And your configure line is..?

As I said, I'm not using a --with- or --without-pcre option. The other options seem not very relevant in this context but I'll paste the line from the used rpm spec file here. %configure translates to configure ;)

%configure \
	--cache-file=../config.cache \
        --with-libdir=%{_lib} \
	--with-config-file-path=%{_sysconfdir} \
	--with-config-file-scan-dir=%{_sysconfdir}/php.d \
	--disable-debug \
	--with-pic \
	--disable-rpath \
	--without-pear \
	--with-bz2 \
	--with-exec-dir=%{_bindir} \
	--with-freetype-dir=%{_prefix} \
	--with-png-dir=%{_prefix} \
	--enable-gd-native-ttf \
	--without-gdbm \
	--with-gettext \
	--with-gmp \
	--with-iconv \
	--with-jpeg-dir=%{_prefix} \
	--with-openssl \
	--with-zlib \
	--with-layout=GNU \
	--enable-exif \
	--enable-ftp \
	--enable-magic-quotes \
	--enable-sockets \
	--enable-sysvsem --enable-sysvshm --enable-sysvmsg \
	--with-kerberos \
	--enable-ucd-snmp-hack \
	--enable-shmop \
	--enable-calendar \
        --without-mime-magic \
        --without-sqlite \
        --with-libxml-dir=%{_prefix} \
	--enable-xml \
        --with-system-tzdata \
	$* 

I'd say, just open ext/pcre/config0.m4 and see there's no PHP_ADD_INCLUDE inside the second (nested) if that causes httpd.h to be unable to locate pcreposix.h if no pcre headers are installed on the system.

If there is already a local copy of the pcre headers installed the -I/usr/include will cause the build to still find a (possible incorrect) version of the headers, and it succeeds (if the versions are close enough).

On my system these headers aren't available as on CentOS-4 they are version 4.5, so I removed them. This is an unusual situation, which is probably why nobody noticed this issue before (the local headers are probably available on most systems because builds like apache depend on them).

I am unsure why this report was labeled "No Feedback" as I provided the requested configure line within 2 hours after the request was made. I was not aware of this state change as I haven't received an email indicting this.

Doing a quick checkup in SVN it seems this issue was not fixed. In 5.3.2 the block where $PHP_PCRE_REGEX" = "yes" tests true got moved to the bottom of the file, but the required include path still seems not to be provided.

To shortly restate the issue:
On a system where no other pcre headers are available the headers of the bundled pcre are not found due to a missing include path and the build fails.

Since on most systems pcre headers will be available you will need to explicitly remove the pcre headers provided by the build system (pcre-devel package or similar) to reproduce this issue. If any other pcre headers than the bundled ones are available on the system the build will use those and succeed where it shouldn't.

Build still fails on CentOS(/RHEL)-4 for php-5.2.12. Old headers have been removed using rpm -e --nodeps pcre-devel. I am aware this is an unusual situation, but what is the point of building against the bundled pcre source when the build uses the (old and wrong) headers provided by the build system? PHP should find and use the headers of the bundled pcre when building against these, not some random headers available on the system.

"no feedback" means you didn't provide the feedback from the correct tab but failed and used "Add Comment" instead (the right place is "Edit Submission" for you since you reported this). 

Now, can you please provide the actual configure line? Something I can copy'n'paste and which has ONLY the required options to reproduce this. Note: I can not reproduce this with or without the pcre headers around..

I narrowed the offending configure option down to

--with-apxs2=/usr/sbin/apxs

Afaik I need to specify that option to build the apache module... Or am I mistaken?

Considering the error really happens inside Apache headers, how is this a PHP bug? From your compile error:

/usr/src/redhat/BUILD/php-5.2.9/sapi/apache2handler/mod_php5.c:26:
/usr/include/httpd/httpd.h:43:23: pcreposix.h: No such file or
directory

Blindly adding unnecessary include paths to fix something outside our control is not very wise..

The issue is that the apache headers that you include in the module build expect the pcre headers in one of the default locations. Since we build against the pcre library that you bundle you should provide that extra path to those headers. You cannot expect apache to look for them in an unknown build path and an unknown subdiretory.

Btw, I'm not saying the proposed patch is the best place to fix this. You might want to fix this missing include path around where the option --with-apxs2 is parsed and set the include path there in case we build against the bundled pcre.

But again, since only PHP knows the path to it's own bundled pcre headers it's PHP's task to make the path to those bundled headers available.

You have deleted required header files and expect _PHP_ to fix it's configure to allow building against 3rd party headers _requiring_ those header files you have deleted, that's is quite insane.

It's _APACHE_ requiring the headers, using the headers, needing the headers and linking to the specific library. (Try ldd httpd..) You can't just expect the bundled PCRE the be the correct one, can you?

Now, thanks to our "broken" stuff you have found this problem in your system which you should fix.

Are you telling me that even though I build the apache module against a newer bundled version of pcre the apache headers still require the old pcre headers to be available? Shouldn't they be using the headers of the newer bundled version of pcre we are building against?