rework Preprocess builder to consider deep dependencies - fix #21

lib/rscons/builders/preprocess.rb

@@ -1,7 +1,10 @@
+require "fileutils"
+
 module Rscons
   module Builders
     # The Preprocess builder invokes the C preprocessor
     class Preprocess < Builder
+
       # Return default construction variables for the builder.
       #
       # @param env [Environment] The Environment using the builder.
@@ -9,7 +12,9 @@ module Rscons
       # @return [Hash] Default construction variables for the builder.
       def default_variables(env)
         {
-          "CPP_CMD" => ["${_PREPROCESS_CC}", "-E", "-o", "${_TARGET}", "-I${CPPPATH}", "${CPPFLAGS}", "${CFLAGS}", "${_SOURCES}"],
+          "CPP_CMD" => %w[
+            ${_PREPROCESS_CC} -E ${_PREPROCESS_DEPGEN}
+            -o ${_TARGET} -I${CPPPATH} ${CPPFLAGS} ${_SOURCES}],
         }
       end
 
@@ -24,17 +29,32 @@ module Rscons
       # @return [String,false]
       #   Name of the target file on success or false on failure.
       def run(target, sources, cache, env, vars)
-        pp_cc = if sources.find {|s| s.end_with?(*env.expand_varref("${CXXSUFFIX}", vars))}
-                  "${CXX}"
-                else
-                  "${CC}"
-                end
+        if sources.find {|s| s.end_with?(*env.expand_varref("${CXXSUFFIX}", vars))}
+          pp_cc = "${CXX}"
+          depgen = "${CXXDEPGEN}"
+        else
+          pp_cc = "${CC}"
+          depgen = "${CCDEPGEN}"
+        end
         vars = vars.merge("_PREPROCESS_CC" => pp_cc,
+                          "_PREPROCESS_DEPGEN" => depgen,
                           "_TARGET" => target,
-                          "_SOURCES" => sources)
+                          "_SOURCES" => sources,
+                          "_DEPFILE" => Rscons.set_suffix(target, env.expand_varref("${DEPFILESUFFIX}", vars)))
         command = env.build_command("${CPP_CMD}", vars)
-        standard_build("Preprocess #{target}", target, command, sources, env, cache)
+        unless cache.up_to_date?(target, command, sources, env)
+          cache.mkdir_p(File.dirname(target))
+          return false unless env.execute("Preprocess #{target}", command)
+          deps = sources
+          if File.exists?(vars["_DEPFILE"])
+            deps += Environment.parse_makefile_deps(vars["_DEPFILE"], nil)
+            FileUtils.rm_f(vars["_DEPFILE"])
+          end
+          cache.register_build(target, command, deps.uniq, env)
+        end
+        target
       end
+
     end
   end
 end