[Buildroot] [PATCH 1/1] package/brltty: fix build with expat

Hello Fabrice,

On Sun, 29 Sep 2019 10:40:04 +0200
Fabrice Fontaine [off-list ref] wrote:

tbl2hex is a host command line that is built with:

TBL2HEX_OBJECTS_FOR_BUILD = tbl2hex.$(O_FOR_BUILD) $(PROGRAM_OBJECTS_FOR_BUILD) dataarea.$(O_FOR_BUILD) ttb_compile.$(O_FOR_BUILD) ttb_native.$(O_FOR_BUILD) atb_compile.$(O_FOR_BUILD) ctb_compile.$(O_FOR_BUILD) cldr.$(O_FOR_BUILD)
TBL2HEX_OBJECTS = $(TBL2HEX_OBJECTS_FOR_BUILD:.$(O_FOR_BUILD)=.$B)

tbl2hex$(X_FOR_BUILD): $(TBL2HEX_OBJECTS)
$(CC_FOR_BUILD) $(LDFLAGS_FOR_BUILD) -o $@ $(TBL2HEX_OBJECTS) $(EXPAT_LIBS_FOR_BUILD) $(LDLIBS_FOR_BUILD)

So build fails if expat is enabled on target but not found on host:

gcc -DFOR_BUILD -I. -I. -I./../Programs -I../Programs -I../Headers -I./.. -I.. -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  -D_DEFAULT_SOURCE -D_POSIX_C_SOURCE=2 -D_BSD_SOURCE -D_XOPEN_SOURCE=500 -D_XOPEN_SOURCE_EXTENDED -D_GNU_SOURCE  -D_DEFAULT_SOURCE -D_POSIX_C_SOURCE=2 -D_BSD_SOURCE -D_XOPEN_SOURCE=500 -D_XOPEN_SOURCE_EXTENDED -D_GNU_SOURCE -DHAVE_CONFIG_H -g -O2 -std=gnu99 -Wall -Werror=format-security -o cldr.build.o -c cldr.c
cldr.c:31:10: fatal error: expat.h: No such file or directory
 #include <expat.h>
          ^~~~~~~~~

Did you really test this patch on a system where expat was not
installed system-wide ? Because I did, and building host-expat before
building brltty doesn't solve the build issue, I still get:

cldr.c:31:19: fatal error: expat.h: No such file or directory
compilation terminated.

And this is quite expected if you look at the build command line:

gcc -DFOR_BUILD -I. -I. -I./../Programs -I../Programs -I../Headers -I./.. -I.. -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  -D_DEFAULT_SOURCE -D_POSIX_C_SOURCE=2 -D_BSD_SOURCE -D_XOPEN_SOURCE=500 -D_XOPEN_SOURCE_EXTENDED -D_GNU_SOURCE  -D_DEFAULT_SOURCE -D_POSIX_C_SOURCE=2 -D_BSD_SOURCE -D_XOPEN_SOURCE=500 -D_XOPEN_SOURCE_EXTENDED -D_GNU_SOURCE -DHAVE_CONFIG_H -g -O2 -std=gnu99 -Wall -Werror=format-security -o cldr.build.o -c cldr.c

There's nowhere a -I flag that points to $(HOST_DIR)/include. I guess
it at least needs passing some CFLAGS_FOR_BUILD or something like that.

Could you have a look ?

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com