support compiling C++ objects with Object builder

lib/rscons/builders/object.rb

@@ -12,20 +12,28 @@ module Rscons
         'ASDEPGEN' => ['-MMD', '-MF', '$DEPFILE'],
         'ASCOM' => ['$AS', '-c', '-o', '$TARGET', '$ASDEPGEN', '-I$[ASPPPATH]', '$ASPPFLAGS', '$ASFLAGS', '$SOURCES'],
 
-        'CC' => 'gcc',
-        'CFLAGS' => [],
         'CPPFLAGS' => [],
         'CPPPATH' => [],
+
+        'CC' => 'gcc',
+        'CFLAGS' => [],
         'CSUFFIX' => '.c',
         'CCDEPGEN' => ['-MMD', '-MF', '$DEPFILE'],
         'CCCOM' => ['$CC', '-c', '-o', '$TARGET', '$CCDEPGEN', '-I$[CPPPATH]', '$CPPFLAGS', '$CFLAGS', '$SOURCES'],
+
+        'CXX' => 'g++',
+        'CXXFLAGS' => [],
+        'CXXSUFFIX' => '.cc',
+        'CXXDEPGEN' => ['-MMD', '-MF', '$DEPFILE'],
+        'CXXCOM' =>['$CXX', '-c', '-o', '$TARGET', '$CXXDEPGEN', '-I$[CPPPATH]', '$CPPFLAGS', '$CXXFLAGS', '$SOURCES'],
       }
     end
 
     def produces?(target, source, env)
       target.has_suffix?(env['OBJSUFFIX']) and (
         source.has_suffix?(env['ASSUFFIX']) or
-        source.has_suffix?(env['CSUFFIX']))
+        source.has_suffix?(env['CSUFFIX']) or
+        source.has_suffix?(env['CXXSUFFIX']))
     end
 
     def run(target, sources, cache, env)
@@ -38,6 +46,8 @@ module Rscons
                      'AS'
                    elsif sources.first.has_suffix?(env['CSUFFIX'])
                      'CC'
+                   elsif sources.first.has_suffix?(env['CXXSUFFIX'])
+                     'CXX'
                    else
                      raise "Error: unknown input file type: #{sources.first.inspect}"
                    end

lib/rscons/builders/program.rb

@@ -14,7 +14,7 @@ module Rscons
 
     def run(target, sources, cache, env)
       # convert sources to object file names
-      sources = sources.map do |source|
+      objects = sources.map do |source|
         if source.has_suffix?([env['OBJSUFFIX'], env['LIBSUFFIX']])
           source
         else
@@ -24,16 +24,20 @@ module Rscons
           builder.run(o_file, [source], cache, env) or break
         end
       end
-      if sources
+      if objects
+        use_cxx = sources.map do |s|
+          s.has_suffix?(env['CXXSUFFIX'])
+        end.any?
+        ld_alt = use_cxx ? env['CXX'] : env['CC']
         vars = {
           'TARGET' => target,
-          'SOURCES' => sources,
-          'LD' => env['LD'] || env['CC'], # TODO: figure out whether to use CC or CXX
+          'SOURCES' => objects,
+          'LD' => env['LD'] || ld_alt,
         }
         command = env.build_command(env['LDCOM'], vars)
-        unless cache.up_to_date?(target, command, sources)
+        unless cache.up_to_date?(target, command, objects)
           return false unless env.execute("LD #{target}", command)
-          cache.register_build(target, command, sources)
+          cache.register_build(target, command, objects)
         end
         target
       end