Unexpected memory layout of variant #206
Description
I expect variant to be equivalent to the following C program, i.e. payload always starts at the same byte offset.
typedef union {
...
} Data;
typedef struct {
int type;
Data data;
} Variant;
But with the following program, it's clear that this is not the case.
(import variant)
(import cstdio)
(def Y (struct intern ((a float) (b float))))
(def-variant X ((A ((x uint64)))
(B ((x Y)))))
(def dump-hex (fn intern void ((ptr (p uint8)) (n size))
(for (i \ 0) (< i (cast n int)) (incv i)
(printf " %02x" (@ (p+ ptr i))))
(printf "\n")))
(def main (fn extern-c int (void)
(def X1 (var auto \ (A (cast 1 uint64))))
(dump-hex (cast (# X1) (p uint8)) (sizeof X1))
(def X2 (var auto \ (B (Y ((a 1.0) (b 1.0))))))
(dump-hex (cast (# X2) (p uint8)) (sizeof X2))
0))
The above program outputs:
00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00
01 00 00 00 00 00 80 3f 00 00 80 3f 00 00 00 00