PR gdb/28480: Improve ambiguous member detection

[deliverable/binutils-gdb.git] / gdb / valops.c

diff --git a/gdb/valops.c b/gdb/valops.c
index bd547923496f4b39a3651b47679771eaf3feb4fc..3769ab9630a4c610d40fd263438a1ab0d9a7f3bf 100644 (file)
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -1969,6 +1969,34 @@ struct_field_searcher::update_result (struct value *v, LONGEST boffset)
             space.  */
          if (m_fields.empty () || m_last_boffset != boffset)
            m_fields.push_back ({m_struct_path, v});
+         else
+           {
+           /*Fields can occupy the same space and have the same name (be
+             ambiguous).  This can happen when fields in two different base
+             classes are marked [[no_unique_address]] and have the same name.
+             The C++ standard says that such fields can only occupy the same
+             space if they are of different type, but we don't rely on that in
+             the following code. */
+             bool ambiguous = false, insert = true;
+             for (const found_field &field: m_fields)
+               {
+                 if(field.path.back () != m_struct_path.back ())
+                   {
+                   /* Same boffset points to members of different classes.
+                      We have found an ambiguity and should record it.  */
+                     ambiguous = true;
+                   }
+                 else
+                   {
+                   /* We don't need to insert this value again, because a
+                      non-ambiguous path already leads to it.  */
+                     insert = false;
+                     break;
+                   }
+               }
+             if (ambiguous && insert)
+               m_fields.push_back ({m_struct_path, v});
+           }
        }
     }
 }