having defined "C-c (" onto some useful function here,
when in Shell-script mode `sh-function` took it.
Seems bad, as "C-c" should be a reserved key for users.
See (elisp)Coding Conventions.
The last section quoted here covers `C-c ('.
Don't define `C-c LETTER' as a key in Lisp programs. Sequences
consisting of `C-c' and a letter (either upper or lower case) are
reserved for users; they are the *only* sequences reserved for
users, so do not block them.
Changing all the Emacs major modes to respect this convention was a
lot of work; abandoning this convention would make that work go to
waste, and inconvenience users. Please comply with it.
...
* Sequences consisting of `C-c' followed by a control character or a
digit are reserved for major modes.
* Sequences consisting of `C-c' followed by `{', `}', `<', `>', `:'
or `;' are also reserved for major modes.
* Sequences consisting of `C-c' followed by any other punctuation
character are allocated for minor modes. Using them in a major
mode is not absolutely prohibited, but if you do that, the major
mode binding may be shadowed from time to time by minor modes.