Statically enforce some metrics properties at compile time.

[BillyONeal]

This exposes that the lists of all metrics are actually std::arrays, which allows for compile time enforcement of properties like:

• All metrics have entries in the name list
• COUNT is the last entry in the enum list
• All string metrics have corresponding example values

[wolfv]

It seems that this gives a compiler error on potentially older MSVC?
You can find the log from conda-forge here: https://dev.azure.com/conda-forge/feedstock-builds/_build/results?buildId=584303&view=logs&jobId=a70f640f-cc53-5cd3-6cdc-236a1aa90802&j=a70f640f-cc53-5cd3-6cdc-236a1aa90802&t=f5d15007-a01c-5ad8-c9ce-4d519d3b275f

C:\PROGRA~2\MICROS~2\2019\ENTERP~1\VC\Tools\MSVC\1429~1.301\bin\Hostx64\x64\cl.exe  /nologo /TP -DVCPKG_BASE_VERSION=2999-12-31 -DVCPKG_VERSION=unknownhash -I%SRC_DIR%\include -I%SRC_DIR%\build\_deps\fmt-src\include /DWIN32 /D_WINDOWS /GR /EHsc /EHsc /Zi /guard:cf /O2 /Ob2 /DNDEBUG -MT -FC -permissive- -utf-8 /Yupch.h /FIpch.h /Zm200 -std:c++17 /showIncludes /FoCMakeFiles\vcpkglib.dir\src\vcpkg\metrics.cpp.obj /FdCMakeFiles\vcpkglib.dir\ /FS -c %SRC_DIR%\src\vcpkg\metrics.cpp
%SRC_DIR%\src\vcpkg\metrics.cpp(43): error C2370: 'vcpkg::all_define_metrics': redefinition; different storage class
%SRC_DIR%\include\vcpkg\metrics.h(49): note: see declaration of 'vcpkg::all_define_metrics'
%SRC_DIR%\src\vcpkg\metrics.cpp(71): error C2370: 'vcpkg::all_string_metrics': redefinition; different storage class
%SRC_DIR%\include\vcpkg\metrics.h(77): note: see declaration of 'vcpkg::all_string_metrics'
%SRC_DIR%\src\vcpkg\metrics.cpp(90): error C2370: 'vcpkg::all_bool_metrics': redefinition; different storage class
%SRC_DIR%\include\vcpkg\metrics.h(93): note: see declaration of 'vcpkg::all_bool_metrics'
[94/162] Building CXX object CMakeFiles\vcpkglib.dir\src\vcpkg\packagespec.cpp.obj
[95/162] Building CXX object CMakeFiles\vcpkglib.dir\src\vcpkg\install.cpp.obj

[BillyONeal]

It seems that this gives a compiler error on potentially older MSVC?

We care about older Linux compilers because we know there are platforms we can't reach effectively (raspberrypi anyone?) but I don't see much reason to care about old msvc when we ship binaries that work on all Windowses.

[wolfv]

@BillyONeal conda-forge works very much like a linux-distribution (but for Windows and macOS, too) and we're not that free to choose any random compiler :) I can try to update the compiler to e.g. VS2022 but still, I think some backwards compatibility and support for alternative package managers that package your software would be nice!

[BillyONeal]

Can it just download our official copies when they match rather than rebuilding? We would take contributions to fix things but we aren't going to add regular testing for Windows compilers other than our release one.