--- old/make/common/Defs.gmk	2012-09-06 09:37:39.000000000 -0700
+++ new/make/common/Defs.gmk	2012-09-06 09:37:39.000000000 -0700
@@ -542,6 +542,21 @@
 CXXFLAGS_$(VARIANT)/BYFILE  = $(CXXFLAGS_$(VARIANT)/$(@F)) \
                               $(CXXFLAGS_$(VARIANT)$(CXXFLAGS_$(VARIANT)/$(@F)))
 
+# Command line define to provide basename of file being compiled to source.
+#   The C macro THIS_FILE can replace the use of __FILE__ in the source
+#   files for the current filename being compiled.
+#   The value of the __FILE__ macro is unpredictable and can be anything
+#   from a relative path to a full path, THIS_FILE will be more consistent..
+#   The THIS_FILE macro will always be just the basename of the file being
+#   compiled.
+#   Different string literals in the the object files makes it difficult to
+#   compare shared libraries from different builds.
+#
+#   NOTE: If the THIS_FILE macro is actually expanded while in an included
+#         source file, it will not return the name of the included file.
+#
+CPP_THIS_FILE = -DTHIS_FILE='"$(<F)"'
+
 #
 # Tool flags
 #
@@ -551,7 +566,7 @@
 CFLAGS          = $(CFLAGS_$(VARIANT)/BYFILE)   $(CFLAGS_COMMON) $(OTHER_CFLAGS) $(EXTRA_CFLAGS)
 CXXFLAGS        = $(CXXFLAGS_$(VARIANT)/BYFILE) $(CXXFLAGS_COMMON) $(OTHER_CXXFLAGS) $(EXTRA_CFLAGS)
 CPPFLAGS        = $(CPPFLAGS_$(VARIANT)) $(CPPFLAGS_COMMON) $(OTHER_CPPFLAGS) \
-		  $(DEFINES) $(OPTIONS:%=-D%)
+		  $(DEFINES) $(OPTIONS:%=-D%) $(CPP_THIS_FILE)
 LDFLAGS         = $(LDFLAGS_$(VARIANT)) $(LDFLAGS_COMMON) $(OTHER_LDFLAGS)
 LDLIBS          = $(OTHER_LDLIBS) $(LDLIBS_$(VARIANT)) $(LDLIBS_COMMON)
 LINTFLAGS       = $(LINTFLAGS_$(VARIANT)) $(LINTFLAGS_COMMON) \