The macros @code{AC_CHECK_LIB}, @code{AC_SEARCH_LIBS} from GNU Autoconf check
for the presence of certain C, C++, or Fortran library archive files.
-The libraries are looked up in the default linker path -- a system dependent
-list of directories, that usually contains the @file{/usr/lib} directory --
- and those directories given by @code{-L} options in the @code{LDFLAGS}
+The libraries are looked up in the default linker path---a system dependent
+list of directories, that usually contains the @file{/usr/lib} directory---and
+those directories given by @code{-L} options in the @code{LDFLAGS}
variable.
@unnumberedsubsec Locating Libraries
This macro should be used when @code{lib<@var{name}>} is expected to be found.
@end deffn
-@deffn Macro @code{AC_LIB_HAVE_LINKFLAGS(@var{name}, [@var{dependencies}], [@var{includes}], [@var{testcode}])}
+@deffn Macro @code{AC_LIB_HAVE_LINKFLAGS(@var{name}, [@var{dependencies}], [@var{includes}], [@var{testcode}], [@var{missing-message}])}
Searches for @code{lib<@var{name}>} and the libraries corresponding to
explicit and implicit dependencies, together with the specified include files
-and the ability to compile and link the specified @var{testcode}. If found,
-it sets and AC_SUBSTs @code{HAVE_LIB<@var{NAME}>=yes} and the
-@code{LIB<@var{NAME}>} and @code{LTLIB<@var{NAME}>} variables (with
+and the ability to compile and link the specified @var{testcode}. The
+@var{missing-message} defaults to @code{no} and may contain additional hints
+for the user. If found, it sets and AC_SUBSTs @code{HAVE_LIB<@var{NAME}>=yes}
+and the @code{LIB<@var{NAME}>} and @code{LTLIB<@var{NAME}>} variables (with
@code{<@var{NAME}>} in upper case) and augments the @code{CPPFLAGS} variable
by @code{-I} options, and #defines @code{HAVE_LIB<@var{NAME}>} to 1.
Otherwise, it sets and AC_SUBSTs @code{HAVE_LIB<@var{NAME}>=no} and