The Jargon File (version 4.4.7, 29 Dec 2003):

syntactic salt
 n.

    The opposite of syntactic sugar, a feature designed to make it harder to
    write bad code. Specifically, syntactic salt is a hoop the programmer must
    jump through just to prove that he knows what's going on, rather than to
    express a program action. Some programmers consider required type
    declarations to be syntactic salt. A requirement to write end if, end while
    , end do, etc.: to terminate the last block controlled by a control
    construct (as opposed to just end) would definitely be syntactic salt.
    Syntactic salt is like the real thing in that it tends to raise hackers'
    blood pressures in an unhealthy way. Compare candygrammar.


The Free On-line Dictionary of Computing (30 December 2018):

syntactic salt

   The opposite of syntactic sugar, a feature designed to make
   it harder to write bad code.  Specifically, syntactic salt is
   a hoop the programmer must jump through just to prove that he
   knows what's going on, rather than to express a program
   action.  Some programmers consider required type declarations
   to be syntactic salt.  A requirement to write "end if", "end
   while", "end do", etc. to terminate the last block controlled
   by a control construct (as opposed to just "end") would
   definitely be syntactic salt.  Syntactic salt is like the real
   thing in that it tends to raise hackers' blood pressures in an
   unhealthy way.  Compare candygrammar.

   [Jargon File]