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Add Cygwin CI and stop installing unwanted plugins #2529

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merged 25 commits into from
Nov 8, 2022

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DWesl
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@DWesl DWesl commented Oct 13, 2022

This adds a CI job for my development platform, which will hopefully avoid issues like #2196 and #2446.

This also avoids installing test plugins (or any plugins if --without-plugin-dir is passed to configure), which is especially noticed by distribution package managers using a DESTDIR install: that issue was previously raised as #2431.

I tried to get CMake CI runs working on Cygwin and MinGW, but couldn't get any tests to pass on Cygwin or complete the build on MinGW; this is likely due to the problems highlighted in #2290.

Includes cross-compilation suggestion from this comment.

Also includes a few markdown cleanups that seem to have been fixed in other ways since I started working; let me know if you want to approach those changes differently

Replaces #2431; replaces #2440
Might close #2468
Might replace #2479
Might close #2396

They weren't in git; I'm assuming that's on purpose.
Most changes are to get plugins working.
libdispatchdreg.c went in in Unidata#2460,
after I'd done it here.

Summary of individual changes below.

BLD: Remove declspec(dllexport); in dreg.c.

By removing the explicit handling, the automatic handling
(equivalent to --export-all-symbols with recent GNU tools)
will be enabled again, so the generated library will have
more than one function exported.

BLD: Link plugins against libnetcdf on Cygwin.

BLD: Add AM_LDFLAGS to plugin _LDFLAGS to pass -no-undefined.

BLD: Link ncz*filters plugins against libnetcdf.

BLD: Add AM_LDFLAGS to test plugin _LDFLAGS.

Also move rpath from AM_LDFLAGS to test plugin _LDFLAGS.

TST: Don't run nczarr_test/run_specific_filters.sh on Cygwin.

It takes over half an hour to complete, where the others take a minute or less.

TST: Try to find the hanging Cygwin test.
…RARIES.

Don't install test plugins; don't install any plugins if not
requested.

DEV: Remove plugins installed to ALTPLUGINDIR.

These get put in the build tree if ENABLE_PLUGIN_DIR is not true.
I want to remove these first, then look into skipping the plugins
directory if plugins are disabled.

DEV: don't install plugins if there's no install dir

Still build them, since they might be needed for tests, but don't mark them for install.

BLD, FIX: Add -rpath to noinst plugin links.

Since I stopped installing the plugins, I need to manually add `-rpath` to their link line so `libtool` actually bothers linking them.
It's not exporting symbols at the moment, and I'd prefer to avoid -Wl,--export-all-symbols.
Attempting to add a filter to a netCDF file using `nccopy` results in
a file without `_Filter` attribute set.  I suspect this is a problem
with HDF5, but I don't remember why and never got around to testing
that.  The rest of the plugin tests pass, so I'm telling the test
runner to expect this one test to fail and see if there are other
failures.
Not sure why --disable-nczarr-filters doesn't exclude them, but let's check the rest of the functionality.
Mostly changing to Markdown files to a format Doxygen recognizes.
Probably unnecessary, but should avoid a warning and documents what happens.
It might be nice to be told when it starts passing.
This probably requires installing s3 on Cygwin.
Cygwin tests don't pass for no reason I can discern; MinGW tests don't
build, again for no reason I can discern.
@DWesl DWesl requested a review from WardF as a code owner October 13, 2022 14:25
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CLAassistant commented Oct 13, 2022

CLA assistant check
All committers have signed the CLA.

@DennisHeimbigner
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This PR will take some time to digest,
but thanks for doing this.

@@ -46,9 +48,24 @@ jobs:
run: cat libnetcdf.settings

- name: (Autotools) Build Library and Utilities
run: make -j 8 LDFLAGS="-no-undefined -Wl,--export-all-symbols"
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Why remove the -no-undefined?

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It's already in the Makefile.am, and I like having the flags necessary for things to build actually specified by the build system.

I tried removing -Wl,--export-all-symbols as well, but that led to a number of "unresolved reference to symbol nc..." errors at link time. I might be able to make more progress by specifying AM_CPPFLAGS=-DDLL_EXPORT -DDLL_NETCDF in the top-level Makefile.am so the source files properly specify __declspec(dllexport), but given that CMake fails to link I'm not sure that would be enough.

ltmain.sh
m4
missing
test-driver
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Are you sure that test--driver and ltmain.sh should be ignored?

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@DWesl DWesl Oct 13, 2022

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For the developers' git repository? Almost certainly. For release tarballs (made with make dist or make distcheck), no, they should absolutely be included.

On a related note, what is the policy on building GitHub's automatic repository tarballs? Do you assume everyone has a full Autotools or CMake install (the assumption I made here) or only POSIX Make and Bourne Shell (the assumption made for Autotools release tarballs)?

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We turn on maintainer mode in the release branches, so full installs should not be required. A lot of the generated files are explicitly kept out of version tracking, and only added to the 'v[xyz]-release' branch which gets tagged.

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This will help keep the generated files out of version tracking, but will make adding them to the release branches a bit trickier unless the release branches drop this part of the .gitignore file; should I add a comment at the start to that effect?

E.g.

# Autotools-generated files
# Delete this section on release branches

MINGW*) ISMINGW=yes;;
MSYS*) ISMINGW=yes;;
esac
AC_CANONICAL_HOST
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I vaguely recall that we had problems in the past using AC_CANONICAL_HOST.
Wish I could remember the details.

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It won't auto-discover MSVC, but it should help with #2396, since the current assumption made in using uname directly is that nobody will want to cross-compile at any time for any reason

@@ -28,6 +29,72 @@ static const char* driveletters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRS
/* Forward */
static int isAbsolutePath(const char* path);

#if !defined(nulldup) && !defined(HAVE_STRDUP)
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Not sure what is the point of this change. Also, I believe we have tried to
avoid use of inline because older versions of some C compilers do not support it.

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The point of this change is defining a fallback definition of nulldup in case strdup is not provided by the C runtime. I don't remember if that was a problem on Cygwin or MinGW (EDIT: given the commit, I suspect this is a MinGW problem, not a Cygwin problem), but the current definitions all assume that strdup will be provided if nulldup isn't.

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I tried adding inline, but since it wasn't in the declaration (or the other twenty definitions) the C compiler rejected it and I took it out of the definition.

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Good point about strdup; you might consider putting the body of the
alternate nulldup into a more general location such as libdispatch/dutil.c
or putting it into ncconfigure.h as a static function.

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Moved to include/ncconfigure.h


endif #ENABLE_FILTER_TESTING

if ENABLE_PLUGIN_DIR
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Have you tested this on the platforms we support?

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I've tested this on Cygwin and MinGW on my fork and locally.

I think you've also tested this, since this is basically the solution proposed in #2440.

I have a test for what this is trying to do (fix #2431) in the Cygwin CI (make install DESTDIR=/tmp/pretend-root && test ! -d /tmp/pretend-root/$(pwd), more or less); I could try to add a similar test to the installcheck target, but that might take a while.

I requested this when working on a branch,
rather than a pull request.
This is a PR now, so I should go back to how
things were before.
The command looks much more like test than
any command I can think of that would be called text.
@WardF WardF self-assigned this Oct 14, 2022
@WardF WardF added this to the 4.9.1 milestone Oct 14, 2022
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DennisHeimbigner commented Oct 14, 2022

OK, I think this is ok to merge subject to testing with Visual Studio.
[Update tested with visual studio (with filters off) and all tests passed]

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DWesl commented Oct 15, 2022

Do you want me to try to add MSVC testing to CI as part of this PR? CMake should be straightforward; Autotools will need help (specifically, someone telling me what values to specify for CC, CPP, and LD)

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I do note that the Mac build is currently failing for filters.

Removing -avoid-version seems to have broken MinGW and Cygwin but fixed MacOS.  Hopefully this gets everything working.
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DWesl commented Oct 27, 2022

Apparently -version-info is required for plugins on MacOS and breaks plugins on MinGW and Cygwin, which is not what I expected

Allow definition to be used in more places.
Should probably consolidate definition a few places.
The use of this function currently runs into problems with multiple definitions: once for each file including ncconfigure.h.  Defining this as static rather than extern should hide the definitions from each other.

static inline would still be closer to the definition as a macro, but that requires a #define to work on all platforms (not all compilers have inline yet).
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WardF commented Nov 8, 2022

Reviewing extant PR's to pull into v4.9.1-rc2; thanks a lot, I just noticed the checks hadn't run. Running now.

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WardF commented Nov 8, 2022

@DennisHeimbigner checks are passing, but you are more plugged into the cygwin ecosystem. Any blocking issues I'm not seeing, here? Otherwise I'll merge it later this afternoon :).

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I think my previous review holds, so it should be ok to merge it.

@WardF WardF merged commit e57e742 into Unidata:main Nov 8, 2022
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WardF commented Nov 8, 2022

Thanks @DennisHeimbigner !

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I am revisiting this because it is causing some problems.
Specifically, I do not understand why github action run_tests_cygin.yml contains the code below.
What is its purpose?

if [ -d "/tmp/pretend-root/$(pwd)" ];
then
find /tmp/pretend-root/$(pwd)
if [ $(find /tmp/pretend-root/$(pwd) -type f | wc -l) -gt 0 ]; then exit 1; fi
fi

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DWesl commented Mar 11, 2023

The original issue prompting this was that the test plugins were getting installed, reproducing the source directory in the install directory. This makes sure that neither the source directory nor any of its subdirectories gets installed. I'll look into the problems.

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DWesl commented Mar 11, 2023

I am revisiting this because it is causing some problems.

Could you elaborate on what problems you run into? I'm not finding any cases where only the Cygwin workflow fails, only ones that also fail on Ubuntu.

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The problem is that noinst causes my test filters to not get built at test time, hence those tests fail.
I am modifying the Makefile.am to use test_LTLIBRARIES and testdir instead. But am running up against
the above piece of code during github action execution.

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DWesl commented Mar 11, 2023

Found it here:
main...DennisHeimbigner:netcdf-c:s3lib.tmp#diff-72bb278809ac7dbe0329f064d73cbe73a5dda1d45ea85c288f5b9d3f3cbc07fbL39-R43
you tell Automake you do not have any test libraries, no libraries you don't want to install, only libraries you want to install to the source directory. Here
main...DennisHeimbigner:netcdf-c:s3lib.tmp#diff-72bb278809ac7dbe0329f064d73cbe73a5dda1d45ea85c288f5b9d3f3cbc07fbL123-R125
you tell Automake that you do, in fact, want to install the test plugins, to a rather odd installation directory under what would be the source directory if it were installed at root on the same computer.

The test is checking whether Autotools is installing anything to that rather odd installation directory, and fails, as it is supposed to, when it finds that Autotools has installed the test plugins to that directory, rather than not installing them at all, as you likely intended.

The test is there because many distribution package managers use DESTDIR to install to an empty directory so that creating an archive to install on another computer looks like cd ${DESTDIR}; tar caf ../netcdf-c-${VERSION}.tar.gz *. They would rather not install the test plugins, not least because the people who install the package from their archive would not have the rest of the files to run the tests.

When you change from a target that installs to one that doesn't (i.e. check_LTLIBRARIES, which runs at make check time, or noinst_LTLIBRARIES, which runs at make time), you will need to add -rpath /tmp or similar to the _LDFLAGS of the test plugins, otherwise Autotools will assume the library is for linking into a test executable and not bother creating a shared library (after all, the flag for saying "I want a shared library I can dlopen later" is -rpath rather than -shared, because that isn't the least bit confusung to anyone)

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DWesl commented Mar 11, 2023

The problem is that noinst causes my test filters to not get built at test time, hence those tests fail.

That is very odd, since noinst_LTLIBRARIES builds at the same time as everything else (i.e. when you run make). I can't see any reason that wouldn't run before make check, though you could try check_LTLIBRARIES, which would build the library before running the tests.

Can I see the test logs where noinst_LTLIBRARIES fails?

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Nevertheless. It does not work.

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If there was some way to force DESTDIR to not be applied to the testdir, then things would work ok, I think.

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DWesl commented Mar 11, 2023

Nevertheless. It does not work.

The only thing I can think of is maybe someone added new test plugins and forgot to add -rpath /tmp to their _LDFLAGS, so Autotools just build a static library, which the test couldn't dlopen.

It would be more convenient if Autotools had a sensible flag for to tell it we're building a test plugin, rather than it deciding -rpath is the flag to use to tell it "I want to build something I can dlopen later, not just something I can link to a test executable".

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AFAIK using your solution, the test filters never get built at make check time in any form, static or dynamic.

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DWesl commented Mar 11, 2023

AFAIK using your solution, the test filters never get built at make check time in any form, static or dynamic.

That is very odd. I'd like to check this; where are the plugin tests that are failing? I put all test plugins in check_LTLIBRARIES. I built and ran the tests locally when creating this PR, so those should be passing.

The other option is reverting this PR and using the original version of #2431, allowing Autotools to install the files to wherever and then removing them right after. /tmp/testplugins might be a convenient install directory for the test plugins, since the tests use the versions in the current directory.

I still like the "don't install the test plugins in the first place" option, which is why I made this PR. It did take a fair bit of digging (discussion around this from here to here to find out that just adding the test libraries to check_LTLIBRARIES wouldn't build the shared libraries the tests need, since the tests dlopen the plugins rather than linking to them; you need to add -rpath to the corresponding lib__plugin_name_la_LDFLAGS variables, which is done automatically for all _LTLIBRARIES variables except check_LTLIBRARIES and noinst_LTLIBRARIES.

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DWesl commented Mar 13, 2023

I'm attempting to reproduce this with your branch s3lib.tmp, and the following configure line:

../configure --enable-doxygen --enable-dot --disable-static --enable-shared -C --no-create --no-recursion --enable-s3 --enable-s3-internal --enable-nczarr-s3-tests --enable-nczarr --enable-nczarr-filters --enable-byterange --enable-hdf5 --enable-dap --enable-dap-remote-tests --enable-logging

The first problem I run into is that something in libdispatch uses SSL functions directly, and appears to assume that linking against libcurl will bring those functions in at runtime, and all will be well. However, this breaks the assumptions of the -no-undefined libtool flag, which states that all functions will be resolvable at link time and is required on Windows (and therefore Cygwin).

I have jury-rigged shims in there that should let me compile, but I am unsure how to do this properly or generally; perhaps Autoconf Archive's ax_check_openssl would help, at least for platforms that are neither Windows or Apple?

DennisHeimbigner added a commit to DennisHeimbigner/netcdf-c that referenced this pull request Mar 13, 2023
re: Issue Unidata#2656

Charlie Zender notes that *nc_open()* does not immediately detect that the given path refers to a file not in zarr format. Rather it fails later when trying to read the (meta-)data.

The reason is that the Zarr format is highly decentralized. There is no easily testable magic number or superblock to look for. In effect the only way to see if a directory is Zarr is to successfully read it.

It is possible to heuristically detect that a path refers to an NCZarr/Zarr file by doing a breadth-first search of the file tree starting at the given path. If the search encounters a file whose name starts with ".z", then assume it is a legitimate NCZarr/Zarr file. Of course, this test could be costly. One hopes that in practice that it is not.

In addition to this fix, a corresponding test case was added.

## Other Changes

re: PR Unidata#2529

There was an error under Cygwin for this PR that is fixed in this PR. The fix was to convert all *noinst_* references to *check_*.
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I fixed this in PR #2658.

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DWesl commented Mar 13, 2023

It looks like I forgot to test with ENABLE_PLUGIN_DIR false/--without-plugin-dir; should I add something like that to the Cygwin CI workflow?

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Good idea.

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DWesl commented Mar 14, 2023

Now #2659.

Looks like I was wrong. Still no idea what was wrong or why that fixed things.

netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Jun 3, 2023
Release Notes       {#RELEASE_NOTES}
=============

\brief Release notes file for the netcdf-c package.

This file contains a high-level description of this package's
evolution. Releases are in reverse chronological order (most recent
first). Note that, as of netcdf 4.2, the `netcdf-c++` and
`netcdf-fortran` libraries have been separated into their own
libraries.

## 4.9.3 - TBD

## 4.9.2 - March 14, 2023

This is the maintenance release which adds support for HDF5 version
1.14.0, in addition to a handful of other changes and bugfixes.

* Fix 'make distcheck' error in run_interop.sh. See [Github
  #????](https://github.com/Unidata/netcdf-c/pull/????).
* Update `nc-config` to remove inclusion from automatically-detected
  `nf-config` and `ncxx-config` files, as the wrong files could be
  included in the output.  This is in support of [GitHub
  #2274](Unidata/netcdf-c#2274).

* Update H5FDhttp.[ch] to work with HDF5 version 1.13.2 and later. See
  [Github #2635](Unidata/netcdf-c#2635).

* [Bug Fix] Update DAP code to enable CURLOPT_ACCEPT_ENCODING by
  default. See [Github
  #2630](Unidata/netcdf-c#2630).

* [Bug Fix] Fix byterange failures for certain URLs. See [Github
  #2649](Unidata/netcdf-c#2649).

* [Bug Fix] Fix 'make distcheck' error in run_interop.sh. See [Github
  #2631](Unidata/netcdf-c#2631).

* [Enhancement] Update `nc-config` to remove inclusion from
  automatically-detected `nf-config` and `ncxx-config` files, as the
  wrong files could be included in the output.  This is in support of
  [GitHub #2274](Unidata/netcdf-c#2274).

* [Enhancement] Update H5FDhttp.[ch] to work with HDF5 version
  1.14.0. See [Github
  #2615](Unidata/netcdf-c#2615).

## 4.9.1 - February 2, 2023

## Known Issues

* A test in the `main` branch of `netcdf-cxx4` is broken by this rc; this will
  bear further investigation, but not being treated as a roadblock for the
  release candidate.

* The new document, `netcdf-c/docs/filter_quickstart.md` is in
  rough-draft form.

* Race conditions exist in some of the tests when run concurrently with large
  numbers of processors

## What's Changed from v4.9.0 (automatically generated)

* Fix nc_def_var_fletcher32 operation by \@DennisHeimbigner in
  Unidata/netcdf-c#2403

* Merge relevant info updates back into `main` by \@WardF in
  Unidata/netcdf-c#2387

* Add manual GitHub actions triggers for the tests. by \@WardF in
  Unidata/netcdf-c#2404

* Use env variable USERPROFILE instead of HOME for windows and mingw. by
  \@DennisHeimbigner in Unidata/netcdf-c#2405

* Make public a limited API for programmatic access to internal .rc tables by
  \@DennisHeimbigner in Unidata/netcdf-c#2408

* Fix typo in CMakeLists.txt by \@georgthegreat in
  Unidata/netcdf-c#2412

* Fix choice of HOME dir by \@DennisHeimbigner in
  Unidata/netcdf-c#2416

* Check for libxml2 development files by \@WardF in
  Unidata/netcdf-c#2417

* Updating Doxyfile.in with doxygen-1.8.17, turned on WARN_AS_ERROR, added
  doxygen build to CI run by \@edwardhartnett in
  Unidata/netcdf-c#2377

* updated release notes by \@edwardhartnett in
  Unidata/netcdf-c#2392

* increase read block size from 1 KB to 4 MB by \@wkliao in
  Unidata/netcdf-c#2319

* fixed RELEASE_NOTES.md by \@edwardhartnett in
  Unidata/netcdf-c#2423

* Fix pnetcdf tests in cmake by \@WardF in
  Unidata/netcdf-c#2437

* Updated CMakeLists to avoid corner case cmake error by \@WardF in
  Unidata/netcdf-c#2438

* Add `--disable-quantize` to configure by \@WardF in
  Unidata/netcdf-c#2439

* Fix the way CMake handles -DPLUGIN_INSTALL_DIR by \@DennisHeimbigner in
  Unidata/netcdf-c#2430

* fix and test quantize mode for NC_CLASSIC_MODEL by \@edwardhartnett in
  Unidata/netcdf-c#2445

* Guard _declspec(dllexport) in support of #2446 by \@WardF in
  Unidata/netcdf-c#2460

* Ensure that netcdf_json.h does not interfere with ncjson. by
  \@DennisHeimbigner in Unidata/netcdf-c#2448

* Prevent cmake writing to source dir by \@magnusuMET in
  Unidata/netcdf-c#2463

* more quantize testing and adding pre-processor constant NC_MAX_FILENAME to
  nc_tests.h by \@edwardhartnett in
  Unidata/netcdf-c#2457

* Provide a default enum const when fill value does not match any enum
  constant by \@DennisHeimbigner in
  Unidata/netcdf-c#2462

* Fix support for reading arrays of HDF5 fixed size strings by
  \@DennisHeimbigner in Unidata/netcdf-c#2466

* fix musl build by \@magnusuMET in
  Unidata/netcdf-c#1701

* Fix AWS SDK linking errors by \@dzenanz in
  Unidata/netcdf-c#2470

* Address jump-misses-init issue. by \@WardF in
  Unidata/netcdf-c#2488

* Remove stray merge conflict markers by \@WardF in
  Unidata/netcdf-c#2493

* Add support for Zarr string type to NCZarr by \@DennisHeimbigner in
  Unidata/netcdf-c#2492

* Fix some problems with PR 2492 by \@DennisHeimbigner in
  Unidata/netcdf-c#2497

* Fix some bugs in the blosc filter wrapper by \@DennisHeimbigner in
  Unidata/netcdf-c#2461

* Add option to control accessing external servers by \@DennisHeimbigner in
  Unidata/netcdf-c#2491

* Changed attribute case in documentation by \@WardF in
  Unidata/netcdf-c#2482

* Adding all-error-codes.md back in to distribution documentation. by \@WardF in
  Unidata/netcdf-c#2501

* Update hdf5 version in github actions. by \@WardF in
  Unidata/netcdf-c#2504

* Minor update to doxygen function documentation by \@gsjaardema in
  Unidata/netcdf-c#2451

* Fix some addtional errors in NCZarr by \@DennisHeimbigner in
  Unidata/netcdf-c#2503

* Cleanup szip handling some more by \@DennisHeimbigner in
  Unidata/netcdf-c#2421

* Check for zstd development headers in autotools by \@WardF in
  Unidata/netcdf-c#2507

* Add new options to nc-config by \@WardF in
  Unidata/netcdf-c#2509

* Cleanup built test sources in nczarr_test by \@DennisHeimbigner in
  Unidata/netcdf-c#2508

* Fix inconsistency in netcdf_meta.h by \@WardF in
  Unidata/netcdf-c#2512

* Small fix in nc-config.in by \@WardF in
  Unidata/netcdf-c#2513

* For loop initial declarations are only allowed in C99 mode by \@gsjaardema in
  Unidata/netcdf-c#2517

* Fix some dependencies in tst_nccopy3 by \@WardF in
  Unidata/netcdf-c#2518

* Update plugins/Makefile.am by \@WardF in
  Unidata/netcdf-c#2519

* Fix prereqs in ncdump/tst_nccopy4 in order to avoid race conditions. by
  \@WardF in Unidata/netcdf-c#2520

* Move construction of VERSION file to end of the build by \@DennisHeimbigner in
  Unidata/netcdf-c#2527

* Add draft filter quickstart guide by \@WardF in
  Unidata/netcdf-c#2531

* Turn off extraneous debug output by \@DennisHeimbigner in
  Unidata/netcdf-c#2537

* typo fix by \@wkliao in Unidata/netcdf-c#2538

* replace 4194304 with READ_BLOCK_SIZE by \@wkliao in
  Unidata/netcdf-c#2539

* Rename variable to avoid function name conflict by \@ibaned in
  Unidata/netcdf-c#2550

* Add Cygwin CI and stop installing unwanted plugins by \@DWesl in
  Unidata/netcdf-c#2529

* Merge subset of v4.9.1 files back into main development branch by \@WardF in
  Unidata/netcdf-c#2530

* Add a Filter quickstart guide document by \@WardF in
  Unidata/netcdf-c#2524

* Fix race condition in ncdump (and other) tests. by \@DennisHeimbigner in
  Unidata/netcdf-c#2552

* Make dap4 reference dap instead of hard-wired to be disabled. by \@WardF in
  Unidata/netcdf-c#2553

* Suppress nczarr_test/tst_unknown filter test by \@DennisHeimbigner in
  Unidata/netcdf-c#2557

* Add fenceposting for HAVE_DECL_ISINF and HAVE_DECL_ISNAN by \@WardF in
  Unidata/netcdf-c#2559

* Add an old static file. by \@WardF in
  Unidata/netcdf-c#2575

* Fix infinite loop in file inferencing by \@DennisHeimbigner in
  Unidata/netcdf-c#2574

* Merge Wellspring back into development branch by \@WardF in
  Unidata/netcdf-c#2560

* Allow ncdump -t to handle variable length string attributes by \@srherbener in
  Unidata/netcdf-c#2584

* Fix an issue I introduced with make distcheck by \@WardF in
  Unidata/netcdf-c#2590

* make UDF0 not require NC_NETCDF4 by \@jedwards4b in
  Unidata/netcdf-c#2586

* Expose user-facing documentation related to byterange DAP functionality.  by
  \@WardF in Unidata/netcdf-c#2596

* Fix Memory Leak by \@DennisHeimbigner in
  Unidata/netcdf-c#2598

* CI: Change autotools CI build to out-of-tree build. by \@DWesl in
  Unidata/netcdf-c#2577

* Update github action configuration scripts. by \@WardF in
  Unidata/netcdf-c#2600

* Update the filter quickstart guide.  by \@WardF in
  Unidata/netcdf-c#2602

* Fix symbol export on Windows by \@WardF in
  Unidata/netcdf-c#2604

## New Contributors
* \@georgthegreat made their first contribution in Unidata/netcdf-c#2412
* \@dzenanz made their first contribution in Unidata/netcdf-c#2470
* \@DWesl made their first contribution in Unidata/netcdf-c#2529
* \@srherbener made their first contribution in Unidata/netcdf-c#2584
* \@jedwards4b made their first contribution in Unidata/netcdf-c#2586

**Full Changelog**: Unidata/netcdf-c@v4.9.0...v4.9.1

### 4.9.1 - Release Candidate 2 - November 21, 2022

#### Known Issues

* A test in the `main` branch of `netcdf-cxx4` is broken by this rc;
  this will bear further investigation, but not being treated as a
  roadblock for the release candidate.

* The new document, `netcdf-c/docs/filter_quickstart.md` is in rough-draft form.

#### Changes

* [Bug Fix] Fix a race condition when testing missing filters. See
  [Github #2557](Unidata/netcdf-c#2557).

* [Bug Fix] Fix some race conditions due to use of a common file in multiple
  shell scripts . See [Github
  #2552](Unidata/netcdf-c#2552).


### 4.9.1 - Release Candidate 1 - October 24, 2022

* [Enhancement][Documentation] Add Plugins Quick Start Guide.  See
  [GitHub #2524](Unidata/netcdf-c#2524) for
  more information.

* [Enhancement] Add new entries in `netcdf_meta.h`, `NC_HAS_BLOSC` and
  `NC_HAS_BZ2`. See [Github
  #2511](Unidata/netcdf-c#2511) and [Github
  #2512](Unidata/netcdf-c#2512) for more
  information.

* [Enhancement] Add new options to `nc-config`: `--has-multifilters`,
  `--has-stdfilters`, `--has-quantize`, `--plugindir`.  See [Github
  #2509](Unidata/netcdf-c#2509) for more
  information.

* [Bug Fix] Fix some errors detected in PR 2497. [PR
  #2497](Unidata/netcdf-c#2497) . See [Github
  #2503](Unidata/netcdf-c#2503).

* [Bug Fix] Split the remote tests into two parts: one for the
  remotetest server and one for all other external servers. Also add a
  configure option to enable the latter set. See [Github
  #2491](Unidata/netcdf-c#2491).

* [Bug Fix] Fix blosc plugin errors. See [Github
  #2461](Unidata/netcdf-c#2461).

* [Bug Fix] Fix support for reading arrays of HDF5 fixed size
  strings. See [Github
  #2466](Unidata/netcdf-c#2466).

* [Bug Fix] Fix some errors detected in [PR
  #2492](Unidata/netcdf-c#2492) . See [Github
  #2497](Unidata/netcdf-c#2497).

* [Enhancement] Add support for Zarr (fixed length) string type in
  nczarr. See [Github
  #2492](Unidata/netcdf-c#2492).

* [Bug Fix] Split the remote tests into two parts: one for the
  remotetest server and one for all other external servers. Also add a
  configure option to enable the latter set. See [Github
  #2491](Unidata/netcdf-c#2491).

* [Bug Fix] Fix support for reading arrays of HDF5 fixed size
  strings. See [Github
  #2462](Unidata/netcdf-c#2466).

* [Bug Fix] Provide a default enum const when fill value does not
  match any enum constant for the value zero. See [Github
  #2462](Unidata/netcdf-c#2462).

* [Bug Fix] Fix the json submodule symbol conflicts between libnetcdf
  and the plugin specific netcdf_json.h. See [Github
  #2448](Unidata/netcdf-c#2448).

* [Bug Fix] Fix quantize with CLASSIC_MODEL files. See [Github
  #2405](Unidata/netcdf-c#2445).

* [Enhancement] Add `--disable-quantize` option to `configure`.

* [Bug Fix] Fix CMakeLists.txt to handle all acceptable boolean values
  for -DPLUGIN_INSTALL_DIR. See [Github
  #2430](Unidata/netcdf-c#2430).

* [Bug Fix] Fix tst_vars3.c to use the proper szip flag. See [Github
  #2421](Unidata/netcdf-c#2421).

* [Enhancement] Provide a simple API to allow user access to the
  internal .rc file table: supports get/set/overwrite of entries of
  the form "key=value". See [Github
  #2408](Unidata/netcdf-c#2408).

* [Bug Fix] Use env variable USERPROFILE instead of HOME for windows
  and mingw. See [Github
  #2405](Unidata/netcdf-c#2405).

* [Bug Fix] Fix the nc_def_var_fletcher32 code in hdf5 to properly
  test value of the fletcher32 argument. See [Github
  #2403](Unidata/netcdf-c#2403).

## 4.9.0 - June 10, 2022

* [Enhancement] Add quantize functions nc_def_var_quantize() and
  nc_inq_var_quantize() to enable lossy compression. See [Github
  #1548](Unidata/netcdf-c#1548).

* [Enhancement] Add zstandard compression functions nc_def_var_zstandard() and
  nc_inq_var_zstandard(). See [Github
  #2173](Unidata/netcdf-c#2173).

* [Enhancement] Have netCDF-4 logging output one file per processor when used
  with parallel I/O. See [Github
  #1762](Unidata/netcdf-c#1762).

* [Enhancement] Improve filter installation process to avoid use of an extra
  shell script. See [Github
  #2348](Unidata/netcdf-c#2348).

* [Bug Fix] Get "make distcheck" to work See [Github
  #2343](Unidata/netcdf-c#2343).

* [Enhancement] Allow the read/write of JSON-valued Zarr attributes to allow for
  domain specific info such as used by GDAL/Zarr. See [Github
  #2278](Unidata/netcdf-c#2278).

* [Enhancement] Turn on the XArray convention for NCZarr files by
  default. WARNING, this means that the mode should explicitly specify "nczarr"
  or "zarr" even if "xarray" or "noxarray" is specified. See [Github
  #2257](Unidata/netcdf-c#2257).

* [Enhancement] Update the documentation to match the current filter
  capabilities See [Github
  #2249](Unidata/netcdf-c#2249).

* [Enhancement] Update the documentation to match the current filter
  capabilities. See [Github
  #2249](Unidata/netcdf-c#2249).

* [Enhancement] Support installation of pre-built standard filters into
  user-specified location. See [Github
  #2318](Unidata/netcdf-c#2318).

* [Enhancement] Improve filter support. More specifically (1) add
  nc_inq_filter_avail to check if a filter is available, (2) add the notion of
  standard filters, (3) cleanup szip support to fix interaction with NCZarr. See
  [Github #2245](Unidata/netcdf-c#2245).

* [Enhancement] Switch to tinyxml2 as the default xml parser implementation. See
  [Github #2170](Unidata/netcdf-c#2170).

* [Bug Fix] Require that the type of the variable in nc_def_var_filter is not
  variable length. See [Github
  #/2231](Unidata/netcdf-c#2231).

* [File Change] Apply HDF5 v1.8 format compatibility when writing to previous
  files, as well as when creating new files.  The superblock version remains at
  2 for newly created files.  Full backward read/write compatibility for
  netCDF-4 is maintained in all cases.  See [Github
  #2176](Unidata/netcdf-c#2176).

* [Enhancement] Add ability to set dataset alignment for netcdf-4/HDF5
  files. See [Github #2206](Unidata/netcdf-c#2206).

* [Bug Fix] Improve UTF8 support on windows so that it can use utf8
  natively. See [Github #2222](Unidata/netcdf-c#2222).

* [Enhancement] Add complete bitgroom support to NCZarr. See [Github
  #2197](Unidata/netcdf-c#2197).

* [Bug Fix] Clean up the handling of deeply nested VLEN types. Marks
  nc_free_vlen() and nc_free_string as deprecated in favor of
  ncaux_reclaim_data(). See [Github
  #2179](Unidata/netcdf-c#2179).

* [Bug Fix] Make sure that netcdf.h accurately defines the flags in the
  open/create mode flags. See [Github
  #2183](Unidata/netcdf-c#2183).

* [Enhancement] Improve support for msys2+mingw platform. See [Github
  #2171](Unidata/netcdf-c#2171).

* [Bug Fix] Clean up the various inter-test dependencies in ncdump for
  CMake. See [Github #2168](Unidata/netcdf-c#2168).

* [Bug Fix] Fix use of non-aws appliances. See [Github
  #2152](Unidata/netcdf-c#2152).

* [Enhancement] Added options to suppress the new behavior from [Github
  #2135](Unidata/netcdf-c#2135).  The options for
  `cmake` and `configure` are, respectively `-DENABLE_LIBXML2` and
  `--(enable/disable)-libxml2`. Both of these options defaul to 'on/enabled'.
  When disabled, the bundled `ezxml` XML interpreter is used regardless of
  whether `libxml2` is present on the system.

* [Enhancement] Support optional use of libxml2, otherwise default to ezxml. See
  [Github #2135](Unidata/netcdf-c#2135) -- H/T to
  [Egbert Eich](https://github.com/e4t).

* [Bug Fix] Fix several os related errors. See [Github
  #2138](Unidata/netcdf-c#2138).

* [Enhancement] Support byte-range reading of netcdf-3 files stored in private
  buckets in S3. See [Github
  #2134](Unidata/netcdf-c#2134)

* [Enhancement] Support Amazon S3 access for NCZarr. Also support use of the
  existing Amazon SDK credentials system. See [Github
  #2114](Unidata/netcdf-c#2114)

* [Bug Fix] Fix string allocation error in H5FDhttp.c. See [Github
  #2127](Unidata/netcdf-c#2127).

* [Bug Fix] Apply patches for ezxml and for selected oss-fuzz detected
  errors. See [Github #2125](Unidata/netcdf-c#2125).

* [Bug Fix] Ensure that internal Fortran APIs are always defined. See [Github
  #2098](Unidata/netcdf-c#2098).

* [Enhancement] Support filters for NCZarr. See [Github
  #2101](Unidata/netcdf-c#2101)

* [Bug Fix] Make PR 2075 long file name be idempotent. See [Github
  #2094](Unidata/netcdf-c#2094).


## 4.8.1 - August 18, 2021

* [Bug Fix] Fix multiple bugs in libnczarr. See [Github
  #2066](Unidata/netcdf-c#2066).

* [Enhancement] Support windows network paths (e.g. \\svc\...). See [Github
  #2065](Unidata/netcdf-c#2065).

* [Enhancement] Convert to a new representation of the NCZarr meta-data
  extensions: version 2. Read-only backward compatibility is provided. See
  [Github #2032](Unidata/netcdf-c#2032).

* [Bug Fix] Fix dimension_separator bug in libnczarr. See [Github
  #2035](Unidata/netcdf-c#2035).

* [Bug Fix] Fix bugs in libdap4. See [Github
  #2005](Unidata/netcdf-c#2005).

* [Bug Fix] Store NCZarr fillvalue as a singleton instead of a 1-element
  array. See [Github #2017](Unidata/netcdf-c#2017).

* [Bug Fixes] The netcdf-c library was incorrectly determining the scope of
  dimension; similar to the type scope problem. See [Github
  #2012](Unidata/netcdf-c#2012) for more information.

* [Bug Fix] Re-enable DAP2 authorization testing. See [Github
  #2011](Unidata/netcdf-c#2011).

* [Bug Fix] Fix bug with windows version of mkstemp that causes failure to
  create more than 26 temp files. See [Github
  #1998](Unidata/netcdf-c#1998).

* [Bug Fix] Fix ncdump bug when printing VLENs with basetype char. See [Github
  #1986](Unidata/netcdf-c#1986).

* [Bug Fixes] The netcdf-c library was incorrectly determining the scope of
  types referred to by nc_inq_type_equal. See [Github
  #1959](Unidata/netcdf-c#1959) for more information.

* [Bug Fix] Fix bug in use of XGetopt when building under Mingw. See [Github
  #2009](Unidata/netcdf-c#2009).

* [Enhancement] Improve the error reporting when attempting to use a filter for
  which no implementation can be found in HDF5_PLUGIN_PATH. See [Github
  #2000](Unidata/netcdf-c#2000) for more information.

* [Bug Fix] Fix `make distcheck` issue in `nczarr_test/` directory. See [Github
  #2007](Unidata/netcdf-c#2007).

* [Bug Fix] Fix bug in NCclosedir in dpathmgr.c. See [Github
  #2003](Unidata/netcdf-c#2003).

* [Bug Fix] Fix bug in ncdump that assumes that there is a relationship between
  the total number of dimensions and the max dimension id. See [Github
  #2004](Unidata/netcdf-c#2004).

* [Bug Fix] Fix bug in JSON processing of strings with embedded quotes. See
  [Github #1993](Unidata/netcdf-c#1993).

* [Enhancement] Add support for the new "dimension_separator" enhancement to
  Zarr v2. See [Github #1990](Unidata/netcdf-c#1990) for
  more information.

* [Bug Fix] Fix hack for handling failure of shell programs to properly handle
  escape characters. See [Github
  #1989](Unidata/netcdf-c#1989).

* [Bug Fix] Allow some primitive type names to be used as identifiers depending
  on the file format. See [Github
  #1984](Unidata/netcdf-c#1984).

* [Enhancement] Add support for reading/writing pure Zarr storage format that
  supports the XArray _ARRAY_DIMENSIONS attribute. See [Github
  #1952](Unidata/netcdf-c#1952) for more information.

* [Update] Updated version of bzip2 used in filter testing/functionality, in
  support of [Github #1969](Unidata/netcdf-c#1969).

* [Bug Fix] Corrected HDF5 version detection logic as described in [Github
  #1962](Unidata/netcdf-c#1962).

## 4.8.0 - March 30, 2021

* [Enhancement] Bump the NC_DISPATCH_VERSION from 2 to 3, and as a side effect,
  unify the definition of NC_DISPATCH_VERSION so it only needs to be defined in
  CMakeLists.txt and configure.ac. See [Github
  #1945](Unidata/netcdf-c#1945) for more information.

* [Enhancement] Provide better cross platform path name management. This
  converts paths for various platforms (e.g. Windows, MSYS, etc.) so that they
  are in the proper format for the executing platform. See [Github
  #1958](Unidata/netcdf-c#1958) for more information.

* [Bug Fixes] The nccopy program was treating -d0 as turning deflation on rather
  than interpreting it as "turn off deflation". See [Github
  #1944](Unidata/netcdf-c#1944) for more information.

* [Enhancement] Add support for storing NCZarr data in zip files. See [Github
  #1942](Unidata/netcdf-c#1942) for more information.

* [Bug Fixes] Make fillmismatch the default for DAP2 and DAP4; too many servers
  ignore this requirement.

* [Bug Fixes] Fix some memory leaks in NCZarr, fix a bug with long strides in
  NCZarr. See [Github #1913](Unidata/netcdf-c#1913) for
  more information.

* [Enhancement] Add some optimizations to NCZarr, dosome cleanup of code cruft,
  add some NCZarr test cases, add a performance test to NCZarr. See [Github
  #1908](Unidata/netcdf-c#1908) for more information.

* [Bug Fix] Implement a better chunk cache system for NCZarr. The cache now uses
  extendible hashing plus a linked list for provide a combination of
  expandibility, fast access, and LRU behavior. See [Github
  #1887](Unidata/netcdf-c#1887) for more information.

* [Enhancement] Provide .rc fields for S3 authentication: HTTP.S3.ACCESSID and
  HTTP.S3.SECRETKEY.

* [Enhancement] Give the client control over what parts of a DAP2 URL are URL
  encoded (i.e. %xx). This is to support the different decoding rules that
  servers apply to incoming URLS. See [Github
  #1884](Unidata/netcdf-c#1884) for more information.

* [Bug Fix] Fix incorrect time offsets from `ncdump -t`, in some cases when the
  time `units` attribute contains both a **non-zero** time-of-day, and a time
  zone suffix containing the letter "T", such as "UTC".  See [Github
  #1866](Unidata/netcdf-c#1866) for more information.

* [Bug Fix] Cleanup the NCZarr S3 build options. See [Github
  #1869](Unidata/netcdf-c#1869) for more information.

* [Bug Fix] Support aligned access for selected ARM processors.  See [Github
  #1871](Unidata/netcdf-c#1871) for more information.

* [Documentation] Migrated the documents in the NUG/ directory to the dedicated
  NUG repository found at https://github.com/Unidata/netcdf

* [Bug Fix] Revert the internal filter code to simplify it. From the user's
  point of view, the only visible change should be that (1) the functions that
  convert text to filter specs have had their signature reverted and renamed and
  have been moved to netcdf_aux.h, and (2) Some filter API functions now return
  NC_ENOFILTER when inquiry is made about some filter. Internally, the dispatch
  table has been modified to get rid of the complex structures.

* [Bug Fix] If the HDF5 byte-range Virtual File Driver is available )HDf5 1.10.6
  or later) then use it because it has better performance than the one currently
  built into the netcdf library.

* [Bug Fix] Fixed byte-range support with cURL > 7.69. See
  [Unidata/netcdf-c#1798].

* [Enhancement] Added new test for using compression with parallel I/O:
  nc_test4/tst_h_par_compress.c. See
  [Unidata/netcdf-c#1784].

* [Bug Fix] Don't return error for extra calls to nc_redef() for netCDF/HDF5
  files, unless classic model is in use. See
  [Unidata/netcdf-c#1779].

* [Enhancement] Added new parallel I/O benchmark program to mimic NOAA UFS data
  writes, built when --enable-benchmarks is in configure. See
  [Unidata/netcdf-c#1777].

* [Bug Fix] Now allow szip to be used on variables with unlimited dimension
  [Unidata/netcdf-c#1774].

* [Enhancement] Add support for cloud storage using a variant of the Zarr
  storage format. Warning: this feature is highly experimental and is subject to
  rapid evolution
  [https://www.unidata.ucar.edu/blogs/developer/en/entry/overview-of-zarr-support-in].

* [Bug Fix] Fix nccopy to properly set default chunking parameters when not
  otherwise specified. This can significantly improve performance in selected
  cases. Note that if seeing slow performance with nccopy, then, as a
  work-around, specifically set the chunking
  parameters. [Unidata/netcdf-c#1763].

* [Bug Fix] Fix some protocol bugs/differences between the netcdf-c library and
  the OPeNDAP Hyrax server. Also cleanup checksum handling
  [https://github.com/Unidata/netcdf-c/issues/1712].* [Bug Fix] IMPORTANT: Ncgen
  was not properly handling large data sections. The problem manifests as
  incorrect ordering of data in the created file. Aside from examining the file
  with ncdump, the error can be detected by running ncgen with the -lc flag (to
  produce a C file). Examine the file to see if any variable is written in pieces
  as opposed to a single call to nc_put_vara. If multiple calls to nc_put_vara are
  used to write a variable, then it is probable that the data order is
  incorrect. Such multiple writes can occur for large variables and especially
  when one of the dimensions is unlimited.

* [Bug Fix] Add necessary __declspec declarations to allow compilation of netcdf
  library without causing errors or (_declspec related) warnings
  [Unidata/netcdf-c#1725].

* [Enhancement] When a filter is applied twice with different
parameters, then the second set is used for writing the dataset
[Unidata/netcdf-c#1713].

* [Bug Fix] Now larger cache settings are used for sequential HDF5 file creates/opens on parallel I/O capable builds; see [Github #1716](Unidata/netcdf-c#1716) for more information.

* [Bug Fix] Add functions to libdispatch/dnotnc4.c to support
   dispatch table operations that should work for any dispatch
   table, even if they do not do anything; functions such as
   nc_inq_var_filter [Unidata/netcdf-c#1693].

* [Bug Fix] Fixed a scalar annotation error when scalar == 0; see [Github
  #1707](Unidata/netcdf-c#1707) for more information.

* [Bug Fix] Use proper CURLOPT values for VERIFYHOST and VERIFYPEER; the
  semantics for VERIFYHOST in particular changed. Documented in NUG/DAP2.md. See
  [Unidata/netcdf-c#1684].

* [Bug Fix][cmake] Correct an issue with parallel filter test logic in
  CMake-based builds.

* [Bug Fix] Now allow nc_inq_var_deflate()/nc_inq_var_szip() to be called for
  all formats, not just HDF5. Non-HDF5 files return NC_NOERR and report no
  compression in use. This reverts behavior that was changed in the 4.7.4
  release. See [Unidata/netcdf-c#1691].

* [Bug Fix] Compiling on a big-endian machine exposes some missing forward
  delcarations in dfilter.c.

* [File Change] Change from HDF5 v1.6 format compatibility, back to v1.8
  compatibility, for newly created files.  The superblock changes from version 0
  back to version 2.  An exception is when using libhdf5 deprecated versions
  1.10.0 and 1.10.1, which can only create v1.6 compatible format.  Full
  backward read/write compatibility for netCDF-4 is maintained in all cases.
  See [Github #951](Unidata/netcdf-c#951).

## 4.7.4 - March 27, 2020

* [Windows] Bumped packaged HDF5 to 1.10.6, HDF4 to 4.2.14, and libcurl to
  7.60.0.

* [Enhancement] Support has been added for HDF5-1.12.0.  See
  [Unidata/netcdf-c#1528].

* [Bug Fix] Correct behavior for the command line utilities when directly
  accessing a directory using utf8 characters. See
  [Github #1669] (Unidata/netcdf-c#1669),
  [Github #1668] (Unidata/netcdf-c#1668) and
  [Github #1666] (Unidata/netcdf-c#1666) for more information.

* [Bug Fix] Attempts to set filters or chunked storage on scalar vars will now
  return NC_EINVAL. Scalar vars cannot be chunked, and only chunked vars can
  have filters. Previously the library ignored these attempts, and always
  storing scalars as contiguous storage. See
  [Unidata/netcdf-c#1644].

* [Enhancement] Support has been added for multiple filters per variable.  See
  [Unidata/netcdf-c#1584].

* [Enhancement] Now nc_inq_var_szip retuns 0 for parameter values if szip is not
  in use for var. See [Unidata/netcdf-c#1618].

* [Enhancement] Now allow parallel I/O with filters, for HDF5-1.10.3 and
  later. See [Unidata/netcdf-c#1473].

* [Enhancement] Increased default size of cache buffer to 16 MB, from 4
  MB. Increased number of slots to 4133. See
  [Unidata/netcdf-c#1541].

* [Enhancement] Allow zlib compression to be used with parallel I/O writes, if
  HDF5 version is 1.10.3 or greater. See
  [Unidata/netcdf-c#1580].

* [Enhancement] Restore use of szip compression when writing data (including
  writing in parallel if HDF5 version is 1.10.3 or greater). See
  [Unidata/netcdf-c#1546].

* [Enhancement] Enable use of compact storage option for small vars in
  netCDF/HDF5 files. See [Unidata/netcdf-c#1570].

* [Enhancement] Updated benchmarking program bm_file.c to better handle very
  large files. See [Unidata/netcdf-c#1555].

* [Enhancement] Added version number to dispatch table, and now check version
  with nc_def_user_format(). See
  [Unidata/netcdf-c#1599].

* [Bug Fix] Fixed user setting of MPI launcher for parallel I/O HDF5 test in
  h5_test. See [Unidata/netcdf-c#1626].

* [Bug Fix] Fixed problem of growing memory when netCDF-4 files were opened and
  closed. See [Unidata/netcdf-c#1575 and
  Unidata/netcdf-c#1571].

* [Enhancement] Increased size of maximum allowed name in HDF4 files to
  NC_MAX_NAME. See [Unidata/netcdf-c#1631].

## 4.7.3 - November 20, 2019

* [Bug Fix]Fixed an issue where installs from tarballs will not properly compile
  in parallel environments.

* [Bug Fix] Library was modified so that rewriting the same attribute happens
  without deleting the attribute, to avoid a limit on how many times this may be
  done in HDF5. This fix was thought to be in 4.6.2 but was not. See
  [Unidata/netcdf-c#350].

* [Enhancement] Add a dispatch version number to netcdf_meta.h and
  libnetcdf.settings, in case we decide to change dispatch table in future. See
  [Unidata/netcdf-c#1469].

* [Bug Fix] Now testing that endianness can only be set on atomic ints and
  floats. See [Unidata/netcdf-c#1479].

* [Bug Fix] Fix for subtle error involving var and unlimited dim of the same
  name, but unrelated, in netCDF-4. See
  [Unidata/netcdf-c#1496].

* [Enhancement] Update for attribute documentation. See
  [Unidata/netcdf-c#1512].

* [Bug Fix][Enhancement] Corrected assignment of anonymous (a.k.a. phony)
  dimensions in an HDF5 file. Now when a dataset uses multiple dimensions of the
  same size, netcdf assumes they are different dimensions. See [GitHub
  #1484](Unidata/netcdf-c#1484) for more information.

## 4.7.2 - October 22, 2019

* [Bug Fix][Enhancement] Various bug fixes and enhancements.

* [Bug Fix][Enhancement] Corrected an issue where protected memory was being
  written to with some pointer slight-of-hand.  This has been in the code for a
  while, but appears to be caught by the compiler on OSX, under circumstances
  yet to be completely nailed down.  See
  [GitHub #1486] (Unidata/netcdf-c#1486) for more information.

* [Enhancement] [Parallel IO] Added support for parallel functions in MSVC. See
  [Github #1492](Unidata/netcdf-c#1492) for more
  information.

* [Enhancement] Added a function for changing the ncid of an open file.  This
  function should only be used if you know what you are doing, and is meant to
  be used primarily with PIO integration. See
  [GitHub #1483] (Unidata/netcdf-c#1483) and
  [GitHub #1487] (Unidata/netcdf-c#1487) for more information.

## 4.7.1 - August 27, 2019

* [Enhancement] Added unit_test directory, which contains unit tests for the
  libdispatch and libsrc4 code (and any other directories that want to put unit
  tests there). Use --disable-unit-tests to run without unit tests (ex. for code
  coverage analysis). See
  [GitHub #1458] (Unidata/netcdf-c#1458).

* [Bug Fix] Remove obsolete _CRAYMPP and LOCKNUMREC macros from code. Also
  brought documentation up to date in man page. These macros were used in
  ancient times, before modern parallel I/O systems were developed. Programmers
  interested in parallel I/O should see nc_open_par() and nc_create_par(). See
  [GitHub #1459](Unidata/netcdf-c#1459).

* [Enhancement] Remove obsolete and deprecated functions nc_set_base_pe() and
  nc_inq_base_pe() from the dispatch table. (Both functions are still supported
  in the library, this is an internal change only.) See [GitHub
  #1468](Unidata/netcdf-c#1468).

* [Bug Fix] Reverted nccopy behavior so that if no -c parameters are given, then
  any default chunking is left to the netcdf-c library to decide. See [GitHub
  #1436](Unidata/netcdf-c#1436).

## 4.7.0 - April 29, 2019

* [Enhancement] Updated behavior of `pkgconfig` and `nc-config` to allow the use
  of the `--static` flags, e.g. `nc-config --libs --static`, which will show
  information for linking against `libnetcdf` statically. See
  [Github #1360] (Unidata/netcdf-c#1360) and
  [Github #1257] (Unidata/netcdf-c#1257) for more information.

* [Enhancement] Provide byte-range reading of remote datasets. This allows
  read-only access to, for example, Amazon S3 objects and also Thredds Server
  datasets via the HTTPService access method.  See
  [GitHub #1251] (Unidata/netcdf-c#1251).

* Update the license from the home-brewed NetCDF license to the standard
  3-Clause BSD License.  This change does not result in any new restrictions; it
  is merely the adoption of a standard, well-known and well-understood license
  in place of the historic NetCDF license written at Unidata.  This is part of a
  broader push by Unidata to adopt modern, standardized licensing.

## 4.6.3 - February 28, 2019

* [Bug Fix] Correctly generated `netcdf.pc` generated either by `configure` or
  `cmake`.  If linking against a static netcdf, you would need to pass the
  `--static` argument to `pkg-config` in order to list all of the downstream
  dependencies.  See
  [Github #1324](Unidata/netcdf-c#1324) for more information.

* Now always write hidden coordinates attribute, which allows faster file opens
  when present. See
  [Github #1262](Unidata/netcdf-c#1262) for more information.

* Some fixes for rename, including fix for renumbering of varids after a rename
  (#1307), renaming var to dim without coordinate var. See
  [Github #1297] (Unidata/netcdf-c#1297).

* Fix of NULL parameter causing segfaults in put_vars functions. See
   [Github #1265] (Unidata/netcdf-c#1265) for more information.

* Fix of --enable-benchmark benchmark tests
   [Github #1211] (Unidata/netcdf-c#1211)

* Update the license from the home-brewed NetCDF license to the standard
  3-Clause BSD License.  This change does not result in any new restrictions; it
  is merely the adoption of a standard, well-known and well-understood license
  in place of the historic NetCDF license written at Unidata.  This is part of a
  broader push by Unidata to adopt modern, standardized licensing.

* [BugFix] Corrected DAP-related issues on big-endian machines. See
  [Github #1321] (Unidata/netcdf-c#1321),
  [Github #1302] (Unidata/netcdf-c#1302) for more information.

* [BugFix][Enhancement] Various and sundry bugfixes and performance
  enhancements, thanks to \@edhartnett, \@gsjarrdema, \@t-b, \@wkliao, and all
  of our other contributors.

* [Enhancement] Extended `nccopy -F` syntax to support multiple variables with a
  single invocation. See
  [Github #1311](Unidata/netcdf-c#1311) for more information.

* [BugFix] Corrected an issue where DAP2 was incorrectly converting signed
  bytes, resulting in an erroneous error message under some circumstances. See
  [GitHub #1317] (Unidata/netcdf-c#1317) for more
  information.  See
  [Github #1319] (Unidata/netcdf-c#1319) for related information.

* [BugFix][Enhancement] Modified `nccopy` so that `_NCProperties` is not copied
  over verbatim but is instead generated based on the version of `libnetcdf`
  used when copying the file.  Additionally, `_NCProperties` are displayed
  if/when associated with a netcdf3 file, now. See
  [GitHub#803] (Unidata/netcdf-c#803) for more information.
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