"Sun took the C compiler out of Solaris 2.x. Am I stuck?"
No; prep.ai.mit.edu and its mirror sites provide GCC binaries for Solaris. As a rule, these binaries are not updated as often as the sources are, so if you want the very latest version of gcc/g++, you may need to grab and install binaries for an older version and use it to bootstrap the latest version from source.
The latest gcc binaries on prep.ai.mit.edu and its mirror sites are for version 2.5.6 for Solaris on the Sparc, and version 2.4.5 for Solaris on Intel 386/486 machines (the Solaris/Intel binaries seem to be gone from prep but still exist on some mirrors).
There are also binaries for "gzip", the GNU compression utility, which you'll need for uncompressing the binary distribution. On any GNU archive site, look in subdirectories `i486-sun-solaris2' or `sparc-sun-solaris2'.
The ftp directory `ftp://ftp.quintus.com/pub/GNU' contains various GNU and freeware programs for Solaris2.X running on the sparc. These are packaged to enable installation using the Solaris "pkgadd" utility. These include GNU emacs 19.27, gcc (and g++) 2.6.0, Perl 4.036, and others.