NAME

gpt_undefines - Generate a list of preprocessor macros that are not defined.

SYNOPSIS

gpt_undefines [-srcdir=PATH -config -disable-undefs -verbose -help] headers containing defines

DESCRIPTION

gpt_undefines Generates a list of preprocessor macros that are not defined internally in the source code. Macros that are defined in the header files listed during gpt_undefines's invocation will also be excluded.

OPTIONS

-srcdir=PATH

Use PATH as the directory containing the source code. Source code in the entire directory tree will be scanned. Default PATH is the directory gpt_undefines was invoked in.

-config

Prints the list out in a format that can be pasted into an installable header file.

-disable-undefs

Do not count commented out undefines as a define. This technique is used by autoconf to indicate a negative test result. Example:

   /* #undef HAVE_TCP_FASTACK */

Managing Autoconf defines.

By default the defines tested for by the configure script are stored in a file called config.h. This file should never be installed. to add autoconf defines to config.h simply add the define in the following format to the file acconfig.h:

   #undef AUTOCONF_DEFINE

acconfig.h is tranformed into a config.h.in by the script autoheader. Then the configure script transform it into config.h.

A problem occurs when the autoconf defines are used in installed header files. In this case the defines should be put in an installable header file using the following format:

   #ifndef AUTOCONF_DEFINE
   #undef AUTOCONF_DEFINE
   #endif

AUTHOR