looking up the paths for extern crates" }
+        }
     }
 
     TypeChecking {

src/librustc_middle/ty/context.rs

@@ -62,7 +62,6 @@ use std::hash::{Hash, Hasher};
 use std::iter;
 use std::mem;
 use std::ops::{Bound, Deref};
-use std::path::PathBuf;
 use std::sync::Arc;
 
 type InternedSet<'tcx, T> = ShardedHashMap<Interned<'tcx, T>, ()>;
@@ -1253,14 +1252,6 @@ impl<'tcx> TyCtxt<'tcx> {
         if cnum == LOCAL_CRATE { false } else { self.cstore.crate_is_private_dep_untracked(cnum) }
     }
 
-    pub fn crate_extern_paths(&self, cnum: CrateNum) -> Vec<PathBuf> {
-        if cnum == LOCAL_CRATE {
-            self.sess.local_crate_source_file.iter().cloned().collect()
-        } else {
-            self.cstore.crate_extern_paths(cnum)
-        }
-    }
-
     #[inline]
     pub fn def_path_hash(self, def_id: DefId) -> rustc_hir::definitions::DefPathHash {
         if let Some(def_id) = def_id.as_local() {

src/librustc_middle/ty/query/mod.rs

@@ -57,6 +57,7 @@ use rustc_span::{Span, DUMMY_SP};
 use std::borrow::Cow;
 use std::collections::BTreeMap;
 use std::ops::Deref;
+use std::path::PathBuf;
 use std::sync::Arc;
 
 #[macro_use]

src/librustc_passes/lang_items.rs

@@ -147,23 +147,24 @@ impl LanguageItemCollector<'tcx> {
                         }
                     }
                     let mut note_def = |which, def_id: DefId| {
-                        let location = if def_id.is_local() {
-                            "the local crate".to_string()
+                        let crate_name = self.tcx.crate_name(def_id.krate);
+                        let note = if def_id.is_local() {
+                            format!("{} definition in the local crate (`{}`)", which, crate_name)
                         } else {
                             let paths: Vec<_> = self
                                 .tcx
                                 .crate_extern_paths(def_id.krate)
                                 .iter()
                                 .map(|p| p.display().to_string())
                                 .collect();
-                            paths.join(", ")
+                            format!(
+                                "{} definition in `{}` loaded from {}",
+                                which,
+                                crate_name,
+                                paths.join(", ")
+                            )
                         };
-                        err.note(&format!(
-                            "{} definition in `{}` loaded from {}",
-                            which,
-                            self.tcx.crate_name(def_id.krate),
-                            location
-                        ));
+                        err.note(&note);
                     };
                     note_def("first", original_def_id);
                     note_def("second", item_def_id);

src/test/ui/duplicate_entry_error.stderr

@@ -9,7 +9,7 @@ LL | | }
    |
    = note: the lang item is first defined in crate `std` (which `duplicate_entry_error` depends on)
    = note: first definition in `std` loaded from SYSROOT/libstd-*.rlib
-   = note: second definition in `duplicate_entry_error` loaded from the local crate
+   = note: second definition in the local crate (`duplicate_entry_error`)
 
 error: aborting due to previous error
 

src/test/ui/error-codes/E0152.stderr

@@ -6,7 +6,7 @@ LL | struct Foo;
    |
    = note: the lang item is first defined in crate `alloc` (which `std` depends on)
    = note: first definition in `alloc` loaded from SYSROOT/liballoc-*.rlib
-   = note: second definition in `E0152` loaded from the local crate
+   = note: second definition in the local crate (`E0152`)
 
 error: aborting due to previous error
 

src/test/ui/panic-handler/panic-handler-std.stderr

@@ -8,7 +8,7 @@ LL | | }
    |
    = note: the lang item is first defined in crate `std` (which `panic_handler_std` depends on)
    = note: first definition in `std` loaded from SYSROOT/libstd-*.rlib
-   = note: second definition in `panic_handler_std` loaded from the local crate
+   = note: second definition in the local crate (`panic_handler_std`)
 
 error: argument should be `&PanicInfo`
   --> $DIR/panic-handler-std.rs:8:16