byte-compile-file-form-defmumble is a compiled Lisp function in `bytecomp.el'.

(byte-compile-file-form-defmumble NAME MACRO ARGLIST BODY REST)

Process a `defalias' for NAME.
If MACRO is non-nil, the definition is known to be a macro.
ARGLIST is the list of arguments, if it was recognized or t otherwise.
BODY of the definition, or t if not recognized.
Return non-nil if everything went as planned, or nil to imply that it decided
not to take responsibility for the actual compilation of the code.