[PATCH] make diff against copy-source by default

Hi all,

This patch is a follow up to the patch that I gave last month
(November).
Here is the link to the mail archive...
http://mail-archives.apache.org/mod_mbox/subversion-dev/201011.mbox/%
3C1291110994.4021.66.camel_at_prabhugnanasundar%3E

After a few discussions about the inconsistent behaviour of 'svn diff'
in different scenarios, Kamesh suggested that let 'svn diff' be done
against the copy-source by default, making use of the copyfrom info.

Now this patch would do 'diff' against the copy-source by default,
whereas the prevailing default behaviour(of showing a *modified copy* as
all adds) can be achieved by using the '--show-copies-as-adds'
switch(that already exists in the code-base!).

I was quickly in to it and after spending some time in the process I
came to know that several existing 'test cases' *failed* due to the
change in the behaviour of the 'svn diff'. Later found that the 'wc
editor' needs to be taught to handle this behaviour (handling the
copyfrom info and retrieving it from the repository as against working
copy text-base).

This took quite some amount of time...

See [1] below of the mailer.py usecase which tries to get the same
output as my patch do.

May be that's the behaviour of the 'diff' that is prefered ? :)

I have attached the patch and the log message with this mail. Please
review and respond.

[1]
I found the following usecase which is already doing the same as what my
patch intends to do.

The mailer.py script has the same behaviour of 'diff'ing just as this
patch does.
http://mail-archives.apache.org/mod_mbox/subversion-commits/201012.mbox/%3C20101228204459.1E42D238890A@eris.apache.org%3E

<snip from the above commit email>
Copied:
subversion/branches/1.6.x-svn_fs_commit_txn/subversion/include/private/svn_repos_private.h
(from r1051763,
subversion/trunk/subversion/include/private/svn_repos_private.h)
URL:
http://svn.apache.org/viewvc/subversion/branches/1.6.x-svn_fs_commit_txn/subversion/include/private/svn_repos_private.h?p2=subversion/branches/1.6.x-svn_fs_commit_txn/subversion/include/private/svn_repos_private.h&p1=subversion/trunk/subversion/include/private/svn_repos_private.h&r1=1051763&r2=1053428&rev=1053428&view=diff
==============================================================================
--- subversion/trunk/subversion/include/private/svn_repos_private.h
(original)
+++
subversion/branches/1.6.x-svn_fs_commit_txn/subversion/include/private/svn_repos_private.h
Tue Dec 28 20:44:58 2010
@@ -38,53 +38,6 @@ extern "C" {

/**
- * Permanently delete @a path at revision @a revision in @a fs.
- *
- * Do not change the content of any other node in the repository, even
other
- * nodes that were copied from this one. The only other change in the
- * repository is to "copied from" pointers that were pointing to the
- * now-deleted node. These are removed or made to point to a previous
- * version of the now-deleted node.
- * (### TODO: details.)
- *
- * @a path is relative to the repository root and must start with "/".
- *
- * If administratively forbidden, return @c SVN_ERR_RA_NOT_AUTHORIZED.
If not
- * implemented by the RA layer or by the server, return
- * @c SVN_ERR_RA_NOT_IMPLEMENTED.
- *
- * @note This functionality is not implemented in pre-1.7 servers and
may not
- * be implemented in all 1.7 and later servers.
- *
- * @note TODO: Maybe create svn_repos_fs_begin_obliteration_txn() and
- * svn_repos_fs_commit_obliteration_txn() to enable an obliteration txn
to be
- * constructed at a higher level.
- *
- * @since New in 1.7.
- */
-svn_error_t *
-svn_repos__obliterate_path_rev(svn_repos_t *repos,
- const char *username,
- svn_revnum_t revision,
- const char *path,
- apr_pool_t *pool);
-
-
-/** Validate that property @a name is valid for use in a Subversion
- * repository; return @c SVN_ERR_REPOS_BAD_ARGS if it isn't. For some
- * "svn:" properties, also validate the @a value, and return
- * @c SVN_ERR_BAD_PROPERTY_VALUE if it is not valid.
- *
- * Use @a pool for temporary allocations.
- *
- * @since New in 1.7.
- */
-svn_error_t *
-svn_repos__validate_prop(const char *name,
- const svn_string_t *value,
- apr_pool_t *pool);
-
-/**
* Given the error @a err from svn_repos_fs_commit_txn(), return an
* string containing either or both of the svn_fs_commit_txn() error
* and the SVN_ERR_REPOS_POST_COMMIT_HOOK_FAILED wrapped error from
</snip>

Thanks and regards
Prabhu