Stop treating extern crate loading failures as fatal errors

compiler/rustc_metadata/src/creader.rs

@@ -9,6 +9,7 @@ use rustc_ast::{self as ast, *};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::Lrc;
+use rustc_errors::FatalError;
 use rustc_expand::base::SyntaxExtension;
 use rustc_hir::def_id::{CrateNum, LocalDefId, StableCrateId, LOCAL_CRATE};
 use rustc_hir::definitions::Definitions;
@@ -507,18 +508,31 @@ impl<'a> CrateLoader<'a> {
         }))
     }
 
-    fn resolve_crate<'b>(
+    fn resolve_crate_or_abort<'b>(
         &'b mut self,
         name: Symbol,
         span: Span,
         dep_kind: CrateDepKind,
     ) -> CrateNum {
+        self.resolve_crate(name, span, dep_kind).unwrap_or_else(|| FatalError.raise())
+    }
+
+    fn resolve_crate<'b>(
+        &'b mut self,
+        name: Symbol,
+        span: Span,
+        dep_kind: CrateDepKind,
+    ) -> Option<CrateNum> {
         self.used_extern_options.insert(name);
-        self.maybe_resolve_crate(name, dep_kind, None).unwrap_or_else(|err| {
-            let missing_core =
-                self.maybe_resolve_crate(sym::core, CrateDepKind::Explicit, None).is_err();
-            err.report(&self.sess, span, missing_core)
-        })
+        self.maybe_resolve_crate(name, dep_kind, None).map_or_else(
+            |err| {
+                let missing_core =
+                    self.maybe_resolve_crate(sym::core, CrateDepKind::Explicit, None).is_err();
+                err.report(&self.sess, span, missing_core);
+                None
+            },
+            |cnum| Some(cnum),
+        )
     }
 
     fn maybe_resolve_crate<'b>(
@@ -751,7 +765,7 @@ impl<'a> CrateLoader<'a> {
         };
         info!("panic runtime not found -- loading {}", name);
 
-        let cnum = self.resolve_crate(name, DUMMY_SP, CrateDepKind::Implicit);
+        let cnum = self.resolve_crate_or_abort(name, DUMMY_SP, CrateDepKind::Implicit);
         let data = self.cstore.get_crate_data(cnum);
 
         // Sanity check the loaded crate to ensure it is indeed a panic runtime
@@ -791,7 +805,7 @@ impl<'a> CrateLoader<'a> {
             );
         }
 
-        let cnum = self.resolve_crate(name, DUMMY_SP, CrateDepKind::Implicit);
+        let cnum = self.resolve_crate_or_abort(name, DUMMY_SP, CrateDepKind::Implicit);
         let data = self.cstore.get_crate_data(cnum);
 
         // Sanity check the loaded crate to ensure it is indeed a profiler runtime
@@ -991,7 +1005,7 @@ impl<'a> CrateLoader<'a> {
         item: &ast::Item,
         definitions: &Definitions,
         def_id: LocalDefId,
-    ) -> CrateNum {
+    ) -> Option<CrateNum> {
         match item.kind {
             ast::ItemKind::ExternCrate(orig_name) => {
                 debug!(
@@ -1011,7 +1025,7 @@ impl<'a> CrateLoader<'a> {
                     CrateDepKind::Explicit
                 };
 
-                let cnum = self.resolve_crate(name, item.span, dep_kind);
+                let cnum = self.resolve_crate(name, item.span, dep_kind)?;
 
                 let path_len = definitions.def_path(def_id).data.len();
                 self.update_extern_crate(
@@ -1023,14 +1037,14 @@ impl<'a> CrateLoader<'a> {
                         dependency_of: LOCAL_CRATE,
                     },
                 );
-                cnum
+                Some(cnum)
             }
             _ => bug!(),
         }
     }
 
     pub fn process_path_extern(&mut self, name: Symbol, span: Span) -> CrateNum {
-        let cnum = self.resolve_crate(name, span, CrateDepKind::Explicit);
+        let cnum = self.resolve_crate_or_abort(name, span, CrateDepKind::Explicit);
 
         self.update_extern_crate(
             cnum,

compiler/rustc_metadata/src/locator.rs

@@ -220,7 +220,7 @@ use rustc_data_structures::memmap::Mmap;
 use rustc_data_structures::owning_ref::OwningRef;
 use rustc_data_structures::svh::Svh;
 use rustc_data_structures::sync::MetadataRef;
-use rustc_errors::struct_span_err;
+use rustc_errors::{struct_span_err, DiagnosticBuilder, FatalError};
 use rustc_session::config::{self, CrateType};
 use rustc_session::cstore::{CrateSource, MetadataLoader};
 use rustc_session::filesearch::{FileDoesntMatch, FileMatches, FileSearch};
@@ -814,11 +814,11 @@ pub fn find_plugin_registrar(
     span: Span,
     name: Symbol,
 ) -> PathBuf {
-    match find_plugin_registrar_impl(sess, metadata_loader, name) {
-        Ok(res) => res,
+    find_plugin_registrar_impl(sess, metadata_loader, name).unwrap_or_else(|err| {
         // `core` is always available if we got as far as loading plugins.
-        Err(err) => err.report(sess, span, false),
-    }
+        err.report(sess, span, false);
+        FatalError.raise()
+    })
 }
 
 fn find_plugin_registrar_impl<'a>(
@@ -931,8 +931,8 @@ impl fmt::Display for MetadataError<'_> {
 }
 
 impl CrateError {
-    crate fn report(self, sess: &Session, span: Span, missing_core: bool) -> ! {
-        let mut err = match self {
+    fn build_diag(self, sess: &Session, span: Span, missing_core: bool) -> DiagnosticBuilder<'_> {
+        match self {
             CrateError::NonAsciiName(crate_name) => sess.struct_span_err(
                 span,
                 &format!("cannot load a crate with a non-ascii name `{}`", crate_name),
@@ -1208,10 +1208,10 @@ impl CrateError {
                 "plugin `{}` only found in rlib format, but must be available in dylib format",
                 crate_name,
             ),
-        };
+        }
+    }
 
-        err.emit();
-        sess.abort_if_errors();
-        unreachable!();
+    crate fn report(self, sess: &Session, span: Span, missing_core: bool) {
+        self.build_diag(sess, span, missing_core).emit();
     }
 }