--- a/configure.ac Wed Nov 06 16:27:54 2019 +0100 +++ b/configure.ac Wed Nov 06 20:34:54 2019 +0100 @@ -28,6 +28,7 @@ # the package version must match the macros in ucx.h # the lib version must follow the libtool versioning convention +AC_PREREQ([2.60]) AC_INIT([ucx], [2.1.0], [olaf.wintermann@gmail.com]) AC_SUBST([UCX_LIB_VERSION], [4:0:1]) @@ -44,20 +45,17 @@ # we are compiling a library LT_INIT -# we are dealing with C source code -AC_PROG_CC +# we want c11, and may fall back to c99 +AX_CHECK_COMPILE_FLAG([-std=c11], + [AX_APPEND_FLAG([-std=c11])], + AC_PROG_CC_C99 +) # we want to support automake < 1.14, so we need this deprecated macro # it tests, whether the compiler allows -c and -o simultaneously # in modern versions of autoconf, this is done by AC_PROG_CC AM_PROG_CC_C_O -# we want c11, and may fall back to c99 -AX_CHECK_COMPILE_FLAG([-std=c11], - [AX_APPEND_FLAG([-std=c11])], - [AC_PROG_CC_C99] -) - # where to place config macros AC_CONFIG_HEADERS([config.h])