Not repeatable with mysql 5.1.54. 5.1-micro will not compile with ./BUILD/compile-pentium and ./BUILD/compile-pentium64 . The compilation aborts as follows:

ccache gcc --pipe -DDEFAULT_BASEDIR=\"/usr/local/mysql\" -DMYSQL_DATADIR="\"/usr/local/mysql/var\"" -DDEFAULT_CHARSET_HOME="\"/usr/local/mysql\"" -DSHAREDIR="\"/usr/local/mysql/share/mysql\"" -DDEFAULT_HOME_ENV=MYSQL_HOME -DDEFAULT_GROUP_SUFFIX_ENV=MYSQL_GROUP_SUFFIX -DDEFAULT_SYSCONFDIR="\"/usr/local/mysql/etc\"" -DHAVE_CONFIG_H -I. -I../include -I../include -I../include -I. -Wall -Wextra -Wunused -Wwrite-strings -mtune=native -m64 -O3 -fno-omit-frame-pointer -MT my_thr_init.o -MD -MP -MF .deps/my_thr_init.Tpo -c -o my_thr_init.o my_thr_init.c
mv -f .deps/mf_keycache.Tpo .deps/mf_keycache.Po
mv -f .deps/my_pthread.Tpo .deps/my_pthread.Po
mv -f .deps/thr_lock.Tpo .deps/thr_lock.Po
mv -f .deps/thr_mutex.Tpo .deps/thr_mutex.Po
mv -f .deps/my_thr_init.Tpo .deps/my_thr_init.Po
thr_alarm.c: In function ‘thr_alarm’:
thr_alarm.c:163: error: ‘my_time_t’ undeclared (first use in this function)
thr_alarm.c:163: error: (Each undeclared identifier is reported only once
thr_alarm.c:163: error: for each function it appears in.)
thr_alarm.c: In function ‘process_alarm_part2’:
thr_alarm.c:374: error: ‘my_time_t’ undeclared (first use in this function)
thr_alarm.c: In function ‘thr_alarm_info’:
thr_alarm.c:511: error: ‘my_time_t’ undeclared (first use in this function)
gmake[1]: *** [thr_alarm.o] Error 1
gmake[1]: Leaving directory `/home/philips/bzr/micro/mysql-5.1-micro/mysys'
gmake: *** [all-recursive] Error 1

[philips@fedora13 mysql-5.1-micro]$ uname -a
Linux fedora13 2.6.34.7-63.fc13.x86_64 #1 SMP Fri Dec 3 12:38:46 UTC 2010 x86_64 x86_64 x86_64 GNU/Linux

[philips@fedora13 mysql-5.1-micro]$ gcc --version
gcc (GCC) 4.4.4 20100503 (Red Hat 4.4.4-2)