Serialization of a Derived Class from a Base Class Pointer is Incorrect in Boost 1.85

[ckreatsoMW]

We have some code which is similar to repro.zip.

In Boost 1.81, the code successfully serializes and deserializes the Derived class from its Base pointer. However, in Boost 1.85, the deserialization fails when using a Text or Binary archive.

We tracked down this issue to the one identified in the comments of #287. If we manually revert this change and rerun the serialization/deserialization, the library behaves as expected.

Boost 1.81 Text Serialization:

22 serialization::archive 19 1 1 1
0 0 3 0 0 0 0 16 This is a string

Boost 1.85 Text Serialization:

22 serialization::archive 20 1 1 1
0 0 3
1 0 0 0 0 16 This is a string

As #287 did not make a corresponding deserialization change, this seems to be a bug

To reproduce this issue, do the following:

1. Download repro.zip
2. Build and run the "repro" executable and its dependencies with Boost 1.81. Everything passes as expected.
3. Build and run the "repro" executable and its dependencies with Boost 1.85. The "derivedData" string fails to deserialize.

[tcormackMW]

Hi I am also running into this issue and am following up here to see if anyone had thoughts about this.