I tried to build the CVS version of Mesa with function name mangling
(added -DUSE_MGL_NAMESPACE to the defines in sunos5-gcc) on Solaris 9
with the gcc 3.4.2 of sunfreeware and it breaks with errors.

GCC version:
egger@blade02 configs$ gcc -v
Reading specs from /usr/local/lib/gcc/sparc-sun-solaris2.9/3.4.2/specs
Configured with: ../configure --with-as=/usr/ccs/bin/as
--with-ld=/usr/ccs/bin/ld --disable-nls --disable-libgcj --enable-languages=c,c+
: (reconfigured) ../configure --with-as=/usr/ccs/bin/as
--with-ld=/usr/ccs/bin/ld --disable-nls --disable-libgcj --enable-languages=c,c++
Thread model: posix
gcc version 3.4.2

The link errors:
make[2]: Leaving directory `/export/home/egger/src/mesa/cvs/Mesa/src'
make[2]: Entering directory `/export/home/egger/src/mesa/cvs/Mesa/progs'
Making programs for sunos5-gcc
make[3]: Entering directory `/export/home/egger/src/mesa/cvs/Mesa/progs/demos'
cp ../../progs/util/readtex.c .
cp ../../progs/util/readtex.h .
gcc -c -I../../include -Wall -O3 -g -fomit-frame-pointer -pipe -fPIC 
-D_REENTRANT -DUSE_XSHM -DUSE_MGL_NAMESPACE -  DUSE_SPARC_ASM -std=c99
-ffast-math -I/usr/openwin/include readtex.c
gcc -I../../include -Wall -O3 -g -fomit-frame-pointer -pipe -fPIC  -D_REENTRANT
-DUSE_XSHM -DUSE_MGL_NAMESPACE -DUS  E_SPARC_ASM -std=c99 -ffast-math
-I/usr/openwin/include arbfplight.c readtex.o -L../../lib -lX11 -lglut -lGLU
-lGL   -lm -o arbfplight
Undefined                       first referenced
 symbol                             in file
mglGetMinmax                        ../../lib/libGL.so
mglNormal3fv                        ../../lib/libglut.so
mglNormal3dv                        ../../lib/libGL.so
mglNormal3bv                        ../../lib/libGL.so
mglNormal3iv                        ../../lib/libGL.so
mglNormal3sv                        ../../lib/libGL.so
mglSecondaryColor3s                 ../../lib/libGL.so
mglSecondaryColor3b                 ../../lib/libGL.so
mglSecondaryColor3d                 ../../lib/libGL.so
mglSecondaryColor3f                 ../../lib/libGL.so
mglSecondaryColor3i                 ../../lib/libGL.so
mglGetFloatv                        ../../lib/libGLU.so
...
ld: fatal: Symbol referencing errors. No output written to arbfplight
collect2: ld returned 1 exit status
make[3]: *** [arbfplight] Error 1
make[3]: Leaving directory `/export/home/egger/src/mesa/cvs/Mesa/progs/demos'
make[2]: *** [subdirs] Error 1
make[2]: Leaving directory `/export/home/egger/src/mesa/cvs/Mesa/progs'
make[1]: *** [default] Error 1
make[1]: Leaving directory `/export/home/egger/src/mesa/cvs/Mesa'
make: *** [sunos5-gcc] Error 2