Ada compilers are allowed to supplement the language-defined pragmas, and
these are a potential source of non-portability. All GNAT-defined pragmas
are described in Implementation Defined Pragmas, and these include several that are specifically
intended to correspond to other vendors' Ada 83 pragmas.
For migrating from VADS, the pragma
Use_VADS_Size may be useful.
For compatibility with HP Ada 83, GNAT supplies the pragmas
Other relevant pragmas include
Ada 83 pragmas (
avoiding compiler rejection of units that contain such pragmas; they are not
relevant in a GNAT context and hence are not otherwise implemented.