Hi bug-gnu-emacs,

Many programming modes don't have a single possible indentation, and instead use a custom indent-line-function to let users cycle through reasonable indentation.
When that function is exactly indent-relative or indent-relative-maybe, indent-according-to-mode ignores it:

> However, if the value of that variable is `indent-relative' or
> `indent-relative-maybe', handle it specially (since those functions
> are used for tabbing); in that case, indent by aligning to the
> previous non-blank line.

It would be great to make the list of ignored functions extensible — this way, modes that use a variant of indent-relative could recover an appropriate behavior for indent-according-to-mode.

Clément.