Re: [PATCH] Document check option to git diff.

Bill Lear [off-list ref] writes:

I believe that an accurate and concise statement would be:

    Warn if changes introduce trailing whitespace
    or an indent that uses a space before a tab.

I think it should be explicitly limited to "space" and not
"whitespace" before the tab, as "whitespace" really includes tab.

Do I really need to say "trailing whitespace at the end of the line"?
That seems overly verbose: trailing whitespace is, I think, understood
to trail at the end of the line.

All true.  Thanks for rewording.

Also: I suppose I am wondering about the motivation for this switch.
It seems to reflect the aesthetics of the git project.  Whitespace at
the end of a line is meaningless and wasteful, so I understand and
sympathize with the judgment that this is undesirable.  Spaces
preceding tabs are somewhat murkier: two tabs, a space, and text pass
the check, but a tab, space, tab and text do not.  Why is this bad?

The trailing space removal comes from the kernel project
aesthetics:

	http://www.zip.com.au/~akpm/linux/patches/stuff/tpp.txt
	linux-2.6/Documentation/CodingStyle (end of Chapter 1)

"TAB SP TAB blah" visually is the same as "TAB TAB blah".  It is
bad for the same reason as "fofofofo SP TAB EOL" (which is
visually the same as "fofofofo EOL") is bad.  This is not from
the kernel project, so if the above reasoning is flawed, it is
my fault.  I once considered saying 8 spaces are bad and should
be replaced with a tab, but I refrained from going that far ;-).

I'm sure there is a better way to categorize these violations other
than "funny".  Should we not say "wasteful and inelegant, and
therefore anathema to any decent, self-respecting person"?

"Wasteful" is probably better than "funny"; I do not think of a
good wording.

Sometimes we do want to keep the trailing whitespaces (the patch
that came over e-mail to produce commit c7c24889, for example),
so getting warnings from "git-diff --check" (or its counterpart,
"git-apply --whitespace=warn") is not a crime.  But most of the
time, they only waste space and bandwidth and many people who
are conscious about hygiene of their sources seem to avoid them
like the plague.