Alpha OSF/1 (Digital UNIX) V4.0

The C compiler provided with Alpha OSF/1 V4.0 (a.k.a. Digital UNIX) defaults to an extended K&R C mode, not ANSI C. You need to provide the -std argument to the compiler (i.e., ./configure CC='cc -std') to enable extended ANSI C mode. More recent versions of the operating system, such as 5.0, seem to have C compilers which default to -std.