Phillip Wood [off-list ref] writes:

The subject would make more sense as 'xdiff: rename XDL_MERGE_DIFF3 to
XDL_MERGE_STYLE_DIFF3' rather than using the new name of the constant
alone.

True.

quoted

If we don't specify we are talking about a style, XDL_MERGE_MINIMAL
could be confused with a valid value instead of XDL_MERGE_DIFF3, which
it isn't.

I don't object to the rename but what is the source of the confusion
with XDL_MERGE_MINIMAL?

I do not see any confusion, either, but the current XDL_MERGE_DIFF3
being a boolean (i.e. if false, use the output style of the 'merge'
command) and our lack of an enumeration constant for 'merge' means
that a future addition of the third output style would require us to
add XDL_MERGE_$STYLE for both the new style and the traditional
'merge' style.  And If we would end up with XDL_MERGE_DIFF3,
XDL_MERGE_MERGE and XDL_MERGE_FOO for that third output style.

The 'merge' one simply looks strange in that context.  And from that
point of view, this change might be a good way to futureproof the
codebase.

Thanks.