[…] The control-flow problem asks, “Which procedures may the expression $f$ be in the call $left-parenthesis f x right-parenthesis$?”.

In programming languages, and static analysis in particular, the higher-order control-flow problem refers to the fact that the precise target of a function call may not be obvious.

The problem afflicts functional languages in the form of first-class functions, and it afflicts object-oriented languages in the form of dynamically dispatched methods.

[0] http://matt.might.net/articles/implementation-of-kcfa-and-0cfa/