1 files changed, 6 insertions, 3 deletions
diff --git a/llvm/lib/Object/IRSymtab.cpp b/llvm/lib/Object/IRSymtab.cpp
index 668cf62..7fc84e2 100644
--- a/llvm/lib/Object/IRSymtab.cpp
+++ b/llvm/lib/Object/IRSymtab.cpp
@@ -231,11 +231,14 @@ Error Builder::addSymbol(const ModuleSymbolTable &Msymtab,
 
     if ((Flags & object::BasicSymbolRef::SF_Weak) &&
         (Flags & object::BasicSymbolRef::SF_Indirect)) {
+      auto *Fallback = dyn_cast<GlobalValue>(
+          cast<GlobalAlias>(GV)->getAliasee()->stripPointerCasts());
+      if (!Fallback)
+        return make_error<StringError>("Invalid weak external",
+                                       inconvertibleErrorCode());
       std::string FallbackName;
       raw_string_ostream OS(FallbackName);
-      Msymtab.printSymbolName(
-          OS, cast<GlobalValue>(
-                  cast<GlobalAlias>(GV)->getAliasee()->stripPointerCasts()));
+      Msymtab.printSymbolName(OS, Fallback);
       OS.flush();
       setStr(Uncommon().COFFWeakExternFallbackName, Saver.save(FallbackName));
     }