Several C compilers implement two non-standard C/C++ extensions relating to gotos originally introduced by gcc.[46][47] The GNU extension allows the address of a label inside the current function to be obtained as a void* using the unary, prefix label value operator &&. The goto instruction is also extended to allow jumping to an arbitrary void* expression. This C extension is referred to as a computed goto in documentation of the C compilers that support it; its semantics are a superset of Fortran's assigned goto, because it allows arbitrary pointer expressions as the goto target, while Fortran's assigned goto doesn't allow arbitrary expressions as jump target.[48] As with the standard goto in C, the GNU C extension allows the target of the computed goto to reside only in the current function. Attempting to jump outside the current function results in unspecified behavior.[48]
Computed GOTO served the same purpose as the C programing language's switch...case statement, which is more readable and easier to reason about, so the lack of computed GOTO isn't really a deficiency. You could even implement a FORTRAN/BASIC style multiway branch statement using C preprocessor macros, though it's not really useful in the modern era, since most use cases for that kind of construct are better served by using switch...case or if...else if...else. Multiway GOTO was valuable in the punched card era, when it was beneficial to fit complex control flow statements into just 72 characters, but these days its better to write less compact code, if doing so lets you get away with writing less external documentation.