[cfe-dev] reinterpret_cast of pointer-to-member

[Deep Majumder via cfe-dev]

Hi everyone,
I am working on a patch that involves reinterpret_cast of pointer to
member. Working on Godbolt, it seems that the casts don't always make
sense. Take a look at https://godbolt.org/z/6E7aoK.
Both c and cs are supposed to point to the same field. However, c has the
wrong offset (12) while cs has the right offset (0). This can be seen from
the return value also (returns 16 instead of the expected 29).
So my query is: are reinterpret_cast on pointer-to-member considered
undefined behaviour? Because different optimisation levels give different
answers (try -O2).
Warm regards,
Deep
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