Length of PARI types

[Jeroen Demeyer <jdemeyer@cage.ugent.be>]

Hello,

I have a question about the following paragraph from the libpari 
documentation about cgetg():

Note that the length argument $l$ is predetermined for a number of 
types: 3 for types \typ{INTMOD}, \typ{FRAC}, \typ{COMPLEX}, 
\typ{POLMOD}, \typ{RFRAC}, 4 for type \typ{QUAD} and \typ{QFI}, and 5 
for type \typ{PADIC} and \typ{QFR}. However for the sake of efficiency, 
\kbd{cgetg} does not check this: disasters will occur if you give an 
incorrect length for those types.

I can imagine that "disasters" can occur if these types are allocated 
with too few space, but what can go wrong if any of these types is 
allocated with more codewords than required?  I think that should be okay?

Cheers,
Jeroen.