[Bug libstdc++/82558] [8 Regression] V8 JavaScript engine segfaults since r249235

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82558

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
--- a/libstdc++-v3/include/bits/stl_bvector.h
+++ b/libstdc++-v3/include/bits/stl_bvector.h
@@ -417,7 +417,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
        if (__last._M_offset != 0)
          __fill_bvector(__last._M_p, 0, __last._M_offset, __x);
       }
-    else
+    else if (__first._M_offset != __last._M_offset)
       __fill_bvector(__first._M_p, __first._M_offset, __last._M_offset, __x);
   }