きしもとです

[ruby-list:47092] で振ってみた話題に関係して、なのですが(ツリーになりませんでしたが)、
mkmf に C++ のヘッダをチェックする機能を追加するパッチです。

Index: configure.in
===================================================================
--- configure.in	(revision 27940)
+++ configure.in	(working copy)
@@ -243,6 +243,7 @@
 fi
 AC_PROG_CC
 AC_PROG_CXX
+AC_PROG_CXXCPP
 AC_PROG_GCC_TRADITIONAL
 AC_SUBST(GCC)
 if test "$GCC" = yes; then
Index: lib/mkmf.rb
===================================================================
--- lib/mkmf.rb	(revision 27940)
+++ lib/mkmf.rb	(working copy)
@@ -408,6 +408,14 @@
 		   conf)
 end
 
+def cxxcpp_command(outfile, opt="")
+  conf = RbConfig::CONFIG.merge('hdrdir' => $hdrdir.quote, 'srcdir' => $srcdir.quote,
+                                'arch_hdrdir' => "#$arch_hdrdir",
+                                'top_srcdir' => $top_srcdir.quote)
+  RbConfig::expand("$(CXXCPP) #$INCFLAGS #$CPPFLAGS #$CXXFLAGS #{opt} #{CONFTEST_C} #{outfile}",
+		   conf)
+end
+
 def libpathflag(libpath=$DEFLIBPATH|$LIBPATH)
   libpath.map{|x|
     case x
@@ -454,8 +462,15 @@
   rm_f "conftest*"
 end
 
+def try_cxxcpp(src, opt="", &b)
+  try_do(src, cxxcpp_command(CPPOUTFILE, opt), &b)
+ensure
+  rm_f "conftest*"
+end
+
 class Object
   alias_method :try_header, (config_string('try_header') || :try_cpp)
+  alias_method :try_cxx_header, (config_string('try_cxx_header') || :try_cxxcpp)
 end
 
 def cpp_include(header)
@@ -840,6 +855,24 @@
   end
 end
 
+# Returns whether or not the given C plus plus +header+ file can be found on
+# your system. If found, a macro is passed as a preprocessor constant to the
+# compiler using the header file name, in uppercase, prepended with 'HAVE_'.
+#
+# For example, if have_header('foo.h') returned true, then the HAVE_FOO_H
+# preprocessor macro would be passed to the compiler.
+#
+def have_cxx_header(header, preheaders = nil, &b)
+  checking_for header do
+    if try_cxx_header(cpp_include(preheaders)+cpp_include(header), &b)
+      $defs.push(format("-DHAVE_%s", header.tr_cpp))
+      true
+    else
+      false
+    end
+  end
+end
+
 # Instructs mkmf to search for the given +header+ in any of the +paths+
 # provided, and returns whether or not it was found in those paths.
 #
@@ -867,6 +900,33 @@
   end
 end
 
+# Instructs mkmf to search for the given C plus plus +header+ in any of the
+# +paths+ provided, and returns whether or not it was found in those paths.
+#
+# If the header is found then the path it was found on is added to the list
+# of included directories that are sent to the compiler (via the -I switch).
+#
+def find_cxx_header(header, *paths)
+  message = checking_message(header, paths)
+  header = cpp_include(header)
+  checking_for message do
+    if try_cxx_header(header)
+      true
+    else
+      found = false
+      paths.each do |dir|
+        opt = "-I#{dir}".quote
+        if try_cxx_header(header, opt)
+          $INCFLAGS << " " << opt
+          found = true
+          break
+        end
+      end
+      found
+    end
+  end
+end
+
 # Returns whether or not the struct of type +type+ contains +member+.  If
 # it does not, or the struct type can't be found, then false is returned.  You
 # may optionally specify additional +headers+ in which to look for the struct