On 04.02.2021 10:59, Roger Pau Monné wrote: > On Thu, Feb 04, 2021 at 10:46:58AM +0100, Jan Beulich wrote: >> On 04.02.2021 10:38, Roger Pau Monne wrote: >>> --- a/tools/configure.ac >>> +++ b/tools/configure.ac >>> @@ -74,6 +74,7 @@ m4_include([../m4/ax_compare_version.m4]) >>> m4_include([../m4/paths.m4]) >>> m4_include([../m4/systemd.m4]) >>> m4_include([../m4/golang.m4]) >>> +m4_include([../m4/header.m4]) >>> >>> AX_XEN_EXPAND_CONFIG() >>> >>> @@ -517,4 +518,6 @@ AC_ARG_ENABLE([pvshim], >>> ]) >>> AC_SUBST(pvshim) >>> >>> +AX_FIND_HEADER([INCLUDE_ENDIAN_H], [endian.h sys/endian.h]) >> >> Instead of a new macro, can't you use AC_CHECK_HEADERS()? > > AC_CHECK_HEADERS doesn't do what we want here: it will instead produce > a HAVE_header-file define for each header on the list that's present, > and the action-if-found doesn't get passed the path of the found > header according to the documentation. > > Here I want the variable to be set to the include path of the first > header on the list that's present on the system.
I was thinking of #if defined(HAVE_SYS_ENDIAN_H) # include <sys/endian.h> #elif defined(HAVE_ENDIAN_H) # include <endian.h> #else # error ... #endif >> I'm also not certain about the order of checks - what if both >> exist? > > With my macro the first one will be picked. And which one is to be the first one? IOW how likely is it that on a system having both the first one is what we're after vs the second one? Jan
