Problems on OpenIndiana 151a with the g++ from the SFE repository

I'm trying to compile a simple C++ file on my OpenIndiana 151a with
the g++ from the SFE repository.

root@solewer:/usr/gcc/4.6# g++ --version
g++ (GCC) 4.6.2
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

But this results in a lot of errors during the assembly stage:

root@solewer:~# g++ a.cpp
Assembler: a.cpp
    "/var/tmp//cclAa4ot.s", line 80 : Syntax error
    Near line: "    .uleb128 .LLSDACSE549-.LLSDACSB549"
    "/var/tmp//cclAa4ot.s", line 82 : Syntax error
    Near line: "    .uleb128 .LEHB0-.LFB549"
    "/var/tmp//cclAa4ot.s", line 83 : Syntax error
    Near line: "    .uleb128 .LEHE0-.LEHB0"

With the g++ from /usr/sfw/bin ( pkg://openindiana.org/developer/gcc-3
)  the compilation succeeded.

I've now started with execsnoop to see whats happening:

g++ from the SFE repository uses the default assembler:

 UID    PID   PPID ARGS
    0   7755   7662 g++ a.cpp
    0   7756   7755
/usr/gcc/4.6/lib/gcc/i386-pc-

solaris2.11/4.6.2/cc1plus -quiet a.cpp
-quiet -dum
    0   7758   7662 /usr/bin/hostname
    0   7757   7755 /usr/ccs/bin/as -s -o /var/tmp//ccYHayjp.o
/var/tmp//ccXHayjp.s

but using /usr/sfw/bin/g++ from (
pkg://openindiana.org/developer/gcc-3 ) the gcc  has its own assembler

    0   7762   7662 /usr/sfw/bin/g++ a.cpp
    0   7763   7762
/usr/sfw/libexec/gcc/i386-pc-solaris2.11/3.4.3/cc1plus -quiet a.cpp
-quiet -dum
    0   7764   7762 /usr/sfw/libexec/gcc/i386-pc-solaris2.11/3.4.3/as
--traditional-format -Qy -s -
    0   7765   7762
/usr/sfw/libexec/gcc/i386-pc-solaris2.11/3.4.3/collect2 -Y
P,/usr/ccs/lib:/lib:

Compiling a C file with  gcc works for both 4.6.2 and 3.4.3

The usage of the assembler under ccs is the problem. I searched for
other assemblers on my system and found:

root@solewer:/usr# find . -name as -print
./gnu/i386-pc-solaris2.11/bin/

as
./bin/as
./sfw/libexec/gcc/i386-pc-solaris2.11/3.4.3/as
./ccs/bin/as
./share/locale/as

But the searchpath of gcc does not search in /usr/gnu:

[ewer@solewer:~/tmp]$g++ -print-search-dirs
...
programs: =/usr/gcc/4.6/lib/gcc/i386-pc-solaris2.11/4.6.2/:/usr/gcc/4.6/lib/gcc/i386-pc-solaris2.11/4.6.2/:/usr/gcc/4.6/lib/gcc/i386-pc-solaris2.11/:/usr/gcc/4.6/lib/gcc/i386-pc-solaris2.11/4.6.2/:/usr/gcc/4.6/lib/gcc/i386-pc-solaris2.11/:/usr/gcc/4.6/lib/gcc/i386-pc-solaris2.11/4.6.2/../../../../i386-pc-solaris2.11/bin/i386-pc-solaris2.11/4.6.2/:/usr/gcc/4.6/lib/gcc/i386-pc-solaris2.11/4.6.2/../../../../i386-pc-solaris2.11/bin/:/usr/ccs/bin/i386-pc-solaris2.11/4.6.2/:/usr/ccs/bin/
...

Programs are only search in the /usr/gcc/4.6 folders. So I made a soft
link from

/usr/gcc/4.6/i386-pc-solaris2.11 -> /usr/gnu/i386-pc-solaris2.11/

After this link the compilation and linking works again without
problems and the
created executeables can run.

But I don't know why or if this has changed. Because I had already compiled

with this compiler from the SFE repository.