c-lineup-arglist-close-under-paren is a compiled Lisp function in `cc-align.el'.

(c-lineup-arglist-close-under-paren LANGELEM)

Line up a line under the enclosing open paren.
Normally used to line up a closing paren in the same column as its
corresponding open paren, but can also be used with arglist-cont and
arglist-cont-nonempty to line up all lines inside a parenthesis under
the open paren.

As a special case, if a brace block construct starts at the same line
as the open parenthesis of the argument list, the indentation is
`c-basic-offset' only. See `c-lineup-arglist' for further discussion
of this "DWIM" measure.

Works with: Almost all symbols, but are typically most useful on
arglist-close, brace-list-close, arglist-cont and arglist-cont-nonempty.