Previously, we were conditionally trying to set `min_header_version` to
the lowest possible value, and relying on a "legacy" Google interface to
determine the file descriptor's syntax version as part of that
determination.

Instead, simply bump the minimum version to 1003000 (1.3.0). This
release was almost 7 years ago. In practice protobuf-c users should not
be shipping pre-compiled .pb-c.c/.pb-c.h files, anyway.

Miscellaneous CI updates

That gives us the entire weekend to investigate build failures.

Update actions

build.yml: Set "fail-fast: false" so we can tell which jobs are failing

build.yml: Install libtool on OS X

This might fix the new CI build failure:

    → Run ./autogen.sh
    autoreconf: export WARNINGS=
    autoreconf: Entering directory '.'
    autoreconf: configure.ac: not using Gettext
    autoreconf: running: aclocal --force -I m4 ${ACLOCAL_FLAGS}
    autoreconf: configure.ac: tracing
    autoreconf: configure.ac: creating directory build-aux
    autoreconf: configure.ac: not using Libtool
    autoreconf: configure.ac: not using Intltool
    autoreconf: configure.ac: not using Gtkdoc
    autoreconf: running: /opt/homebrew/Cellar/autoconf/2.72/bin/autoconf --force
    autoreconf: running: /opt/homebrew/Cellar/autoconf/2.72/bin/autoheader --force
    autoreconf: running: automake --add-missing --copy --force-missing
    configure.ac:14: installing 'build-aux/compile'
    configure.ac:13: installing 'build-aux/install-sh'
    configure.ac:13: installing 'build-aux/missing'
    Makefile.am:4: error: Libtool library used but 'LIBTOOL' is undefined
    Makefile.am:4:   The usual way to define 'LIBTOOL' is to add 'LT_INIT'
    Makefile.am:4:   to 'configure.ac' and run 'aclocal' and 'autoconf' again.
    Makefile.am:4:   If 'LT_INIT' is in 'configure.ac', make sure
    Makefile.am:4:   its definition is in aclocal's search path.
    Makefile.am: installing 'build-aux/depcomp'
    parallel-tests: installing 'build-aux/test-driver'
    autoreconf: error: automake failed with exit status: 1

Fix CI issues with CMake

cxx-generate-packed-data needs to link with protobuf library for the C++
source file.

Use the protobuf::libprotobuf to get both library and include directory.
Signed-off-by: Clément Péron <peron.clem@gmail.com>

PROTOBUF_PROTOC_EXECUTABLE is not set in the Protobuf CMake config file.
Set it properly in case we use CMake protobuf config file.
Signed-off-by: Clément Péron <peron.clem@gmail.com>

Keep the DART compatibility enabled until test are moved
to CTest.
Signed-off-by: Clément Péron <peron.clem@gmail.com>

APT cache could be out of date leading to a:
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

Fix this by always calling apt-get update before an apt-get install.
Signed-off-by: Clément Péron <peron.clem@gmail.com>

The CMake module is used by default but isn't compatible with
recent protobuf version.

Try to first look for a protobuf config then fallback to legacy
cmake module.
Signed-off-by: Clément Péron <peron.clem@gmail.com>

protobuf_c_message_unpack(): Fix memory corruption by initializing unknown_fields pointer

The canonical doman is no longer dot-io, though both work.

Makefile.am: Distribute missing Config.cmake.in

CMakeLists.txt: Remove double hyphens

A memory corruption in protobuf_c_message_free_unpacked happens at the
following line:

        if (message->unknown_fields != NULL)
                do_free(allocator, message->unknown_fields);

The do_free will free ->unknown_fields. This is may be wrong, because
protobuf_c_message_unpack uses malloc as the default allocator, allocates
rv with malloc. At the end, however, ->unknown_fields is only initialized
if there are some. That means if there are no such fields ->unknown_fields
is an uninitialized pointer.

The patch initializes the pointer to NULL to ensure the check before free
is performed on initialized memory in case there is no unknown_field.

This fixes https://github.com/protobuf-c/protobuf-c/issues/690Signed-off-by: Stephan Mueller <smueller@chronox.de>

Closes: https://github.com/protobuf-c/protobuf-c/issues/698

Otherwise cmake won't reconize the command.

With double hyphens:
```
$ cmake -E env TESTENV=value -- env | grep TESTENV
cmake -E env: unknown option '--'
```

Without double hyphens:
```
$ cmake -E env TESTENV=value env | grep TESTENV
TESTENV=value
```

[edmonds: Adjust commit message.]

Fixing MSVC build for Msbuild and Makefile generators

Signed-off-by: Guybrush <miguel.barro@live.com>

Signed-off-by: Guybrush <miguel.barro@live.com>

Led to some fixes in the CMake too.
Signed-off-by: Guybrush <miguel.barro@live.com>

Signed-off-by: MiguelBarro <miguelbarro@eprosima.com>

Signed-off-by: MiguelBarro <miguelbarro@eprosima.com>

Silence some compiler diagnostics

This file uses declarations after statements and fixing it would make
the code less readable, so silence this particular diagnostic in this
particular file.

This diagnostic isn't particularly useful since it fires on generated
.pb-c.h files.

Remove protobuf 2.x support

Since we now require protobuf >= 3.0.0, we don't have to support older
protobuf versions that don't recognize the `syntax` syntax, so we can
put `syntax = "proto2";` on these proto files to silence the protoc
compiler's diagnostic "No syntax specified for the proto file".