Add additional metrics to the vcpkg.json to help with C++20 modules adoption

[kelteseth]

Hi 👋,

I'm the developer of arewemodulesyet.org that heavily relies on vcpkg to track the most popular open source packages (based on update count of the portfile). Now, there are some things I would like to see added to the vcpkg.json that would make at least my life easier:

• Used build system and the required version range
• Used c++ standard version range
• Level of modules adoption:
  1. LibraryX cannot be used in a modules project (Often due to bugs in the compiler, for example see this issue)
  2. LibraryX can be used in a modules project
  3. LibraryX itself is a modules project
  4. All of LibraryX dependencies are modules
  5. LibraryX uses C++23 import std;
  6. All of LibraryX dependencies are using C++23 import std;
• Default C++ import statement for every library, we already track that here https://github.com/kelteseth/arewemodulesyet/blob/master/data/progress_overwrite.yml#L17

Cheers,
Eli

[dg0yt]

to track the most popular open source packages (based on update count of the portfile).

Not convincing.

Now, there are some things I would like to see added to the vcpkg.json that would make at least my life easier

Who is going to supply this information? There is already insufficient validation of updates, insufficient validation of installation order control and exported usage, insufficient validation of supported platforms and insufficient upstreaming of patches. Plus occasional circumventing of upstream build systems, making vpckg non-representative for the given ports.

However, once you publish a well researched database, it might work the other way: port maintainers might be willing to check if the vcpkg port doesn't lag behind.

[kelteseth]

Not convincing.

Do you have a better way we could track this? #17795 Has been open for about 6 years now...

Who is going to supply this information?

Well, we? The goal of the arewemodulesyet projects is to get the modules support rolling and the first thing I would do is to check if

A. My build system supports modules
B. My compiler supports modules
C. My dependencies support modules <- We are here

I do not want to move the work to you, but I think vcpkg would honestly be the best place to specify these informations.

[Neumann-A]

Just take the CI file list and check if the required files for module support are there?

[dg0yt]

These file lists are in the artifacts of the runs at https://dev.azure.com/vcpkg/public/_build?definitionId=29&_a=summary.

[kelteseth]

@Neumann-A not sure how I would check for modules support here. For example fmt:

VCPKGHeadersDatabase.txt

fmt:x64-windows:fmt/args.h
fmt:x64-windows:fmt/chrono.h
fmt:x64-windows:fmt/color.h
fmt:x64-windows:fmt/compile.h
fmt:x64-windows:fmt/core.h
fmt:x64-windows:fmt/format-inl.h
fmt:x64-windows:fmt/format.h
fmt:x64-windows:fmt/locale.h
fmt:x64-windows:fmt/os.h
fmt:x64-windows:fmt/ostream.h
fmt:x64-windows:fmt/printf.h
fmt:x64-windows:fmt/ranges.h
fmt:x64-windows:fmt/xchar.h

VCPKGDatabase.txt

fmt:x64-windows:/bin/fmt.dll
fmt:x64-windows:/bin/fmt.pdb
fmt:x64-windows:/debug/bin/fmtd.dll
fmt:x64-windows:/debug/bin/fmtd.pdb
fmt:x64-windows:/debug/lib/fmtd.lib
fmt:x64-windows:/debug/lib/pkgconfig/fmt.pc
fmt:x64-windows:/include/fmt/args.h
fmt:x64-windows:/include/fmt/chrono.h
fmt:x64-windows:/include/fmt/color.h
fmt:x64-windows:/include/fmt/compile.h
fmt:x64-windows:/include/fmt/core.h
fmt:x64-windows:/include/fmt/format-inl.h
fmt:x64-windows:/include/fmt/format.h
fmt:x64-windows:/include/fmt/locale.h
fmt:x64-windows:/include/fmt/os.h
fmt:x64-windows:/include/fmt/ostream.h
fmt:x64-windows:/include/fmt/printf.h
fmt:x64-windows:/include/fmt/ranges.h
fmt:x64-windows:/include/fmt/xchar.h
fmt:x64-windows:/lib/fmt.lib
fmt:x64-windows:/lib/pkgconfig/fmt.pc
fmt:x64-windows:/share/fmt/copyright
fmt:x64-windows:/share/fmt/fmt-config-version.cmake
fmt:x64-windows:/share/fmt/fmt-config.cmake
fmt:x64-windows:/share/fmt/fmt-targets-debug.cmake
fmt:x64-windows:/share/fmt/fmt-targets-release.cmake
fmt:x64-windows:/share/fmt/fmt-targets.cmake
fmt:x64-windows:/share/fmt/usage
fmt:x64-windows:/share/fmt/vcpkg_abi_info.txt

[Neumann-A]

Maybe read:
https://learn.microsoft.com/en-us/cpp/cpp/modules-cpp?view=msvc-170
and
https://learn.microsoft.com/en-us/cpp/build/compare-inclusion-methods?view=msvc-170

After that you can probably answer the question yourself

[kelteseth]

I do not see any module, so nope. Please enlightened me.

[Neumann-A]

I do not see any module, so nope. Please enlightened me.

I see you didn't read it:
The .ixx extension is required for module interface files in Visual Studio

No files with .ixx installed -> no module support within vcpkg.