-dnl Only allow AC_PROG_CXX if it's explicitly called (by PHP_REQUIRE_CXX)
-dnl otherwise AC_PROG_LIBTOOL fails if there is no working C++ compiler
-AC_PROVIDE_IFELSE([PHP_REQUIRE_CXX], [AC_PROG_CXX], [undefine([AC_PROG_CXX])
-AC_DEFUN([AC_PROG_CXX], [])])
+dnl Only allow AC_PROG_CXX and AC_PROG_CXXCPP if they are explicitly called (by PHP_REQUIRE_CXX).
+dnl Otherwise AC_PROG_LIBTOOL fails if there is no working C++ compiler.
+AC_PROVIDE_IFELSE([PHP_REQUIRE_CXX], [], [
+ undefine([AC_PROG_CXX])
+ AC_DEFUN([AC_PROG_CXX], [])
+ undefine([AC_PROG_CXXCPP])
+ AC_DEFUN([AC_PROG_CXXCPP], [])
+])
AC_PROG_LIBTOOL
This causes a syntax error in configure after doing a buildconf.