I came across the following obviously corrupt macro in pg_lzcompress.h:
#define PGLZ_IS_COMPRESSED(_lzdata) ((_lzdata)->varsize != \
e (_lzdata)->rawsize + e \
sizeof(PGLZ_Header))
The reason we have not noticed its brokenness is that it's only used in
macro pglz_decomp_init, which is used nowhere. In fact there seems to
be quite a lot of dead code in this header. I'm inclined to remove
everything that's not referenced, rather than try to fix it.
regards, tom lane