No one talks about patents on programming-language features. So, there is an example for you. In the 1990s or early 2000s, the designers of a programming language named Curl out of MIT tried to protect their design with patents, but they were a very small minority among PL designers (at least at that time and since that time), and I don't think their PL has any remaining users.

Because of the nature of the patent system, it is impossible to state definitively that none of the currently-popular PLs currently have any patent encumberances, but we can say that none of the project leaders or main contributors to the design of any of the popular PLs have been accused of pursuing patents on their creations. Nor does anyone AFAIK complain or warn about any popular PL's being patent-encumbered.

Although most designers of instruction-set architectures that have seen significant economic use have pursued patents on this or that feature or technique, Itanium is AFAIK the only one where the patent lawyers were involved in the early stages of the design of the architecture.