Log Message:
Xapian-core 1.4.10 (2019-02-12):

API:

* DatabaseClosedError: New exception class thrown instead of DatabaseError when
  an operation is attempted which can't be completed because it involves a
  database which close() was previously called on.  DatabaseClosedError is a
  subclass of DatabaseError so existing code catching DatabaseError will still
  work as before.  Fixes #772, reported by Germán M. Bravo.  Patch from
  Vaibhav Kansagara.

* DatabaseNotFoundError: New exception class thrown instead of
  DatabaseOpeningError when the problem is the problem is "file not \ 
found" or
  similar.  DatabaseNotFoundError is a subclass of DatabaseOpeningError so
  existing code catching DatabaseOpeningError will still work as before.  Fixes
  #773, reported by Germán M. Bravo.  Patch from Vaibhav Kansagara.

* Query: Make &=, |= and ^= on Query objects opportunistically append to
  an existing query with a matching query operator which has a reference
  count of 1.  This provides an easy way to incrementally build flatter query
  trees.

* Query: Support `query &= ~query2` better - this now is handled exactly
  equivalent to `query = query & ~query2` and gives `query AND_NOT query2`
  instead of `query AND (<alldocuments> AND_NOT query2)`.

* QueryParser: Now uses &=, |= and ^= to produce flatter query trees.  This
  fixes problems with running out of stack space when handling Query object
  trees built by abusing QueryParser to parse very large machine-generated
  queries.

* Stopper: Fix incorrect accents in Hungarian stopword list.  Patch from David
  Corbett.

testsuite:

* Test MSet::snippet() with small and zero lengths.  Fixes #759.  Patch from
  Vaibhav Kansagara.

* Fix testcase stubdb4 annotations - this testcase doesn't need a backend.

* Add PATH annotation for testcases needing get_database_path() to avoid having
  to repeatedly list the backends where this is supported in testcase
  annotations.

* TEST_EXCEPTION helper macro now checks that the exact specified exception
  type is thrown.  Previously it would allow a subclass of the specified
  exception type, but in testcases we really want to be able to test for an
  exact type.  Issue noted by Vaibhav Kansagara on IRC.

matcher:

* Map OP_VALUE_GE/OP_VALUE_LE on an empty slot to EmptyPostList.  We already do
  this for OP_VALUE_RANGE, and it's a little more efficient than creating a
  postlist object which checks the empty value slot.

glass backend:

* We no longer flush all pending positional changes when a postlist, termlist
  or all-terms is opened on a modified WritableDatabase.  Doing so was
  incurring a significant performance cost, and the first of these happens
  internally when `replace_document(term, doc)` is used, which is the usual way
  to support non-numeric unique ids.  We now only flush pending positional
  changes when committing.  Reported and diagnosed by Germán M. Bravo.

remote backend:

* Use poll() where available instead of select().  poll() is specified by
  POSIX.1-2001 so should be widely available by now, and it allows watching any
  fd (select() is limited to watching fds < FD_SETSIZE).  For any platforms
  which still lack poll() we now workaround this select() limitation when a
  high numbered fd needs to be watched (for example, by trying a non-blocking
  read or write and on EAGAIN sleeping for a bit before retrying).

* Stop watching fds for "exceptional conditions" - none of these are \ 
relevant
  to our usage.

* Remove 0.1s timeout in ready_to_read().  The comment says this is to avoid a
  busy loop, but that's out of date - the matcher first checks which remotes
  are ready to read and then does a second pass to handle those which weren't
  with a blocking read.

build system:

* Stop probing for header sys/errno.h which is no longer used - it was only
  needed for Compaq C++, support for which was dropped in 1.4.8.

documentation:

* docs/valueranges.html: Update to document RangeProcessor instead of
  ValueRangeProcessor - the latter is deprecated and will be gone in the next
  release series.

* Document RangeProcessor::operator()() returns OP_INVALID to signal it doesn't
  recognise a range.

* Update some URLs for pages which have moved.

* Use https for URLs where available.

* HACKING: Update "empty()" section for changes in C++11.

portability:

* Suppress clang warnings for self-assignment tests.  Some testcases trigger
  this new-ish clang warning while testing that self-assignment works, which
  seems a useful thing to be testing - at least one of these is a regression
  test.

* Add std::move to fix clang -Wreturn-std-move warning (which is enabled by
  -Wall).

* Add casts to fix ubsan warnings.  These cases aren't undefined behaviour, but
  are reported by ubsan extra checks implicit-integer-truncation and/or
  implicit-conversion which it is useful to be able to enable to catch
  potential bugs.

* Fix check for when to use _byteswap_ulong() - in practice this would only
  have caused a problem if a platform provided _byteswap_ushort() but not
  _byteswap_ulong(), but we're not aware of any which do.

* Fix return values of do_bswap() helpers to match parameter types (previously
  we always returned int and only supported swapping types up to 32 bits, so
  this probably doesn't result in any behavioural changes).

* Only include <intrin.h> if we'll use it instead of always including it when
  it exists.  Including <intrin.h> can result in warnings about duplicate
  declarations of builtin functions under mingw.

* Remove call to close()/closesocket() when the argument is always -1 (since
  the change to use getaddrinfo() in 1.3.3).