bug#68570: 29.1; recompile might not re-use project-compile's buffer

[Pengji Zhang]

Hi!

I think you meant running `M-x recompile' not in a compilation buffer?
While I agree that is convenient, I suppose it is better to only use
`recompile' in a compilation buffer due to security reasons.

`compile-command' is marked as a safe local variable assuming that the
user would be prompted to check and confirm the command before running
it. That is the behavior of `compile' but not `recompile'. For
example, create a file '/tmp/test.c' with the following contents:

    /* Local Variables: */
    /* compile-command: "echo 1" */
    /* End: */

Then:
  - emacs -Q --eval "(require 'compile)"
  - C-x C-f /tmp/test.c
  - M-x recompile

So we could run arbitrary commands without any warning or confirmation.

Instead of a `project-recompile' command, it might be better to make
`recompile' find the existing compilation buffer for the current
buffer, and refuse to run the command (or ask for confirmation) if
there is no such buffer.