The STLport bundled with the SunStudio11 generates alot of warnings. I beleive most compilers have a way to disable warnings from certain source files, like this:
Sun C<
If you'd rather use a command line option than #pragmas, a simple answer is that you can use -erroff=%all on your compile line.
You can suppress specific warning messages with -erroff=%tag
You can print out the tags for the warning messages by adding -errtags to your compile line. You can then define a set of comma-separated values for -erroff that suppress just those tags.
See http://docs.oracle.com/cd/E19205-01/820-7599/bkapa/index.html for more info.
Note that Sun Studio 12 update 1 is now available, and I'm referencing the SS12u1 doc here.