Previous: autoheader Invocation, Up: Configuration Headers
autoheader scans configure.ac and figures out which C
preprocessor symbols it might define. It knows how to generate
templates for symbols defined by
AC_CHECK_FUNCS etc., but if you
AC_DEFINE any additional
symbol, you must define a template for it. If there are missing
templates, autoheader fails with an error message.
The template for a symbol is created
by autoheader from
the description argument to an
see Defining Symbols.
For special needs, you can use the following macros.
Tell autoheader to generate a template for key. This macro generates standard templates just like
AC_DEFINEwhen a description is given.
For example:AH_TEMPLATE([CRAY_STACKSEG_END], [Define to one of _getb67, GETB67, getb67 for Cray-2 and Cray-YMP systems. This function is required for alloca.c support on those systems.])
generates the following template, with the description properly justified./* Define to one of _getb67, GETB67, getb67 for Cray-2 and Cray-YMP systems. This function is required for alloca.c support on those systems. */ #undef CRAY_STACKSEG_END
Tell autoheader to include the template as-is in the header template file. This template is associated with the key, which is used to sort all the different templates and guarantee their uniqueness. It should be a symbol that can be defined via
Please note that text gets included “verbatim” to the template file, not to the resulting config header, so it can easily get mangled when the template is processed. There is rarely a need for something other than