Hi, I got this symptom by compiling PHP:
xlc  -I. -I/home/pistoor/php-4.0.4pl1/ext/ftp -I/home/pistoor/php-4.0.4pl1/main -I/home/pistoor/php-4.0.4pl1 -I/home/pistoor/php-4.0.4pl1/Zend -I/home/pistoor/php-4.0.4pl1/ext/mysql/libmysql -I/home/pistoor/php-4.0.4pl1/ext/xml/expat/xmltok -I/home/pistoor/php-4.0.4pl1/ext/xml/expat/xmlparse -I/home/pistoor/php-4.0.4pl1/TSRM  -DXML_BYTE_ORDER=21 -qsource -qshowinc -I/home/pistoor  -c php_ftp.c && touch php_ftp.lo
"ftp.h", line 47.22: 1506-046 (S) Syntax error.

 I use the xlc-version of the C Set ++ for AIX compiler, as it is more ANSI-C than the cc-version. It also shows more errors.
 My configuration of PHP (as a CGI-program to be used by Lynx):
CC=xlc ./configure --prefix=/home/pistoor/php \
  --with-config-file-path=/home/pistoor/php --enable-debug \
  --enable-sigchild --enable-calendar --enable-ftp \
  --enable-trans-sid --enable-shmop --with-regex=php \
  --enable-sysvsem --enable-sysvshm --enable-wddx \
  --enable-yp

The file ext/ftp/ftp.h contains these lines:
typedef enum ftptype {
        FTPTYPE_ASCII,
        FTPTYPE_IMAGE,
} ftptype_t;

The last "," is too much. I removed it.

 Regard
 Andreas Pistoor