Are Ada 95 compilers compatible with Ada 83?
Yes, absolutely. Ada 95 is very close to upwards compatible with Ada 83, so you will find that an Ada 95 compiler is in practice “compatible” with the Ada 83 compiler you have used or are using. The compatibility really depends on what kind of code you have written, so one should understand what has evolved, what was considered broken and is now fixed, as well as what is new. There are two excellent documents that will help immensely in that respect: • Changes to Ada — 1987 to 1995, in a Postscript 362KB file: ftp://sw-eng.falls-church.va.us/public/AdaIC/standards/95lrm_rat/v6.0/chg83.ps also available in a text-only 207KB file: ftp://sw-eng.falls-church.va.us/public/AdaIC/standards/95lrm_rat/v6.0/chg83.doc • Ada 9X Compatibility Guide, by Bill Taylor, in directory ftp://sw-eng.falls-church.va.us/public/AdaIC/docs/compat-guide Furthermore, GNAT has a -gnat83 switch which enforces most of the Ada 83 restrictions, and other compilers have similar 95/83 modes.
