Please try APC-3.1.2

Starting to download APC-3.1.2.tgz (123,459 bytes)
.........................done: 123,459 bytes
45 source files, building

[snip]

configure: WARNING: unrecognized options: --enable-spinlocks
running: make
/bin/sh /private/var/tmp/pear-build-root/APC-3.1.2/libtool --mode=compile gcc  -I. -I/private/tmp/pear/temp/APC -DPHP_ATOM_INC -I/private/var/tmp/pear-build-root/APC-3.1.2/include -I/private/var/tmp/pear-build-root/APC-3.1.2/main -I/private/tmp/pear/temp/APC -I/sw/include/php5 -I/sw/include/php5/main -I/sw/include/php5/TSRM -I/sw/include/php5/Zend -I/sw/include/php5/ext -I/sw/include/php5/ext/date/lib  -DHAVE_CONFIG_H  -g -O2   -c /private/tmp/pear/temp/APC/apc.c -o apc.lo
mkdir .libs
 gcc -I. -I/private/tmp/pear/temp/APC -DPHP_ATOM_INC -I/private/var/tmp/pear-build-root/APC-3.1.2/include -I/private/var/tmp/pear-build-root/APC-3.1.2/main -I/private/tmp/pear/temp/APC -I/sw/include/php5 -I/sw/include/php5/main -I/sw/include/php5/TSRM -I/sw/include/php5/Zend -I/sw/include/php5/ext -I/sw/include/php5/ext/date/lib -DHAVE_CONFIG_H -g -O2 -c /private/tmp/pear/temp/APC/apc.c  -fno-common -DPIC -o .libs/apc.o
In file included from /private/tmp/pear/temp/APC/apc.c:38:
/sw/include/php5/ext/pcre/php_pcre.h:29:18: error: pcre.h: No such file or directory
In file included from /private/tmp/pear/temp/APC/apc.c:38:
/sw/include/php5/ext/pcre/php_pcre.h:45: error: syntax error before '*' token
/sw/include/php5/ext/pcre/php_pcre.h:45: error: syntax error before 'pcre_extra'
/sw/include/php5/ext/pcre/php_pcre.h:45: warning: data definition has no type or storage class
/sw/include/php5/ext/pcre/php_pcre.h:46: error: syntax error before '*' token
/sw/include/php5/ext/pcre/php_pcre.h:46: error: syntax error before 'pcre_extra'
/sw/include/php5/ext/pcre/php_pcre.h:46: warning: data definition has no type or storage class
/sw/include/php5/ext/pcre/php_pcre.h:52: error: syntax error before 'pcre'
/sw/include/php5/ext/pcre/php_pcre.h:52: warning: no semicolon at end of struct or union
/sw/include/php5/ext/pcre/php_pcre.h:53: warning: data definition has no type or storage class
/sw/include/php5/ext/pcre/php_pcre.h:61: error: syntax error before '}' token
/sw/include/php5/ext/pcre/php_pcre.h:61: warning: data definition has no type or storage class
/sw/include/php5/ext/pcre/php_pcre.h:63: error: syntax error before '*' token
/sw/include/php5/ext/pcre/php_pcre.h:63: warning: data definition has no type or storage class
/sw/include/php5/ext/pcre/php_pcre.h:65: error: syntax error before '*' token
/sw/include/php5/ext/pcre/php_pcre.h:68: error: syntax error before '*' token
/sw/include/php5/ext/pcre/php_pcre.h:71: error: syntax error before '*' token
/sw/include/php5/ext/pcre/php_pcre.h:74: error: syntax error before '*' token
/private/tmp/pear/temp/APC/apc.c:362: error: syntax error before 'pcre'
/private/tmp/pear/temp/APC/apc.c:362: warning: no semicolon at end of struct or union
/private/tmp/pear/temp/APC/apc.c:363: warning: data definition has no type or storage class
/private/tmp/pear/temp/APC/apc.c:364: error: syntax error before '}' token
/private/tmp/pear/temp/APC/apc.c:364: warning: data definition has no type or storage class
/private/tmp/pear/temp/APC/apc.c: In function 'apc_regex_compile_array':
/private/tmp/pear/temp/APC/apc.c:389: error: 'regs' undeclared (first use in this function)
/private/tmp/pear/temp/APC/apc.c:389: error: (Each undeclared identifier is reported only once
/private/tmp/pear/temp/APC/apc.c:389: error: for each function it appears in.)
/private/tmp/pear/temp/APC/apc.c:398: error: syntax error before ')' token
/private/tmp/pear/temp/APC/apc.c: In function 'apc_regex_destroy_array':
/private/tmp/pear/temp/APC/apc.c:431: error: 'regs' undeclared (first use in this function)
/private/tmp/pear/temp/APC/apc.c:431: error: syntax error before ')' token
/private/tmp/pear/temp/APC/apc.c: In function 'apc_regex_match_array':
/private/tmp/pear/temp/APC/apc.c:445: error: 'regs' undeclared (first use in this function)
/private/tmp/pear/temp/APC/apc.c:450: error: syntax error before ')' token
make: *** [apc.lo] Error 1
ERROR: `make' failed

The spinlocks warning is now fixed in CVS.

Do you have /opt/local/include/pcre.h?  Are you specifying any pcre options in your build of PHP (or is this the default PHP build that comes with OS X?)

> Do you have /opt/local/include/pcre.h?

I'm on Fink <http://finkproject.org/>, my PHP is built from this info-File: http://fink.cvs.sourceforge.net/viewvc/fink/dists/10.4/unstable/main/finkinfo/languages/php5.info?view=markup

(The only change I did by myself is adding --with-apxs2 for CLI, as per default apache2handler is built with ZTS and CLI is built without.)

There is an /opt/local/include/pcre.h on my system, but as Fink should be more or less self-contained (prefix /sw) I guess it should rather use the also availeable /sw/include/pcre.h?

You're sure you are building aganist php-5.2.5?  This builds against my system.  If you add: 

-I/opt/local/include

to the INCLUDES line in the apc Makefile should allow this to compile correctly. Can you verify your php version and let us know if the above change works?

No feedback was provided. The bug is being suspended because
we assume that you are no longer experiencing the problem.
If this is not the case and you are able to provide the
information that was requested earlier, please do so and
change the status of the bug back to "Open". Thank you.

I can confirm that Shire's solution of adding -
I/opt/local/include works. Macports experiences the same issue 
because it doesn't use PHP's builtin PCRE. Adding the external 
libs folder fixes the issue.

Installing pcre-devel helped me