xapian-core-1.4.5-bp150.2.4

- Update to 1.4.5:
  * Add Database::get_total_length() method.  Previously you had to calculate
    this from get_avlength() and get_doccount(), taking into account rounding
    issues.  But even then you couldn't reliably get the exact value when total
    length is large since a double's mantissa has more limited precision than an
    unsigned long long.
  * Add Xapian::iterator_rewound() for bidirectional iterators, to test if the
    iterator is at the start (useful for testing whether we're done when
    iterating backwards).
  * DatabaseOpeningError exceptions now provide errno via get_error_string()
    rather than turning it into a string and including it in the exception
    message.
  * WritableDatabase::replace_document(): when passed a Document object which
    came from a database and has unmodified values, we used to always read
    those values into a memory structure.  Now we only do this if the document
    is being replaced to the same document ID which it came from, which should
    make other cases a bit more efficient.
  * Enquire::get_eset(): When approximating term frequencies we now round to the
    nearest integer - previously we always rounded down.
  * See also https://xapian.org/docs/xapian-core-1.4.5/NEWS

- Update to 1.4.4:
  * Database::check():
  + Fix checking a single table - changes in 1.4.2 broke such checks unless
    you specified the table without any extension.
  + Errors from failing to find the file specified are now thrown as
    DatabaseOpeningError (was DatabaseError, of which DatabaseOpeningError is
    a subclass so existing code should continue to work).  Also improved the
    error message when the file doesn't exist is better.
  * Drop OP_SCALE_WEIGHT over OP_VALUE_RANGE, OP_VALUE_GE and OP_VALUE_LE in
    the Query constructor.  These operators always return weight 0 so
    OP_SCALE_WEIGHT over them has no effect.  Eliminating it at query
    construction time is cheap (we only need to check the type of the
    subquery), eliminates the confusing "0 * " from the query description,
    and means the OP_SCALE_WEIGHT Query object can be released sooner.
    Inspired by Shivanshu Chauhan asking about the query description on IRC.
  * Drop OP_SCALE_WEIGHT on the right side of OP_AND_NOT in the Query
    constructor.  OP_AND_NOT takes no weight from the right so OP_SCALE_WEIGHT
    has no effect there.  Eliminating it at query construction time is cheap
    (just need to check the subquery's type), eliminates the confusing "0 * "
    from the query description, and means the OP_SCALE_WEIGHT object can be
    released sooner.
  * See also https://xapian.org/docs/xapian-core-1.4.4/NEWS

- Update to 1.4.3:
  * MSet::snippet(): Favour candidate snippets which contain more of a diversity
  of matching terms by discounting the relevance of repeated terms using an
  exponential decay.  A snippet which contains more terms from the query is
  likely to be better than one which contains the same term or terms multiple
  times, but a repeated term is still interesting, just less with each
  additional appearance.  Diversity issue highlighted by Robert Stepanek's
  patch in https://github.com/xapian/xapian/pull/117 - testcases taken from his
  patch.
  * MSet::snippet(): New flag SNIPPET_EMPTY_WITHOUT_MATCH to get an empty snippet
  if there are no matches in the text passed in.  Implemented by Robert
  Stepanek.
  * Round MSet::get_matches_estimated() to an appropriate number of significant
  figures.  The algorithm used looks at the lower and upper bound and where the
  estimate sits between them, and then picks an appropriate number of
  significant figures.  Thanks to Sébastien Le Callonnec for help sorting out a
  portability issue on OS X.
  * Add Database::locked() method - where possible this non-invasively checks if
  the database is currently open for writing, which can be useful for
  dashboards and other status reporting tools.
  * See also https://xapian.org/docs/xapian-core-1.4.3/NEWS
- Update to 1.4.2:
  * Add XAPIAN_AT_LEAST(A,B,C) macro.
  * MSet::snippet(): Optimise snippet generation - it's now ~46% faster in a
  simple test.
  * Add Xapian::DOC_ASSUME_VALID flag which tells Database::get_document() that
  it doesn't need to check that the passed docid is valid.  Fixes #739,
  reported by Germán M. Bravo.
  * TfIdfWeight: Add support for the L wdf normalisation.  Patch from Vivek Pal.
  * BB2Weight: Fix weights when database has just one document.  Our existing
  attempt to clamp N to be at least 2 was ineffective due to computing
  N - 2 < 0 in an unsigned type.
  * DPHWeight: Fix reversed sign in quadratic formula, making the upper bound a
  tiny amount higher.
  * DLHWeight: Correct upper bound which was a bit too low, due to flawed logic
  in its derivation.  The new bound is slightly less tight (by a few percent).
  * DLHWeight,DPHWeight: Avoid calculating log(0) when wdf is equal to the
  document length.
  * TermGenerator: Handle stemmer returning empty string - the Arabic stemmer
  can currently do this (e.g. for a single tatweel) and user stemmers can too.
  Fixes #741, reported by Emmanuel Engelhart.
  * Database::check(): Fix check that the first docid in each doclength chunk is
  more than the last docid in the previous chunk - this code was in the wrong
  place so didn't actually work.
  * Database::get_unique_terms(): Clamp returned value to be <= document length.
  Ideally get_unique_terms() ought to only count terms with wdf > 0, but that's
  expensive to calculate on demand.
  * See also https://xapian.org/docs/xapian-core-1.4.2/NEWS

- Update to 1.4.1
  * Constructing a Query for a non-reference counted PostingSource object will
  now try to clone the PostingSource object (as happened in 1.3.4 and
  earlier).  This clone code was removed as part of the changes in 1.3.5 to
  support optional reference counting of PostingSource objects, but that breaks
  the case when the PostingSource object is on the stack and goes out of scope
  before the Query object is used.  Issue reported by Till Schäfer and analysed
  by Daniel Vrátil in a bug report against Akonadi:
  https://bugs.kde.org/show_bug.cgi?id=363741
  * Add BM25PlusWeight class implementing the BM25+ weighting scheme, implemented
  by Vivek Pal (https://github.com/xapian/xapian/pull/104).
  * Add PL2PlusWeight class implementing the PL2+ weighting scheme, implemented
  by Vivek Pal (https://github.com/xapian/xapian/pull/108).
  * LMWeight: Implement Dir+ weighting scheme as DIRICHLET_PLUS_SMOOTHING.
  Patch from Vivek Pal.
  * Add CoordWeight class implementing coordinate matching.  This can be useful
  for specialised uses - e.g. to implement sorting by the number of matching
  filters.
  * DLHWeight,DPHWeight,PL2Weight: With these weighting schemes, the formulae
  can give a negative weight contribution for a term in extreme cases.  We
  used to try to handle this by calculating a per-term lower bound on the
  contribution and subtracting this from the contribution, but this idea
  is fundamentally flawed as the total offset it adds to a document depends on
  what combination of terms that document matches, meaning in general the
  offset isn't the same for every matching document.  So instead we now clamp
  each term's weight contribution to be >= 0.
  * TfIdfWeight: Always scale term weight by wqf - this seems the logical
  approach as it matches the weighting we'd get if we weighted every non-unique
  term in the query, as well as being explicit in the Piv+ formula.
  * Fix OP_SCALE_WEIGHT to work with all weighting schemes - previously it was
  ignored when using PL2Weight and LMWeight.
  * PL2Weight: Greatly improve upper bound on weight:
  + Split the weight equation into two parts and maximise each separately as
    that gives an easily solvable problem, and in common cases the maximum is
    at the same value of wdfn for both parts.  In a simple test, the upper
    bounds are now just over double the highest weight actually achieved -
    previously they were several hundred times.  This approach was suggested by
    Aarsh Shah in: https://github.com/xapian/xapian/pull/48
  + Improve upper bound on normalised wdf (wdfn) - when wdf_upper_bound >
    doclength_lower_bound, we get a tighter bound by evaluating at
    wdf=wdf_upper_bound.  In a simple test, this reduces the upper bound on
    wdfn by 36-64%, and the upper bound on the weight by 9-33%.
  * PL2Weight: Fix calculation of upper_bound when P2>0.  P2 is typically
  negative, but for a very common term it can be positive and then we should
  use wdfn_lower not wdfn_upper to adjust P_max.
  * Weight::unserialise(): Check serialised form is empty when unserialising
  parameter-free schemes BoolWeight, DLHWeight and DPHWeight.
  * TermGenerator::set_stopper_strategy(): New method to control how the Stopper
  object is used.  Patch from Arnav Jain.
  * QueryParser: Fix handling of CJK query over multiple prefixes.  Previously
  all the n-gram terms were AND-ed together - now we AND together for each
  prefix, then OR the results.  Fixes #719, reported by Aaron Li.
  * Add Database::get_revision() method which provides access to the database
  revision number for chert and glass, intended for use by xapiand.  Marked
  as experimental, so we don't have to go through the usual deprecation cycle
  if this proves not to be the approach we want to take.  Fixes #709,
  reported by German M. Bravo.
  * Mark RangeProcessor constructor as `explicit`.
  * See also https://xapian.org/docs/xapian-core-1.4.1/NEWS
- A compiler with support for C++11 is required, so
  specify BuildRequires gcc-c++ >= 4.6

- Update to 1.4.0
  * API
    + Update to Unicode 9.0.0
    + Reimplement ESet and ESetIterator
    + MSetIterator and ESetIterator are now STL-compatible
    random_access_iterators
  * See also http://xapian.org/docs/xapian-core-1.4.0/NEWS

- Update to 1.2.23
  * API
    + PostingSource: Public member variables are now wrapped by methods
  * chert backend
    + xapian-check now performs additional consistency checks for chert.
  * omega
    + Fix HTML/XML entity decoding to be O(n) not O(n) - indexing
    HTML/XML with a lot of entities is now much faster.

- Update to 1.2.21
  * API:
    + QueryParser: Extend the set of characters allowed in the
    start of a range to be anything except for '(' and characters <= ' '.
  * matcher:
    + Reimplement OP_PHRASE for non-exact phrases.
    + Reimplement OP_NEAR - the new implementation consistently
    requires the terms to occur at different positions, and fixes
    some previously missed matches.
    + Fix a reversed check for picking the shorter position list
    for an exact phrase of two terms.
    + When matching an exact phrase, if a term doesn't occur where
    we want, use its actual position to advance the anchor term,
    rather than just checking the next position of the anchor term.
  * brass backend:
    + Fix cursor versioning to consider cancel() and reopen() as
    events where the cursor version may need incrementing,
    and flag the current cursor version as used when a cursor is rebuilt.
    + Avoid using file descriptions < 3 for writable database tables,
    as it risks corruption if some code in the same process tries
    to write to stdout or stderr without realising it is closed.
  * chert backend:
    + Fix cursor versioning to consider cancel() and reopen() as
    events where the cursor version may need incrementing,
    and flag the current cursor version as used when a cursor is rebuilt.
    + Avoid using file descriptions < 3 for writable database tables,
    as it risks corruption if some code in the same process tries
    to write to stdout or stderr without realising it is closed.
  * flint backend:
    + Fix cursor versioning to consider cancel() and reopen() as
    events where the cursor version may need incrementing,
    and flag the current cursor version as used when a cursor is rebuilt.
  * remote backend:
    + Fix sort by value when multiple databases are in use and one or
    more are remote.
  * build system:
    + The compiler ABI check in the public API headers now issues a
    warning (instead of an error) for an ABI mismatch for ABI versions
    2 and later (which means GCC >= 3.4).
    + xapian-config,xapian-core.pc: When compiling with xlC on AIX, the
    reported --cxxflags/--cflags now include -D_LARGE_FILES=1 as this
    is defined for the library, and defining it changes the ABI of
    std::string with this compiler, so it must also be defined when
    building code using the Xapian API.
    + xapian-core.pc: Include --enable-runtime-pseudo-reloc in --libs
    output for mingw and cygwin, like xapian-config does.
    + xapian-core.pc: Fix include directory reported by `pkg-config --cflags`.
    + xapian-config: Fix typo so cached result of test in is_uninstalled()
    is actually used on subsequent calls.
    + configure: Changes in 1.2.19 broke the custom macro we use to probe
    for supported compiler flags such that the flags never got used.
    + configure: Set default value for AUTOM4TE before AC_OUTPUT so the
    default will actually get used.
    + soaktest: Link with libtool's '-no-install' or '-no-fast-install',
    like we already do for other test programs, which means that libtool
    doesn't need to generate shell script wrappers for them on most platforms.
  * documentation:
    + API documentation: Minor wording tweaks and formatting improvements.
    + docs/deprecation.rst: Add deprecation of omindex --preserve-nonduplicates
    which happened in 1.2.4.
    + HACKING: libtool 2.4.6 is now used for bootstrapping snapshots and releases.
  * tools:
    + xapian-compact: Make sure we open all the tables of input databases at the
    same revision.
    + xapian-metadata: Add 'list' subcommand to list all the metadata keys.
    + xapian-replicate: Fix connection timeout to be 10 seconds rather than 10000
    seconds (the incorrect timeout has been the case since 1.2.3).
    + xapian-replicate: Set SO_KEEPALIVE for xapian-replicate's connection to the
    master, and add command line option to allow setting socket-level timeouts
    (SO_RCVTIMEO and SO_SNDTIMEO) on platforms that support them.
    + xapian-replicate-server: Avoid potentially reading uninitialised data if a
    changeset file is truncated.
  * portability:
    + Add spaces between literal strings and macros which expand to literal strings
    for C++11 compatibility.
    + ValueCountMatchSpy::top_values_begin(): Fix the comparison function not to
    return true for two equal elements, which manifests as incorrect sorting in
    some cases when using clang's libc++ (which recent OS X versions do).
    + apitest: The adddoc5 testcase fails under clang due to an exception handling
    bug, so just #ifdef out the problematic part of the testcase when building
    with clang for now.
    + configure: Improve the probe for whether the test harness can use RTTI to
    work for IBM's xlC compiler (which defaults to not generating RTTI).
    + Use F_DUPFD where available to dup to a file descriptor which is >= 2, rather
    than calling dup() until we get one.
    + When unserialising a double, avoid reading one byte past the end of the
    serialised value.
    + When unserialising a double, add missing cast to unsigned char when we check
    if the value will fit in the double type.
    + Fix incorrect use of "delete" which should be "delete []".  This is
    undefined behaviour in C++, though the type is POD, so in practice this
    probably worked OK on many platforms.
- Drop patch 0001-backends-chert-chert_cursor.cc-backends-chert-chert_.patch
  due to upstream inclusion

- Add 0001-backends-chert-chert_cursor.cc-backends-chert-chert_.patch
  from upstream (kde#341990, http://trac.xapian.org/ticket/675)

- Update to 1.2.20
  * chert backend
    + After splitting a block, we always insert the new block in
    the parent right after the block it was split from - there's
    no need to binary chop.
  * build system
    + Generate and install a file for pkg-config.
    + configure: Update link to cygwin FAQ in error message.
  * tools
    + xapian-check: For chert and brass, cross-check the position
    and postlist tables to detect positional data for non-existent
    documents.
  * portability
    + When locking a database for writing, use F_OFD_SETLK where
    available, which avoids having to fork() a child process to
    hold the lock.  This currently requires Linux kernel >= 3.15,
    but it has been submitted to POSIX so hopefully will be widely
    supported eventually.  Thanks to Austin Clements for pointing
    out this now exists.
    + Fix detection of fdatasync(), which appears to have been
    broken practically forever - this means we've probably been
    using fsync() instead, which probably isn't a big additional
    overhead.  Thanks to Vlad Shablinsky for helping with Mac
    OS X portability of this fix.
    + configure: Define MINGW_HAS_SECURE_API under mingw to get
    _putenv_s() declared in stdlib.h.
    + Use POSIX O_NONBLOCK in preference to O_NDELAY - the
    semantics of the latter differ between BSD and System V.
    + According to POSIX, strerror() may not be thread safe, so
    use alternative thread-safe ways to translate errno values
    where possible.
    + On Microsoft Windows, avoid defining EADDRINUSE, etc if
    they're already defined, and use WSAE* constants un-negated -
    they start from a high value so won't collide with E*
    constants.

- Tiny spec file cleanups
- Add gpg signature

- Update to 1.2.19
  - API:
  * Xapian::BM5Weight:
    + Improve BM25 upper bound in the case when our wdf upper
    bound > our document length lower bound.
    + Pre-multiply termweight by (param_k1 + 1) rather than
    doing it for every weighted term in every document considered.
  - testsuite:
  * Don't report apparent leaks of fds opened on /dev/urandom
  - matcher:
  * Fix false matches reported for non-exact phrases in some cases.
  - build system:
  * For Sun's C++ compiler, pass -library=Crun separately since
    libtool looks for " -library=stlport4 " (with the spaces).
  * Remove .replicatmp (created by the test suite) upon "make clean".
  - documentation:
  * include/xapian/compactor.h: Fix formatting of doxygen comment.
  * HACKING: freecode no longer accepts updates, so drop that item
    from the release checklist.
  * docs/overview.rst: Add missing database path to example of using
    xapian-progsrv in a stub database file.
  - portability:
  * Suppress unused typedef warnings from debugging logging macros,
    which occur in functions which always exit via throwing an
    exception when compiling with recent versions of GCC or clang.
  * Fix debug logging code to compile with clang.

- Add baselibs.conf, needed by baloo 32bit libraries

- Switch the SSE instruction set of for x86 builds.

- Update to 1.2.17
  - API:
  * Enquire::set_sort_by_relevance_then_value() and
    Enquire::set_sort_by_relevance_then_key(): Fix sense of reverse
    parameter.
  * BM25Weight: Fix case where (k1 == 0 || b == 0) but k2 != 0.
  * Unicode::tolower(): Fix to give correct results for U+01C5,
    U+01C8, U+01CB, and U+01F2
  - testsuite:
  * Automatically probe for and hook in eatmydata to the testsuite
    using the wrapper script it now includes.
  * Fix apitest to build when brass, chert or flint are disabled.
  - brass backend:
  * Fix handling of invalid block sizes passed to Xapian::Brass::open()
  - the size gets fixed as documented, but the uncorrected size
    was passed to the base file (and abort() was called if 0
    was passed).
  * Validate "dir_end" when reading a block.  (fixes #592)
  - chert backend:
  * Fix handling of invalid block sizes passed to Xapian::Chert::open()
  - the size gets fixed as documented, but the uncorrected size was
    passed to the base file (and abort() was called if 0 was passed).
  * Validate "dir_end" when reading a block.  (fixes #592)
  - flint backend:
  * Fix handling of invalid block sizes passed to Xapian::Flint::open()
  - the size gets fixed as documented, but the uncorrected size was
    passed to the base file (and abort() was called if 0 was passed).
  * Validate "dir_end" when reading a block.  (fixes #592)
  - build system:
  * configure: Improve reporting of GCC version.
  * Use -no-fast-install on platforms where -no-install causes
    libtool to emit a warning.
  * docs/Makefile.am: Fix handling of MAINTAINER_NO_DOCS.
  * Include UnicodeData.txt and the script to generate the unicode
    tables from it.
  - documentation:
  * postingsource.rst: Clarify a couple of points
  - portability:
  * Protect the ValueIterator::check() method against Mac OS X SDK
    headers which define a check() macro.
  * Fix warning from xlC compiler.
  * Avoid use of grep -e in configure, as /usr/bin/grep on Solaris
    doesn't support -e.
  * Fix check for flags which might be needed for ANSI mode for
    compilers called 'cxx'.
  * configure: Improve handling of Sun's C++ compiler - trick libtool
    into not adding -library=Cstd, and prefer -library=stdcxx4 if
    supported.  Explicitly add -library=Crun which seems to be required,
    even though the documentation suggests otherwise.

- Update to 1.2.16
  - API:
  * PositionIterator,PostingIterator,TermIterator,ValueIterator:
    Don't segfault if skip_to() or check() is called on an iterator
    which is already at_end().
  * ValueCountMatchSpy: get_description() on a default-constructed
    ValueCountMatchSpy object no longer fails when xapian-core is
    built with --enable-log.
  * ValueCountMatchSpy: get_total() on a default-constructed
    ValueCountMatchSpy object now returns 0 rather than segfaulting.
  - brass backend:
  * When moving a cursor on a read-only table, check if the block we
    want is in the internal cursor.  We already do this for a
    writable table, as it is necessary for correctness, but it's a
    cheap check and may avoid asking the OS for a block we actually
    already have.
  * Correctly report the database as closed rather than
    'Bad file descriptor' in certain cases.
  * Reuse a cursor for reading values from valuestreams rather than
    creating a new one each time.  This can dramatically reduce the
    number of blocks redundantly reread when sorting by value.
    The rereads will generally get served from VM cache, but there's
    still an overhead to that.
  - chert backend:
  * When moving a cursor on a read-only table, check if the block
    we want is in the internal cursor. We already do this for a
    writable table, as it is necessary for correctness, but it's
    a cheap check and may avoid asking the OS for a block we actually
    already have.
  * Correctly report the database as closed rather than
    'Bad file descriptor' in certain cases.
  * Reuse a cursor for reading values from valuestreams rather than
    creating a new one each time.  This can dramatically reduce the
    number of blocks redundantly reread when sorting by value.
    The rereads will generally get served from VM cache, but there's
    still an overhead to that.
  - flint backend:
  * When moving a cursor on a read-only table, check if the block we
    want is in the internal cursor. We already do this for a writable
    table, as it is necessary for correctness, but it's a cheap check
    and may avoid asking the OS for a block we actually already have.
  * Correctly report the database as closed rather than
    'Bad file descriptor' in certain cases.
  - tools:
  * xapian-chert-update: Fix -b to work rather than always
    segfaulting (reported in http://bugs.debian.org/716484).
  * xapian-chert-update: The documented alias --blocksize for -b has
    never actually been supported, so just drop mentions of it
    from --help and the man page.
  - xapian-check:
  * Fix chert database check that first docid in each doclength
    chunk is more than the last docid in the previous chunk
  - previously this didn't actually work.
  * Fix database check not to falsely report "position table: Junk
    after position data" whenever there are 7 unused bits (7 is OK,
  * more* than 7 isn't).
  * Fix to report block numbers correctly for links within the B-tree.
  * If the METAINFO key is missing, only report it once per table.
  * Fix database consistency checking to always open all the tables
    at the same revision - not doing this could lead to false errors
    being reported after a commit interrupted by the process being
    killed or the machine crashing.
- Change tarball to xz. Added xz BuildRequires: xz for that purpose

- Update to version 1.2.15
  * See http://svn.xapian.org/*checkout*/tags/1.2.15/xapian-core/NEWS

- Update to version 1.2.12
  * 1.2.11 had its library version information incorrectly set.
    This resulted in the shared library having an incorrect SONAME.
    This release has been made to fix this problem.
  * Fix issue with running AND, OR and XOR queries against a
    database with no documents in it - this was leading to a divide
    by zero, which led to MSet::get_matches_estimated() reporting
    2147483648 on i386.
  * Don't count unweighted subqueries of MultiAndPostList in
    percentage calculations, as OP_FILTER maps to MultiAndPostList
    now.  (ticket#590)
  * When compacting, if the output database is empty, don't write
    out a metainfo tag.  Take care not to divide by zero when
    computing the percentage size change for a table.
    (brass and chert backend)
  * Add new QueryParser::STEM_ALL_Z stemming strategy, which
    stems all terms and adds a Z prefix.
  * Add TermGenerator::set_stemming_strategy() method, with
    strategies which correspond to those of QueryParser.
  * Correct "BM25Weight" to "TradWeight" in exception message
    from TradWeight.
  * We were failing to call init() for user-defined Weight objects
    providing the term-independent weight.  These now get called
    with init(0.0).
  * Xapian::Auto::open_stub() now throws a Xapian::DatabaseOpeningError
    exception if the stub file can't be opened.  Previously we
    failed to check for this condition, which resulted in us
    treating the file as empty.
  * See http://svn.xapian.org/*checkout*/tags/1.2.12/xapian-core/NEWS
  * http://svn.xapian.org/*checkout*/tags/1.2.11/xapian-core/NEWS
  * http://svn.xapian.org/*checkout*/tags/1.2.10/xapian-core/NEWS
  * http://svn.xapian.org/*checkout*/tags/1.2.9/xapian-core/NEWS

- update to 1.2.8:
  * Add support to TermGenerator and QueryParser for indexing and searching CJK
  text using n-grams.  Currently this is only enabled when the environmental
  variable XAPIAN_CJK_NGRAM is set to a non-empty value.
  * overview.html,quickstart.html: Fix several factual errors.
  * Improve documentation comments for several methods.
  * Add documentation for function parameters which didn't have it.

- avoid packaging files twice

- updated to 1.2.7

- Update to 1.4.17:
  + API:
  * Database::get_average_length(): Add this as an alias for Database::get_avlen().
    In git master we've added this as a preferred new name - adding it to 1.4.x too
    will make it easier for users to update to using this.
  * Database::get_spelling_suggestion(): Optimise edit distance initialisation
    loop to significantly reduce the cost of a typical edit distance calculation.
  * Fix query expansion on sharded databases.  The mechanism for passing in which
    shard a TermList is from wasn't hooked up and as a result we'd always think
    it's from the first shard, meaning the statistics would be wrong and that our
    suggested terms may not have been as good as they should be in this
    situation.
  * Enquire::get_eset(): Use string::compare() to avoid 1/3 of the string compares
    on average.
  + documentation:
  * Update doxygen HTML headers and footers to resolve issues with some
    interactive features of the API docs not working.  Reported by Enrico Zini.
  * Stop specifying obsolete doxygen settings PERL_PATH and MSCGEN_PATH.
  * Clarify API docs for MSet::get_termfreq() to make it clear that this
    considers all documents in the database, not only those that matched the
    searched (it would sometimes be useful to be able to report the number of
    occurrences of a term in the matched documents, but it's not something we
    currently keep track of).  Reported by Tadeusz So?nierz and Peter Salomonsen.

- update to 1.4.16:
  * MSet::snippet(): The snippet now includes trailing punctuation which carries
    meaning or gives useful context.  See
    https://github.com/xapian/xapian/pull/180, reported by Robert Stepanek.
  * MSet::snippet(): Fix segfault generating snippet from default-constructed
    MSet.  This probably isn't something you'd typically do, but it shouldn't
    crash.  Found during extended testing of #803 (which only affected git
    master) which was reported by Robert Stepanek.
  * Remove trailing full stop from exception messages.  We conventionally don't
    include one, but a few cases didn't follow that convention.
  testsuite:
  * Replace direct use of ftime() which gives deprecation warnings with recent
    mingw.  Reported by srinivasyadav22.
  matcher:
  * Fix segfault in rare cases in the query optimiser.  We keep a pointer to the
    most recent posting list to use as a hint for opening the next posting list,
    but the existing mechanism to take ownership of this hint had a flaw.  We now
    invalidate the hint in situations where it might be indirectly deleted which
    is safe, but somewhat conservative.
  * Improve the optimisation of an always-matching OP_VALUE_GE to also take
    effect when the value slot's lower bound is equal to the limit of the
    OP_VALUE_GE.  Patch from boda sadalla.
  glass backend:
  * Report the correct errno value if commit() fails.  We were potentially
    reporting ENOENT from an unlink() call cleaning up a temporary file prior to
    throwing the exception instead.
  documentation:
  * Fix missing menus in API documentation.  Newer doxygen generates .js files
    which we also need to distribute and install.  Reported by sec^nd on #xapian.
  * Note OP_FILTER ignored subquery bug fixed in 1.4.15 as present in 1.4.14 and
    older.
  portability:
  * Use our own autoconf cache variable namespace (xo_cv_ prefix instead of
    ac_cv_) to avoid colliding with standard autoconf macro use if config.site or
    a shared config.cache is used.  The former case caused a build failure for
    the OpenBSD port with 1.4.15, reported by Lucas R.
  * Use clock_gettime() and nanosleep() under modern mingw as these allow higher
    precision than what we previously used.

- Update to version 1.4.15:
  + API:
  * Database::check(): Fix checking of replication changesets.
    This reverts a change incorrectly made in 1.3.7.
  * Database::locked(): Return false instead of true for a closed inmemory DB.
  * Database::commit(): If commit() failed with an exception while trying to add
    pending changes (e.g. InvalidArgumentError due to a long term containing zero
    bytes) then a subsequent commit() on the same object would throw the same
    exception.  Now we clear the pending changes in this situation (like we
    already did for failure at other stages in the commit).  This bug remains
    unfixed for the chert backend as it's harder to fix there and the effort to
    fix it and extra risk of breakage don't seem justified for a backend we
    recommend people migrate away from.
  * QueryParser::parse_query(): Optimise parsing of multi-word synonyms.
  + Testsuite fixes.
  + matcher:
  * Hoist positional check above OP_FILTER.
  * Handle OP_FILTER with more than two subqueries correctly.  Previously we'd
    only check the first two subqueries in some situations.
  + remote backend:
  * For a remote WritableDatabase, the client now keeps track of whether there
    are pending changes, and if there aren't then we now do nothing for commit()
    or cancel() calls.  In particular this saves a message exchange when the
    WritableDatabase destructor is called when changes have already been
    committed with an explicit call to commit() (which is what we recommend
    doing, since with an explicit call to commit() you get to see any exception
    which gets thrown).
  * When closing a remote prog WritableDatabase, previously an exception could
    leave the remote connection open with the remote server running, and we'd
    then wait for the specified timeout before closing the connection.  Now we
    close the connection before letting the exception propagate.
  * Don't swallow exceptions from Database::close() on a remote database.  If
    we aren't in a transaction and so try to commit() and that fails then
    previously the caller would have no indication of the failure.
  * Fix handling the reported term weight when remote shards are searched.
    Fixes 5 XFAILs in the testsuite.
  * Add missing space to mismatching protocol versions error message.
  + build system:
  * Fix to build when configured with --disable-backend-remote, broken by changes
    in 1.4.14.  Fixes #797, reported by ????? ????????.
  * The clang and icc compilers both define __GNUC__, which led our ABI mismatch
    message to report them as "g++" with a bogus version (the version of GCC that
    these compilers advertise themselves as, which for clang is always 4.2.0) -
    now we report clang++ or icc along with the actual version of that compiler.
  + updated documentation.

- Update to 1.4.14:
  * API:
    + Xapian::QueryParser: Handle "" inside a quoted phrase better.  In a quoted
    boolean term, "" is treated as an escaped ", so handle it in a compatible way
    for quoted phrases.  Previously we'd drop out of the phrase and start a new
    phrase.  Fixes #630, reported by Austin Clements.
    + Xapian::Stem: The constructor which takes a stemmer name now takes an
    optional second bool parameter - if this is true, then an unknown stemmer
    name falls back to using the "none" stemmer instead of throwing an exception.
    This allows simply constructing a stemmer from an ISO language code without
    having to worry about whether there's a stemmer for that language, and
    without having to handle an exception if there isn't.
    + Xapian::Stem: Fix a bug with handling 4-byte UTF-8 sequences which
    potentially affects most of the stemmers.  None of the stemmers work in
    languages where 4-byte UTF-8 sequences are part of the alphabet, but this
    bug could result in invalid UTF-8 sequences in terms generated from text
    containing high Unicode codepoints such as emoji, which can cause issues (for
    example, in some language bindings).  Fix synced from Snowball git post
    2.0.0.
    + Xapian::Stem: Add a new is_none() method which tests if this is a "none"
    stemmer.
    + Xapian::Weight: The total length of all documents is now made available to
    Xapian::Weight subclasses, and this is now used by DLHWeight, DPHWeight and
    LMWeight.  To maintain ABI compatibility, internally this still fetches the
    average length and the number of documents, multiplies them, then rounds the
    result, but in the next release series this will be handled directly.
    + Xapian::Database::locked() on an inmemory database used to always return
    false, but an inmemory Database is always actually a WritableDatabase
    underneath, so now we always report true in this case because it's really
    always report being locked for writing.
  + testsuite:
  * Fix failing multi_glass_remoteprog_glass tests on x86.  When the tests are
    run under valgrind, remote servers should be run using the runsrv wrapper
    script, but this wasn't happening for remote servers in multi-databases - now
    it is.  Also, previously runsrv only used valgrind for the remote for an x86
    build that didn't use SSE, but it seems there are x87 instructions in libc
    that are affected by valgrind not providing excess precision, so do this for
    x86 builds which use SSE too.  Together these changes fix failures of
    topercent2, xor2, tradweight1 under backend multi_glass_remoteprog_glass on
    x86.
  * Fix C++ One-Definition Rule (ODR) violation in testsuite code.  Two different
    source files linked into apitest were each defining a different `struct
    test`.  Wrap each in an anonymous namespace to localise it to the file it is
    defined and used in.  This was probably harmless in practice, unless trying
    to build with Link-Time Optimisation or similar (which is how it was
    detected).
  * Test all language codes in stemlangs1.  The testsuite hardcodes a list of
    supported language codes which hadn't been updated since 2008.
  * Improve DateRangeProcessor test coverage.
  + matcher:
  * Handle pruning under a positional check.  This used to be impossible, but
    since 1.4.13 it can happen as we now hoist AND_NOT to just below where we
    hoist the positional checks.  The code on master already handles pruning here
    so this bug is specific to the RELEASE/1.4 branch.
  * When searching with collapsing over multiple shards, at least some of which
    are remote, uncollapsed_upper_bound could be too low and
    uncollapsed_lower_bound too high.  This was causing assertion failures in
    testcases msize1 and msize2 under test harness backends
    multi_glass_remoteprog_glass and multi_remoteprog_glass.
  * Internally we no longer calculate a bogus total_term_count as the sum of
    total_length * doc_count for all shards.  Instead we just use the sum of
    total_length, which gives the total number of term occurrences.  This change
    should improve the estimated collection_freq values for synonyms.
  * Several places where we might divide zero by zero in a database where wdf was
    always zero have been fixed.
  + build system:
  * configure: Stop using AC_FUNC_MEMCMP.  The autoconf manual marks it as
    "obsolescent", and it seems clear that nobody's relying on it as we're
    missing the "'AC_LIBOBJ' replacement for 'memcmp'" which it would try to
    use if needed.
  + documentation:
  * HACKING: Replace release docs with pointer to the developer guide where they
    are now maintained.
  + portability:
  * Eliminate 2 uses of atoi().  These are potentially problematic in a
    multithreaded application if setlocale() is called by another thread at the
    same time.
  * Don't check __GNUC__ in visibility.h as the configure probe before defining
    XAPIAN_ENABLE_VISIBILITY checks that the visibility attributes work.  This
    probably makes no difference in practice, as all compilers we're aware of
    which support symbol visibility also define __GNUC__.
  * Document Sun C++ requires --disable-shared.
- Update to 1.4.13:
  + API:
  * Fix write one past end of std::vector on certain QueryParser parser errors.
    This is undefined behaviour, but the write was always into reserved space, so
    in practice we'd actually get away with it (it was noticed because it
    triggers an error when running under ubsan and using libc++).
  * MSet::get_matches_estimated(): Improve rounding of result - a bug meant we
    would almost always round down.
  * Optimise test for UTF-8 continuation character.  Performing a signed char
    comparison shaves an instruction or two on most architectures.
  * Database::get_revision(): Return revision 0 for a Database with no shards
    rather that throwing InvalidOperationError.
  * DPHWeight: Avoid dividing by 0 when searching a sharded database when one
    shard is empty.  The result wasn't used in this case, but it's still
    undefined behaviour.  Detected by UBSan.
  + testsuite:
  * The "singlefile" test harness backend manager now creates databases by
    compacting the corresponding underlying backend database (creating it first
    if need be) rather than always creating a temporary database to compact.
  * Enable compaction testcases for multi and singlefile test harness backends.
  * Add generated database support for remoteprog and remotetcp test harness
    backends.
  * Add test harness support for running testcases using a multi database
    comprised of one local and one remote shard, or two remote shards.
  * Check if removing existing multi stub failed.  Previously if removing an
    existing stub failed, the test harness would create a temporary new stub and
    then try to rename it over the old one, which will always fail on Microsoft
    Windows.
  * Wait for xapian-tcpsrv processes to finish before moving on to the next
    testcase under __WIN32__ like we already do on POSIX platforms.
  + matcher:
  * Optimise OP_AND_NOT better.  We now combine its left argument with other
    connected and-like subqueries, and gather up and hoist the negated subqueries
    and apply them together above the combined and-like subqueries, just below
    any positional filters.
  * Optimise OP_AND_MAYBE better.  We now combine its left argument with other
    connected and-like subqueries, and gather up and hoist the optional
    subqueries and apply them together above the combined and-like subqueries and
    any hoisted positional filters.
  * Treat all BoolWeight queries as scaled by 0 - we can optimise better if we
    know the query is unweighted.
  + glass backend:
  * Allow zlib compression to reduce size by one byte.  We were specifying an
    output buffer size one byte smaller than the input, but it appears zlib won't
    use the final byte in the buffer, so we actually need to pass the input size
    as the output buffer size.
  * Only try to compress Btree item values > 18 bytes, which saves CPU time
    without sacrificing any significant size savings.
  + remote backend:
  * Fix match stats when searching with collapsing over multiple shards and at
    least some shards are remote.
  * Ignore orphaned remote protocol replies which can happen when searching with
    a remote shard if an exception is thrown by another shard.
  * Wait for xapian-progsrv child to exit when a remote Database or
    WritableDatabase object is closed under __WIN32__ like we already do for
    POSIX platforms.
  + documentation:
  * Correct documentation of initial messages in replication protocol.
  + tools:
  * quest: Report bounds and estimate of number of matches.
  * xapian-delve: Improve output when database revision information is not
    available.  We now specially handle the cases of a DB with multiple shards
    and a backend which doesn't support get_revision().
  + portability:
  * Fix warning from GCC 9 with -Wdeprecated-copy (which is enabled by -Wextra)
    if a reference to an Error object is thrown.
  * Suppress GCC warning in our API headers when compiling code using Xapian with
    GCC and -Wduplicated-branches.
  * Mark some internal classes as final (following GCC -Wsuggest-final-types
    suggestions to allow some method calls to be devirtualised).
  * Fix to build with --enable-maintainer-mode and Perl < 5.10, which doesn't
    have the `//=` operator.  It's unlikely developers will have such an old
    Perl, but the mingw environment on appveyor CI does.  The use of `//=` was
    introduced by changes in 1.4.10.
- Update to 1.4.12:
  + API:
  * Xapian::PostingSource: When a PostingSource without a clone() method is used
    with a Database containing multiple shards, the documented behaviour has
    always been that Xapian::InvalidOperationError is thrown.  However, since at
    least 1.4.0, this exception hasn't been thrown, but instead a single
    PostingSource object would get used for all the shards, typically leading to
    incorrect results.  The actual behaviour now matches what was documented.
  * Xapian::Database: Add size() method which reports the number of shards.
  * Xapian::Database::check(): You can now pass a stub database which will check
    all the databases listed in it (or throw Xapian::UnimplementError for
    backends which don't support checking).
  * Xapian::Document: When updating a document use a emplace_hint() to make the
    bulk insertion O(n) instead of O(nlog(n)), and use std::move() to avoid
    copying OmDocumentTerm objects.
  * Xapian::Query: Add missing get_unique_terms_end() method.
  * Xapian::iterator_valid(): Implement for Utf8Iterator
  + testsuite:
  * Fix keepalive1 failures on some platforms.  On some platforms a timeout
    gives NetworkTimeoutError and on others NetworkError - since 1.4.10 changed
    to checking the exact exception type, keepalive1 has been failing on the
    former set of platforms.  We now just check for NetworkError or a subclass
    here (since NetworkTimeoutError is a subclass of NetworkError).
  * Run cursordelbug1 testcase with multi databases too.
  + matcher:
  * Ownership of PostingSource objects during the match now makes use of the
    optional reference-counting mechanism rather than a separate flag.
  + remote backend:
  * Fix remote protocol design bug.  Previously some messages didn't send a reply
    but could result in an exception being sent over the link.  That exception
    would then get read as a response to the next message instead of its actual
    response so we'd be out of step.
    This fix necessitated a minor version bump in the remote protocol (to 39.1).
    If you are upgrading a live system which uses the remote backend, upgrade the
    servers before the clients.
  * Fix socket leaks on errors during opening a database.
  * Don't close remote DB socket on receiving EOF as the levels above won't
    know it's been closed and may try to perform operations on it, which would be
    problematic if that fd gets reused in the meantime.  Leaving it open means
    any further operations will also get EOF.
  * We add a wrapper around the libc socket() function which deals with the
    corner case where SOCK_CLOEXEC is defined but socket() fails if it is
    specified (which can happen with a newer libc and older kernel).
    Unfortunately, this wrapper wasn't checking the returned value from socket()
    correctly, so when SOCK_CLOEXEC was specified and non-zero it would create
    the socket() with SOCK_CLOEXEC, then leak that one and create it again
    without SOCK_CLOEXEC.  We now check the return value properly.
  * Fix potential infinite loop in ValueCountMatchSpy::merge_results() if passed
    serialised results with extra data appended (which shouldn't happen in normal
    use).
  + build system:
  * Current versions of valgrind result in false positives on current versions of
    macOS, so on this platform configure now only enables use of valgrind if it's
    specified explicitly.
  * Refactor macros to probe for compiler flags so they automatically cache
    their results and consistently report success/failure.
  * Rename our custom TYPE_SOCKLEN_T macro to XAPIAN_TYPE_SOCKLEN_T.  The
    AX_TYPE_SOCKLEN_T macro defines an alias of TYPE_SOCKLEN_T for itself which
    means it can get used instead in some situations, but it isn't compatible
    with our macro.  We can't just switch to AX_TYPE_SOCKLEN_T as it doesn't
    handle cases we need, so just rename our macro to avoid potential problems.
  + documentation:
  * Improve API documentation for Xapian::Query class.  Add missing doc
    comments and improve some of the existing ones.
  * Add Unicode consortium names and codes for categories from Chapter 4, Version
    11 of the Unicode standard.  Patch from David Bremner.
  * Improve configure --help output - drop "[default=no]" for --enable-*
    options which default off.
    ????????.
  * Fix API documentation typo - Query::op (the type) not op_ (a parameter name).
  * Note which version Document::remove_postings() was added in.
  * In the remote protocol documentation, MSG_REPLACEDOCUMENTTERM was documented
    as not having a reply, but actually REPLY_ADDDOCUMENT is sent.
  * Update list of <xapian/iterator.h> users.
  + tools:
  * copydatabase: A change in 1.4.6 which added support for \ as directory
    separator on platforms where that's the norm broke the code in copydatabase
    which removes a trailing slash from input databases.
  + portability:
  * Add missing '#include <cstring>'.
  * Fix str() helper function when converting the most negative value
    of a signed integer type.
  * Avoid calling close() on fd we know must actually be a WIN32 SOCKET.
  * Include <ios> not <iomanip> for std::boolalpha.
  * Rework setenv() compatibility handling.  Now that Solaris 9 is dead we can
    assume setenv() is provided by Unix-like platforms (POSIX requires it).  For
    other platforms, provide a compatibility implementation of setenv() which
    so the compatibility code is encapsulated in one place rather than replicated
    at every use.
  * Fix maintainer-mode builds on Solaris where /bin/tr is not POSIX compliant.
    We now use the simple workaround suggested by the autoconf manual.
  * Improve support for Sun C++:
    + Suppress unhelpful warning for lambda with multiple return statements.
    + Enable reporting the tags corresponding to warnings, which we need
    to know in order to suppress any new unhelpful warnings.
    + Adjust our workaround for bug with this compiler's <cmath> header to avoid
    a compiler warning.
    + Use -xldscope=symbolic for Sun C++.  This flag is roughly equivalent to
  - Bsymbolic-functions which we've probed for with GNU ld since Xapian 1.0.0.
- Update to 1.4.11:
  + API:
  * MSet::SNIPPET_CJK_NGRAM - new flag for use with MSet::snippet() to enable
    support for selecting and highlighting snippets which works with the
    QueryParser and TermGenerator FLAG_CJK_NGRAM flags.  This mode can also be
    enabled by setting environment variable XAPIAN_CJK_NGRAM to a non-empty
    value.  (There was nominally already support for XAPIAN_CJK_NGRAM in
    MSet::snippet(), but it didn't work usefully - the highlighting added was all
    empty start/end pairs at the end of the span of CJK characters containing the
    CJK ngram terms, which to the user would typically look like it was selecting
    the end of the text and not highlighting anything).
  * Deprecate XAPIAN_CJK_NGRAM environment variable.  There are now flags which
    can be used instead in all cases, and there's sadly no portable thread-safe
    way to read an environment variable so checking environment variables is
    problematic in library code that may be used in multithreaded programs.
  * Query::OP_ELITE_SET currently incorrectly recursively flattens any OP_OR (or
    OP_OR-like) subqueries into the list of subqueries it selects from - until
    that's fixed, we now select from the full exploded list rather than the last
    n (where n is the number of direct subqueries of the OP_ELITE_SET).
  + testsuite:
  * Testcases which need a generated database now get run with a sharded
    database.
  * Avoid using strerror() in the testsuite which removes an obstacle to running
    tests in parallel in separate threads.
  + matcher:
  * Extend detection of cases of OP_SYNONYM with disjoint subqueries (which means
    we don't need document length) which was added in 1.4.8 - we now detect when
    all subqueries are different terms, or when all subqueries are
    non-overlapping wildcards.  The second case is what QueryParser produces for
    a wildcard or partial query with a query prefix which maps to more than one
    term prefix.
  + glass backend:
  * Handle an empty value slot lower bound gracefully.  This shouldn't happen for
    a non-empty slot, but has been reported by a notmuch user so it seems there
    is (or perhaps was as the database was several years old) a way it can come
    about.  We now check for this situation and set the smallest possible valid
    lower bound instead, so other code assuming a valid lower bound will work
    correctly.
  + chert backend:
  * Handle an empty value slot lower bound gracefully, equivalent to the change
    made for glass.
  + documentation:
  * HACKING: We no longer use auto_ptr<>.
  * NEWS: Correct factual error in old entry - the 0.4.1 release was Open Muscat
    not OmSee (the OmSee name was only applied after that final release was made,
    and only used internally to BrightStation).
  + portability:
  * Suppress more clang -Wself-assign-overloaded warnings in testcases which are
    deliberately testing handling of self-assignment.
  * Add missing includes of <cerrno>.
  + debug code:
  * When configured with --enable-log, the O_SYNC flag was always specified when
    opening the logfile, with the intention that the most recent log entries
    wouldn't get lost if there was a crash, but O_SYNC can incur a significant
    performance overhead and most debugging is not of such crashes.  So we no
    longer specify O_SYNC by default, but you can now request synchronous logging
    by including %! anywhere in the filename specified with XAPIAN_DEBUG_LOG
    (the %! is replaced with the empty string).  We also now use O_DSYNC if
    available in preference to O_SYNC, since the mtime of the log file isn't
    important.
- Update to 1.4.10:
  + 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.
  * 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.
  * 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.
  * 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.
  + 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.
  + 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).

- Update to 1.4.17:
  + API:
  * Database::get_average_length(): Add this as an alias for Database::get_avlen().
    In git master we've added this as a preferred new name - adding it to 1.4.x too
    will make it easier for users to update to using this.
  * Database::get_spelling_suggestion(): Optimise edit distance initialisation
    loop to significantly reduce the cost of a typical edit distance calculation.
  * Fix query expansion on sharded databases.  The mechanism for passing in which
    shard a TermList is from wasn't hooked up and as a result we'd always think
    it's from the first shard, meaning the statistics would be wrong and that our
    suggested terms may not have been as good as they should be in this
    situation.
  * Enquire::get_eset(): Use string::compare() to avoid 1/3 of the string compares
    on average.
  + documentation:
  * Update doxygen HTML headers and footers to resolve issues with some
    interactive features of the API docs not working.  Reported by Enrico Zini.
  * Stop specifying obsolete doxygen settings PERL_PATH and MSCGEN_PATH.
  * Clarify API docs for MSet::get_termfreq() to make it clear that this
    considers all documents in the database, not only those that matched the
    searched (it would sometimes be useful to be able to report the number of
    occurrences of a term in the matched documents, but it's not something we
    currently keep track of).  Reported by Tadeusz So?nierz and Peter Salomonsen.

- update to 1.4.16:
  * MSet::snippet(): The snippet now includes trailing punctuation which carries
    meaning or gives useful context.  See
    https://github.com/xapian/xapian/pull/180, reported by Robert Stepanek.
  * MSet::snippet(): Fix segfault generating snippet from default-constructed
    MSet.  This probably isn't something you'd typically do, but it shouldn't
    crash.  Found during extended testing of #803 (which only affected git
    master) which was reported by Robert Stepanek.
  * Remove trailing full stop from exception messages.  We conventionally don't
    include one, but a few cases didn't follow that convention.
  testsuite:
  * Replace direct use of ftime() which gives deprecation warnings with recent
    mingw.  Reported by srinivasyadav22.
  matcher:
  * Fix segfault in rare cases in the query optimiser.  We keep a pointer to the
    most recent posting list to use as a hint for opening the next posting list,
    but the existing mechanism to take ownership of this hint had a flaw.  We now
    invalidate the hint in situations where it might be indirectly deleted which
    is safe, but somewhat conservative.
  * Improve the optimisation of an always-matching OP_VALUE_GE to also take
    effect when the value slot's lower bound is equal to the limit of the
    OP_VALUE_GE.  Patch from boda sadalla.
  glass backend:
  * Report the correct errno value if commit() fails.  We were potentially
    reporting ENOENT from an unlink() call cleaning up a temporary file prior to
    throwing the exception instead.
  documentation:
  * Fix missing menus in API documentation.  Newer doxygen generates .js files
    which we also need to distribute and install.  Reported by sec^nd on #xapian.
  * Note OP_FILTER ignored subquery bug fixed in 1.4.15 as present in 1.4.14 and
    older.
  portability:
  * Use our own autoconf cache variable namespace (xo_cv_ prefix instead of
    ac_cv_) to avoid colliding with standard autoconf macro use if config.site or
    a shared config.cache is used.  The former case caused a build failure for
    the OpenBSD port with 1.4.15, reported by Lucas R.
  * Use clock_gettime() and nanosleep() under modern mingw as these allow higher
    precision than what we previously used.

- Update to version 1.4.15:
  + API:
  * Database::check(): Fix checking of replication changesets.
    This reverts a change incorrectly made in 1.3.7.
  * Database::locked(): Return false instead of true for a closed inmemory DB.
  * Database::commit(): If commit() failed with an exception while trying to add
    pending changes (e.g. InvalidArgumentError due to a long term containing zero
    bytes) then a subsequent commit() on the same object would throw the same
    exception.  Now we clear the pending changes in this situation (like we
    already did for failure at other stages in the commit).  This bug remains
    unfixed for the chert backend as it's harder to fix there and the effort to
    fix it and extra risk of breakage don't seem justified for a backend we
    recommend people migrate away from.
  * QueryParser::parse_query(): Optimise parsing of multi-word synonyms.
  + Testsuite fixes.
  + matcher:
  * Hoist positional check above OP_FILTER.
  * Handle OP_FILTER with more than two subqueries correctly.  Previously we'd
    only check the first two subqueries in some situations.
  + remote backend:
  * For a remote WritableDatabase, the client now keeps track of whether there
    are pending changes, and if there aren't then we now do nothing for commit()
    or cancel() calls.  In particular this saves a message exchange when the
    WritableDatabase destructor is called when changes have already been
    committed with an explicit call to commit() (which is what we recommend
    doing, since with an explicit call to commit() you get to see any exception
    which gets thrown).
  * When closing a remote prog WritableDatabase, previously an exception could
    leave the remote connection open with the remote server running, and we'd
    then wait for the specified timeout before closing the connection.  Now we
    close the connection before letting the exception propagate.
  * Don't swallow exceptions from Database::close() on a remote database.  If
    we aren't in a transaction and so try to commit() and that fails then
    previously the caller would have no indication of the failure.
  * Fix handling the reported term weight when remote shards are searched.
    Fixes 5 XFAILs in the testsuite.
  * Add missing space to mismatching protocol versions error message.
  + build system:
  * Fix to build when configured with --disable-backend-remote, broken by changes
    in 1.4.14.  Fixes #797, reported by ????? ????????.
  * The clang and icc compilers both define __GNUC__, which led our ABI mismatch
    message to report them as "g++" with a bogus version (the version of GCC that
    these compilers advertise themselves as, which for clang is always 4.2.0) -
    now we report clang++ or icc along with the actual version of that compiler.
  + updated documentation.

- Update to 1.4.14:
  * API:
    + Xapian::QueryParser: Handle "" inside a quoted phrase better.  In a quoted
    boolean term, "" is treated as an escaped ", so handle it in a compatible way
    for quoted phrases.  Previously we'd drop out of the phrase and start a new
    phrase.  Fixes #630, reported by Austin Clements.
    + Xapian::Stem: The constructor which takes a stemmer name now takes an
    optional second bool parameter - if this is true, then an unknown stemmer
    name falls back to using the "none" stemmer instead of throwing an exception.
    This allows simply constructing a stemmer from an ISO language code without
    having to worry about whether there's a stemmer for that language, and
    without having to handle an exception if there isn't.
    + Xapian::Stem: Fix a bug with handling 4-byte UTF-8 sequences which
    potentially affects most of the stemmers.  None of the stemmers work in
    languages where 4-byte UTF-8 sequences are part of the alphabet, but this
    bug could result in invalid UTF-8 sequences in terms generated from text
    containing high Unicode codepoints such as emoji, which can cause issues (for
    example, in some language bindings).  Fix synced from Snowball git post
    2.0.0.
    + Xapian::Stem: Add a new is_none() method which tests if this is a "none"
    stemmer.
    + Xapian::Weight: The total length of all documents is now made available to
    Xapian::Weight subclasses, and this is now used by DLHWeight, DPHWeight and
    LMWeight.  To maintain ABI compatibility, internally this still fetches the
    average length and the number of documents, multiplies them, then rounds the
    result, but in the next release series this will be handled directly.
    + Xapian::Database::locked() on an inmemory database used to always return
    false, but an inmemory Database is always actually a WritableDatabase
    underneath, so now we always report true in this case because it's really
    always report being locked for writing.
  + testsuite:
  * Fix failing multi_glass_remoteprog_glass tests on x86.  When the tests are
    run under valgrind, remote servers should be run using the runsrv wrapper
    script, but this wasn't happening for remote servers in multi-databases - now
    it is.  Also, previously runsrv only used valgrind for the remote for an x86
    build that didn't use SSE, but it seems there are x87 instructions in libc
    that are affected by valgrind not providing excess precision, so do this for
    x86 builds which use SSE too.  Together these changes fix failures of
    topercent2, xor2, tradweight1 under backend multi_glass_remoteprog_glass on
    x86.
  * Fix C++ One-Definition Rule (ODR) violation in testsuite code.  Two different
    source files linked into apitest were each defining a different `struct
    test`.  Wrap each in an anonymous namespace to localise it to the file it is
    defined and used in.  This was probably harmless in practice, unless trying
    to build with Link-Time Optimisation or similar (which is how it was
    detected).
  * Test all language codes in stemlangs1.  The testsuite hardcodes a list of
    supported language codes which hadn't been updated since 2008.
  * Improve DateRangeProcessor test coverage.
  + matcher:
  * Handle pruning under a positional check.  This used to be impossible, but
    since 1.4.13 it can happen as we now hoist AND_NOT to just below where we
    hoist the positional checks.  The code on master already handles pruning here
    so this bug is specific to the RELEASE/1.4 branch.
  * When searching with collapsing over multiple shards, at least some of which
    are remote, uncollapsed_upper_bound could be too low and
    uncollapsed_lower_bound too high.  This was causing assertion failures in
    testcases msize1 and msize2 under test harness backends
    multi_glass_remoteprog_glass and multi_remoteprog_glass.
  * Internally we no longer calculate a bogus total_term_count as the sum of
    total_length * doc_count for all shards.  Instead we just use the sum of
    total_length, which gives the total number of term occurrences.  This change
    should improve the estimated collection_freq values for synonyms.
  * Several places where we might divide zero by zero in a database where wdf was
    always zero have been fixed.
  + build system:
  * configure: Stop using AC_FUNC_MEMCMP.  The autoconf manual marks it as
    "obsolescent", and it seems clear that nobody's relying on it as we're
    missing the "'AC_LIBOBJ' replacement for 'memcmp'" which it would try to
    use if needed.
  + documentation:
  * HACKING: Replace release docs with pointer to the developer guide where they
    are now maintained.
  + portability:
  * Eliminate 2 uses of atoi().  These are potentially problematic in a
    multithreaded application if setlocale() is called by another thread at the
    same time.
  * Don't check __GNUC__ in visibility.h as the configure probe before defining
    XAPIAN_ENABLE_VISIBILITY checks that the visibility attributes work.  This
    probably makes no difference in practice, as all compilers we're aware of
    which support symbol visibility also define __GNUC__.
  * Document Sun C++ requires --disable-shared.
- Update to 1.4.13:
  + API:
  * Fix write one past end of std::vector on certain QueryParser parser errors.
    This is undefined behaviour, but the write was always into reserved space, so
    in practice we'd actually get away with it (it was noticed because it
    triggers an error when running under ubsan and using libc++).
  * MSet::get_matches_estimated(): Improve rounding of result - a bug meant we
    would almost always round down.
  * Optimise test for UTF-8 continuation character.  Performing a signed char
    comparison shaves an instruction or two on most architectures.
  * Database::get_revision(): Return revision 0 for a Database with no shards
    rather that throwing InvalidOperationError.
  * DPHWeight: Avoid dividing by 0 when searching a sharded database when one
    shard is empty.  The result wasn't used in this case, but it's still
    undefined behaviour.  Detected by UBSan.
  + testsuite:
  * The "singlefile" test harness backend manager now creates databases by
    compacting the corresponding underlying backend database (creating it first
    if need be) rather than always creating a temporary database to compact.
  * Enable compaction testcases for multi and singlefile test harness backends.
  * Add generated database support for remoteprog and remotetcp test harness
    backends.
  * Add test harness support for running testcases using a multi database
    comprised of one local and one remote shard, or two remote shards.
  * Check if removing existing multi stub failed.  Previously if removing an
    existing stub failed, the test harness would create a temporary new stub and
    then try to rename it over the old one, which will always fail on Microsoft
    Windows.
  * Wait for xapian-tcpsrv processes to finish before moving on to the next
    testcase under __WIN32__ like we already do on POSIX platforms.
  + matcher:
  * Optimise OP_AND_NOT better.  We now combine its left argument with other
    connected and-like subqueries, and gather up and hoist the negated subqueries
    and apply them together above the combined and-like subqueries, just below
    any positional filters.
  * Optimise OP_AND_MAYBE better.  We now combine its left argument with other
    connected and-like subqueries, and gather up and hoist the optional
    subqueries and apply them together above the combined and-like subqueries and
    any hoisted positional filters.
  * Treat all BoolWeight queries as scaled by 0 - we can optimise better if we
    know the query is unweighted.
  + glass backend:
  * Allow zlib compression to reduce size by one byte.  We were specifying an
    output buffer size one byte smaller than the input, but it appears zlib won't
    use the final byte in the buffer, so we actually need to pass the input size
    as the output buffer size.
  * Only try to compress Btree item values > 18 bytes, which saves CPU time
    without sacrificing any significant size savings.
  + remote backend:
  * Fix match stats when searching with collapsing over multiple shards and at
    least some shards are remote.
  * Ignore orphaned remote protocol replies which can happen when searching with
    a remote shard if an exception is thrown by another shard.
  * Wait for xapian-progsrv child to exit when a remote Database or
    WritableDatabase object is closed under __WIN32__ like we already do for
    POSIX platforms.
  + documentation:
  * Correct documentation of initial messages in replication protocol.
  + tools:
  * quest: Report bounds and estimate of number of matches.
  * xapian-delve: Improve output when database revision information is not
    available.  We now specially handle the cases of a DB with multiple shards
    and a backend which doesn't support get_revision().
  + portability:
  * Fix warning from GCC 9 with -Wdeprecated-copy (which is enabled by -Wextra)
    if a reference to an Error object is thrown.
  * Suppress GCC warning in our API headers when compiling code using Xapian with
    GCC and -Wduplicated-branches.
  * Mark some internal classes as final (following GCC -Wsuggest-final-types
    suggestions to allow some method calls to be devirtualised).
  * Fix to build with --enable-maintainer-mode and Perl < 5.10, which doesn't
    have the `//=` operator.  It's unlikely developers will have such an old
    Perl, but the mingw environment on appveyor CI does.  The use of `//=` was
    introduced by changes in 1.4.10.
- Update to 1.4.12:
  + API:
  * Xapian::PostingSource: When a PostingSource without a clone() method is used
    with a Database containing multiple shards, the documented behaviour has
    always been that Xapian::InvalidOperationError is thrown.  However, since at
    least 1.4.0, this exception hasn't been thrown, but instead a single
    PostingSource object would get used for all the shards, typically leading to
    incorrect results.  The actual behaviour now matches what was documented.
  * Xapian::Database: Add size() method which reports the number of shards.
  * Xapian::Database::check(): You can now pass a stub database which will check
    all the databases listed in it (or throw Xapian::UnimplementError for
    backends which don't support checking).
  * Xapian::Document: When updating a document use a emplace_hint() to make the
    bulk insertion O(n) instead of O(nlog(n)), and use std::move() to avoid
    copying OmDocumentTerm objects.
  * Xapian::Query: Add missing get_unique_terms_end() method.
  * Xapian::iterator_valid(): Implement for Utf8Iterator
  + testsuite:
  * Fix keepalive1 failures on some platforms.  On some platforms a timeout
    gives NetworkTimeoutError and on others NetworkError - since 1.4.10 changed
    to checking the exact exception type, keepalive1 has been failing on the
    former set of platforms.  We now just check for NetworkError or a subclass
    here (since NetworkTimeoutError is a subclass of NetworkError).
  * Run cursordelbug1 testcase with multi databases too.
  + matcher:
  * Ownership of PostingSource objects during the match now makes use of the
    optional reference-counting mechanism rather than a separate flag.
  + remote backend:
  * Fix remote protocol design bug.  Previously some messages didn't send a reply
    but could result in an exception being sent over the link.  That exception
    would then get read as a response to the next message instead of its actual
    response so we'd be out of step.
    This fix necessitated a minor version bump in the remote protocol (to 39.1).
    If you are upgrading a live system which uses the remote backend, upgrade the
    servers before the clients.
  * Fix socket leaks on errors during opening a database.
  * Don't close remote DB socket on receiving EOF as the levels above won't
    know it's been closed and may try to perform operations on it, which would be
    problematic if that fd gets reused in the meantime.  Leaving it open means
    any further operations will also get EOF.
  * We add a wrapper around the libc socket() function which deals with the
    corner case where SOCK_CLOEXEC is defined but socket() fails if it is
    specified (which can happen with a newer libc and older kernel).
    Unfortunately, this wrapper wasn't checking the returned value from socket()
    correctly, so when SOCK_CLOEXEC was specified and non-zero it would create
    the socket() with SOCK_CLOEXEC, then leak that one and create it again
    without SOCK_CLOEXEC.  We now check the return value properly.
  * Fix potential infinite loop in ValueCountMatchSpy::merge_results() if passed
    serialised results with extra data appended (which shouldn't happen in normal
    use).
  + build system:
  * Current versions of valgrind result in false positives on current versions of
    macOS, so on this platform configure now only enables use of valgrind if it's
    specified explicitly.
  * Refactor macros to probe for compiler flags so they automatically cache
    their results and consistently report success/failure.
  * Rename our custom TYPE_SOCKLEN_T macro to XAPIAN_TYPE_SOCKLEN_T.  The
    AX_TYPE_SOCKLEN_T macro defines an alias of TYPE_SOCKLEN_T for itself which
    means it can get used instead in some situations, but it isn't compatible
    with our macro.  We can't just switch to AX_TYPE_SOCKLEN_T as it doesn't
    handle cases we need, so just rename our macro to avoid potential problems.
  + documentation:
  * Improve API documentation for Xapian::Query class.  Add missing doc
    comments and improve some of the existing ones.
  * Add Unicode consortium names and codes for categories from Chapter 4, Version
    11 of the Unicode standard.  Patch from David Bremner.
  * Improve configure --help output - drop "[default=no]" for --enable-*
    options which default off.
    ????????.
  * Fix API documentation typo - Query::op (the type) not op_ (a parameter name).
  * Note which version Document::remove_postings() was added in.
  * In the remote protocol documentation, MSG_REPLACEDOCUMENTTERM was documented
    as not having a reply, but actually REPLY_ADDDOCUMENT is sent.
  * Update list of <xapian/iterator.h> users.
  + tools:
  * copydatabase: A change in 1.4.6 which added support for \ as directory
    separator on platforms where that's the norm broke the code in copydatabase
    which removes a trailing slash from input databases.
  + portability:
  * Add missing '#include <cstring>'.
  * Fix str() helper function when converting the most negative value
    of a signed integer type.
  * Avoid calling close() on fd we know must actually be a WIN32 SOCKET.
  * Include <ios> not <iomanip> for std::boolalpha.
  * Rework setenv() compatibility handling.  Now that Solaris 9 is dead we can
    assume setenv() is provided by Unix-like platforms (POSIX requires it).  For
    other platforms, provide a compatibility implementation of setenv() which
    so the compatibility code is encapsulated in one place rather than replicated
    at every use.
  * Fix maintainer-mode builds on Solaris where /bin/tr is not POSIX compliant.
    We now use the simple workaround suggested by the autoconf manual.
  * Improve support for Sun C++:
    + Suppress unhelpful warning for lambda with multiple return statements.
    + Enable reporting the tags corresponding to warnings, which we need
    to know in order to suppress any new unhelpful warnings.
    + Adjust our workaround for bug with this compiler's <cmath> header to avoid
    a compiler warning.
    + Use -xldscope=symbolic for Sun C++.  This flag is roughly equivalent to
  - Bsymbolic-functions which we've probed for with GNU ld since Xapian 1.0.0.
- Update to 1.4.11:
  + API:
  * MSet::SNIPPET_CJK_NGRAM - new flag for use with MSet::snippet() to enable
    support for selecting and highlighting snippets which works with the
    QueryParser and TermGenerator FLAG_CJK_NGRAM flags.  This mode can also be
    enabled by setting environment variable XAPIAN_CJK_NGRAM to a non-empty
    value.  (There was nominally already support for XAPIAN_CJK_NGRAM in
    MSet::snippet(), but it didn't work usefully - the highlighting added was all
    empty start/end pairs at the end of the span of CJK characters containing the
    CJK ngram terms, which to the user would typically look like it was selecting
    the end of the text and not highlighting anything).
  * Deprecate XAPIAN_CJK_NGRAM environment variable.  There are now flags which
    can be used instead in all cases, and there's sadly no portable thread-safe
    way to read an environment variable so checking environment variables is
    problematic in library code that may be used in multithreaded programs.
  * Query::OP_ELITE_SET currently incorrectly recursively flattens any OP_OR (or
    OP_OR-like) subqueries into the list of subqueries it selects from - until
    that's fixed, we now select from the full exploded list rather than the last
    n (where n is the number of direct subqueries of the OP_ELITE_SET).
  + testsuite:
  * Testcases which need a generated database now get run with a sharded
    database.
  * Avoid using strerror() in the testsuite which removes an obstacle to running
    tests in parallel in separate threads.
  + matcher:
  * Extend detection of cases of OP_SYNONYM with disjoint subqueries (which means
    we don't need document length) which was added in 1.4.8 - we now detect when
    all subqueries are different terms, or when all subqueries are
    non-overlapping wildcards.  The second case is what QueryParser produces for
    a wildcard or partial query with a query prefix which maps to more than one
    term prefix.
  + glass backend:
  * Handle an empty value slot lower bound gracefully.  This shouldn't happen for
    a non-empty slot, but has been reported by a notmuch user so it seems there
    is (or perhaps was as the database was several years old) a way it can come
    about.  We now check for this situation and set the smallest possible valid
    lower bound instead, so other code assuming a valid lower bound will work
    correctly.
  + chert backend:
  * Handle an empty value slot lower bound gracefully, equivalent to the change
    made for glass.
  + documentation:
  * HACKING: We no longer use auto_ptr<>.
  * NEWS: Correct factual error in old entry - the 0.4.1 release was Open Muscat
    not OmSee (the OmSee name was only applied after that final release was made,
    and only used internally to BrightStation).
  + portability:
  * Suppress more clang -Wself-assign-overloaded warnings in testcases which are
    deliberately testing handling of self-assignment.
  * Add missing includes of <cerrno>.
  + debug code:
  * When configured with --enable-log, the O_SYNC flag was always specified when
    opening the logfile, with the intention that the most recent log entries
    wouldn't get lost if there was a crash, but O_SYNC can incur a significant
    performance overhead and most debugging is not of such crashes.  So we no
    longer specify O_SYNC by default, but you can now request synchronous logging
    by including %! anywhere in the filename specified with XAPIAN_DEBUG_LOG
    (the %! is replaced with the empty string).  We also now use O_DSYNC if
    available in preference to O_SYNC, since the mtime of the log file isn't
    important.
- Update to 1.4.10:
  + 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.
  * 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.
  * 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.
  * 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.
  + 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.
  + 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).

- Update to 1.4.9:
  * API:
    + Document::add_posting(): Fix bugs with the change in 1.4.8 to more
    efficiently handle insertion of a batch of extra positions in ascending
    order.  These could lead to missing positions and corrupted encoded
    positional data.
  * remote backend:
    + Avoid hang if remote connection shutdown fails by not waiting for the
    connection to close in this situation.  Seems to fix occasional hangs seen on
    macOS.  Patch from Germán M. Bravo.
- Update to 1.4.8:
  * API:
    + QueryParser,TermGenerator: Add new stemming mode STEM_SOME_FULL_POS.
    This stores positional information for both stemmed and unstemmed terms,
    allowing NEAR and ADJ to work with stemmed terms.  The extra positional
    information is likely to take up a significant amount of extra disk space so
    the default STEM_SOME is likely to be a better choice for most users.
    + Database::check(): Fetch and decompress the document data to catch problems
    with the splitting of large data into multiple entries, corruption of the
    compressed data, etc.  Also check that empty document data isn't explicitly
    stored for glass.
    + Fix an incorrect type being used for term positions in the TermGenerator API.
    These were Xapian::termcount but should be Xapian::termpos.  Both are
    typedefs for the same 32-bit unsigned integer type by default (almost always
    "unsigned int") so this change is entirely compatible, except that if you
    were configuring 1.4.7 or earlier with --enable-64bit-termcount you need to
    also use the new --enable-64bit-termpos configure option with 1.4.8 and up or
    rebuild your applications.  This change was necessary to make
  - -enable-64bit-termpos actually useful.
    + Add Document::remove_postings() method which removes all postings in a
    specified term position range much more efficiently than by calling
    remove_posting() repeatedly.  It returns the number of postings removed.
    + Fix bugs with handling term positions >= 0x80000000.  Reported by Gaurav
    Arora.
    + Document::add_posting(): More efficiently handle insertion of a batch of
    extra positions in ascending order.
    + Query: Simplify OP_SYNONYM with single OP_WILDCARD subquery by converting to
    OP_WILDCARD with combiner OP_SYNONYM, which means such cases can take
    advantage of the new matcher optimisation in this release to avoid needing
    document length for OP_WILDCARD with combiner OP_SYNONYM.
  * testsuite:
    + Catch and report std::exception from the test harness itself.
    + apitest: Drop special case for not storing doc length in testcase postlist5 -
    all backends have stored document lengths for a long time.
    + test_harness: Create directories in a race-free way.
  * matcher:
    + Avoid needing document length for an OP_WILDCARD with combiner OP_SYNONYM.
    We know that we can't get any duplicate terms in the expansion of a wildcard
    so the sum of the wdf from them can't possibly exceed the document length.
    + OP_SYNONYM: No longer tries to initialise weights for its subquery, which
    should reduce the time taken to set up a large wildcard query.
    + OP_SYNONYM: Fix frequency estimates when OP_SYNONYM is used with a
    subquery containing OP_XOR or OP_MAX - in such cases the frequency
    estimates for the first subquery of the OP_XOR/OP_MAX were used for
    all its subqueries.  Also the estimated collection frequency is
    now rounded to the nearest integer rather than always being rounded
    down.
  * glass backend:
    + Revert change made in 1.4.6:
    Enable glass's "open_nearby_postlist" optimisation (which especially helps
    large wildcard queries) for writable databases without any uncommitted
    changes as well.
    The amended check isn't conservative enough as there may be postlist changes
    in the inverter while the table is unmodified.  This breaks testcase
    T150-tagging.sh in notmuch's testsuite, reported by David Bremner.
    + When indexing a document without any terms we now avoid some unnecessary work
    when storing its termlist.
  * build system:
    + New --enable-64bit-termpos configure option which makes Xapian::termpos a
    64-bit type and enables support for storing 64-bit termpos values in the
    glass backend in an upwardly compatible way.  Few people will actually want
    to index documents more than 4 billion words long, but the extra numbering
    space can be helpful if you want to use term positions in "interesting" ways.
    + Hook up configure --disable-sse/--enable-sse=sse options for MSVC.
    + Fix configure probes for builtin functions for clang.  We need to specify the
    argument types for each builtin since otherwise AC_CHECK_DECLS tries to
    compile code which just tries to take a pointer to the builtin function
    causing clang to give an error saying that's not allowed.  If the argument
    types are specified then AC_CHECK_DECLS tries to compile a call to the
    builtin function instead.
  * documentation:
    + Fix documentation comment typo.
  * tools:
    + xapian-delve: Test for all docs empty using get_total_length() which is
    slightly simpler internally than get_avlength(), and avoids an exact floating
    point equality check.
  * examples:
    + quest: Support --weight=coord.
    + xapian-pos: New tool to show term position info to help debugging when using
    positional information in more complex ways.
  * portability:
    + Fix undefined behaviour from C++ ODR violation due to using the same name
    two different non-static inline functions.  It seems that with current GCC
    versions the desired function always ends up being used, but with current
    clang the other function is sometimes used, resulting in database corruption
    when using value slots in docid 16384 or higher with the default glass
    backend.  Patch from Germán M. Bravo.
    + Suppress alignment cast warning on sparc Linux.  The pointer being cast is to
    a record returned by getdirentries(), so it should be suitable aligned.
    + Drop special handling for Compaq C++.  We never actually achieved a working
    build using it, and I can find no evidence that this compiler still exists,
    let alone that it was updated for C++11 which we now require.
    + Create new database directories in race-free way.
    + Avoid throwing and handling an exception in replace_document() when
    adding a document with a specified docid which is <= last_docid but currently
    unused.
    + Use our portable code for handling UUIDs on all platforms, and only use
    platform-specific code for generating a new UUID.  This fixes a bug with
    converting UUIDs to and from string representation on FreeBSD, NetBSD and
    OpenBSD on little-endian platforms which resulted in reversed byte order in
    the first three components, so the same database would report a different
    UUID on these platforms compared to other platforms.  With this fix, the
    UUIDs of existing databases will appear to change on these platforms
    (except in rare "palindronic" cases).  Reported by Germán M. Bravo.
    + Fix to build with a C++17 compiler.  Previously we used a "byte" type
    internally which clashed with "std::byte" in source files which use
    "using namespace std;".  Fixes #768, reported by Laurent Stacul.
    + Adjust apitest testcase stubdb2 to allow for NetBSD oddity: NetBSD's
    getaddrinfo() in IPv4 mode seems to resolve ::1 to an IPv4 address on the
    local network.
    + Avoid timer_create() on OpenBSD and NetBSD.  On OpenBSD it always fails with
    ENOSYS (and there's no prototype in the libc headers), while on NetBSD it
    seems to work, but the timer never seems to fire, so it's useless to us (see
    [#770]).
    + Use SOCK_NONBLOCK if available to avoid a call to fcntl().  It's supported by
    at least Linux, FreeBSD, NetBSD and OpenBSD.
    + Use O_NOINHERIT for O_CLOEXEC on Windows.  This flag has essentially the same
    effect, and it's common in other codebases to do this.
    + On AIX O_CLOEXEC may be a 64-bit constant which won't fit in an int.  To
    workaround this stupidity we now call the non-standard open64x() instead
    of open() when the flags don't fit in an int.
    + Add functions to add/multiply with overflow check.  These are implemented
    with compiler builtins or equivalent where possible, so the overflow check
    will typically just require a check of the processor's overflow or carry
    flag.

- Update to 1.4.7:
  * API:
    + Database::check(): Fix bogus error reports for documents with length
    zero due to a new check added in 1.4.6 that the doclength was between the
    stored upper and lower bounds, which failed to allow for the lower bound
    ignoring documents with length zero (since documents indexed only by
    boolean terms aren't involved in weighted searches).
    + Query: Use of Query::MatchAll in multithreaded code causes problems
    because the reference counting gets messed up by concurrent updates.
    Document that Query(string()) should be used instead of MatchAll in
    multithreaded code, and avoid using it in library code.
  * Stem:
    + Stemming algorithms added for Irish, Lithuanian, Nepali and Tamil.
    + Merge Snowball compiler changes which improve code generation.
    + Merge optimisations to the Arabic and Turkish stemmers.
  * testsuite:
    + Fix duplicate test in apitest closedb10 testcase.
  * See also https://xapian.org/docs/xapian-core-1.4.7/NEWS

- Fix RPM groups.
- Trim bias and redundancies from description.

- Update to 1.4.6:
  * API classes now support C++11 move semantics when using a compiler which
    we are confident supports them (currently compilers which define
    __cplusplus >= 201103 plus a special check for MSVC 2015 or later).
    C++11 move semantics provide a clean and efficient way for threaded code to
    hand-off Xapian objects to worker threads, but in this case it's very
    unhelpful for availability of these semantics to vary by compiler as it
    quietly leads to a build with non-threadsafe behaviour.  To address this,
    user code can #define XAPIAN_MOVE_SEMANTICS before #include <xapian.h> to
    force this on, and will then get a compilation failure if the compiler
    lacks suitable support.
  * MSet::snippet():
    + We were only escaping output for HTML/XML in some cases, which would
    potentially allow HTML to be injected into output (this fixes
    bnc#1099925, CVE-2018-0499).
    + Include certain leading non-word characters in snippets.  Previously we
    started the snippet at the start of the first actual word, but there are
    various cases where including non-word characters in front of the actual
    word adds useful context or otherwise aids comprehension.
  * Add MSetIterator::get_sort_key() method.  The sort key has always been
    available internally, but wasn't exposed via the public API before, which
    seems like an oversight as the collapse key has long been available.
  * Database::compact():
    + Allow Compactor::resolve_duplicate_metadata() implementations to delete
    entries.  Previously if an implementation returned an empty string this
    would result in a user meta-data entry with an empty value, which isn't
    normally achievable (empty meta-data values aren't stored), and so will
    cause odd behaviour.  We now handle an empty returned value by
    interpreting it in the natural way - it means that the merged result is
    to not set a value for that key in the output database.
    + Since 1.3.5 compacting a WritableDatabase with uncommitted changes throws
    Xapian::InvalidOperationError when compacting to a single-file glass
    database.  This release adds similar checks for chert and when compacting
    to a multiple-file glass database.
    + In the unlikely event that the total number of documents or the total
    length of all documents overflow when trying to compact a multi-database,
    we throw an exception.  This is now a DatabaseError exception instead of a
    const char* exception (a hang-over from before this code was turned into a
    public API in the library).
  * See also https://xapian.org/docs/xapian-core-1.4.6/NEWS