Hi Andres,
Commit ec3c9cc add pg_attribute_aligned in MSVC[1],
which was pushed one day before the meson commits,
so meson build missed this feature.
[1]: https://www.postgresql.org/message-id/CAAaqYe-HbtZvR3msoMtk+hYW2S0e0OapzMW8icSMYTMA+mN8Aw@mail.gmail.com
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Regards
Junwang Zhao