re PR bootstrap/31020 (cannot write in </test/gnu/gcc/objdir/prev-gcc/../gcc/./include>)

fixincludes:
	* mkheaders.in: Fix headers for each multilib required.

gcc:
	PR bootstrap/31020
	* configure.ac (CROSS_SYSTEM_HEADER_DIR, build_system_header_dir):
	Define using $${sysroot_headers_suffix}.
	* configure: Regenerate.
	* cppdefault.c (cpp_include_defaults): Make FIXED_INCLUDE_DIR a
	multilib-suffixed directory if SYSROOT_HEADERS_SUFFIX_SPEC
	defined.
	* doc/invoke.texi (-print-sysroot-headers-suffix): Document.
	* gcc.c (print_sysroot_headers_suffix): New.
	(option_map): Include --print-sysroot-headers-suffix.
	(display_help): Mention -print-sysroot-headers-suffix.
	(process_command): Handle -print-sysroot-headers-suffix.
	(do_spec_1): Append multilib directory to include-fixed path if
	sysroot suffixes in use.
	(main): Handle -print-sysroot-headers-suffix.
	* Makefile.in (start.encap): Don't depend on xlimits.h
	(xlimits.h): Remove.
	(stmp-int-hdrs): Don't depend on xlimits.h.  Inline generation of
	limits.h for each multilib in fixinc_list.
	(fixinc_list, s-fixinc_list): New.
	(stmp-fixinc): Depend on fixinc_list.  If not copying headers,
	generate them for each multilib in fixinc_list.
	(stmp-fixproto): Use include-fixed.  Run fixproto for each
	multilib in fixinc_list.
	(mostlyclean): Don't remove xlimits.h.
	(clean): Remove include-fixed.
	(real-install-headers-tar, real-install-headers-cpio,
	real-install-headers-cp): Don't copy include, only include-fixed.
	(install-mkheaders): Depend on fixinc_list.  Don't depend on
	xlimits.h.  Save limits.h files for each multilib in fixinc_list.
	Always save mkinstalldirs.  Preserve ${sysroot_headers_suffix} in
	SYSTEM_HEADER_DIR setting in mkheaders.conf.

From-SVN: r122620

fixincludes/ChangeLog

@@ -1,3 +1,7 @@
+2007-03-06  Joseph Myers  <joseph@codesourcery.com>
+
+	* mkheaders.in: Fix headers for each multilib required.
+
 2007-03-01  Brooks Moses  <brooks.moses@codesourcery.com>
 
 	* Makefile.in: Add dummy install-pdf target.

fixincludes/mkheaders.in

@@ -78,29 +78,33 @@ libexecsubdir=${libexecdir}/gcc/${target_noncanonical}/${version}
 itoolsdir=${libexecsubdir}/install-tools
 itoolsdatadir=${libsubdir}/install-tools
 incdir=${libsubdir}/include-fixed
-
+mkinstalldirs="@SHELL@ ${itoolsdir}/mkinstalldirs"
-. ${itoolsdatadir}/mkheaders.conf
 
 cd ${itoolsdir}
 rm -rf ${incdir}/*
 
+for ml in `cat ${itoolsdatadir}/fixinc_list`; do
+  sysroot_headers_suffix=`echo ${ml} | sed -e 's/;.*$//'`
+  multi_dir=`echo ${ml} | sed -e 's/^[^;]*;//'`
+  subincdir=${incdir}${multi_dir}
+  . ${itoolsdatadir}/mkheaders.conf
   if [ x${STMP_FIXINC} != x ] ; then
 	TARGET_MACHINE="${target}" target_canonical="${target}" \
 	    MACRO_LIST="${itoolsdatadir}/macro_list" \
-	    @SHELL@ ./fixinc.sh ${incdir} \
+	    @SHELL@ ./fixinc.sh ${subincdir} \
 	    ${isysroot}${SYSTEM_HEADER_DIR} ${OTHER_FIXINCLUDES_DIRS}
-	rm -f ${incdir}/syslimits.h
+	rm -f ${subincdir}/syslimits.h
-	if [ -f ${incdir}/limits.h ]; then
+	if [ -f ${subincdir}/limits.h ]; then
-	  mv ${incdir}/limits.h ${incdir}/syslimits.h
+	  mv ${subincdir}/limits.h ${subincdir}/syslimits.h
 	else
-	  cp ${itoolsdatadir}/gsyslimits.h ${incdir}/syslimits.h
+	  cp ${itoolsdatadir}/gsyslimits.h ${subincdir}/syslimits.h
 	fi
   fi
 
-cp ${itoolsdatadir}/include/* ${incdir}
+  cp ${itoolsdatadir}/include${multi_dir}/limits.h ${subincdir}
 
   if [ x${STMP_FIXPROTO} != x ] ; then
-  mkinstalldirs="@SHELL@ ${itoolsdir}/mkinstalldirs"
     export FIXPROTO_DEFINES mkinstalldirs
-  @SHELL@ fixproto ${incdir} ${incdir} ${isysroot}${SYSTEM_HEADER_DIR} || exit 1
+    @SHELL@ fixproto ${subincdir} ${subincdir} ${isysroot}${SYSTEM_HEADER_DIR} || exit 1
   fi
+done

gcc/ChangeLog

@@ -1,3 +1,38 @@
+2007-03-06  Joseph Myers  <joseph@codesourcery.com>
+
+	PR bootstrap/31020
+	* configure.ac (CROSS_SYSTEM_HEADER_DIR, build_system_header_dir):
+	Define using $${sysroot_headers_suffix}.
+	* configure: Regenerate.
+	* cppdefault.c (cpp_include_defaults): Make FIXED_INCLUDE_DIR a
+	multilib-suffixed directory if SYSROOT_HEADERS_SUFFIX_SPEC
+	defined.
+	* doc/invoke.texi (-print-sysroot-headers-suffix): Document.
+	* gcc.c (print_sysroot_headers_suffix): New.
+	(option_map): Include --print-sysroot-headers-suffix.
+	(display_help): Mention -print-sysroot-headers-suffix.
+	(process_command): Handle -print-sysroot-headers-suffix.
+	(do_spec_1): Append multilib directory to include-fixed path if
+	sysroot suffixes in use.
+	(main): Handle -print-sysroot-headers-suffix.
+	* Makefile.in (start.encap): Don't depend on xlimits.h
+	(xlimits.h): Remove.
+	(stmp-int-hdrs): Don't depend on xlimits.h.  Inline generation of
+	limits.h for each multilib in fixinc_list.
+	(fixinc_list, s-fixinc_list): New.
+	(stmp-fixinc): Depend on fixinc_list.  If not copying headers,
+	generate them for each multilib in fixinc_list.
+	(stmp-fixproto): Use include-fixed.  Run fixproto for each
+	multilib in fixinc_list.
+	(mostlyclean): Don't remove xlimits.h.
+	(clean): Remove include-fixed.
+	(real-install-headers-tar, real-install-headers-cpio,
+	real-install-headers-cp): Don't copy include, only include-fixed.
+	(install-mkheaders): Depend on fixinc_list.  Don't depend on
+	xlimits.h.  Save limits.h files for each multilib in fixinc_list.
+	Always save mkinstalldirs.  Preserve ${sysroot_headers_suffix} in
+	SYSTEM_HEADER_DIR setting in mkheaders.conf.
+
 2007-03-06  Jan Hubicka  <jh@suse.cz>
 
 	* regstack.c (reg_to_stack): When in 64bit PIC mode, we still can load

gcc/Makefile.in

@@ -1418,7 +1418,7 @@ all.cross: native gcc-cross$(exeext) cpp$(exeext) specs \
 	libgcc-support lang.all.cross doc @GENINSRC@ srcextra
 # This is what must be made before installing GCC and converting libraries.
 start.encap: native xgcc$(exeext) cpp$(exeext) specs \
-	libgcc-support xlimits.h lang.start.encap @GENINSRC@ srcextra
+	libgcc-support lang.start.encap @GENINSRC@ srcextra
 # These can't be made until after GCC can run.
 rest.encap: $(STMP_FIXPROTO) lang.rest.encap
 # This is what is made with the host's compiler
@@ -1542,14 +1542,6 @@ cc1$(exeext): $(C_OBJS) cc1-checksum.o $(BACKEND) $(LIBDEPS)
 	$(CC) $(ALL_CFLAGS) $(LDFLAGS) -o $@ $(C_OBJS) cc1-checksum.o \
 	  $(BACKEND) $(LIBS)
 
-# Build the version of limits.h that we will install.
-xlimits.h: glimits.h limitx.h limity.h
-	if $(LIMITS_H_TEST) ; then \
-	  cat $(srcdir)/limitx.h $(srcdir)/glimits.h $(srcdir)/limity.h > tmp-xlimits.h; \
-	else \
-	  cat $(srcdir)/glimits.h > tmp-xlimits.h; \
-	fi
-	mv tmp-xlimits.h xlimits.h
 #
 # Build libgcc.a.
 
@@ -3325,7 +3317,7 @@ gcov-dump$(exeext): $(GCOV_DUMP_OBJS) $(LIBDEPS)
 # be rebuilt.
 
 # Build the include directories.
-stmp-int-hdrs: $(STMP_FIXINC) $(USER_H) xlimits.h $(UNWIND_H)
+stmp-int-hdrs: $(STMP_FIXINC) $(USER_H) $(UNWIND_H)
 # Copy in the headers provided with gcc.
 # The sed command gets just the last file name component;
 # this is necessary because VPATH could add a dirname.
@@ -3342,11 +3334,23 @@ stmp-int-hdrs: $(STMP_FIXINC) $(USER_H) xlimits.h $(UNWIND_H)
 	    chmod a+r include/$$realfile; \
 	  fi; \
 	done
-	rm -f include-fixed/limits.h
-	cp xlimits.h include-fixed/limits.h
-	chmod a+r include-fixed/limits.h
 	rm -f include/unwind.h
 	cp $(UNWIND_H) include/unwind.h
+	set -e; for ml in `cat fixinc_list`; do \
+	  sysroot_headers_suffix=`echo $${ml} | sed -e 's/;.*$$//'`; \
+	  multi_dir=`echo $${ml} | sed -e 's/^[^;]*;//'`; \
+	  fix_dir=include-fixed$${multi_dir}; \
+	  if $(LIMITS_H_TEST) ; then \
+	    cat $(srcdir)/limitx.h $(srcdir)/glimits.h $(srcdir)/limity.h > tmp-xlimits.h; \
+	  else \
+	    cat $(srcdir)/glimits.h > tmp-xlimits.h; \
+	  fi; \
+	  $(mkinstalldirs) $${fix_dir}; \
+	  chmod a+rx $${fix_dir} || true; \
+	  rm -f $${fix_dir}/limits.h; \
+	  mv tmp-xlimits.h $${fix_dir}/limits.h; \
+	  chmod a+r $${fix_dir}/limits.h; \
+	done
 # Install the README
 	rm -f include-fixed/README
 	cp $(srcdir)/../fixincludes/README-fixinc include-fixed/README
@@ -3366,6 +3370,28 @@ s-macro_list : $(GCC_PASSES)
 	$(SHELL) $(srcdir)/../move-if-change tmp-macro_list macro_list
 	$(STAMP) s-macro_list
 
+fixinc_list: s-fixinc_list; @true
+s-fixinc_list : $(GCC_PASSES)
+# Build up a list of multilib directories and corresponding sysroot
+# suffixes, in form sysroot;multilib.
+	if $(GCC_FOR_TARGET) -print-sysroot-headers-suffix > /dev/null 2>&1; then \
+	  set -e; for ml in `$(GCC_FOR_TARGET) -print-multi-lib`; do \
+	    multi_dir=`echo $${ml} | sed -e 's/;.*$$//'`; \
+	    flags=`echo $${ml} | sed -e 's/^[^;]*;//' -e 's/@/ -/g'`; \
+	    sfx=`$(GCC_FOR_TARGET) $${flags} -print-sysroot-headers-suffix`; \
+	    if [ "$${multi_dir}" = "." ]; \
+	      then multi_dir=""; \
+	    else \
+	      multi_dir=/$${multi_dir}; \
+	    fi; \
+	    echo "$${sfx};$${multi_dir}"; \
+	  done; \
+	else \
+	  echo ";"; \
+	fi > tmp-fixinc_list
+	$(SHELL) $(srcdir)/../move-if-change tmp-fixinc_list fixinc_list
+	$(STAMP) s-fixinc_list
+
 # The line below is supposed to avoid accidentally matching the
 # built-in suffix rule `.o:' to build fixincl out of fixincl.o.  You'd
 # expect fixincl to be newer than fixincl.o, such that this situation
@@ -3383,16 +3409,9 @@ s-macro_list : $(GCC_PASSES)
 # Build fixed copies of system files.
 # Abort if no system headers available, unless building a crosscompiler.
 # FIXME: abort unless building --without-headers would be more accurate and less ugly
-stmp-fixinc: gsyslimits.h macro_list \
+stmp-fixinc: gsyslimits.h macro_list fixinc_list \
   $(build_objdir)/fixincludes/fixincl \
   $(build_objdir)/fixincludes/fixinc.sh
-	@if ! $(inhibit_libc) && test ! -d ${SYSTEM_HEADER_DIR}; then \
-	  echo The directory that should contain system headers does not exist: >&2 ; \
-	  echo "  ${SYSTEM_HEADER_DIR}" >&2 ; \
-	  tooldir_sysinc=`echo "${gcc_tooldir}/sys-include" | sed -e :a -e "s,[^/]*/\.\.\/,," -e ta`; \
-	  if test "x${SYSTEM_HEADER_DIR}" = "x$${tooldir_sysinc}"; \
-	  then sleep 1; else exit 1; fi; \
-	fi
 	rm -rf include-fixed; mkdir include-fixed
 	-chmod a+rx include-fixed
 	if [ -d ../prev-gcc ]; then \
@@ -3400,20 +3419,34 @@ stmp-fixinc: gsyslimits.h macro_list \
 	  $(MAKE) real-$(INSTALL_HEADERS_DIR) DESTDIR=`pwd`/../gcc/ \
 	    libsubdir=. ; \
 	else \
+	  set -e; for ml in `cat fixinc_list`; do \
+	    sysroot_headers_suffix=`echo $${ml} | sed -e 's/;.*$$//'`; \
+	    multi_dir=`echo $${ml} | sed -e 's/^[^;]*;//'`; \
+	    fix_dir=include-fixed$${multi_dir}; \
+	    if ! $(inhibit_libc) && test ! -d ${SYSTEM_HEADER_DIR}; then \
+	      echo The directory that should contain system headers does not exist: >&2 ; \
+	      echo "  ${SYSTEM_HEADER_DIR}" >&2 ; \
+	      tooldir_sysinc=`echo "${gcc_tooldir}/sys-include" | sed -e :a -e "s,[^/]*/\.\.\/,," -e ta`; \
+	      if test "x${SYSTEM_HEADER_DIR}" = "x$${tooldir_sysinc}"; \
+	      then sleep 1; else exit 1; fi; \
+	    fi; \
+	    $(mkinstalldirs) $${fix_dir}; \
+	    chmod a+rx $${fix_dir} || true; \
 	    (TARGET_MACHINE='$(target)'; srcdir=`cd $(srcdir); ${PWD_COMMAND}`; \
 	      SHELL='$(SHELL)'; MACRO_LIST=`${PWD_COMMAND}`/macro_list ; \
 	      export TARGET_MACHINE srcdir SHELL MACRO_LIST && \
 	      cd $(build_objdir)/fixincludes && \
-	    $(SHELL) ./fixinc.sh ../../gcc/include-fixed \
+	      $(SHELL) ./fixinc.sh ../../gcc/$${fix_dir} \
 	        $(SYSTEM_HEADER_DIR) $(OTHER_FIXINCLUDES_DIRS) ); \
-	  rm -f include-fixed/syslimits.h; \
+	    rm -f $${fix_dir}/syslimits.h; \
-	  if [ -f include-fixed/limits.h ]; then \
+	    if [ -f $${fix_dir}/limits.h ]; then \
-	    mv include-fixed/limits.h include-fixed/syslimits.h; \
+	      mv $${fix_dir}/limits.h $${fix_dir}/syslimits.h; \
 	    else \
-	    cp $(srcdir)/gsyslimits.h include-fixed/syslimits.h; \
+	      cp $(srcdir)/gsyslimits.h $${fix_dir}/syslimits.h; \
 	    fi; \
+	    chmod a+r $${fix_dir}/syslimits.h; \
+	  done; \
 	fi
-	chmod a+r include-fixed/syslimits.h
 	$(STAMP) stmp-fixinc
 
 # Files related to the fixproto script.
@@ -3480,9 +3513,13 @@ fixhdr.ready: build/fix-header$(build_exeext)
 
 # stmp-int-hdrs is to make sure fixincludes has already finished.
 # The if statement is so that we don't run fixproto a second time
-# if it has already been run on the files in `include'.
+# if it has already been run on the files in `include-fixed'.
-stmp-fixproto: fixhdr.ready fixproto stmp-int-hdrs
+stmp-fixproto: fixhdr.ready fixproto fixinc_list stmp-int-hdrs
-	if [ -f include/fixed ] ; then true; \
+	set -e; for ml in `cat fixinc_list`; do \
+	  sysroot_headers_suffix=`echo $${ml} | sed -e 's/;.*$$//'`; \
+	  multi_dir=`echo $${ml} | sed -e 's/^[^;]*;//'`; \
+	  fix_dir=include-fixed$${multi_dir}; \
+	  if [ -f $${fix_dir}/fixed ] ; then true; \
 	  else \
 	    : This line works around a 'make' bug in BSDI 1.1.; \
 	    FIXPROTO_DEFINES="$(FIXPROTO_DEFINES)"; export FIXPROTO_DEFINES; \
@@ -3490,11 +3527,12 @@ stmp-fixproto: fixhdr.ready fixproto stmp-int-hdrs
 	    mkinstalldirs="$(mkinstalldirs)"; \
 	      export mkinstalldirs; \
 	    if [ -d "$(SYSTEM_HEADER_DIR)" ]; then \
-	    $(SHELL) ${srcdir}/fixproto include include $(SYSTEM_HEADER_DIR); \
+	      $(SHELL) ${srcdir}/fixproto $${fix_dir} $${fix_dir} $(SYSTEM_HEADER_DIR); \
 	      if [ $$? -eq 0 ] ; then true ; else exit 1 ; fi ; \
 	    else true; fi; \
-	  $(STAMP) include/fixed; \
+	    $(STAMP) $${fix_dir}/fixed; \
-	fi
+	  fi; \
+	done
 	$(STAMP) stmp-fixproto
 
 # We can't run fixproto (it's being built for a different host), but we still
@@ -3696,8 +3734,6 @@ mostlyclean: lang.mostlyclean
 # Delete build programs
 	-rm -f build/*
 	-rm -f mddeps.mk
-# Delete the temp files made in the course of building libgcc.a.
-	-rm -f xlimits.h
 # Delete other built files.
 	-rm -f xsys-protos.hT
 	-rm -f specs.h gencheck.h options.c options.h
@@ -3738,8 +3774,8 @@ clean: mostlyclean lang.clean
 	-rm -f cs-*
 	-rm -f doc/*.dvi
 	-rm -f doc/*.pdf
-# Delete the include directory.
+# Delete the include directories.
-	-rm -rf include
+	-rm -rf include include-fixed
 # Delete files used by the "multilib" facility (including libgcc subdirs).
 	-rm -f multilib.h tmpmultilib*
 	-if [ "x$(MULTILIB_DIRNAMES)" != x ] ; then \
@@ -4017,35 +4053,36 @@ install-headers-cp: stmp-int-hdrs $(STMP_FIXPROTO) install-include-dir
 
 # Targets without dependencies, for use in prev-gcc during bootstrap.
 real-install-headers-tar:
-	(cd `${PWD_COMMAND}`/include ; \
-	 tar -cf - .; exit 0) | (cd $(DESTDIR)$(libsubdir)/include; tar xpf - )
 	(cd `${PWD_COMMAND}`/include-fixed ; \
 	 tar -cf - .; exit 0) | (cd $(DESTDIR)$(libsubdir)/include-fixed; tar xpf - )
 
 real-install-headers-cpio:
-	cd `${PWD_COMMAND}`/include ; \
-	find . -print | cpio -pdum $(DESTDIR)$(libsubdir)/include
 	cd `${PWD_COMMAND}`/include-fixed ; \
 	find . -print | cpio -pdum $(DESTDIR)$(libsubdir)/include-fixed
 
 real-install-headers-cp:
-	cp -p -r include $(DESTDIR)$(libsubdir)
 	cp -p -r include-fixed $(DESTDIR)$(libsubdir)
 
 # Install supporting files for fixincludes to be run later.
 install-mkheaders: stmp-int-hdrs $(STMP_FIXPROTO) install-itoolsdirs \
-  macro_list xlimits.h
+  macro_list fixinc_list
-	$(INSTALL_DATA) xlimits.h $(DESTDIR)$(itoolsdatadir)/include/limits.h
 	$(INSTALL_DATA) $(srcdir)/gsyslimits.h \
 	  $(DESTDIR)$(itoolsdatadir)/gsyslimits.h
 	$(INSTALL_DATA) macro_list $(DESTDIR)$(itoolsdatadir)/macro_list
-	if [ x$(STMP_FIXPROTO) != x ] ; then \
+	$(INSTALL_DATA) fixinc_list $(DESTDIR)$(itoolsdatadir)/fixinc_list
-	  $(INSTALL_SCRIPT) $(mkinstalldirs) \
+	set -e; for ml in `cat fixinc_list`; do \
+	  multi_dir=`echo $${ml} | sed -e 's/^[^;]*;//'`; \
+	  $(mkinstalldirs) $(DESTDIR)$(itoolsdatadir)/include$${multi_dir}; \
+	  $(INSTALL_DATA) include-fixed$${multidir}/limits.h $(DESTDIR)$(itoolsdatadir)/include$${multi_dir}/limits.h; \
+	done
+	$(INSTALL_SCRIPT) $(srcdir)/../mkinstalldirs \
 		$(DESTDIR)$(itoolsdir)/mkinstalldirs ; \
+	if [ x$(STMP_FIXPROTO) != x ] ; then \
 	  $(INSTALL_SCRIPT) $(srcdir)/fixproto $(DESTDIR)$(itoolsdir)/fixproto ; \
 	  $(INSTALL_PROGRAM) build/fix-header$(build_exeext) \
 		$(DESTDIR)$(itoolsdir)/fix-header$(build_exeext) ; \
 	else :; fi
+	sysroot_headers_suffix='$${sysroot_headers_suffix}'; \
 		echo 'SYSTEM_HEADER_DIR="'"$(SYSTEM_HEADER_DIR)"'"' \
 		> $(DESTDIR)$(itoolsdatadir)/mkheaders.conf
 	echo 'OTHER_FIXINCLUDES_DIRS="$(OTHER_FIXINCLUDES_DIRS)"' \

gcc/configure

@@ -7128,7 +7128,7 @@ if test "${with_sysroot+set}" = set; then
  esac
 
  TARGET_SYSTEM_ROOT_DEFINE='-DTARGET_SYSTEM_ROOT=\"$(TARGET_SYSTEM_ROOT)\"'
- CROSS_SYSTEM_HEADER_DIR='$(TARGET_SYSTEM_ROOT)$(NATIVE_SYSTEM_HEADER_DIR)'
+ CROSS_SYSTEM_HEADER_DIR='$(TARGET_SYSTEM_ROOT)$${sysroot_headers_suffix}$(NATIVE_SYSTEM_HEADER_DIR)'
 
  if test "x$exec_prefix" = xNONE; then
   if test "x$prefix" = xNONE; then
@@ -13121,7 +13121,7 @@ ALL=all.internal
 SYSTEM_HEADER_DIR='$(NATIVE_SYSTEM_HEADER_DIR)'
 
 if test "x$with_build_sysroot" != x; then
-  build_system_header_dir=$with_build_sysroot'$(NATIVE_SYSTEM_HEADER_DIR)'
+  build_system_header_dir=$with_build_sysroot'$${sysroot_headers_suffix}$(NATIVE_SYSTEM_HEADER_DIR)'
 else
   # This value is used, even on a native system, because
   # CROSS_SYSTEM_HEADER_DIR is just

gcc/configure.ac

@@ -754,7 +754,7 @@ AC_ARG_WITH(sysroot,
  esac
    
  TARGET_SYSTEM_ROOT_DEFINE='-DTARGET_SYSTEM_ROOT=\"$(TARGET_SYSTEM_ROOT)\"'
- CROSS_SYSTEM_HEADER_DIR='$(TARGET_SYSTEM_ROOT)$(NATIVE_SYSTEM_HEADER_DIR)'
+ CROSS_SYSTEM_HEADER_DIR='$(TARGET_SYSTEM_ROOT)$${sysroot_headers_suffix}$(NATIVE_SYSTEM_HEADER_DIR)'
 	
  if test "x$exec_prefix" = xNONE; then
   if test "x$prefix" = xNONE; then
@@ -1704,7 +1704,7 @@ ALL=all.internal				AC_SUBST(ALL)
 SYSTEM_HEADER_DIR='$(NATIVE_SYSTEM_HEADER_DIR)'	AC_SUBST(SYSTEM_HEADER_DIR)
 
 if test "x$with_build_sysroot" != x; then
-  build_system_header_dir=$with_build_sysroot'$(NATIVE_SYSTEM_HEADER_DIR)'
+  build_system_header_dir=$with_build_sysroot'$${sysroot_headers_suffix}$(NATIVE_SYSTEM_HEADER_DIR)'
 else
   # This value is used, even on a native system, because 
   # CROSS_SYSTEM_HEADER_DIR is just 

gcc/cppdefault.c

@@ -71,7 +71,15 @@ const struct default_include cpp_include_defaults[]
 #endif
 #ifdef FIXED_INCLUDE_DIR
     /* This is the dir for fixincludes.  */
-    { FIXED_INCLUDE_DIR, "GCC", 0, 0, 0, 0 },
+    { FIXED_INCLUDE_DIR, "GCC", 0, 0, 0,
+      /* A multilib suffix needs adding if different multilibs use
+	 different headers.  */
+#ifdef SYSROOT_HEADERS_SUFFIX_SPEC
+      1
+#else
+      0
+#endif
+    },
 #endif
 #ifdef CROSS_INCLUDE_DIR
     /* One place the target system's headers might be.  */

gcc/doc/invoke.texi

@@ -302,6 +302,7 @@ Objective-C and Objective-C++ Dialects}.
 -p  -pg  -print-file-name=@var{library}  -print-libgcc-file-name @gol
 -print-multi-directory  -print-multi-lib @gol
 -print-prog-name=@var{program}  -print-search-dirs  -Q @gol
+-print-sysroot-headers-suffix @gol
 -save-temps  -time}
 
 @item Optimization Options
@@ -4697,6 +4698,12 @@ variable @env{GCC_EXEC_PREFIX} to the directory where you installed them.
 Don't forget the trailing @samp{/}.
 @xref{Environment Variables}.
 
+@item -print-sysroot-headers-suffix
+@opindex print-sysroot-headers-suffix
+Print the suffix added to the target sysroot when searching for
+headers, or give an error if the compiler is not configured with such
+a suffix---and don't do anything else.
+
 @item -dumpmachine
 @opindex dumpmachine
 Print the compiler's target machine (for example,

gcc/gcc.c

@@ -168,6 +168,11 @@ static int print_multi_lib;
 
 static int print_help_list;
 
+/* Flag saying to print the sysroot suffix used for searching for
+   headers.  */
+
+static int print_sysroot_headers_suffix;
+
 /* Flag indicating whether we should print the command and arguments */
 
 static int verbose_flag;
@@ -1125,6 +1130,7 @@ static const struct option_map option_map[] =
    {"--print-multi-directory", "-print-multi-directory", 0},
    {"--print-multi-os-directory", "-print-multi-os-directory", 0},
    {"--print-prog-name", "-print-prog-name=", "aj"},
+   {"--print-sysroot-headers-suffix", "-print-sysroot-headers-suffix", 0},
    {"--profile", "-p", 0},
    {"--profile-blocks", "-a", 0},
    {"--quiet", "-q", 0},
@@ -3193,6 +3199,7 @@ display_help (void)
   -print-multi-lib         Display the mapping between command line options and\n\
                            multiple library search directories\n"), stdout);
   fputs (_("  -print-multi-os-directory Display the relative path to OS libraries\n"), stdout);
+  fputs (_("  -print-sysroot-headers-suffix Display the sysroot suffix used to find headers\n"), stdout);
   fputs (_("  -Wa,<options>            Pass comma-separated <options> on to the assembler\n"), stdout);
   fputs (_("  -Wp,<options>            Pass comma-separated <options> on to the preprocessor\n"), stdout);
   fputs (_("  -Wl,<options>            Pass comma-separated <options> on to the linker\n"), stdout);
@@ -3637,6 +3644,8 @@ warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\n"
 	print_multi_directory = 1;
       else if (! strcmp (argv[i], "-print-multi-os-directory"))
 	print_multi_os_directory = 1;
+      else if (! strcmp (argv[i], "-print-sysroot-headers-suffix"))
+	print_sysroot_headers_suffix = 1;
       else if (! strncmp (argv[i], "-Wa,", 4))
 	{
 	  int prev, j;
@@ -4066,6 +4075,8 @@ warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\n"
 	;
       else if (! strcmp (argv[i], "-print-multi-os-directory"))
 	;
+      else if (! strcmp (argv[i], "-print-sysroot-headers-suffix"))
+	;
       else if (! strncmp (argv[i], "--sysroot=", strlen ("--sysroot=")))
 	{
 	  target_system_root = argv[i] + strlen ("--sysroot=");
@@ -4978,6 +4989,9 @@ do_spec_1 (const char *spec, int inswitch, const char *soft_matched_part)
 			     spec_path, &info);
 
 	      info.append = "include-fixed";
+	      if (*sysroot_hdrs_suffix_spec)
+		info.append = concat (info.append, dir_separator_str,
+				      multilib_dir, NULL);
 	      info.append_len = strlen (info.append);
 	      for_each_path (&include_prefixes, false, info.append_len,
 			     spec_path, &info);
@@ -6394,6 +6408,19 @@ main (int argc, char **argv)
       return (0);
     }
 
+  if (print_sysroot_headers_suffix)
+    {
+      if (*sysroot_hdrs_suffix_spec)
+	{
+	  printf("%s\n", target_sysroot_hdrs_suffix);
+	  return (0);
+	}
+      else
+	/* The error status indicates that only one set of fixed
+	   headers should be built.  */
+	fatal ("not configured with sysroot headers suffix");
+    }
+
   if (print_help_list)
     {
       display_help ();