This guide describes the use of GNAT, a compiler and software development toolset for the full Ada programming language. It documents the features of the compiler and tools, and explains how to use them to build Ada applications.
GNAT implements Ada 95, Ada 2005, Ada 2012, and Ada 202x, and it may also be invoked in Ada 83 compatibility mode. By default, GNAT assumes Ada 2012, but you can override with a compiler switch (Compiling Different Versions of Ada) to explicitly specify the language version. Throughout this manual, references to ‘Ada’ without a year suffix apply to all Ada versions of the language, starting with Ada 95.