Re: [PATCH v2] doc: make clear --assume-unchanged's user contract

> On Sáb, 2014-12-06 at 15:04 +0000, Philip Oakley wrote:
>> Many users misunderstand the --assume-unchanged contract, believing
>> it means Git won't look at the flagged file.
>>
>> Be explicit that the --assume-unchanged contract is by the user that
>> they will NOT change the file so that Git does not need to look (and
>> expend, for example, lstat(2) cycles)
>>
>> Mentioning "Git stops checking" does not help the reader, as it is
>> only one possible consequence of what that assumption allows Git to
>> do, but
>>
>>    (1) there are things other than "stop checking" that Git can do
>>        based on that assumption; and
>>    (2) Git is not obliged to stop checking; it merely is allowed to.
>>
>> Also, this is a single flag bit, correct the plural to singular, and
>> the verb, accordingly.
>>
>> Drop the stale and incorrect information about "poor-man's ignore",
>> which is not what this flag bit is about at all.
>>
>> Signed-off-by: Philip Oakley <philipoakley@iee.org>
>> ---
>>  Documentation/git-update-index.txt | 18 ++++++++----------
>>  1 file changed, 8 insertions(+), 10 deletions(-)
>>
>> diff --git a/Documentation/git-update-index.txt 
>> b/Documentation/git-update-index.txt
>> index e0a8702..da1ccbc 100644
>> --- a/Documentation/git-update-index.txt
>> +++ b/Documentation/git-update-index.txt
>> @@ -78,20 +78,18 @@ OPTIONS
>>          Set the execute permissions on the updated files.
>>
>>  --[no-]assume-unchanged::
>> - When these flags are specified, the object names recorded
>> - for the paths are not updated.  Instead, these options
>> - set and unset the "assume unchanged" bit for the
>> - paths.  When the "assume unchanged" bit is on, Git stops
>> - checking the working tree files for possible
>> - modifications, so you need to manually unset the bit to
>> - tell Git when you change the working tree file. This is
>> + When this flag is specified, the object names recorded
>> + for the paths are not updated.  Instead, this option
>> + sets/unsets the "assume unchanged" bit for the
>> + paths.  When the "assume unchanged" bit is on, the user
>> + promises not to change the file and allows Git to assume
>> + that the working tree file matches what is recorded in
>> + the index.  If you want to change the working tree file,
>> + you need to unset the bit to tell Git.  This is
>>  sometimes helpful when working with a big project on a
>>  filesystem that has very slow lstat(2) system call
>>  (e.g. cifs).
>>  +
>> -This option can be also used as a coarse file-level mechanism
>> -to ignore uncommitted changes in tracked files (akin to what
>> -`.gitignore` does for untracked files).
>>  Git will fail (gracefully) in case it needs to modify this file
>>  in the index e.g. when merging in a commit;
>>  thus, in case the assumed-untracked file is changed upstream,
>
> I don't understand why you insist that we have a contract,

> when :
> "git diff .", "git diff -a" and "git commit -a" have a different
> behavior of "git commit ." , this is not about any contract this is
> about coherency and be user friendly .
>
> At least if you want keep things like that, wrote in doc, clearly, 
> that
> assume-unchanged flag *is not*, to git ignoring changes in tracked 
> files
> and currently not ignore files for git commit <path> and may not work 
> in
> other cases .
>
> Also don't understand why --assumed-untracked shouldn't deal with
> changed files instead fallback in "the user promises not to change the
> file" and sometimes works others not.
>
> Also if this is the contract when a file is different from commit,
> should warning the user that is not in contract (modify files that are
> assumed-untracked )
>