https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88993
--- Comment #11 from Martin Sebor <msebor at gcc dot gnu.org> --- There is no reliable way. The limit may not be fixed, or can be different for different directives or format strings. A test case like the one in the Red Hat bug #441945 linked at comment #2 might tell you there is a limit but not necessarily what it is. A case that interposes a custom malloc/free that fails at different points/different sizes might expose other limits (or bugs) altogether. If that doesn't cause any trouble it's pretty safe to assume that there is no limit. I tried both approaches with a few systems in the compile farm (I think AIX, FreeBSD, NetBSD, Glibc, and Solaris) and only got Glibc to fail (as in either return an error or crash).
