When macros statically diagnose abnormal situations, benign or fatal, it
is possible to make
autoconf detect the problem, and refuse to
create configure in the case of an error. The macros in this
section are considered obsolescent, and new code should use M4sugar
macros for this purpose, see Diagnostic Macros.
On the other hand, it is possible to want to detect errors when
configure is run, which are dependent on the environment of
the user rather than the maintainer. For dynamic diagnostics, see
Report message as a warning (or as an error if requested by the user) if warnings of the category are turned on. This macro is obsolescent; you are encouraged to use:
instead. See m4_warn for more details, including valid category names.
Report message as a syntax warning. This macro is obsolescent; you are encouraged to use:
instead. See m4_warn for more details, as well as better finer-grained categories of warnings (not all problems have to do with syntax).
Report a severe error message, and have
This macro is obsolescent; you are encouraged to use:
instead. See m4_fatal for more details.
When the user runs ‘autoconf -W error’, warnings from
m4_warn (including those issued through
AC_WARNING) are reported as errors, see autoconf Invocation.