[$] C, Fortran, and single-character strings

The calling interfaces between programming languages are, by their nature,
ripe for misunderstandings; different languages can have subtly different
ideas of how data should be passed around. Such misunderstandings often
have the effect of making things break right away; these are quickly
fixed. Others can persist for years or even decades before jumping out of
the shadows and making things fail. A problem of the latter variety
recently turned up in how some C programs are passing strings to Fortran
subroutines, with unpleasant effects on widely used packages like LAPACK.