For various reasons I've been forced to use Emacs git master for development. In this version I'm regularly getting lots of warnings in the form
No docstring slot for tags-lazy-completion-table
No docstring slot for etags--xref-backend
No docstring slot for gnus-intersection
No docstring slot for grep-compute-defaults
...
which often are so many that it slows down my interaction. Is it possible to set the docstring of a an already defined Emacs Lisp function without modifying its existing body definition?
Stefan has addressed your actual problem, but to answer the stated question:
Is it possible to set the docstring of a an already defined Emacs Lisp function without modifying its existing body definition?
Yes, you can, via the function-documentation symbol property.
(put FUNCTIONSYMBOL 'function-documentation VALUE)
In most cases VALUE would be a string.
See:
(elisp)Documentation Basics(elisp)Accessing Documentation