cl-defsubstcl-defsubst is an autoloaded Lisp macro in `
cl-macs.el'. (cl-defsubst NAME ARGLIST [DOCSTRING] BODY...) Define NAME as a function. Like `defun', except the function is automatically declared `inline' and the arguments are immutable. ARGLIST allows full Common Lisp conventions, and BODY is implicitly surrounded by (cl-block NAME ...). The function's arguments should be treated as immutable.