Make PYBIND11_CPP_STANDARD work under MSVC
Under MSVC we were ignoring PYBIND11_CPP_STANDARD and simply not
passing any standard (which makes MSVC default to its C++14 mode).
MSVC 2015u3 added the `/std:c++14` and `/std:c++latest` flags; the
latter, under MSVC 2017, enables some C++17 features (such as
`std::optional` and `std::variant`), so it is something we need to
start supporting under MSVC.
This makes the PYBIND11_CPP_STANDARD cmake variable work under MSVC,
defaulting it to /std:c++14 (matching the default -std=c++14 for
non-MSVC).
It also adds a new appveyor test running under MSVC 2017 with
/std:c++latest, which runs (and passes) the
`std::optional`/`std::variant` tests.
Also updated the documentation to clarify the c++ flags and add show
MSVC flag examples.
diff --git a/docs/compiling.rst b/docs/compiling.rst
index c7053db..c218959 100644
--- a/docs/compiling.rst
+++ b/docs/compiling.rst
@@ -92,17 +92,28 @@
Configuration variables
-----------------------
-By default, pybind11 will compile modules with the latest C++ standard
-available on the target compiler. To override this, the standard flag can
-be given explicitly in ``PYBIND11_CPP_STANDARD``:
+By default, pybind11 will compile modules with the C++14 standard, if available
+on the target compiler, falling back to C++11 if C++14 support is not
+available. Note, however, that this default is subject to change: future
+pybind11 releases are expected to migrate to newer C++ standards as they become
+available. To override this, the standard flag can be given explicitly in
+``PYBIND11_CPP_STANDARD``:
.. code-block:: cmake
+ # Use just one of these:
+ # GCC/clang:
set(PYBIND11_CPP_STANDARD -std=c++11)
+ set(PYBIND11_CPP_STANDARD -std=c++14)
+ set(PYBIND11_CPP_STANDARD -std=c++1z) # Experimental C++17 support
+ # MSVC:
+ set(PYBIND11_CPP_STANDARD /std:c++14)
+ set(PYBIND11_CPP_STANDARD /std:c++latest) # Enables some MSVC C++17 features
+
add_subdirectory(pybind11) # or find_package(pybind11)
Note that this and all other configuration variables must be set **before** the
-call to ``add_subdiretory`` or ``find_package``. The variables can also be set
+call to ``add_subdirectory`` or ``find_package``. The variables can also be set
when calling CMake from the command line using the ``-D<variable>=<value>`` flag.
The target Python version can be selected by setting ``PYBIND11_PYTHON_VERSION``