We should use the compiler release version number to safely and reliably detect the version of a OSS compiler. The compiler team has agreed to increase this number in every release including in express releases enabling us to safely distinguish all releases. Moreover the release number will always increase so if we see a larger number than we already have identified, we know it is a future release (as opposite to an older release) giving us an opportunity to safely handle future releases. Because older release didn't follow this pattern we cannot use this number to detect previous release.

The algorithm we should use for Spica express (currently in sstrunk) is

0x5120                          => OSSXSpica
<number> > 0x5120 => future release. Name it OracleSolarisStudio and assume same
                                              capabilities as 0x5120

Past express release, the algorithm should look like this:

0x5120                          => OSSXSpica
0x5130                          => OracleSolarisStudio12.3 (guessing the name here)
<number> > 0x5130 => future release. Name it OracleSolarisStudio and assume same
                                              capabilities as 0x5130

and so on. 

Note: Fortran uses different numbers.

How to get this version from the compilers:

Use these macros:
 cc  __SUNPRO_C=0x5110
 CC  __SUNPRO_CC=0x5110
 f77 __SUNPRO_F95=0x850
 f90 __SUNPRO_F95=0x850
 f95 __SUNPRO_F95=0x850 

Which can be obtained from:
cc: -xdryrun xxx.c
CC: -xdryrun xxx.cc, or -xdumpmacros -E xxx.cc
f77, f90, f95: -dryrun xxx.F <=== capital F is important!