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by aldanor 1098 days ago
It's exactly the flex you might think it is. The point is not in the number, but rather in the fact that you can build and test almost all crates available on almost all supported platforms, regardless of how many there are, and with no human intervention.

For C++, there's no registry to start with, but even if there was: there's no standard way of building and testing projects. So, a crater build like this is simply impossible at a scale.
1 comments
lionkor 1097 days ago
> For C++, there's no registry to start with

That's not right, there are multiple. There's no single registry. You can use the vcpkg registry, for example - that holds all small and large libraries I've ever needed (even one of my own). They also come with a standard way to build them, of course (CMake targets).

Have you done C++ development recently? I fear a large part of the C++ crowd may not be aware that package managers and build systems are available, they're just not preinstalled with C++.

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aldanor 1097 days ago
I know about vcpkg but there's only 2k packages there. The point of the grandparent comment was that there's SO much C++ code / so many packages you can build in a crater run that it would be physically unfeasible.

The problem with vcpkg, just like with any other "ports" package manager, is that it's not maintained by the original authors of the code but rather by a separate community. It's a bunch of "ports", trying to standardise the builds and installs to a common format. Out of wonder, I looked at a few recipes, they seem to just install things for you, but you have no automated way to do a crater run still - since most of those libraries are header-only you will need to write library-specific code in each case to actually use each package; at least a single include. The tests are seemingly also not being run.

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lionkor 1097 days ago
That's fair - but since this is about core language changes, compiling the non-header-only libraries already covers most of the commonly used libraries. Libraries like boost will also use most existing C++ features. I can't think of a single feature boost doesn't use, actually.
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tialaramex 1097 days ago
Even in the best case scenario, where this partial coverage touched everything that mattered, you are still screwed in C++ because of IFNDR ("Ill-formed, no diagnostic required" a recurring phrase in the ISO document).

If what I wrote isn't a Rust program, it doesn't compile. But if what I wrote isn't a C++ program, because of IFNDR it might compile anyway, and in a whole bunch of cases it must compile anyway because the alternative would be that our fundamental understanding of mathematics is wrong (or the compiler is broken).

This makes Crater runs fundamentally more powerful, even ignoring the practical problems C++ hasn't solved such as a lack of tooling.

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