Use <filesystem> for VS2026 (MSVC Build Tools v14.51)

[garethsb]

See May Update 18.6.0 > C++ > MSVC Build Tools v14.51 > Standard Library (STL) > "We've removed long-deprecated non-Standard features" at https://learn.microsoft.com/en-us/visualstudio/releases/2026/release-notes

[garethsb]

Comparing an unsuccessful CI run with a successful one, the pre-existing code is failing on the run where it builds with:

[settings]
arch=x86_64
build_type=Release
compiler=msvc
compiler.cppstd=14
compiler.runtime=dynamic
compiler.runtime_type=Release
compiler.version=195
os=Windows

which results in:

-- Building for: Visual Studio 18 2026
-- Using Conan toolchain: D:/a/nvnmos/nvnmos/src/conan/conan_toolchain.cmake
-- Conan toolchain: CMAKE_GENERATOR_TOOLSET=v145
-- Conan toolchain: Setting CMAKE_MSVC_RUNTIME_LIBRARY=$<$<CONFIG:Release>:MultiThreadedDLL>
-- Conan toolchain: C++ Standard 14 with extensions OFF
-- The C compiler identification is MSVC 19.51.36247.0
-- The CXX compiler identification is MSVC 19.51.36247.0
...
-- Check for working C compiler: C:/Program Files/Microsoft Visual Studio/18/Enterprise/VC/Tools/MSVC/14.51.36231/bin/Hostx64/x64/cl.exe - skipped

In the successful run:

[settings]
arch=x86_64
build_type=Release
compiler=msvc
compiler.cppstd=17
compiler.runtime=dynamic
compiler.runtime_type=Release
compiler.version=194
os=Windows

results in:

-- Building for: Visual Studio 18 2026
-- Using Conan toolchain: D:/a/nvnmos/nvnmos/src/conan/conan_toolchain.cmake
-- Conan toolchain: CMAKE_GENERATOR_TOOLSET=v143
-- Conan toolchain: Setting CMAKE_MSVC_RUNTIME_LIBRARY=$<$<CONFIG:Release>:MultiThreadedDLL>
-- Conan toolchain: C++ Standard 17 with extensions OFF
-- The C compiler identification is MSVC 19.44.35228.0
-- The CXX compiler identification is MSVC 19.44.35228.0
...
-- Check for working C compiler: C:/Program Files/Microsoft Visual Studio/18/Enterprise/VC/Tools/MSVC/14.44.35207/bin/HostX64/x64/cl.exe - skipped

[lo-simon]

Shouldn't it be 1950 instead of 1951?
See MSCV Build Tools version table in https://learn.microsoft.com/en-us/cpp/overview/compiler-versions?view=msvc-180

[garethsb]

No, not according to the release notes that I linked.

[lo-simon]

Yes, you are right.

[garethsb]

FWIW, I'm having a different problem when using the nmos-cpp/cci.20260622 recipe with VS 2026 / MSVC 195.

nmos-cpp/cci.20260602: Running CMake.configure()
nmos-cpp/cci.20260602: RUN: cmake -G "Visual Studio 18 2026" -DCMAKE_TOOLCHAIN_FILE="generators/conan_toolchain.cmake" -DCMAKE_INSTALL_PREFIX="C:/Users/runneradmin/.conan2/p/b/nmos-e4a4df19ec734/p" -DCMAKE_FIND_PACKAGE_PREFER_CONFIG="ON" -DCONAN_EXPORTED="ON" -DCMAKE_POLICY_DEFAULT_CMP0091="NEW" "C:/Users/runneradmin/.conan2/p/b/nmos-e4a4df19ec734/b/src/Development"
CMake Error: Could not create named generator Visual Studio 18 2026

Generators
  Visual Studio 17 2022        = Generates Visual Studio 2022 project files.
                                 Use -A option to specify architecture.
  ...

According to conan-io/conan-center-index#28884, CMake 4.2 is the first version that supports "Visual Studio 18 2026". I'm going to investigate overriding the recipe with cmake/[>=3.17 <5].