1 files changed, 35 insertions, 11 deletions
diff --git a/compiler/rustc_metadata/src/creader.rs b/compiler/rustc_metadata/src/creader.rs
index 23aceca06..aaf72ab94 100644
--- a/compiler/rustc_metadata/src/creader.rs
+++ b/compiler/rustc_metadata/src/creader.rs
@@ -4,7 +4,7 @@ use crate::errors;
 use crate::locator::{CrateError, CrateLocator, CratePaths};
 use crate::rmeta::{CrateDep, CrateMetadata, CrateNumMap, CrateRoot, MetadataBlob};
 
-use rustc_ast::expand::allocator::AllocatorKind;
+use rustc_ast::expand::allocator::{alloc_error_handler_name, global_fn_name, AllocatorKind};
 use rustc_ast::{self as ast, *};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::svh::Svh;
@@ -12,7 +12,7 @@ use rustc_data_structures::sync::{MappedReadGuard, MappedWriteGuard, ReadGuard,
 use rustc_expand::base::SyntaxExtension;
 use rustc_hir::def_id::{CrateNum, LocalDefId, StableCrateId, StableCrateIdMap, LOCAL_CRATE};
 use rustc_hir::definitions::Definitions;
-use rustc_index::vec::IndexVec;
+use rustc_index::IndexVec;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::config::{self, CrateType, ExternLocation};
 use rustc_session::cstore::ExternCrateSource;
@@ -27,6 +27,7 @@ use rustc_span::{Span, DUMMY_SP};
 use rustc_target::spec::{PanicStrategy, TargetTriple};
 
 use proc_macro::bridge::client::ProcMacro;
+use std::error::Error;
 use std::ops::Fn;
 use std::path::Path;
 use std::time::Duration;
@@ -147,11 +148,15 @@ impl CStore {
         assert_eq!(self.metas.len(), self.stable_crate_ids.len());
         let num = CrateNum::new(self.stable_crate_ids.len());
         if let Some(&existing) = self.stable_crate_ids.get(&root.stable_crate_id()) {
-            let crate_name0 = root.name();
-            if let Some(crate_name1) = self.metas[existing].as_ref().map(|data| data.name()) {
+            // Check for (potential) conflicts with the local crate
+            if existing == LOCAL_CRATE {
+                Err(CrateError::SymbolConflictsCurrent(root.name()))
+            } else if let Some(crate_name1) = self.metas[existing].as_ref().map(|data| data.name())
+            {
+                let crate_name0 = root.name();
                 Err(CrateError::StableCrateIdCollision(crate_name0, crate_name1))
             } else {
-                Err(CrateError::SymbolConflictsCurrent(crate_name0))
+                Err(CrateError::NotFound(root.name()))
             }
         } else {
             self.metas.push(None);
@@ -368,7 +373,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         let host_hash = host_lib.as_ref().map(|lib| lib.metadata.get_root().hash());
 
         let private_dep =
-            self.sess.opts.externs.get(name.as_str()).map_or(false, |e| e.is_private_dep);
+            self.sess.opts.externs.get(name.as_str()).is_some_and(|e| e.is_private_dep);
 
         // Claim this crate number and cache it
         let cnum = self.cstore.intern_stable_crate_id(&crate_root)?;
@@ -864,6 +869,17 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         }
     }
 
+    fn inject_forced_externs(&mut self) {
+        for (name, entry) in self.sess.opts.externs.iter() {
+            if entry.force {
+                let name_interned = Symbol::intern(name);
+                if !self.used_extern_options.contains(&name_interned) {
+                    self.resolve_crate(name_interned, DUMMY_SP, CrateDepKind::Explicit);
+                }
+            }
+        }
+    }
+
     fn inject_dependency_if(
         &self,
         krate: CrateNum,
@@ -912,7 +928,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
                 // Don't worry about pathless `--extern foo` sysroot references
                 continue;
             }
-            if entry.nounused_dep {
+            if entry.nounused_dep || entry.force {
                 // We're not worried about this one
                 continue;
             }
@@ -931,7 +947,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
                     lint::builtin::UNUSED_CRATE_DEPENDENCIES,
                     span,
                     ast::CRATE_NODE_ID,
-                    &format!(
+                    format!(
                         "external crate `{}` unused in `{}`: remove the dependency or add `use {} as _;`",
                         name,
                         self.tcx.crate_name(LOCAL_CRATE),
@@ -941,6 +957,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
     }
 
     pub fn postprocess(&mut self, krate: &ast::Crate) {
+        self.inject_forced_externs();
         self.inject_profiler_runtime(krate);
         self.inject_allocator_crate(krate);
         self.inject_panic_runtime(krate);
@@ -1031,7 +1048,7 @@ fn global_allocator_spans(krate: &ast::Crate) -> Vec<Span> {
         }
     }
 
-    let name = Symbol::intern(&AllocatorKind::Global.fn_name(sym::alloc));
+    let name = Symbol::intern(&global_fn_name(sym::alloc));
     let mut f = Finder { name, spans: Vec::new() };
     visit::walk_crate(&mut f, krate);
     f.spans
@@ -1053,7 +1070,7 @@ fn alloc_error_handler_spans(krate: &ast::Crate) -> Vec<Span> {
         }
     }
 
-    let name = Symbol::intern(&AllocatorKind::Global.fn_name(sym::oom));
+    let name = Symbol::intern(alloc_error_handler_name(AllocatorKind::Global));
     let mut f = Finder { name, spans: Vec::new() };
     visit::walk_crate(&mut f, krate);
     f.spans
@@ -1094,5 +1111,12 @@ fn load_dylib(path: &Path, max_attempts: usize) -> Result<libloading::Library, S
     }
 
     debug!("Failed to load proc-macro `{}` even after {} attempts.", path.display(), max_attempts);
-    Err(format!("{} (retried {} times)", last_error.unwrap(), max_attempts))
+
+    let last_error = last_error.unwrap();
+    let message = if let Some(src) = last_error.source() {
+        format!("{last_error} ({src}) (retried {max_attempts} times)")
+    } else {
+        format!("{last_error} (retried {max_attempts} times)")
+    };
+    Err(message)
 }