- If the same name appears multiple times with different types, an error is
- signalled quoting the name, conflicting types, and (if non-nil) the origins
- of the offending argument objects.
+ If the same name appears multiple times with different types, a continuable
+ error will be signalled, and one of the conflicting argument types will be
+ chosen arbitrarily. The @<what-function> will be called to establish
+ information which will be reported to the user. It will be called with no
+ arguments and is expected to return two values:
+ \begin{itemize}
+ \item a file location @<floc> or other object acceptable to
+ \descref{gf}{file-location}, to be used as the location of the main
+ error; and
+ \item an object @<what>, whose printed representation should be a noun
+ phrase describing the object for which the argument lists are being
+ combined.
+ \end{itemize}
+ The phrasing of the error message is `type mismatch in @<what>'. Either,
+ or both, of @<floc> and @<what> may be nil, though this is considered poor
+ practice; if @<what-function> is nil, this is equivalent to a function
+ which returns two nil values. Following the error, the @<report-function>s
+ for the @<args> lists containing the conflicting argument objects are
+ called, in an arbitrary order, with a single argument which is the
+ offending @|argument| object; the function is expected to issue information
+ messages (see \descref{fun}{info}) to give more detail for diagnosing the
+ conflict. If a @<report-function> is nil, then nothing happens; this is
+ considered poor practice.