dead code

English

dead code (uncountable)

(software compilation) Instructions that, when executed, have no effect on the running of the program.
- 2006, William Von Hagen, The definitive guide to GCC:
  Much dead code elimination is actually done on intermediate representations of your code, which may contain unnecessary intermediate calculations […]
(programming) A portion of source code that will never be executed as part of the running program.
Synonym: unreachable code

Many software projects contain much dead code in the form of deprecated functions.
- 2003, Diomidis Spinellis, Code Reading: The Open Source Perspective, Addison-Wesley Professional, →ISBN, page 372:
  If the test data is exhaustive you can even locate dead code: program code that is never executed.

Instructions that will never be executed may also be referred to as unreachable.

instructions that have no effect on the running of the program