gengtype is generated for both the build system and the target. -DGENERATOR_FILE
was added in the patch http://gcc.gnu.org/ml/gcc-patches/2012-07/msg00273.html
and was applied to both versions of gengtype.

Unfortunately the presence of this flag triggers the build configuration (bconfig.h) 
to be included for the target build of gengtype. Compiling gengtype with the target 
compiler and bconfig.h can result in errors if the build and target systems are 
dissimilar. An example case this fails is cross compiling gcc on linux for a darwin 
target system:

In file included from /media/build1/poky/build/tmp/work-shared/gcc-4.8.1-r0/gcc-4.8.1/gcc/gengtype-parse.c:25:0:
| /media/build1/poky/build/tmp/work-shared/gcc-4.8.1-r0/gcc-4.8.1/gcc/gengtype-parse.c: In function 'void parse_error(const char*, ...)':
| /media/build1/poky/build/tmp/work-shared/gcc-4.8.1-r0/gcc-4.8.1/gcc/system.h:93:53: error: 'fputc_unlocked' was not declared in this scope
|  #  define fputc(C, Stream) fputc_unlocked (C, Stream)

which occurs since auto-build.h and auto-host.h have differnet values of
HAVE_FPUTC_UNLOCKED:

#define HAVE_FPUTC_UNLOCKED 1
/* #undef HAVE_FPUTS_UNLOCKED */

The obvious fix is to only include the flag on build/ targets which this patch does, however 
this also leads to compile errors due to const_tree being undefined but used in double_int.h

I added a GENERATOR_FILE2 flag to workaround those in the 
target case and allow the build to succeed.

Only the build/gengtypes should have the -DGENERATOR_FILE 

RP 22/8/2013

Upstream-Status: Pending

Index: gcc-4.8.1/gcc/Makefile.in
===================================================================
--- gcc-4.8.1.orig/gcc/Makefile.in	2013-08-19 11:40:36.844014424 +0000
+++ gcc-4.8.1/gcc/Makefile.in	2013-08-19 11:40:37.784014402 +0000
@@ -3903,27 +3903,29 @@
 
 gengtype-lex.o build/gengtype-lex.o : gengtype-lex.c gengtype.h $(SYSTEM_H)
 gengtype-lex.o: $(CONFIG_H) $(BCONFIG_H)
-CFLAGS-gengtype-lex.o += -DGENERATOR_FILE
+CFLAGS-build/gengtype-lex.o += -DGENERATOR_FILE
 build/gengtype-lex.o: $(BCONFIG_H)
 
 gengtype-parse.o build/gengtype-parse.o : gengtype-parse.c gengtype.h \
   $(SYSTEM_H)
 gengtype-parse.o: $(CONFIG_H)
-CFLAGS-gengtype-parse.o += -DGENERATOR_FILE
+CFLAGS-build/gengtype-parse.o += -DGENERATOR_FILE
 build/gengtype-parse.o: $(BCONFIG_H)
 
 gengtype-state.o build/gengtype-state.o: gengtype-state.c $(SYSTEM_H) \
   gengtype.h errors.h double-int.h version.h $(HASHTAB_H) $(OBSTACK_H) \
   $(XREGEX_H)
 gengtype-state.o: $(CONFIG_H)
-CFLAGS-gengtype-state.o += -DGENERATOR_FILE
+CFLAGS-gengtype-state.o += -DGENERATOR_FILE2
+CFLAGS-build/gengtype-state.o += -DGENERATOR_FILE
 build/gengtype-state.o: $(BCONFIG_H)
 
 gengtype.o build/gengtype.o : gengtype.c $(SYSTEM_H) gengtype.h 	\
   rtl.def insn-notes.def errors.h double-int.h version.h $(HASHTAB_H) \
   $(OBSTACK_H) $(XREGEX_H)
 gengtype.o: $(CONFIG_H)
-CFLAGS-gengtype.o += -DGENERATOR_FILE
+CFLAGS-gengtype.o += -DGENERATOR_FILE2
+CFLAGS-build/gengtype.o += -DGENERATOR_FILE
 build/gengtype.o: $(BCONFIG_H)
 
 build/genmddeps.o: genmddeps.c $(BCONFIG_H) $(SYSTEM_H) coretypes.h	\
@@ -3988,7 +3990,7 @@
 # any system header is included.
 gengtype-lex.c : gengtype-lex.l
 	-$(FLEX) $(FLEXFLAGS) -o$@ $< && { \
-	  echo '#include "bconfig.h"' > $@.tmp; \
+	  echo '' > $@.tmp; \
 	  cat $@ >> $@.tmp; \
 	  mv $@.tmp $@; \
 	}
Index: gcc-4.8.1/gcc/double-int.h
===================================================================
--- gcc-4.8.1.orig/gcc/double-int.h	2013-01-30 11:04:30.000000000 +0000
+++ gcc-4.8.1/gcc/double-int.h	2013-08-19 11:41:51.564012719 +0000
@@ -448,10 +448,12 @@
 
 
 #ifndef GENERATOR_FILE
+#ifndef GENERATOR_FILE2
 /* Conversion to and from GMP integer representations.  */
 
 void mpz_set_double_int (mpz_t, double_int, bool);
 double_int mpz_get_double_int (const_tree, mpz_t, bool);
 #endif
+#endif
 
 #endif /* DOUBLE_INT_H */