Improve recursion protection for VxWorks limits.h

2019-12-30  Olivier Hainque  <hainque@adacore.com>
            Jerome Lambourg  <labourg@adacore.com>

   	* config/t-vxworks: Arrange to alter/restore glimits.h
   	before/after stmp-int-hdrs, so it uses a different macro
   	name to protect itself against recursive inclusions.

Co-Authored-By: Jerome Lambourg <lambourg@adacore.com>

From-SVN: r279777

gcc/ChangeLog

+2019-12-30  Olivier Hainque  <hainque@adacore.com>
+            Jerome Lambourg  <labourg@adacore.com>
+
+	* config/t-vxworks: Arrange to alter/restore glimits.h
+	before/after stmp-int-hdrs, so it uses a different macro
+	name to protect itself against recursive inclusions.
+
 2019-12-30  Peter Bergner <bergner@linux.ibm.com>
 
 	PR target/92923

gcc/config/t-vxworks

@@ -16,9 +16,40 @@
 # along with GCC; see the file COPYING3.  If not see
 # <http://www.gnu.org/licenses/>.
 
-# Both the kernel and RTP headers provide limits.h.
-LIMITS_H_TEST = true
-
 vxworks.o: $(srcdir)/config/vxworks.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
 	$(TARGET_H) output.h $(TM_H)
 	$(COMPILER) -c $(ALL_COMPILERFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) $<
+
+# Both the kernel and RTP headers provide limits.h.  They embed VxWorks
+# specificities and are dated on some configurations so we both need to
+# provide our own version and make sure the system one gets exposed.
+
+LIMITS_H_TEST = true
+STMP_FIXINC = stmp-fixinc
+
+# VxWorks system environments have been GCC based for a long time and we need
+# to make sure that our files and the system ones use distinct macro names to
+# protect against recursive inclusions.  We achieve this by temporarily
+# substituting the headers used by stmp-int-headers with alternative versions
+# where we add some version indication in the inclusion-protection macro
+# names.
+
+# Before the standard stmp-int-headers operations take place, arrange to
+# copy the current version of the relevant header files locally, generate
+# the alternate version and replace the original version with ours:
+
+stmp-int-hdrs: subst-glimits.h
+
+subst-%.h:
+	cp -p $(srcdir)/$*.h orig-$*.h
+	ID=$$(echo $(BASEVER_c) | sed -e 's/\./_/g'); \
+	sed -e "s/_LIMITS_H__/_LIMITS_H_$${ID}_/" < $(srcdir)/$*.h > $@
+	cp $@ $(srcdir)/$*.h
+
+# Then arrange to restore the original versions after the standard
+# operations have taken place:
+
+INSTALL_HEADERS += restore-glimits.h
+
+restore-glimits.h: stmp-int-hdrs
+	cp -p orig-glimits.h $(srcdir)/glimits.h