c-indent-line is a compiled Lisp function in `cc-cmds.el'.

(c-indent-line &optional SYNTAX QUIET IGNORE-POINT-POS)

Indent the current line according to the syntactic context,
if `c-syntactic-indentation' is non-nil. Optional SYNTAX is the
syntactic information for the current line. Be silent about syntactic
errors if the optional argument QUIET is non-nil, even if
`c-report-syntactic-errors' is non-nil. Normally the position of
point is used to decide where the old indentation is on a lines that
is otherwise empty (ignoring any line continuation backslash), but
that's not done if IGNORE-POINT-POS is non-nil. Returns the amount of
indentation change (in columns).