Bug: counting messages twice after excluding tags yields different results

[Franz Fellner]

Your problem: the example sucks ;)
If the query searches for a tag you also have in exclude_tags (in your case: spam) the exclude gets ignored.
Change your query to just "is:inbox" and magically "spam" really gets excluded.

However it is better to create fresh query objects for each new query. I remember there are operations on query objects that are destructive. That's why users of the notmuch API usually create seperate queriy objects for counting messages/threads and getting the results.

On Wed, 31 Aug 2016 10:23:59 +0200, Lucas <luc.lists at gmail.com> wrote:
> Dear list members,
> 
> I think I found a bug or at least undocumented behaviour in the notmuch
> library.  I would like to report this here.  Originally I found the bug
> in the python library but I attached a c program that shows the same
> behaviour.  I am running notmuch version 0.22.1 from the Arch Linux
> repositories.
> 
> The setup:
> 1. chose a query string, e.g. "is:inbox or is:spam"
> 2. chose a tag to exclude that is matched by the query, e.g. "spam"
> 3. open the database
> 4. create a query
> 5. check the message or thread count any number of times
> 6. exclude the tag from the query
> 7. check the message or thread count any number of times
> 
> The result:
> - In step 5 the result stays the same if I repeatedly call
>   notmuch_query_count_messages_st or query.count_messages.
> - In step 7 the count is different between the first call and all
>   subsequent calls.  But neither seems correct to me.  I always get the
>   same number as in step 5 for the first call and 0 afterwards.
> 
> Expected result:
> - subsequent calls to notmuch_query_count_messages_st or
>   query.count_messages should yield the same result
> - the exclusion should change the count to the actual amount (for
>   "is:inbox or is:spam" I get 891 and for a plain "is:inbox" I get 58,
>   which never shows up in step 7)
> 
> Attached you can find a python and a c program that exhibit this
> behaviour.  Please compile the c program with
> 
> cc -DDB_PATH=\"/path/to/your/mail\" -lnotmuch test.c
> 
> My question:
> Is this documented somewhere?  Is it actually a bug or is it already
> fixed in a newer version?
> 
> Thank you for developing notmuch!
> 
> Lucas
> 
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