Error while compiling C code on AIX 7

Question

SO, I have been asked to compile some legacy C code on a AIX7 (64 bit ) box.

And, I just changed the makefiles to edit the compiler that was used (from gcc to xlc_r), and the flags, from (-DAIX3 to -DAIX7).

However, thanks to this tomfoolery, I am getting an error which complains

    xlc_r -c -q64 -O -DAIX -DAIX7  log.c
  "log.c", line 128.7: 1506-343 (S) Redeclaration of log_write differs from previous declaration on line 140 of "lib.h".
  "log.c", line 128.7: 1506-378 (I) Prototype for function log_write cannot contain "..." when mixed with a nonprototype declaration.
  "log.c", line 165.7: 1506-343 (S) Redeclaration of log_errno differs from previous declaration on line 141 of "lib.h".
 "log.c", line 165.7: 1506-378 (I) Prototype for function log_errno cannot contain "..." when mixed with a nonprototype declaration.
 make: 1254-004 The error code from the last command is 1.

The method is question look like

  extern  void    log_write _PROTO(( int, char *, ... ));
  extern  void    log_errno _PROTO(( int, char *, ... ));

I want to know what the ... is, does it make for an open list of parameters? And how do I get this to run on AIX7?

Answer 1

An ellipsis (...) in a function declaration or definition indicates that the function accepts a variable number (zero or more) of parameters.

Back in the days when it was common to need to compile code using both pre-ANSI and ANSI-conforming compilers, a frequent approach for handling function declaration differences between the two flavors of the C language was to conditionally define a macro that could allow either ANSI-style declarations or K&R-style declarations by changing a macro definition. I suspect that the _PROTO() macro used in your example is being defined to have K&R-style declarations instead of ANSI-style declarations with prototypes, fixing this will likely address these compilation issues