diff --git a/ext/gettext/config.m4 b/ext/gettext/config.m4
index bb9c8b24aaeda..e46acf09285f9 100644
--- a/ext/gettext/config.m4
+++ b/ext/gettext/config.m4
@@ -5,12 +5,11 @@ PHP_ARG_WITH([gettext],
 
 if test "$PHP_GETTEXT" != "no"; then
   for i in $PHP_GETTEXT /usr/local /usr; do
-    test -r $i/include/libintl.h && GETTEXT_DIR=$i && break
+    AS_IF([test -r $i/include/libintl.h], [GETTEXT_DIR=$i; break;])
   done
 
-  if test -z "$GETTEXT_DIR"; then
-    AC_MSG_ERROR([Cannot locate header file libintl.h])
-  fi
+  AS_VAR_IF([GETTEXT_DIR],,
+    [AC_MSG_ERROR([Cannot locate header file libintl.h])])
 
   GETTEXT_LIBDIR=$GETTEXT_DIR/$PHP_LIBDIR
   GETTEXT_INCDIR=$GETTEXT_DIR/include
@@ -47,9 +46,8 @@ if test "$PHP_GETTEXT" != "no"; then
       [Define to 1 if you have the 'bind_textdomain_codeset' function.])])
   LDFLAGS=$O_LDFLAGS
 
-  if test -n "$GETTEXT_LIBS"; then
-    PHP_ADD_LIBRARY_WITH_PATH([$GETTEXT_LIBS],
+  AS_VAR_IF([GETTEXT_LIBS],,,
+    [PHP_ADD_LIBRARY_WITH_PATH([$GETTEXT_LIBS],
       [$GETTEXT_LIBDIR],
-      [GETTEXT_SHARED_LIBADD])
-  fi
+      [GETTEXT_SHARED_LIBADD])])
 fi
diff --git a/ext/iconv/config.m4 b/ext/iconv/config.m4
index 0c223a9b22888..d3900323a14c7 100644
--- a/ext/iconv/config.m4
+++ b/ext/iconv/config.m4
@@ -8,8 +8,8 @@ if test "$PHP_ICONV" != "no"; then
   PHP_SETUP_ICONV([ICONV_SHARED_LIBADD],,
     [AC_MSG_FAILURE([The iconv not found.])])
 
-    save_LDFLAGS="$LDFLAGS"
-    save_CFLAGS="$CFLAGS"
+    save_LDFLAGS=$LDFLAGS
+    save_CFLAGS=$CFLAGS
     LDFLAGS="$ICONV_SHARED_LIBADD $LDFLAGS"
     CFLAGS="$INCLUDES $CFLAGS"
 
@@ -124,8 +124,8 @@ int main(void) {
       [AC_DEFINE([ICONV_BROKEN_IGNORE], [1],
         [Define to 1 if iconv has broken IGNORE.])])
 
-    LDFLAGS="$save_LDFLAGS"
-    CFLAGS="$save_CFLAGS"
+    LDFLAGS=$save_LDFLAGS
+    CFLAGS=$save_CFLAGS
 
     AC_DEFINE([HAVE_ICONV], [1],
       [Define to 1 if the PHP extension 'iconv' is available.])
diff --git a/ext/ldap/config.m4 b/ext/ldap/config.m4
index 07f1960921eec..447e9dda2d454 100644
--- a/ext/ldap/config.m4
+++ b/ext/ldap/config.m4
@@ -53,23 +53,18 @@ PHP_ARG_WITH([ldap-sasl],
   [no])
 
 if test "$PHP_LDAP" != "no"; then
-
   PHP_NEW_EXTENSION([ldap],
     [ldap.c],
     [$ext_shared],,
     [-DZEND_ENABLE_STATIC_TSRMLS_CACHE=1])
 
-  if test "$PHP_LDAP" = "yes"; then
+  AS_VAR_IF([PHP_LDAP], [yes], [
     for i in /usr/local /usr; do
-      PHP_LDAP_CHECKS($i)
+      PHP_LDAP_CHECKS([$i])
     done
-  else
-    PHP_LDAP_CHECKS($PHP_LDAP)
-  fi
+  ], [PHP_LDAP_CHECKS([$PHP_LDAP])])
 
-  if test -z "$LDAP_DIR"; then
-    AC_MSG_ERROR([Cannot find ldap.h])
-  fi
+  AS_VAR_IF([LDAP_DIR],, [AC_MSG_ERROR([Cannot find ldap.h])])
 
   dnl -pc removal is a hack for clang
   MACHINE_INCLUDES=$($CC -dumpmachine | $SED 's/-pc//')
diff --git a/ext/libxml/config0.m4 b/ext/libxml/config0.m4
index a2f7c00ba55c6..67ffa9a78ce44 100644
--- a/ext/libxml/config0.m4
+++ b/ext/libxml/config0.m4
@@ -5,7 +5,6 @@ PHP_ARG_WITH([libxml],
   [yes])
 
 if test "$PHP_LIBXML" != "no"; then
-
   dnl This extension can not be build as shared
   ext_shared=no
 
diff --git a/ext/mbstring/config.m4 b/ext/mbstring/config.m4
index b97fbd4ded7aa..890287e3ddd78 100644
--- a/ext/mbstring/config.m4
+++ b/ext/mbstring/config.m4
@@ -173,9 +173,7 @@ if test "$PHP_MBSTRING" != "no"; then
 
   PHP_MBSTRING_ADD_BASE_SOURCES([mbstring.c php_unicode.c mb_gpc.c])
 
-  if test "$PHP_MBREGEX" != "no"; then
-    PHP_MBSTRING_SETUP_MBREGEX
-  fi
+  AS_VAR_IF([PHP_MBREGEX], [no],, [PHP_MBSTRING_SETUP_MBREGEX])
 
   dnl libmbfl is required
   PHP_MBSTRING_SETUP_LIBMBFL
diff --git a/ext/odbc/config.m4 b/ext/odbc/config.m4
index 32c1d09622bff..1b323eb8330a4 100644
--- a/ext/odbc/config.m4
+++ b/ext/odbc/config.m4
@@ -66,7 +66,6 @@ fi
   AC_MSG_RESULT(`echo $ODBC_LIBS | sed -e 's!.*/!!'`)
 ])
 
-
 dnl
 dnl Figure out which library file to link with for the Empress support.
 dnl
@@ -107,9 +106,7 @@ PHP_ARG_WITH([adabas],,
 
   AC_MSG_CHECKING([for Adabas support])
   if test "$PHP_ADABAS" != "no"; then
-    if test "$PHP_ADABAS" = "yes"; then
-      PHP_ADABAS=/usr/local
-    fi
+    AS_VAR_IF([PHP_ADABAS], [yes], [PHP_ADABAS=/usr/local])
     PHP_ADD_INCLUDE([$PHP_ADABAS/incl])
     PHP_ADD_LIBPATH([$PHP_ADABAS/$PHP_LIBDIR])
     ODBC_OBJS="$PHP_ADABAS/$PHP_LIBDIR/odbclib.a"
@@ -138,9 +135,7 @@ PHP_ARG_WITH([sapdb],,
 
   AC_MSG_CHECKING([for SAP DB support])
   if test "$PHP_SAPDB" != "no"; then
-    if test "$PHP_SAPDB" = "yes"; then
-      PHP_SAPDB=/usr/local
-    fi
+    AS_VAR_IF([PHP_SAPDB], [yes], [PHP_SAPDB=/usr/local])
     PHP_ADD_INCLUDE([$PHP_SAPDB/incl])
     PHP_ADD_LIBPATH([$PHP_SAPDB/$PHP_LIBDIR])
     PHP_ADD_LIBRARY([sqlod])
@@ -160,9 +155,7 @@ PHP_ARG_WITH([solid],,
 
   AC_MSG_CHECKING([for Solid support])
   if test "$PHP_SOLID" != "no"; then
-    if test "$PHP_SOLID" = "yes"; then
-      PHP_SOLID=/usr/local/solid
-    fi
+    AS_VAR_IF([PHP_SOLID], [yes], [PHP_SOLID=/usr/local/solid])
     ODBC_INCDIR=$PHP_SOLID/include
     ODBC_LIBDIR=$PHP_SOLID/$PHP_LIBDIR
     ODBC_CFLAGS=-I$ODBC_INCDIR
@@ -304,9 +297,7 @@ PHP_ARG_WITH([custom-odbc],,
 
   AC_MSG_CHECKING([for a custom ODBC support])
   if test "$PHP_CUSTOM_ODBC" != "no"; then
-    if test "$PHP_CUSTOM_ODBC" = "yes"; then
-      PHP_CUSTOM_ODBC=/usr/local
-    fi
+    AS_VAR_IF([PHP_CUSTOM_ODBC], [yes], [PHP_CUSTOM_ODBC=/usr/local])
     ODBC_INCDIR=$PHP_CUSTOM_ODBC/include
     ODBC_LIBDIR=$PHP_CUSTOM_ODBC/$PHP_LIBDIR
     ODBC_LFLAGS=-L$ODBC_LIBDIR
@@ -346,9 +337,7 @@ PHP_ARG_WITH([esoob],,
 
   AC_MSG_CHECKING([for Easysoft ODBC-ODBC Bridge support])
   if test "$PHP_ESOOB" != "no"; then
-    if test "$PHP_ESOOB" = "yes"; then
-      PHP_ESOOB=/usr/local/easysoft/oob/client
-    fi
+    AS_VAR_IF([PHP_ESOOB], [yes], [PHP_ESOOB=/usr/local/easysoft/oob/client])
     ODBC_INCDIR=$PHP_ESOOB/include
     ODBC_LIBDIR=$PHP_ESOOB/$PHP_LIBDIR
     ODBC_LFLAGS=-L$ODBC_LIBDIR
diff --git a/ext/pdo/config.m4 b/ext/pdo/config.m4
index 06e9c8ef3421c..2145f053979db 100644
--- a/ext/pdo/config.m4
+++ b/ext/pdo/config.m4
@@ -5,7 +5,6 @@ PHP_ARG_ENABLE([pdo],
   [yes])
 
 if test "$PHP_PDO" != "no"; then
-
   dnl Make sure $PHP_PDO is 'yes' when it's not 'no' :)
   PHP_PDO=yes
 
diff --git a/ext/pdo_dblib/config.m4 b/ext/pdo_dblib/config.m4
index bef7229b20e68..cff5de794354b 100644
--- a/ext/pdo_dblib/config.m4
+++ b/ext/pdo_dblib/config.m4
@@ -4,7 +4,6 @@ PHP_ARG_WITH([pdo-dblib],
     [PDO: DBLIB-DB support. DIR is the FreeTDS home directory])])
 
 if test "$PHP_PDO_DBLIB" != "no"; then
-
   if test "$PHP_PDO" = "no" && test "$ext_shared" = "no"; then
     AC_MSG_ERROR([PDO is not enabled! Add --enable-pdo to your configure line.])
   fi
@@ -17,7 +16,6 @@ if test "$PHP_PDO_DBLIB" != "no"; then
       [AC_MSG_FAILURE([Cannot find FreeTDS in known installation directories.])])
     PHP_ADD_LIBRARY([sybdb],, [PDO_DBLIB_SHARED_LIBADD])
   elif test "$PHP_PDO_DBLIB" != "no"; then
-
     if test -f $PHP_PDO_DBLIB/include/sybdb.h; then
       PDO_FREETDS_INSTALLATION_DIR=$PHP_PDO_DBLIB
       PDO_FREETDS_INCLUDE_DIR=$PHP_PDO_DBLIB/include
@@ -28,9 +26,7 @@ if test "$PHP_PDO_DBLIB" != "no"; then
       AC_MSG_ERROR([Directory $PHP_PDO_DBLIB is not a FreeTDS installation directory])
     fi
 
-    if test "x$PHP_LIBDIR" = "x" ; then
-      PHP_LIBDIR=lib
-    fi
+    AS_VAR_IF([PHP_LIBDIR],, [PHP_LIBDIR=lib])
 
     if test ! -r "$PDO_FREETDS_INSTALLATION_DIR/$PHP_LIBDIR/libsybdb.a" && test ! -r "$PDO_FREETDS_INSTALLATION_DIR/$PHP_LIBDIR/libsybdb.so"; then
        AC_MSG_ERROR([[Could not find $PDO_FREETDS_INSTALLATION_DIR/$PHP_LIBDIR/libsybdb.[a|so]]])
diff --git a/ext/pdo_firebird/config.m4 b/ext/pdo_firebird/config.m4
index 1f9be45539e7a..40a464a6f4c12 100644
--- a/ext/pdo_firebird/config.m4
+++ b/ext/pdo_firebird/config.m4
@@ -5,7 +5,6 @@ PHP_ARG_WITH([pdo-firebird],
     [/opt/firebird]])])
 
 if test "$PHP_PDO_FIREBIRD" != "no"; then
-
   if test "$PHP_PDO" = "no" && test "$ext_shared" = "no"; then
     AC_MSG_ERROR([PDO is not enabled! Add --enable-pdo to your configure line.])
   fi
diff --git a/ext/readline/config.m4 b/ext/readline/config.m4
index 93f4a69db11c1..856116436650c 100644
--- a/ext/readline/config.m4
+++ b/ext/readline/config.m4
@@ -16,12 +16,11 @@ fi
 
 if test "$PHP_READLINE" && test "$PHP_READLINE" != "no"; then
   for i in $PHP_READLINE /usr/local /usr; do
-    test -f $i/include/readline/readline.h && READLINE_DIR=$i && break
+    AS_IF([test -f $i/include/readline/readline.h], [READLINE_DIR=$i; break;])
   done
 
-  if test -z "$READLINE_DIR"; then
-    AC_MSG_ERROR([Please reinstall readline - I cannot find readline.h])
-  fi
+  AS_VAR_IF([READLINE_DIR],,
+    [AC_MSG_ERROR([Please reinstall readline - I cannot find readline.h])])
 
   PHP_ADD_INCLUDE([$READLINE_DIR/include])
 
@@ -88,9 +87,13 @@ if test "$PHP_READLINE" && test "$PHP_READLINE" != "no"; then
     [Define to 1 if readline extension uses the 'readline' library.])
 
 elif test "$PHP_LIBEDIT" != "no"; then
-  if test "$PHP_LIBEDIT" != "yes"; then
-    AC_MSG_WARN([libedit directory ignored, rely on pkg-config])
-  fi
+  AS_VAR_IF([PHP_LIBEDIT], [yes],,
+    [AC_MSG_WARN(m4_text_wrap([
+      The libedit directory argument is not supported anymore, rely on
+      pkg-config. Replace '--with-libedit=$PHP_LIBEDIT' with '--with-libedit'
+      and use environment variables 'PKG_CONFIG_PATH', 'EDIT_LIBS', or
+      'EDIT_CFLAGS'.
+    ]))])
 
   PKG_CHECK_MODULES([EDIT], [libedit])
   PHP_EVAL_LIBLINE([$EDIT_LIBS], [READLINE_SHARED_LIBADD])
diff --git a/ext/sockets/config.m4 b/ext/sockets/config.m4
index aed78416e8d16..e6d1de4c0c70b 100644
--- a/ext/sockets/config.m4
+++ b/ext/sockets/config.m4
@@ -10,21 +10,24 @@ if test "$PHP_SOCKETS" != "no"; then
     [Define to 1 if the PHP extension 'sockets' is available.])
 
   dnl Check for field ss_family in sockaddr_storage (missing in AIX until 5.3)
-  AC_CHECK_MEMBERS([struct sockaddr_storage.ss_family],,,[#include <sys/socket.h>])
+  AC_CHECK_MEMBERS([struct sockaddr_storage.ss_family],,,
+    [#include <sys/socket.h>])
 
   dnl Check for struct ucred. Checking the header is not enough (DragonFlyBSD).
-  AC_CHECK_TYPES([struct ucred],,,
-    [#ifndef _GNU_SOURCE
+  AC_CHECK_TYPES([struct ucred],,, [
+    #ifndef _GNU_SOURCE
     # define _GNU_SOURCE
     #endif
-    #include <sys/socket.h>])
+    #include <sys/socket.h>
+  ])
 
-  AC_CHECK_TYPES([struct cmsgcred],,,[#include <sys/socket.h>])
+  AC_CHECK_TYPES([struct cmsgcred],,, [#include <sys/socket.h>])
 
   PHP_SOCKETS_CFLAGS=-DZEND_ENABLE_STATIC_TSRMLS_CACHE=1
-  case $host_alias in
-  *darwin*) PHP_SOCKETS_CFLAGS="$PHP_SOCKETS_CFLAGS -D__APPLE_USE_RFC_3542"
-  esac
+  AS_CASE([$host_alias],
+    [*darwin*],
+      [PHP_SOCKETS_CFLAGS="$PHP_SOCKETS_CFLAGS -D__APPLE_USE_RFC_3542"])
+
   PHP_NEW_EXTENSION([sockets],
     [sockets.c multicast.c conversions.c sockaddr_conv.c sendrecvmsg.c],
     [$ext_shared],,
diff --git a/ext/sodium/config.m4 b/ext/sodium/config.m4
index 966eff10a96e7..40da5e5bf2d14 100644
--- a/ext/sodium/config.m4
+++ b/ext/sodium/config.m4
@@ -12,14 +12,15 @@ if test "$PHP_SODIUM" != "no"; then
   AC_DEFINE([HAVE_LIBSODIUMLIB], [1],
     [Define to 1 if the PHP extension 'sodium' is available.])
 
-  SODIUM_COMPILER_FLAGS="$LIBSODIUM_CFLAGS"
+  SODIUM_COMPILER_FLAGS=$LIBSODIUM_CFLAGS
 
   dnl Add -Wno-type-limits and -Wno-logical-op as this may arise on 32bits platforms
   AC_CHECK_SIZEOF([long])
   AS_IF([test "$ac_cv_sizeof_long" -eq 4], [
     SODIUM_COMPILER_FLAGS="$SODIUM_COMPILER_FLAGS -Wno-type-limits"
     AX_CHECK_COMPILE_FLAG([-Wno-logical-op],
-      [SODIUM_COMPILER_FLAGS="$SODIUM_COMPILER_FLAGS -Wno-logical-op"],, [-Werror])
+      [SODIUM_COMPILER_FLAGS="$SODIUM_COMPILER_FLAGS -Wno-logical-op"],,
+      [-Werror])
   ])
 
   PHP_NEW_EXTENSION([sodium],
diff --git a/ext/standard/config.m4 b/ext/standard/config.m4
index acd32d6f14b6c..5975cc2936c11 100644
--- a/ext/standard/config.m4
+++ b/ext/standard/config.m4
@@ -277,7 +277,6 @@ int main(void) {
     ac_cv_crypt_sha256=no
   ])])
 
-
   if test "$ac_cv_crypt_blowfish" = "no" || test "$ac_cv_crypt_des" = "no" || test "$ac_cv_crypt_ext_des" = "no" || test "$ac_cv_crypt_md5" = "no" || test "$ac_cv_crypt_sha512" = "no" || test "$ac_cv_crypt_sha256" = "no"; then
     AC_MSG_FAILURE([Cannot use external libcrypt as some algo are missing.])
   fi
@@ -366,14 +365,14 @@ PHP_ARG_WITH([password-argon2],
   [AS_HELP_STRING([[--with-password-argon2]],
     [Include Argon2 support in password_*])])
 
-if test "$PHP_PASSWORD_ARGON2" != "no"; then
+AS_VAR_IF([PHP_PASSWORD_ARGON2], [no],, [
   PKG_CHECK_MODULES([ARGON2], [libargon2])
   PHP_EVAL_INCLINE([$ARGON2_CFLAGS])
   PHP_EVAL_LIBLINE([$ARGON2_LIBS])
 
   AC_DEFINE([HAVE_ARGON2LIB], [1],
     [Define to 1 if the system has the 'libargon2' library.])
-fi
+])
 
 dnl
 dnl Check net/if.h for net_get_interfaces. Darwin and BSD-like systems need
diff --git a/ext/sysvsem/config.m4 b/ext/sysvsem/config.m4
index 0b9fa255ceb89..80fc7631ece74 100644
--- a/ext/sysvsem/config.m4
+++ b/ext/sysvsem/config.m4
@@ -7,7 +7,9 @@ if test "$PHP_SYSVSEM" != "no"; then
   PHP_NEW_EXTENSION([sysvsem], [sysvsem.c], [$ext_shared])
   AC_DEFINE([HAVE_SYSVSEM], [1],
     [Define to 1 if the PHP extension 'sysvsem' is available.])
-  AC_CHECK_TYPES([union semun],,,[#include <sys/types.h>
+  AC_CHECK_TYPES([union semun],,, [
+    #include <sys/types.h>
     #include <sys/ipc.h>
-    #include <sys/sem.h>])
+    #include <sys/sem.h>
+  ])
 fi