It secures the repo against erroneous or malicious actions from external jobs you call from your workflow. It's specially important for the case they get compromised, for example.

This pull request adds two new exported variables to the CMake config:

YAML_CPP_LIBRARY_DIR - points to the directory containing the built library files
YAML_CPP_SHARED_LIBS_BUILT - boolean value, lets users know whether shared libraries were built or not

Add definitions to static yaml-cpp target (fixes #1116)

Also updates CONTRIBUTING instructions for tests

Minimize warnings when not the top-level project

Should fix #970 and #764 when trying to add yaml-cpp to other project

On Oracle Solaris the following statement is declared in file /usr/include/sys/regset.h:
#define SS 18 /* only stored on a privilege transition */

Because of this template type name SS is substituted by numeric literal, which results in a compilation error:
error: expected nested-name-specifier before numeric constant

Fixed by renaming template type names.

Co-authored-by: Roman Degtyar <Roman.Degtyar@veeam.com>

Windows builds need some defines being set to use the static linking.

Also add bazel builds and test to Github-CI.

Changes YAML_CPP_INSTALL from a cmake_dependent_option to an option.

Fixes #756, #847, and #1011.

The option `YAML_CPP_BUILD_TESTS` currently enables or disables building of tests; but unconditionally the CMake file includes CTest; this PR makes that conditional on the option.

Also, there is no option for enabling formatting, but it does check whether it can find the `clang-format` executable; this PR adds an option (default to true) that skips even looking for the executable if disabled.

After configuring the file `yaml-cpp-config.cmake.in`, the result ends up with
empty variables.  (see also the discussion in #774).

Rework this file and the call to `configure_package_config_file` according the
cmake documentation
(https://cmake.org/cmake/help/v3.22/module/CMakePackageConfigHelpers.html?highlight=configure_package_config#command:configure_package_config_file)
to overcome this issue and allow a simple `find_package` after install.

As there was some discussion about the place where to install the
`yaml-cpp-config.cmake` file, e.g. #1055, factor out the install location into
an extra variable to make it easier changing this location in the future.

Also untabify CMakeLists.txt in some places to align with the other code parts in this file.

Complies with YAML Standard [5.4](https://yaml.org/spec/1.2.2/#54-line-break-characters) [25] instead of matching `\r` only in combination with `\n`.

Fixes issue #1053.

Properly resolves #1083, #996.

Also refactor the build action to use a matrix.

Add copying of shared library to the output directory with a test binary.

[binary] removed using of non unsigned char as argument at
'std::isspace' function that was provokes undefined behavior.

[.github/workflows/build.yml] enabled run of test at the
'windows-latest' environment.

This replaces the old Travis CI badge that didn't mean anything.

Partial revert of "Revert "Revert "Hide most of non-public symbols by default (#984)" (#1038)" (#1045)"

This reverts commit 0733aeb4.

GNUInstallDirs provided may be absolute paths, in which case appending
to the install prefix is not correct. We can instead use the provided
CMAKE_INSTALL_FULL_* variables, which are precomputed absolute paths.

https://cmake.org/cmake/help/latest/module/GNUInstallDirs.html

This reverts commit da1c8d36. and fixes #1036.

* Export YAML::detail::node::m_amount

The internal header node/detail/node.h is included by public headers;
YAML::detail::node is implemented in the header itself, and thus it gets
inlined... except for its static m_amount class member, which is
instantiated in the library only. Right now all the symbols of yaml-cpp
are exported (nothing is hidden), so the linker will find node::m_amount
in the yaml-cpp library.

As solution/workaround, explicitly export YAML::detail::node::m_amount.

* CMake: use GenerateExportHeader

Make use of the GenerateExportHeader CMake module to generate the dll.h
header with export macros.

While the produced dll.h is different, the result should be the same,
i.e. nothing changes for yaml-cpp or its users.

* CMake: hide all the symbols by default

Hide all the symbols that are not explicitly exported with YAML_CPP_API.
This way the ABI will be way smaller, and only actually exposing the
public classes/functions.