I have used all-uppercase to make a distinction like class vs. instance in variables (in case-sensitive languages in which the class might be an ordinary held-in-a-variable value, like Javascript), and I might do it again. But it's very unusual, and it's also the kind of practice that is more suitable for a 1KLOC project that will receive 100 hours of effort from a single maintainer over its lifetime than for a bigger project with many maintainers and a highly motivated community of attackers.
I don't think there was ever a case when I was tempted to name two functions with different cases, but if I ever had to write a modest-sized 1-maintainer system in which many functions came in exactly two different flavors, I might be tempted. (Perhaps threadsafe locked vs. raw? or some C++-like distinction between raw functions and closure-like class instances which can be used in a function-call context? or raw functions vs. wrappers with the extra plumbing required to let them be invoked from a scripting language?)
afterthought: And now that I think of it, in old C code I think I vaguely remember working with macro vs. function implementations of the same operation distinguished by capitalizing the name, and I don't think the name convention was an urgent problem. C macros can breed various errors, but I think bitbang_macro vs. bitbang would breed pretty much the same errors as BITBANG vs. bitbang.
I don't think there was ever a case when I was tempted to name two functions with different cases, but if I ever had to write a modest-sized 1-maintainer system in which many functions came in exactly two different flavors, I might be tempted. (Perhaps threadsafe locked vs. raw? or some C++-like distinction between raw functions and closure-like class instances which can be used in a function-call context? or raw functions vs. wrappers with the extra plumbing required to let them be invoked from a scripting language?)
afterthought: And now that I think of it, in old C code I think I vaguely remember working with macro vs. function implementations of the same operation distinguished by capitalizing the name, and I don't think the name convention was an urgent problem. C macros can breed various errors, but I think bitbang_macro vs. bitbang would breed pretty much the same errors as BITBANG vs. bitbang.