For commercial unixes, it's hard to find documentation on C versions supported by Oracle Solaris Studio, but it was last released in 2011. HPUX ACC was last released in 2010, so I would be very surprised if it supported the 2011 C standard already. That doesn't meant it won't, but it does mean that it moves slowly. Not surprising, since large unix vendors operate in a market where stability is valued above most other things. IBM XLC already supports C11.
While it's true the last release was in Dec. 2011, Solaris Studio receives updates and fixes (just as Visual Studio, etc.) do between releases that may contain significant improvements.
C11 and C++11 support are not yet available in any form, although the Solaris Studio compiler is one of the few that actually has full C99 compliance (yes, even those annoying floating point pragamas).
As for standards conformance, I "googled" it:
C11 and C++11 support are not yet available in any form, although the Solaris Studio compiler is one of the few that actually has full C99 compliance (yes, even those annoying floating point pragamas).Support for C++11 is planned though: