Q: What macros are available for php config.m4 files? When writing a PHP extension, this documentation page indicates that a config.m4 file should be provided for autoconf to use. It gives a couple of examples of such files, but the documentation is incomplete. For example, the example file uses the macro PHP_EVAL_INCLINE, but it isn't mentioned in the documentation that follows it.
So, what PHP-specific macros are available to use in the config.m4 file, and what do they do? Is there any comprehensive documentation for writing those files?

A: I wasn't able to find any such list on the internet.
However, we can just parse the acinclude.m4, where all those macros are defined.
The acinclude.m4 can be found in the root directory of any PHP source tarball, as well as in lib/php/build of any PHP installation.
Macros are declared using the AC_DEFUN([name], [replacement]) macro.
It is usually preceded by one or more comment line(s), starting with dnl, which act as a rudimentary documentation.
I wrote the following script to parse each function declaration into name, usage and description:
$funcs = [];
$matches = [];
// Scan for "AC_DEFUN([FUNCTION_NAME_HERE]..." because those are function declarations,
// and all preceding lines starting with "dbl" because those are comments, probably including documentation
preg_match_all('#((?:dnl(?: .*)?\\n)*)AC_DEFUN\\(\\[(\\w+)\\]#', file_get_contents('acinclude.m4'), $matches);
// $matches[1][$i] contains all lines starting with "dbl"
// $matches[2][$i] contains the function name
for($i = 0; $i < count($matches[1]); $i++)
{
    $name = $matches[2][$i];
    $func =
    [
        'usage' => '',
        'description' => ''
    ];
    $beginning = TRUE;
    // Process each comment line
    // Since comments can, but don't have to include usage information, we try to filter it out.
    foreach(explode("\n", $matches[1][$i]) as $line)
    {
        // Discard empty lines
        if($line == 'dnl')
        {
            // Except if they're inside the description part - blocks shall stay separated.
            if(!$beginning)
            {
                $func['description'] .= "\n\n";
            }
            continue;
        }
        $m = [];
        // If no line had content yet, and the current line starts with the function name, that's the usage information!
        if($beginning && preg_match('#dnl ('.$name.'(?:.*)?)#', $line, $m) === 1)
        {
            $func['usage'] = $m[1];
        }
        // Everything else is just description.
        else
        {
            $func['description'] .= substr($line, 3);
        }
        $beginning = FALSE;
    }
    // Remove unnecessary whitespace, and make sure there's no sneaky HTML in the description.
    $func['description'] = htmlspecialchars(trim($func['description']));
    $funcs[$name] = $func;
}
// Sort by function name
ksort($funcs);

Running this in the folder where your acinclude.m4 is located will populate $funcs with a sorted array with function names as keys and their usage and description as values.
This can be parsed into an HTML table with a few lines of code, like
$html = '';
foreach($funcs as $name => $func)
{
    $html .= '<tr><td>'.$name.'</td><td>'.$func['usage'].'</td><td>'.$func['description'].'</td></tr>';
}
file_put_contents('acinclude.html', '<table>'.$html.'</table>');

Apply some nice CSS to it and add a header row, and you've got a readable list of available macros.
While some macros are quite well documented, some are not, or lacking documentation entirely, but I still think it's better than nothing.
Applied to the acinclude.m4 of PHP 5.6.11, this yields (best viewed fullscreen):


table
{
    border-collapse: collapse;
}
tr
{
    background: #F8F8F8;
}
tr:nth-child(even)
{
    background: #F0F0F0;
}
th
{
  background: #E0E0E0;
}
td, th
{
    padding: 10px;
    border: solid 1px #BBB;
}
td:last-child
{
    white-space: pre-line;
}
<table><tr><th>Name</th><th>Usage</th><th>Description</th></tr>
<tr><td>PHP_AC_BROKEN_SNPRINTF</td><td>PHP_AC_BROKEN_SNPRINTF</td><td>Check for broken snprintf(), C99 conformance</td></tr><tr><td>PHP_AC_BROKEN_SPRINTF</td><td>PHP_AC_BROKEN_SPRINTF</td><td>Check for broken sprintf(), C99 conformance</td></tr><tr><td>PHP_ADD_BUILD_DIR</td><td></td><td></td></tr><tr><td>PHP_ADD_EXTENSION_DEP</td><td>PHP_ADD_EXTENSION_DEP(extname, depends [, depconf])</td><td>This macro is scanned by genif.sh when it builds the internal functions list, so that modules can be init'd in the correct order $1 = name of extension, $2 = extension upon which it depends $3 = optional: if true, it's ok for $2 to have not been configured default is false and should halt the build. To be effective, this macro must be invoked *after* PHP_NEW_EXTENSION. The extension on which it depends must also have been configured. See ADD_EXTENSION_DEP in win32 build</td></tr><tr><td>PHP_ADD_FRAMEWORK</td><td>PHP_ADD_FRAMEWORK(framework [,before])</td><td>add a (Darwin / Mac OS X) framework to the link line. if before is 1, the framework is added to the beginning of the line.</td></tr><tr><td>PHP_ADD_FRAMEWORKPATH</td><td>PHP_ADD_FRAMEWORKPATH(path [,before])</td><td>add a (Darwin / Mac OS X) framework path to the link and include lines. default paths include (but are not limited to) /Local/Library/Frameworks and /System/Library/Frameworks, so these don't need to be specifically added. if before is 1, the framework path is added to the beginning of the relevant lines.</td></tr><tr><td>PHP_ADD_FRAMEWORK_WITH_PATH</td><td>PHP_ADD_FRAMEWORK_WITH_PATH(framework, path)</td><td>Adds a (Darwin / Mac OS X) framework path and the framework itself to the link and include lines.</td></tr><tr><td>PHP_ADD_INCLUDE</td><td>PHP_ADD_INCLUDE(path [,before])</td><td>add an include path.  if before is 1, add in the beginning of INCLUDES.</td></tr><tr><td>PHP_ADD_LIBPATH</td><td>PHP_ADD_LIBPATH(path [, SHARED-LIBADD])</td><td>Adds a path to linkpath/runpath (LDFLAGS)</td></tr><tr><td>PHP_ADD_LIBRARY</td><td>PHP_ADD_LIBRARY(library[, append[, shared-libadd]])</td><td>add a library to the link line</td></tr><tr><td>PHP_ADD_LIBRARY_DEFER</td><td>PHP_ADD_LIBRARY_DEFER(library[, append[, shared-libadd]])</td><td>add a library to the link line (deferred, not used during configure)</td></tr><tr><td>PHP_ADD_LIBRARY_DEFER_WITH_PATH</td><td>PHP_ADD_LIBRARY_DEFER_WITH_PATH(library, path[, shared-libadd])</td><td>add a library to the link line (deferred) and path to linkpath/runpath (not deferred) if shared-libadd is not empty and $ext_shared is yes, shared-libadd will be assigned the library information</td></tr><tr><td>PHP_ADD_LIBRARY_WITH_PATH</td><td>PHP_ADD_LIBRARY_WITH_PATH(library, path[, shared-libadd])</td><td>add a library to the link line and path to linkpath/runpath. if shared-libadd is not empty and $ext_shared is yes, shared-libadd will be assigned the library information</td></tr><tr><td>PHP_ADD_MAKEFILE_FRAGMENT</td><td>PHP_ADD_MAKEFILE_FRAGMENT([srcfile [, ext_srcdir [, ext_builddir]]])</td><td>Processes a file called Makefile.frag in the source directory of the most recently added extension. $(srcdir) and $(builddir) are substituted with the proper paths. Can be used to supply custom rules and/or additional targets.</td></tr><tr><td>PHP_ADD_SOURCES</td><td>PHP_ADD_SOURCES(source-path, sources [, special-flags [, type]])</td><td>Adds sources which are located relative to source-path to the  array of type type.  Sources are processed with optional  special-flags which are passed to the compiler.  Sources can be either written in C or C++ (filenames shall end in .c  or .cpp, respectively).

 Note: If source-path begins with a &quot;/&quot;, the &quot;/&quot; is removed and the path is interpreted relative to the top build-directory.

 which array to append to?</td></tr><tr><td>PHP_ADD_SOURCES_X</td><td>PHP_ADD_SOURCES_X(source-path, sources[, special-flags[, target-var[, shared[, special-post-flags]]]])</td><td>Additional to PHP_ADD_SOURCES (see above), this lets you set the name of the array target-var directly, as well as whether shared objects will be built from the sources.

 Should not be used directly.</td></tr><tr><td>PHP_AP_EXTRACT_VERSION</td><td>PHP_AP_EXTRACT_VERSION(/path/httpd)</td><td>This macro is used to get a comparable version for apache1/2.</td></tr><tr><td>PHP_ARG_ANALYZE</td><td>PHP_ARG_ANALYZE</td><td>internal</td></tr><tr><td>PHP_ARG_ANALYZE_EX</td><td>PHP_ARG_ANALYZE_EX</td><td>internal</td></tr><tr><td>PHP_ARG_ENABLE</td><td>PHP_ARG_ENABLE(arg-name, check message, help text[, default-val[, extension-or-not]])</td><td>Sets PHP_ARG_NAME either to the user value or to the default value. default-val defaults to no.  This will also set the variable ext_shared, and will overwrite any previous variable of that name. If extension-or-not is yes (default), then do the ENABLE_ALL check and run the PHP_ARG_ANALYZE_EX.</td></tr><tr><td>PHP_ARG_WITH</td><td>PHP_ARG_WITH(arg-name, check message, help text[, default-val[, extension-or-not]])</td><td>Sets PHP_ARG_NAME either to the user value or to the default value. default-val defaults to no.  This will also set the variable ext_shared, and will overwrite any previous variable of that name. If extension-or-not is yes (default), then do the ENABLE_ALL check and run the PHP_ARG_ANALYZE_EX.</td></tr><tr><td>PHP_BROKEN_GETCWD</td><td>PHP_BROKEN_GETCWD</td><td>Some systems, notably Solaris, cause getcwd() or realpath to fail if a component of the path has execute but not read permissions</td></tr><tr><td>PHP_BROKEN_GLIBC_FOPEN_APPEND</td><td>PHP_BROKEN_GLIBC_FOPEN_APPEND</td><td></td></tr><tr><td>PHP_BUILD_BUNDLE</td><td>PHP_BUILD_BUNDLE</td><td></td></tr><tr><td>PHP_BUILD_PROGRAM</td><td>PHP_BUILD_PROGRAM</td><td></td></tr><tr><td>PHP_BUILD_SHARED</td><td>PHP_BUILD_SHARED</td><td></td></tr><tr><td>PHP_BUILD_STATIC</td><td>PHP_BUILD_STATIC</td><td></td></tr><tr><td>PHP_BUILD_THREAD_SAFE</td><td>PHP_BUILD_THREAD_SAFE</td><td></td></tr><tr><td>PHP_CANONICAL_HOST_TARGET</td><td>PHP_CANONICAL_HOST_TARGET</td><td></td></tr><tr><td>PHP_CHECK_64BIT</td><td>PHP_CHECK_64BIT([do if 32], [do if 64])</td><td>This macro is used to detect if we're at 64-bit platform or not. It could be useful for those external libs, that have different precompiled  versions in different directories.</td></tr><tr><td>PHP_CHECK_CONFIGURE_OPTIONS</td><td>PHP_CHECK_CONFIGURE_OPTIONS</td><td></td></tr><tr><td>PHP_CHECK_FRAMEWORK</td><td>PHP_CHECK_FRAMEWORK(framework, function [, action-found [, action-not-found ]])</td><td>El cheapo wrapper for AC_CHECK_LIB</td></tr><tr><td>PHP_CHECK_FUNC</td><td>PHP_CHECK_FUNC(func, ...)</td><td>This macro checks whether 'func' or '__func' exists in the default libraries and as a fall back in the specified library. Defines HAVE_func and HAVE_library if found and adds the library to LIBS.</td></tr><tr><td>PHP_CHECK_FUNC_LIB</td><td></td><td></td></tr><tr><td>PHP_CHECK_GCC_ARG</td><td>PHP_CHECK_GCC_ARG(arg, action-if-found, action-if-not-found)</td><td></td></tr><tr><td>PHP_CHECK_IN_ADDR_T</td><td>PHP_CHECK_IN_ADDR_T</td><td></td></tr><tr><td>PHP_CHECK_LIBRARY</td><td>PHP_CHECK_LIBRARY(library, function [, action-found [, action-not-found [, extra-libs]]])</td><td>Wrapper for AC_CHECK_LIB</td></tr><tr><td>PHP_CHECK_PDO_INCLUDES</td><td>PHP_CHECK_PDO_INCLUDES([found [, not-found]])</td><td></td></tr><tr><td>PHP_CHECK_SIZEOF</td><td>PHP_CHECK_SIZEOF(type, cross-value, extra-headers)</td><td></td></tr><tr><td>PHP_CHECK_STDINT_TYPES</td><td>PHP_CHECK_STDINT_TYPES</td><td></td></tr><tr><td>PHP_CHECK_TYPES</td><td>PHP_CHECK_TYPES(type-list, include-file [, extra-headers])</td><td></td></tr><tr><td>PHP_CONFIGURE_PART</td><td>PHP_CONFIGURE_PART(title)</td><td>Adds separator title configure output (idea borrowed from mm)</td></tr><tr><td>PHP_CONFIG_NICE</td><td>PHP_CONFIG_NICE(filename)</td><td>Generates the config.nice file</td></tr><tr><td>PHP_CRYPT_R_STYLE</td><td>PHP_CRYPT_R_STYLE</td><td>detect the style of crypt_r() is any is available see APR_CHECK_CRYPT_R_STYLE() for original version</td></tr><tr><td>PHP_C_BIGENDIAN</td><td>PHP_C_BIGENDIAN</td><td>Replacement macro for AC_C_BIGENDIAN</td></tr><tr><td>PHP_DEBUG_MACRO</td><td>PHP_DEBUG_MACRO(filename)</td><td></td></tr><tr><td>PHP_DECLARED_TIMEZONE</td><td>PHP_DECLARED_TIMEZONE</td><td></td></tr><tr><td>PHP_DEFINE</td><td>PHP_DEFINE(WHAT [, value[, directory]])</td><td>Creates builddir/include/what.h and in there #define WHAT value</td></tr><tr><td>PHP_DEF_HAVE</td><td>PHP_DEF_HAVE(what)</td><td>Generates 'AC_DEFINE(HAVE_WHAT, 1, [ ])'</td></tr><tr><td>PHP_DETECT_ICC</td><td>PHP_DETECT_ICC</td><td>Detect Intel C++ Compiler and unset $GCC if ICC found</td></tr><tr><td>PHP_DETECT_SUNCC</td><td>PHP_DETECT_SUNCC</td><td>Detect if the systems default compiler is suncc. We also set some useful CFLAGS if the user didn't set any</td></tr><tr><td>PHP_DOES_PREAD_WORK</td><td>PHP_DOES_PREAD_WORK</td><td>internal</td></tr><tr><td>PHP_DOES_PWRITE_WORK</td><td>PHP_DOES_PWRITE_WORK</td><td>internal</td></tr><tr><td>PHP_EBCDIC</td><td>PHP_EBCDIC</td><td></td></tr><tr><td>PHP_EVAL_INCLINE</td><td>PHP_EVAL_INCLINE(headerline)</td><td>Use this macro, if you need to add header search paths to the PHP build system which are only given in compiler notation.</td></tr><tr><td>PHP_EVAL_LIBLINE</td><td>PHP_EVAL_LIBLINE(libline, SHARED-LIBADD)</td><td>Use this macro, if you need to add libraries and or library search paths to the PHP build system which are only given in compiler notation.</td></tr><tr><td>PHP_EXPAND_PATH</td><td>PHP_EXPAND_PATH(path, variable)</td><td>expands path to an absolute path and assigns it to variable</td></tr><tr><td>PHP_EXTENSION</td><td></td><td>deprecated</td></tr><tr><td>PHP_FOPENCOOKIE</td><td>PHP_FOPENCOOKIE</td><td></td></tr><tr><td>PHP_GEN_BUILD_DIRS</td><td></td><td></td></tr><tr><td>PHP_GEN_GLOBAL_MAKEFILE</td><td>PHP_GEN_GLOBAL_MAKEFILE</td><td>Generates the global makefile.</td></tr><tr><td>PHP_HELP_SEPARATOR</td><td>PHP_HELP_SEPARATOR(title)</td><td>Adds separator title into the configure --help display.</td></tr><tr><td>PHP_INIT_BUILD_SYSTEM</td><td>PHP_INIT_BUILD_SYSTEM</td><td></td></tr><tr><td>PHP_INIT_DTRACE</td><td>PHP_INIT_DTRACE(providerdesc, header-file, sources [, module])</td><td></td></tr><tr><td>PHP_INSTALL_HEADERS</td><td></td><td>PHP_INSTALL_HEADERS(path [, file ...])

 PHP header files to be installed</td></tr><tr><td>PHP_LIBGCC_LIBPATH</td><td>PHP_LIBGCC_LIBPATH(gcc)</td><td>Stores the location of libgcc in libgcc_libpath</td></tr><tr><td>PHP_MISSING_FCLOSE_DECL</td><td>PHP_MISSING_FCLOSE_DECL</td><td>See if we have broken header files like SunOS has.</td></tr><tr><td>PHP_MISSING_TIME_R_DECL</td><td>PHP_MISSING_TIME_R_DECL</td><td></td></tr><tr><td>PHP_NEW_EXTENSION</td><td>PHP_NEW_EXTENSION(extname, sources [, shared [, sapi_class [, extra-cflags [, cxx [, zend_ext]]]]])</td><td>Includes an extension in the build.

 &quot;extname&quot; is the name of the ext/ subdir where the extension resides. &quot;sources&quot; is a list of files relative to the subdir which are used to build the extension. &quot;shared&quot; can be set to &quot;shared&quot; or &quot;yes&quot; to build the extension as a dynamically loadable library. Optional parameter &quot;sapi_class&quot; can be set to &quot;cli&quot; to mark extension build only with CLI or CGI sapi's. &quot;extra-cflags&quot; are passed to the compiler, with  @ext_srcdir@ and @ext_builddir@ being substituted. &quot;cxx&quot; can be used to indicate that a C++ shared module is desired. &quot;zend_ext&quot; indicates a zend extension.</td></tr><tr><td>PHP_OUTPUT</td><td>PHP_OUTPUT(file)</td><td>Adds &quot;file&quot; to the list of files generated by AC_OUTPUT This macro can be used several times.</td></tr><tr><td>PHP_PREAD_TEST</td><td>PHP_PREAD_TEST</td><td></td></tr><tr><td>PHP_PROG_AWK</td><td>PHP_PROG_AWK</td><td>Some vendors force mawk before gawk; mawk is broken so we don't like that</td></tr><tr><td>PHP_PROG_BISON</td><td>PHP_PROG_BISON</td><td>Search for bison and check it's version</td></tr><tr><td>PHP_PROG_LEX</td><td>PHP_PROG_LEX</td><td>Search for (f)lex and check it's version</td></tr><tr><td>PHP_PROG_RE2C</td><td>PHP_PROG_RE2C</td><td>Search for the re2c binary and check the version</td></tr><tr><td>PHP_PROG_SENDMAIL</td><td>PHP_PROG_SENDMAIL</td><td>Search for the sendmail binary</td></tr><tr><td>PHP_PWRITE_TEST</td><td>PHP_PWRITE_TEST</td><td></td></tr><tr><td>PHP_READDIR_R_TYPE</td><td>PHP_READDIR_R_TYPE</td><td></td></tr><tr><td>PHP_REAL_ARG_ENABLE</td><td>PHP_REAL_ARG_ENABLE</td><td>internal</td></tr><tr><td>PHP_REAL_ARG_WITH</td><td>PHP_REAL_ARG_WITH</td><td>internal</td></tr><tr><td>PHP_REMOVE_USR_LIB</td><td>PHP_REMOVE_USR_LIB(NAME)</td><td>Removes all -L/usr/$PHP_LIBDIR entries from variable NAME</td></tr><tr><td>PHP_REQUIRE_CXX</td><td>PHP_REQUIRE_CXX</td><td></td></tr><tr><td>PHP_RUNPATH_SWITCH</td><td>PHP_RUNPATH_SWITCH</td><td>Checks for -R, etc. switch</td></tr><tr><td>PHP_RUN_ONCE</td><td>PHP_RUN_ONCE(namespace, variable, code)</td><td>execute code, if variable is not set in namespace</td></tr><tr><td>PHP_SELECT_SAPI</td><td>PHP_SELECT_SAPI(name, type[, sources [, extra-cflags [, build-target]]])</td><td>Selects the SAPI name and type (static, shared, bundle, program) and optionally also the source-files for the SAPI-specific objects.</td></tr><tr><td>PHP_SETUP_ICONV</td><td></td><td>PHP_SETUP_ICONV(shared-add [, action-found [, action-not-found]])

 Common setup macro for iconv</td></tr><tr><td>PHP_SETUP_ICU</td><td>PHP_SETUP_ICU([shared-add])</td><td>Common setup macro for ICU</td></tr><tr><td>PHP_SETUP_KERBEROS</td><td>PHP_SETUP_KERBEROS(shared-add [, action-found [, action-not-found]])</td><td>Common setup macro for kerberos</td></tr><tr><td>PHP_SETUP_LIBXML</td><td></td><td>PHP_SETUP_LIBXML(shared-add [, action-found [, action-not-found]])

 Common setup macro for libxml</td></tr><tr><td>PHP_SETUP_OPENSSL</td><td></td><td>PHP_SETUP_OPENSSL(shared-add [, action-found [, action-not-found]])

 Common setup macro for openssl</td></tr><tr><td>PHP_SET_LIBTOOL_VARIABLE</td><td>PHP_SET_LIBTOOL_VARIABLE(var)</td><td>Set libtool variable</td></tr><tr><td>PHP_SHARED_MODULE</td><td>PHP_SHARED_MODULE(module-name, object-var, build-dir, cxx, zend_ext)</td><td>Basically sets up the link-stage for building module-name from object_var in build-dir.</td></tr><tr><td>PHP_SHLIB_SUFFIX_NAMES</td><td>PHP_SHLIB_SUFFIX_NAMES</td><td>Determines link library suffix SHLIB_SUFFIX_NAME which can be: .so, .sl or .dylib

 Determines shared library suffix SHLIB_DL_SUFFIX_NAME suffix can be: .so or .sl</td></tr><tr><td>PHP_SOCKADDR_CHECKS</td><td>PHP_SOCKADDR_CHECKS</td><td></td></tr><tr><td>PHP_SOCKLEN_T</td><td>PHP_SOCKLEN_T</td><td></td></tr><tr><td>PHP_SOLARIS_PIC_WEIRDNESS</td><td>PHP_SOLARIS_PIC_WEIRDNESS</td><td>Solaris requires main code to be position independent in order to let shared objects find symbols.  Weird.  Ugly.

 Must be run after all --with-NN options that let the user choose dynamic extensions, and after the gcc test.</td></tr><tr><td>PHP_STRUCT_FLOCK</td><td>PHP_STRUCT_FLOCK</td><td></td></tr><tr><td>PHP_SUBST</td><td>PHP_SUBST(varname)</td><td>Adds variable with it's value into Makefile, e.g.: CC = gcc</td></tr><tr><td>PHP_SUBST_OLD</td><td>PHP_SUBST_OLD(varname)</td><td>Same as PHP_SUBST() but also substitutes all @VARNAME@ instances in every file passed to AC_OUTPUT()</td></tr><tr><td>PHP_SYS_LFS</td><td>PHP_SYS_LFS</td><td>The problem is that the default compilation flags in Solaris 2.6 won't let programs access large files;  you need to tell the compiler that you actually want your programs to work on large files.  For more details about this brain damage please see: http://www.sas.com/standards/large.file/x_open.20Mar96.html

 Written by Paul Eggert &lt;eggert@twinsun.com&gt;.</td></tr><tr><td>PHP_TARGET_RDYNAMIC</td><td>PHP_TARGET_RDYNAMIC</td><td>Checks whether -rdynamic is supported by the compiler.  This is necessary for some targets to populate the global symbol table.  Otherwise, dynamic modules would not be able to resolve PHP-related symbols.

 If successful, adds -rdynamic to PHP_LDFLAGS.</td></tr><tr><td>PHP_TEST_BUILD</td><td>PHP_TEST_BUILD(function, action-if-ok, action-if-not-ok [, extra-libs [, extra-source]])</td><td>This macro checks whether build works and given function exists.</td></tr><tr><td>PHP_TEST_WRITE_STDOUT</td><td>PHP_TEST_WRITE_STDOUT</td><td></td></tr><tr><td>PHP_TIME_R_TYPE</td><td>PHP_TIME_R_TYPE</td><td>Check type of reentrant time-related functions Type can be: irix, hpux or POSIX</td></tr><tr><td>PHP_TM_GMTOFF</td><td>PHP_TM_GMTOFF</td><td></td></tr><tr><td>PHP_UTILIZE_RPATHS</td><td>PHP_UTILIZE_RPATHS()</td><td>builds RPATHS/LDFLAGS from PHP_RPATHS</td></tr><tr><td>PHP_WITH_SHARED</td><td>PHP_WITH_SHARED</td><td>Checks whether $withval is &quot;shared&quot; or starts with &quot;shared,XXX&quot; and sets $shared to &quot;yes&quot; or &quot;no&quot;, and removes &quot;shared,?&quot; stuff from $withval.</td></tr><tr><td>_PHP_ADD_LIBPATH_GLOBAL</td><td></td><td>internal, don't use</td></tr><tr><td>_PHP_ADD_LIBRARY_SKELETON</td><td></td><td>internal, don't use</td></tr><tr><td>_PHP_ASSIGN_BUILD_VARS</td><td>_PHP_ASSIGN_BUILD_VARS(type)</td><td>internal, don't use</td></tr><tr><td>_PHP_CHECK_SIZEOF</td><td>_PHP_CHECK_SIZEOF(type, cross-value, extra-headers [, found-action [, not-found-action]])</td><td></td></tr><tr><td>_PHP_DEF_HAVE_FILE</td><td></td><td>Internal helper macros

 _PHP_DEF_HAVE_FILE(what, filename)</td></tr><tr><td>_PHP_X_ADD_LIBRARY</td><td></td><td>internal, don't use</td></tr></table>



A: Here is an example for "config.m4" which i often use when developing php extension:
PHP_ARG_ENABLE(extname, whether to enable extname support,
[  --enable-extname           Enable extname support])

if test "$PHP_EXTNAME" != "no"; then
    PHP_REQUIRE_CXX() dnl If you need c++.please add this.
    PHP_ADD_INCLUDE(./include) dnl Extra include file 
    PHP_ADD_LIBRARY_WITH_PATH(staticlib,"./lib", EXTRA_LDFLAGS)  dnl static library needed in the extension
    PHP_ADD_LIBRARY_WITH_PATH(dynamiclib, ./lib, EXTNAME_SHARED_LIBADD)  dnl dynamic libarary needed in the extension
    PHP_NEW_EXTENSION(extname, extname.cpp, $ext_shared)
fi

Actually the example extension generated by 'ext_skel' script, also shows usage of config.m4 file. You may want to read it as well.
