boostrapping on centos 7 with only gcc, no g++?

[jepio]

Is it possible to boostrap properly without having a c++ compiler on the host system? In my case I have a working C toolset, I boostrap bmake, proceed to install pkgsrc's gcc (tried 49 and 5) which pulls in libtool. Libtools fails because it requires a c++ toolchain.

Would this work if I start with an older version of gcc?

[jepio]

To give an update on this issue: I was able to get a full (C/C++) GCC 4.7 running using only a host C compiler. GCC explicitly states that this is the last version that can be built C only, so I should've checked there before writing here. But getting this to work with pkgsrc is not easy either. Here's how it can be done:
ncurses, libtool and gmp need to be built without cxx bindings/support. The patches for ncurses and gmp follow (they won't apply due to tab vs. spaces but they may give you an idea).
ncurses:

diff --git a/devel/ncurses/Makefile.common b/devel/ncurses/Makefile.common
index 1f47109..2151703 100644
--- a/devel/ncurses/Makefile.common
+++ b/devel/ncurses/Makefile.common
@@ -21,7 +21,9 @@ GNU_CONFIGURE=        yes
 CONFIGURE_ARGS+=   --with-libtool
 CONFIGURE_ARGS+=   --enable-bsdpad
 CONFIGURE_ARGS+=   --enable-overwrite
-CONFIGURE_ARGS+=   --with-cxx-binding
+#CONFIGURE_ARGS+=  --with-cxx-binding
+CONFIGURE_ARGS+=   --without-cxx-binding
+CONFIGURE_ARGS+=   --without-cxx
 CONFIGURE_ARGS+=   --without-ada
 CONFIGURE_ARGS+=   --without-gpm
 CONFIGURE_ARGS+=   --with-manpage-format=normal
diff --git a/devel/ncurses/PLIST b/devel/ncurses/PLIST
index 8c9f9f3..ea754fc 100644
--- a/devel/ncurses/PLIST
+++ b/devel/ncurses/PLIST
@@ -11,14 +11,7 @@ bin/toe
 bin/tput
 bin/tset
 include/ncurses/curses.h
-include/ncurses/cursesapp.h
-include/ncurses/cursesf.h
-include/ncurses/cursesm.h
-include/ncurses/cursesp.h
-include/ncurses/cursesw.h
-include/ncurses/cursslk.h
 include/ncurses/eti.h
-include/ncurses/etip.h
 include/ncurses/form.h
 include/ncurses/menu.h
 include/ncurses/nc_tparm.h
@@ -32,7 +25,6 @@ include/ncurses/tic.h
 include/ncurses/unctrl.h
 lib/libform.la
 lib/libmenu.la
-lib/libncurses++.la
 lib/libncurses.la
 lib/libpanel.la
 man/man1/captoinfo.1

I'm not sure exactly how PLIST's work, but i basically applied the second patch above to any .PLIST file in the work directory until pkgsrc allowed me to install.

gmp:

diff --git a/devel/gmp/Makefile b/devel/gmp/Makefile
index c346801..513ad67 100644
--- a/devel/gmp/Makefile
+++ b/devel/gmp/Makefile
@@ -74,6 +74,7 @@ CONFIGURE_ARGS+=  --enable-fat
 .  endif
 .endif

+CONFIGURE_ARGS+=   --disable-cxx
 pre-configure:
    cd ${WRKSRC} && type autoconf && autoconf

libtool
I didn't have time to figure out how to add patches to be applied during the build, but for libtool it's necessary to remove the C++ preprocessor fails sanity check lines from the configure script(s) after the sources are unpacked. They don't seem to affect the build and the package compiles fine without them.

For gcc I applied the following patch to the Makefile

diff --git a/lang/gcc47/Makefile b/lang/gcc47/Makefile
index e333b91..6508a96 100644
--- a/lang/gcc47/Makefile
+++ b/lang/gcc47/Makefile
@@ -121,6 +121,8 @@ CONFIGURE_ARGS+=    --with-gnu-as --with-as=${PREFIX}/bin/gas
 .  endif
 .endif

+CONFIGURE_ARGS+=   --disable-multilib --disable-bootstrap
+
 pre-configure:
    ${RUN} cd ${WRKSRC} && ${MKDIR} ${OBJDIR}

It would be good to incorporate the first two solutions (ncurses and gmp) into pkgsrc using the options framework, as that is what they are. For the libtool it's a simple patch to 2 configure scripts applied conditionally (also as an option), should be doable in the Makefile.