ID:               49648
 Updated by:       j...@php.net
 Reported By:      sven at whgl dot uni-frankfurt dot de
-Status:           Open
+Status:           Feedback
-Bug Type:         Unknown/Other Function
+Bug Type:         Compile Failure
 Operating System: Linux
 PHP Version:      5.2.11
 New Comment:

Not enough information. And there's nothing wrong with the macro
either, it's been used in dozens of places without any problems. 


Previous Comments:
------------------------------------------------------------------------

[2009-09-24 03:59:12] sven at whgl dot uni-frankfurt dot de

Description:
------------
It seems the PHP_CHEC_LIBRARY Macro wrapping AC_CHECK_LIBRARY is broken
for all cases where extra-libs is needed. I'll be quoting directly from
the following svn link:
http://svn.php.net/viewvc/php/php-src/trunk/acinclude.m4?revision=287126&view=markup

--- snip --- Macro Prototype ---
1822    dnl
1823    dnl PHP_CHECK_LIBRARY(library, function [, action-found [,
action-not-found [, extra-libs]]])
1824    dnl
1825    dnl Wrapper for AC_CHECK_LIB
1826    dnl 
--- snip --- End Proto ---

Last Parameter ($5) is extra libs, now we look into the Macro:

1827    AC_DEFUN([PHP_CHECK_LIBRARY], [
1828    save_old_LDFLAGS=$LDFLAGS
1829    ac_stuff="$5"
1830    
1831    save_ext_shared=$ext_shared
1832    ext_shared=yes
1833    PHP_EVAL_LIBLINE([$]ac_stuff, LDFLAGS)
1834    AC_CHECK_LIB([$1],[$2],[
1835    LDFLAGS=$save_old_LDFLAGS
1836    ext_shared=$save_ext_shared
1837    $3
1838    ],[
1839    LDFLAGS=$save_old_LDFLAGS
1840    ext_shared=$save_ext_shared
1841    unset ac_cv_lib_$1[]_$2
1842    $4
1843    ])dnl
1844    ]) 

Instead of passing $5 into $5 of AC_CHECK_LIB some preprocessing is
obviously done, LDFLAGS is stored and PHP_EVAL_LIBLINE is called with $5
and $LDFLAGS. This is indeed completely wrong. When we look at the inner
workings of PHP_EVAL_LIBLINE, we can see the following:

403      -l*[)]
404     ac_ii=`echo $ac_i|cut -c 3-`
405     PHP_ADD_LIBRARY($ac_ii,1,$2)
406     ;;
407     -L*[)]
408     ac_ii=`echo $ac_i|cut -c 3-`
409     PHP_ADD_LIBPATH($ac_ii,$2) 

Though libs and and lib includes are treated by different Macros, they
both operate on $2 and indeed, when using the Macro, libs are added to
LDFLAGS, which is not right.

The autoconf manual states that: -l<libname> Parameters go into LIBS
and only all other linker flags go into LDFLAGS. This is important for
the ordering of libs, because AC_CHECK_LIB will prepend the lib to be
tested to LIBS, so other-libs, need to be in LIBS, because otherwise the
ordering in the call to gcc for the conftest will be wrong and fail.


Reproduce code:
---------------
PHP_CHECK_LIB(libname,libsymbol,,,other-libs) where libname references
symbols from other-libs.

Expected result:
----------------
The check should succeed if the libs are in place and gcc should be
called properly.

Actual result:
--------------
The ordering will be wrong, gcc will fail to compile the conftest.c and
thus the macro fails although it should net.


------------------------------------------------------------------------


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