Hello, This is my configure.ac file: AC_INIT([my-project], [20160412]) AM_INIT_AUTOMAKE AM_PROG_CC_C_O AC_CHECK_HEADER([avr/io.h], [], [AC_MSG_ERROR([missing header: avr/io.h])]) AC_CHECK_HEADER([util/delay.h], [], [AC_MSG_ERROR([missing header: util/delay.h])]) AC_CHECK_HEADER([stdio.h], [], [AC_MSG_ERROR([missing header: stdio.h])]) AC_CHECK_HEADER([time.h], [], [AC_MSG_ERROR([missing header: time.h])]) AC_CONFIG_FILES([Makefile]) AC_OUTPUT The two first header checks must be called only when host is "avr" whereas the two last checks must be called in other cases. Currently, if I call my configure script with host set to "avr" that's what happens: $ ./configure --host=avr checking for a BSD-compatible install... /bin/ginstall -c checking whether build environment is sane... yes checking for avr-strip... avr-strip checking for a thread-safe mkdir -p... /bin/mkdir -p checking for gawk... gawk checking whether make sets $(MAKE)... yes checking for style of include used by make... GNU checking for avr-gcc... avr-gcc checking whether the C compiler works... yes checking for C compiler default output file name... a.out checking for suffix of executables... checking whether we are cross compiling... yes checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether avr-gcc accepts -g... yes checking for avr-gcc option to accept ISO C89... none needed checking dependency style of avr-gcc... gcc3 checking whether avr-gcc and cc understand -c and -o together... yes checking how to run the C preprocessor... avr-gcc -E checking for grep that handles long lines and -e... /bin/grep checking for egrep... /bin/grep -E checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... no checking for stdlib.h... yes checking for string.h... yes checking for memory.h... no checking for strings.h... no checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking avr/io.h usability... yes checking avr/io.h presence... yes checking for avr/io.h... yes checking util/delay.h usability... yes checking util/delay.h presence... yes checking for util/delay.h... yes checking stdio.h usability... yes checking stdio.h presence... yes checking for stdio.h... yes checking time.h usability... yes checking time.h presence... yes checking for time.h... yes configure: creating ./config.status config.status: creating Makefile config.status: executing depfiles commands As you can see the : AC_CHECK_HEADER([stdio.h], [], [AC_MSG_ERROR([missing header: stdio.h])]) AC_CHECK_HEADER([time.h], [], [AC_MSG_ERROR([missing header: time.h])]) calls are done whereas it is useless for my project when host is "avr". And you can guess what happens when I call my configure script with host not set: $ ./configure checking for a BSD-compatible install... /bin/ginstall -c checking whether build environment is sane... yes checking for a thread-safe mkdir -p... /bin/mkdir -p checking for gawk... gawk checking whether make sets $(MAKE)... yes checking for style of include used by make... GNU checking for gcc... gcc checking whether the C compiler works... yes checking for C compiler default output file name... a.out checking for suffix of executables... checking whether we are cross compiling... no checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ISO C89... none needed checking dependency style of gcc... gcc3 checking whether gcc and cc understand -c and -o together... yes checking how to run the C preprocessor... gcc -E checking for grep that handles long lines and -e... /bin/grep checking for egrep... /bin/grep -E checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... yes checking for stdlib.h... yes checking for string.h... yes checking for memory.h... yes checking for strings.h... yes checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking avr/io.h usability... no checking avr/io.h presence... no checking for avr/io.h... no configure: error: missing header: avr/io.h Here, the: AC_CHECK_HEADER([avr/io.h], [], [AC_MSG_ERROR([missing header: avr/io.h])]) AC_CHECK_HEADER([util/delay.h], [], [AC_MSG_ERROR([missing header: util/delay.h])]) calls are done whereas when host is my linux machine, these checks should not be done. So, I would like to call the AC_CHECK_HEADER macro on a condition: AC_INIT([my-project], [20160412]) AM_INIT_AUTOMAKE AM_PROG_CC_C_O if test "x$host" == xavr; then AC_CHECK_HEADER([avr/io.h], [], [AC_MSG_ERROR([missing header: avr/io.h])]) AC_CHECK_HEADER([util/delay.h], [], [AC_MSG_ERROR([missing header: util/delay.h])]) else AC_CHECK_HEADER([stdio.h], [], [AC_MSG_ERROR([missing header: stdio.h])]) AC_CHECK_HEADER([time.h], [], [AC_MSG_ERROR([missing header: time.h])]) fi AC_CONFIG_FILES([Makefile]) AC_OUTPUT With this new configure.ac file, if I call my configure script with host set to "avr" that's what happens: $ ./configure --host=avr checking for a BSD-compatible install... /bin/ginstall -c checking whether build environment is sane... yes checking for avr-strip... avr-strip checking for a thread-safe mkdir -p... /bin/mkdir -p checking for gawk... gawk checking whether make sets $(MAKE)... yes checking for style of include used by make... GNU checking for avr-gcc... avr-gcc checking whether the C compiler works... yes checking for C compiler default output file name... a.out checking for suffix of executables... checking whether we are cross compiling... yes checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether avr-gcc accepts -g... yes checking for avr-gcc option to accept ISO C89... none needed checking dependency style of avr-gcc... gcc3 checking whether avr-gcc and cc understand -c and -o together... yes checking how to run the C preprocessor... avr-gcc -E checking for grep that handles long lines and -e... /bin/grep checking for egrep... /bin/grep -E checking for ANSI C header files... yes checking for sys/types.h... yes checking for sys/stat.h... no checking for stdlib.h... yes checking for string.h... yes checking for memory.h... no checking for strings.h... no checking for inttypes.h... yes checking for stdint.h... yes checking for unistd.h... yes checking avr/io.h usability... yes checking avr/io.h presence... yes checking for avr/io.h... yes checking util/delay.h usability... yes checking util/delay.h presence... yes checking for util/delay.h... yes configure: creating ./config.status config.status: creating Makefile config.status: executing depfiles commands It seems to do the job. The: AC_CHECK_HEADER([stdio.h], [], [AC_MSG_ERROR([missing header: stdio.h])]) AC_CHECK_HEADER([time.h], [], [AC_MSG_ERROR([missing header: time.h])]) calls are not anymore done. And that's what happens when I call my configure script with host not set: $ ./configure checking for a BSD-compatible install... /bin/ginstall -c checking whether build environment is sane... yes checking for a thread-safe mkdir -p... /bin/mkdir -p checking for gawk... gawk checking whether make sets $(MAKE)... yes checking for style of include used by make... GNU checking for gcc... gcc checking whether the C compiler works... yes checking for C compiler default output file name... a.out checking for suffix of executables... checking whether we are cross compiling... no checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ISO C89... none needed checking dependency style of gcc... gcc3 checking whether gcc and cc understand -c and -o together... yes checking stdio.h usability... yes checking stdio.h presence... no configure: WARNING: stdio.h: accepted by the compiler, rejected by the preprocessor! configure: WARNING: stdio.h: proceeding with the compiler's result checking for stdio.h... yes checking time.h usability... yes checking time.h presence... no configure: WARNING: time.h: accepted by the compiler, rejected by the preprocessor! configure: WARNING: time.h: proceeding with the compiler's result checking for time.h... yes configure: creating ./config.status config.status: creating Makefile config.status: executing depfiles commands As you can see, the good thing is that the: AC_CHECK_HEADER([avr/io.h], [], [AC_MSG_ERROR([missing header: avr/io.h])]) AC_CHECK_HEADER([util/delay.h], [], [AC_MSG_ERROR([missing header: util/delay.h])]) calls are not anymore done. However, the bad thing is that I got some warnings: [...] configure: WARNING: stdio.h: accepted by the compiler, rejected by the preprocessor! configure: WARNING: stdio.h: proceeding with the compiler's result [...] configure: WARNING: time.h: accepted by the compiler, rejected by the preprocessor! configure: WARNING: time.h: proceeding with the compiler's result [...] So, I guess my configure.ac file is wrong. How to do the things correctly please to call the AC_CHECK_HEADER macro on a condition? Thank you. Best regards. _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx https://lists.gnu.org/mailman/listinfo/autoconf
