Defect in XCU patch

[yyy@xxxxxxxxxxxxx (Geoff Clare)]

@ page 688 line 26482 section patch comment [gwc patch ifdef]

Problem:

Defect code :  3. Clarification required

The description of the patch -D option does not indicate which way
round the ifdef selection should be.   Given the file source.c and
a patch to be applied to it, when patch is used as follows:

    patch -D DEFNAME source.c < patchfile

is compiling the modified source.c *with* -D DEFNAME equivalent to
compiling the original version of source.c, or is compiling the
modified source.c *without* -D DEFNAME equivalent to compiling the
original version of source.c?

There are existing implementations of patch which differ in this
respect.

Action:

The options would seem to be ...

a. State that the behaviour is unspecified, and add a note under
APPLICATION USAGE to warn application writers about it.

b. Require that the ifdef selection is one way round or the other.
Which way round would depend on historical behaviour and how many
existing implementations do it each way.