--- gcc-master.orig/configure.ac	2020-06-05 23:56:43.588725171 +0100
+++ gcc-master/configure.ac	2020-06-12 10:26:00.362948762 +0100
@@ -23,6 +23,7 @@
 m4_include(config/override.m4)
 m4_include(config/proginstall.m4)
 m4_include(config/elf.m4)
+m4_include(config/ax_cxx_compile_stdcxx.m4)
 m4_include([libtool.m4])
 m4_include([ltoptions.m4])
 m4_include([ltsugar.m4])
@@ -162,6 +163,7 @@
 		target-libffi \
 		target-libobjc \
 		target-libada \
+		target-libgm2 \
 		target-libgo \
 		target-libphobos \
 		target-zlib"
@@ -451,6 +453,12 @@
   noconfigdirs="$noconfigdirs gnattools"
 fi
 
+AC_ARG_ENABLE(libgm2,
+[AS_HELP_STRING([--enable-libgm2], [build libgm2 directory])],
+ENABLE_LIBGM2=$enableval,
+ENABLE_LIBGM2=yes)
+
+
 AC_ARG_ENABLE(libssp,
 [AS_HELP_STRING([--enable-libssp], [build libssp directory])],
 ENABLE_LIBSSP=$enableval,
@@ -1352,6 +1360,7 @@
   GFORTRAN_FOR_BUILD=${GFORTRAN_FOR_BUILD-gfortran}
   GOC_FOR_BUILD=${GOC_FOR_BUILD-gccgo}
   GDC_FOR_BUILD=${GDC_FOR_BUILD-gdc}
+  GM2_FOR_BUILD=${GM2_FOR_BUILD-gm2}
   DLLTOOL_FOR_BUILD=${DLLTOOL_FOR_BUILD-dlltool}
   LD_FOR_BUILD=${LD_FOR_BUILD-ld}
   NM_FOR_BUILD=${NM_FOR_BUILD-nm}
@@ -1366,6 +1375,7 @@
   GFORTRAN_FOR_BUILD="\$(GFORTRAN)"
   GOC_FOR_BUILD="\$(GOC)"
   GDC_FOR_BUILD="\$(GDC)"
+  GM2_FOR_BUILD="\$(GM2)"
   DLLTOOL_FOR_BUILD="\$(DLLTOOL)"
   LD_FOR_BUILD="\$(LD)"
   NM_FOR_BUILD="\$(NM)"
@@ -1463,9 +1473,12 @@
 esac
 
 # When bootstrapping with GCC, build stage 1 in C++11 mode to ensure that a
-# C++11 compiler can still start the bootstrap.
+# C++11 compiler can still start the bootstrap.  Otherwise, if building GCC,
+# require C++11 (or higher).
 if test "$enable_bootstrap:$GXX" = "yes:yes"; then
   CXX="$CXX -std=c++11"
+elif test "$have_compiler" = yes; then
+  AX_CXX_COMPILE_STDCXX(11)
 fi
 
 # Used for setting $lt_cv_objdir
@@ -3387,6 +3400,7 @@
 AC_SUBST(GFORTRAN_FOR_BUILD)
 AC_SUBST(GOC_FOR_BUILD)
 AC_SUBST(GDC_FOR_BUILD)
+AC_SUBST(GM2_FOR_BUILD)
 AC_SUBST(LDFLAGS_FOR_BUILD)
 AC_SUBST(LD_FOR_BUILD)
 AC_SUBST(NM_FOR_BUILD)
@@ -3498,6 +3512,7 @@
 NCN_STRICT_CHECK_TARGET_TOOLS(GFORTRAN_FOR_TARGET, gfortran)
 NCN_STRICT_CHECK_TARGET_TOOLS(GOC_FOR_TARGET, gccgo)
 NCN_STRICT_CHECK_TARGET_TOOLS(GDC_FOR_TARGET, gdc)
+NCN_STRICT_CHECK_TARGET_TOOLS(GM2_FOR_TARGET, gm2)
 
 ACX_CHECK_INSTALLED_TARGET_TOOL(AR_FOR_TARGET, ar)
 ACX_CHECK_INSTALLED_TARGET_TOOL(AS_FOR_TARGET, as)
@@ -3534,6 +3549,8 @@
 		[gcc/gccgo -B$$r/$(HOST_SUBDIR)/gcc/], go)
 GCC_TARGET_TOOL(gdc, GDC_FOR_TARGET, GDC,
 		[gcc/gdc -B$$r/$(HOST_SUBDIR)/gcc/], d)
+GCC_TARGET_TOOL(gm2, GM2_FOR_TARGET, GM2,
+		[gcc/xgm2 -B$$r/$(HOST_SUBDIR)/gcc/], m2)
 GCC_TARGET_TOOL(ld, LD_FOR_TARGET, LD, [ld/ld-new])
 GCC_TARGET_TOOL(lipo, LIPO_FOR_TARGET, LIPO)
 GCC_TARGET_TOOL(nm, NM_FOR_TARGET, NM, [binutils/nm-new])
@@ -3660,6 +3677,7 @@
 # Specify what files to not compare during bootstrap.
 
 compare_exclusions="gcc/cc*-checksum\$(objext) | gcc/ada/*tools/*"
+compare_exclusions="$compare_exclusions | gcc/m2/gm2version\$(objext) | gcc/m2/*/M2Version\$(objext)"
 case "$target" in
   hppa*64*-*-hpux*) ;;
   hppa*-*-hpux*) compare_exclusions="$compare_exclusions | */libgcc/lib2funcs* | gcc/function-tests.o" ;;
