Properly initialise memory when REDIMming with UDT #497
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This allows simplifying how the size of UDT arrays are calculated, and thus not leave memory uninitialised when doing a redim that expands the array size.
allocarray() previously assumed a variable size UDT had only variable-length strings. This caused any numeric elements to remain uninitialised.
RhoSigma-QB64
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This closes #331 with the addition of calls to ZeroMemory() as needed to zero out numeric variables in UDTs with variable length strings.
While implementing that I also found issues with redimming arrays of regular numeric UDTs; the address to start zeroing was off by one. To make this logic a little cleaner we no longer keep track of whether a UDT element should be aligned to a whole number of bytes - they already effectively were, since _BIT types are not allowed in a UDT (this code seemed to be trying to allow for a hypothetical sub-byte alignment).
At some point we may want to revisit this to enforce certain alignments of fields, but that should not be a concern of allocarray() and will never be packing multiple values into one byte.