eldoc-last-data is a variable defined in `eldoc.el'.
Its value is
[nil nil nil]

  • This variable is obsolete since 25.1;
    use your own instead

Bookkeeping; elements are as follows:
0 - contains the last symbol read from the buffer.
1 - contains the string last displayed in the echo area for variables,
or argument string for functions.
2 - `function' if function args, `variable' if variable documentation.