proc fcmp - file log put % bug

Having worked a lot with proc fcmp lately, I think it’s fair to say that the procedure should be ‘handled with care’.

Here’s an example of one of these weird / wonderful bugs (LIN X64, 9.04.01M3P062415):

proc fcmp outlib=work.funcs.pkg;
  function test(cval $);
    file log; put cval=;
    put 'also.. you can % see % this';
options cmplib=work.funcs;
data null;
  x="example %";

When you look at the log, the percent symbols are missing:

also.. you can see this

So this is strange, but it gets stranger.  If you don’t have a clean session, you will also see parts of previous messages in the log.  For instance, if you now run the exact same above code again, you get:

cval=example % see % this
also.. you can see this

So the % symbols return, in a different place!   Now, whilst this is a strange bug, it only seems to affect messages sent to the log.  So not an issue right?

Wrong..  It seems that this can cause a fatal error:

ERROR: An exception has been encountered.
Please contact technical support and provide them with the following traceback information:
The SAS task name is [TKSRV ]
Segmentation Violation
Traceback of the Exception:
/pub/sas/SASFoundation/9.4/sasexe/sas(+0x15aa8e) [0x7f7163e73a8e]
/pub/sas/SASFoundation/9.4/sasexe/sas(+0x4cb0b) [0x7f7163d65b0b]
/pub/sas/SASFoundation/9.4/sasexe/ [0x7f71626873c4]
/lib64/ [0x7f71638ea370]
/pub/sas/SASFoundation/9.4/dbcs/sasexe/sasxkern(+0x7462e) [0x7f7151f4f62e]
/pub/sas/SASFoundation/9.4/dbcs/sasexe/sasxkern(ypslf+0xa2b) [0x7f7151f4eabb]
/pub/sas/SASFoundation/9.4/dbcs/sasexe/sasxkern(ypsllog+0x13c) [0x7f7151f51b9c]
/pub/sas/SASFoundation/9.4/sasexe/sastksrv(adjustline+0x59e) [0x7f714a60c1ce]
/pub/sas/SASFoundation/9.4/sasexe/sastksrv(sastksrv+0xec1) [0x7f714a60b531]
/pub/sas/SASFoundation/9.4/sasexe/sas(vvtentr+0x13d) [0x7f7163d656ad]
/lib64/ [0x7f71638e2dc5]
/lib64/ [0x7f7162ed476d]

Conclusion?  Don’t send code to production that has proc fcmp writing character values to the log that may contain a % symbol!