msvc package

examples/dev_flow.rst

@@ -7,3 +7,4 @@ Developer tools and flows
    :maxdepth: 2
 
    dev_flow/debug/step_into_dependencies
+   dev_flow/msvc_package

examples/dev_flow/msvc_package.rst

@@ -0,0 +1,94 @@
+Packaging Visual Studio as a Conan package
+==========================================
+
+It is possible to package the Visual Studio tools into a Conan package and use it later as a ``tool_requires``.
+This can be convenient in some scenarios, for example in CI, or in some developer setups.
+
+In this example we are going to start with a standard Visual Studio 16 2019 installation on disk. The first
+thing we'll do is to rename the folder ``C:/Program Files (x86)/Microsoft Visual Studio/2019`` to
+``C:/Program Files (x86)/Microsoft Visual Studio/2019_2``. This is not strictly necessary, but in this way
+we make sure that CMake or vswhere are not able to locate it, and we can validate better that the consumer
+project is using VS from the Conan package and not from the system.
+
+This is the recipe to package VS 2019:
+
+.. code-block:: python
+    :caption: conanfile.py
+
+    from conan import ConanFile
+    from conan.tools.files import copy, save
+    import os
+
+    class x86_64_windows_msvc2017Conan(ConanFile):
+        name = "msvc"
+        version = "16"
+        settings = "os", "arch"
+
+        def package(self):
+            # toolchain
+            version_vs = "16.11.34601.136"  # This must be tuned, might be automatically obtained too
+            toolchain = f'set(CMAKE_GENERATOR_INSTANCE "$ENV{{CONAN_MSVC_16_FOLDER}},version={version_vs}" CACHE INTERNAL "")'
+            save(self, os.path.join(self.package_folder, "msvc_toolchain.cmake"), toolchain)
+            # packaging
+            vs_path = "C:/Program Files (x86)/Microsoft Visual Studio/2019_2/Community"
+            copy(self, "*", src=vs_path, dst=self.package_folder)
+
+        def package_info(self):
+            f = os.path.join(self.package_folder, "msvc_toolchain.cmake")
+            self.conf_info.append("tools.cmake.cmaketoolchain:user_toolchain", f)
+            pf = self.package_folder.replace("\\", "/")
+            self.buildenv_info.define("CONAN_MSVC_16_FOLDER", pf)
+
+
+Note a few important things:
+
+- The ``package()`` method is creating a ``msvc_toolchain.cmake`` that defines the ``CMAKE_GENERATOR_INSTANCE``.
+- The ``CMAKE_GENERATOR_INSTANCE`` should point to the location of VS, which is inside the Conan package. But this location
+  will change from machine to machine, so it needs to be generalized.
+- The ``version_vs = "16.11.34601.136"`` needs to match your installation. It can be obtained with ``vswhere``. It is possible
+  to automate that in the recipe, but it is hardcoded for simplicity, like the ``vs_path``.
+- A ``CONAN_MSVC_16_FOLDER`` environment variable, whose value is defined in the ``package_info()`` method is used to 
+  generalize the package folder location.
+- The generated ``msvc_toolchain.cmake`` is passed to consumers with the ``tools.cmake.cmaketoolchain:user_toolchain`` configuration
+
+
+We can use ``conan create .`` to create the Conan package containing a copy of the VS 2019 installation.
+
+Then, we can define a profile like (assuming the ``default`` profile is a Windows-MSVC one):
+
+.. code-block::
+    :caption: msvc16_profile
+
+    include(default)
+
+    [settings]
+    # Note that we need to align the settings with the tool-require
+    compiler.version=192
+
+    [tool_requires]
+    msvc/16
+
+And we can now use it to build a CMake package:
+
+.. code-block:: bash
+
+    $ conan new cmake_lib -d name=mypkg -d version=0.1
+    $ conan create . -pr=msvc16_profile
+    ...
+    -- Check for working CXX compiler: C:/Users/mysuser/.conan2/p/b/msvcfa3a5055acf54/p/VC/Tools/MSVC/14.29.30133/bin/Hostx64/x64/cl.exe - skipped
+    ...
+    mypkg/0.1 (test package): RUN: Release\example
+    mypkg/0.1: _MSC_VER1929
+
+And it will use the compiler from within the ``msvc/16`` Conan package.
+
+
+
+.. note::
+
+    - This example is far from optimal. The whole IDE installation is packaged, which is very large. Most likely
+      it is not necessary to package everything and packaging just a subset (MSBuild, compiler and tools) would be
+      enough, be faster to package and use less space.
+    - Please make sure to comply with the VS licenses while using their tools.
+    - This example works only for CMake consumers. For other build systems, it might be necessary to improve the
+      ``msvc`` recipe.