Copyright © 1996-2011,2013 by Thomas E. Dickey
atac measures how thoroughly a program is tested by a set of tests using data flow coverage techniques, identifies areas that are not well tested, identifies overlap among tests, and finds minimal covering test sets. atac displays C source code, highlighting code fragments not covered by test executions.
This was written by some folks at BellCore around 1992-1994:
who were working (at the end of 1995) on a commercial version.
I made changes to port it to Linux with gcc 2.7.0, and later auto-configured for several Unix hosts to use in testing diffstat, cproto, and other programs.
In its current state, the source can work with gcc up to around 3.0. It needs additional work to accommodate gcc's various nonstandard syntax features to go past that version.