Comment 10 for bug 579909

The command which returns a non-zero exit code is the second "diff" run, the first one works well:
+ gcc -E -nostdinc -dI -I../include -I../include/mysql -I../sql -I./include -I./include/mysql -I./sql ../include/mysql/plugin.h
+ /bin/sed -e '/^# /d' -e '/^[ ]*$/d' -e '/^#pragma GCC set_debug_pwd/d' -e '/^#ident/d'
+ /usr/bin/diff -w ../include/mysql/plugin.h.pp ./abi_check.out
+ /bin/rm ./abi_check.out
The second one does not:
+ /bin/sed -e '/^# /d' -e '/^[ ]*$/d' -e '/^#pragma GCC set_debug_pwd/d' -e '/^#ident/d'
+ gcc -E -nostdinc -dI -I../include -I../include/mysql -I../sql -I./include -I./include/mysql -I./sql ../include/mysql.h
+ /usr/bin/diff -w ../include/mysql.h.pp ./abi_check.out
(diff output follows)

So probably gcc -E ... on ../include/mysql.h is not outputting anything, it would be good to find out what it's doing.