These macros are used to check for types not covered by the “particular” test macros.
Check whether type is defined. It may be a compiler builtin type or defined by the includes (see Default Includes).
For each type of the types that is defined, define
HAVE_type (in all capitals). If no includes are specified, the default includes are used (see Default Includes). If action-if-found is given, it is additional shell code to execute when one of the types is found. If action-if-not-found is given, it is executed when one of the types is not found.
This macro uses M4 lists:AC_CHECK_TYPES([ptrdiff_t]) AC_CHECK_TYPES([unsigned long long int, uintmax_t])
Autoconf, up to 2.13, used to provide to another version of
AC_CHECK_TYPE, broken by design. In order to keep backward
compatibility, a simple heuristics, quite safe but not totally, is
implemented. In case of doubt, read the documentation of the former
AC_CHECK_TYPE, see Obsolete Macros.