Hi, On 2023-02-06 11:55:40 -0500, Tom Lane wrote: > I am, however, very dubious that Andres is correct that there's a > problem here. Given that two of the variants of union NumericChoice > are structs ending with a flexible array, any compiler that thinks > it knows the size of the union precisely is broken.
The compiler just complains about the minimum size of the union, which is Max(offsetof(NumericShort, n_data), offsetof(NumericLong, n_data)) IOW, our trickery with flexible arrays would allow us to allocate just 8 bytes for a NumericData, but not just 6. Flexible arrays allow the compiler to understand the variable size, but we don't use it for all variability. Hence the warnings. Greetings, Andres Freund