Ensure we codegen and don't internalize the entrypoint

2 files changed, 16 insertions, 4 deletions

diff --git a/compiler/rustc_middle/src/mir/mono.rs b/compiler/rustc_middle/src/mir/mono.rs
index 47ba850d50d..c2927361d05 100644
--- a/compiler/rustc_middle/src/mir/mono.rs
+++ b/compiler/rustc_middle/src/mir/mono.rs
@@ -143,10 +143,8 @@ impl<'tcx> MonoItem<'tcx> {
         };
 
         // Similarly, the executable entrypoint must be instantiated exactly once.
-        if let Some((entry_def_id, _)) = tcx.entry_fn(()) {
-            if instance.def_id() == entry_def_id {
-                return InstantiationMode::GloballyShared { may_conflict: false };
-            }
+        if tcx.is_entrypoint(instance.def_id()) {
+            return InstantiationMode::GloballyShared { may_conflict: false };
         }
 
         // If the function is #[naked] or contains any other attribute that requires exactly-once
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 915b062417f..26da2abe126 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -3402,6 +3402,20 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn do_not_recommend_impl(self, def_id: DefId) -> bool {
         self.get_diagnostic_attr(def_id, sym::do_not_recommend).is_some()
     }
+
+    /// Whether this def is one of the special bin crate entrypoint functions that must have a
+    /// monomorphization and also not be internalized in the bin crate.
+    pub fn is_entrypoint(self, def_id: DefId) -> bool {
+        if self.is_lang_item(def_id, LangItem::Start) {
+            return true;
+        }
+        if let Some((entry_def_id, _)) = self.entry_fn(())
+            && entry_def_id == def_id
+        {
+            return true;
+        }
+        false
+    }
 }
 
 /// Parameter attributes that can only be determined by examining the body of a function instead