rustup does not recognize Visual C++ Build Tools

[projektir]

Previously, rustc and related tools worked fine for me, but I had VS itself installed with the C++ tools. I've just reinstalled Windows 10. I've installed Visual C++ Build Tools from the landinghub link, no SDK,, but when I run rustup-init.exe, it still tells me that it's missing. There's nothing else Rust or Visual Studio related on my machine.

I ran the installer again, but it has nothing to offer besides installing SDK's that I don't need.

I've installed updates and restarted my computer, but that didn't help.

I've added the Microsoft Visual C++ Build Tools folder to PATH, that didn't help, either.

Either rustup truly needs more than just the Build Tools themselves, or it's not doing a very good job of detecting it.

[projektir]

Installing Visual Studio 2017 for C++ Desktop Development makes it work. Perhaps specifying installing VS with C++ is the safer bet.

[redstrike]

@projektir I got this issue. I have tested many custom installation settings of Visual C++ 2015 Build Tools installer. But it seems that the installer's custom mode doesn't behave the same as the DEFAULT installation mode no matter the custom packages which we have chosen.

Install Visual C++ 2015 Build Tools with the DEFAULT installation will solve this problem 😄 and remember to re-proceed the installation with rustup-init. It may affect the linker.

Edit: rust requires Windows SDK (8.1 or 10 is ok). Another test: #1003 (comment)

After that, I encountered this linker issue: rust-lang/rust#30319
OMG... develop a Rust HelloWorld program on Windows is tougher than I expected :(

I have tried to install "Visual Studio 2017 for C++ Desktop Development" as suggested, but it still not work, and rustup doesn't recognize Visual C++ Build Tools. Again, I have tested VS 2017 installer by adding more components related to C++ development, also try to strip as much as possible.

Here is the required components to install Visual C++ via Visual Studio for Rust HelloWorld program:

rustup still requires VC++ 2015 toolset, Universal CRT SDK & Windows 8.1 SDK to recognize the build tools. Therefore, I removed all VS 2017 related programs and re-install Visual C++ 2015 Build Tools with the DEFAULT settings for my Rust HelloWorld program.

My linker issue is no longer happen anymore. I don't know why? Maybe, VS 2017's installation fixed it? I have tried to reproduce the linker problem by removing all and install again, but it has been disappeared.

What a horrible getting started experience with Rust on Windows!

[projektir]

@redstrike so happy to see that someone else ran into this! Thanks for describing this in such detail.

I have tested VS 2017 installer by adding more components related to C++ development, also try to strip as much as possible.

I very much had a similar approach that I think was causing issues. I kept trying to strip down what I was installing since I didn't really need much from VS on my machine. Among other things, I get a weird feeling that the Windows SDK is required (and you have it selected in your list), which just doesn't make much sense to me. I may experiment a bit more and see if I can confirm that.

If we can figure out what exactly is needed for install, we could update the README.md. Seems like C++ 2015 Build Tools with DEFAULT settings (lol) is a good safe bet, but would also be nice to know how VS can be installed since many will have that on their machine.

[aturon]

cc @Diggsey @retep998 -- @brson is away right now, but this is a pretty troubling issue, and from what I understand may not be too hard to fix. Any chance either of you can help?

[Diggsey]

@aturon I'm not quite sure what you have in mind, beyond changing the documentation, nor why you consider this particularly troubling?

The fact is, rust currently requires (and has always required) all three of these components, and the components are installed by default when installing the VC++ build tools. If you remove those components it can't work.

I can add a note the installation instructions saying to use the default settings, but anything more detailed, such as exactly which components are required, may be difficult to keep up to date and correct for all versions of the installer, since MS have a tendency to change things up quite a bit!

Here's a breakdown of why each component is required:

• Universal CRT
  Rust programs currently require a CRT
• VC++ toolset
  Rustc needs a linker
• Windows SDK
  libstd imports symbols from advapi32.lib, ws2_32.lib, userenv.lib and shell32.lib which are part of the windows SDK

@projektir @redstrike Is there something further you'd like to see changed?

[retep998]

It doesn't really matter which VC++ toolset version you use, or which Universal CRT version you use, or which Windows SDK version you use as long as you have all three of them. However, it is generally better to have the newest versions when possible.

If you install VC++ via VS 2017, then Rust is currently incapable of autodetecting this VC++ installation, and you'll have to manually configure your environment using a vcvars bat file or the VC++ development command prompt option.

[steveklabnik]

I was just about to jump in here to say

If you install VC++ via VS 2017, then Rust is currently incapable of autodetecting this VC++ installation, and you'll have to manually configure your environment using a vcvars bat file or the VC++ development command prompt option.

👍 we have people hitting this every day now.

[Diggsey]

Here's the relevant issue for VS 2017 detection: rust-lang/rust#38584

[redstrike]

@Diggsey Have more guide text is better than let the users sink themselves in unexpected issues and try to search for the solutions (It costs me a full afternoon to experiment with different installation settings).

I had a great getting started with Golang in the past, I only need to run the official go1.8.windows-amd64.msi and it does the all the tedious tasks for me without relying on Visual Studio/C++ toolchain. Each time, I want to update my Go or Node version, just download the official installer and run... DONE.

I don't have enough background in Computer Science, programming language & compiler design. But I think a modern system programming language like Rust should not rely on C++ build tools to compile & run HelloWorld program. I hope Rust could be that awesome and more beginner friendly.

[Diggsey]

@redstrike I agree we should do more documentation-wise.

I'm afraid what you're suggesting isn't really feasible for rust. Go avoids a dependency on a VC++ toolchain by implementing their own custom linker, which only works for go, and it comes with significant downsides. For example, as soon as you depend on a C library, you're back to needing a proper VC++ linker again.

NodeJS isn't really comparable because javascript isn't a compiled language. However, if you use any npm libraries that have native dependencies, you'll again need the VC++ build tools.

Basically. link.exe is the official microsoft linker, so if you want to link native programs for windows, that's what you use, and link.exe is part of the VC++ build tools.

In the future, we may be able to automatically start the VC++ build tools installation if the user requests it, when rustup is initially installed, and I think that's as good as it's likely to get honestly.

[brson]

There seem to be several interrelated bugs here, and I'm not clear on them.

There's the bug to teach rustc how to find the VC 2017 linker. That is not this bug. This is a bug about rustup-init not detecting a usable VC 2017 install.

I'm not clear on why this is only a crisis now, when the VC 2017 bug in rustc has existed since 2016/12/31. Can anybody explain? (Maybe it only hit stable recently).

Since rustc doesn't work correctly with some VC 2017's, doesn't that mean that even if rustup fixes its own detection, that rust will still be broken?

Does anybody know what the necessary change to rustup is to make this detection work?

How many versions of VS 2017 are there, and which ones work correctly with rustc, which ones don't work correctly with rustc, which ones work with rustup, which don't work with rustup?

[retep998]

@redstrike

Getting Rust to not depend on a C++ toolchain is quite a long way in the future and would involve several things:

1. Using LLD as the linker. It currently has some deficiencies like no debug info on Windows, and still relies on calling other tools from the VC++ toolchain for certain things, so it's not something we can do today.
2. We currently rely on the CRT for a few math and memory functions. We'd have to write our own versions of those functions. Not particularly difficult
3. In order to access all the system functions, we depend on the plethora of import libraries provided by the Windows SDK. To not rely on them would require support for a dll link kind that would emit idata, and then would involve me updating winapi with DLL bindings to the tens of thousands of functions.

[retep998]

I'm not clear on why this is only a crisis now, when the VC 2017 bug in rustc has existed since 2016/12/31.

Because VS 2017 only had its actual stable release in March. Before then it was just previews and release candidates.

Since rustc doesn't work correctly with some VC 2017's, doesn't that mean that even if rustup fixes its own detection, that rust will still be broken?

Unless you use vcvars to manually configure your environment, yes. Or if rustc delegates responsibility for detecting VC++ to rustup, which would involve the rustup proxies doing the autodetection and setting env vars appropriately before calling the actual binaries.

How many versions of VS 2017 are there, and which ones work correctly with rustc, which ones don't work correctly with rustc, which ones work with rustup, which don't work with rustup?

There is just the one VS 2017, and both rustc and rustup do not autodetect it currently. It can however have multiple VC++ toolsets installed and provides a COM api to select one of those toolsets which I am currently working with.

[brson]

Thanks @retep998.

[projektir]

This discussion is getting a bit derailed. This is NOT about VS 2017. This is about rustup not detecting VC++ Build Tools (note the title). The VS 2017 thing just shines light on what's happening.

It doesn't really matter which VC++ toolset version you use, or which Universal CRT version you use, or which Windows SDK version you use as long as you have all three of them. However, it is generally better to have the newest versions when possible.

It is not at all obvious from the rustup installation page that you need, say, the Windows SDK. It just says VC++ toolset, which was installed, and present in the programs list, but not picked up by rustup. When you run rustup, it complains about the toolset.

If you install VC++ via VS 2017, then Rust is currently incapable of autodetecting this VC++ installation, and you'll have to manually configure your environment using a vcvars bat file or the VC++ development command prompt option.

This is true, and that's why I went for the VC++ Build Tools install at first. But it's also a very weird experience when your VC++ 2017 install, which Rust is incapable of detecting, fixes the issue by apparent side effect of installing extra missing components rustup didn't specify were needed (such as the Windows SDK).

The problem I reported is with rustup not detecting the VC++ 2015 Build Tools, not VS 2017. It's completely understandable for rustup to not detect VS 2017. But it's a bad user experience when it tells you that VC++ 2015 Tools are OK, you install them, and it literally tells you they're not installed... when they're there... if it wants the SDK, it should say it wants the SDK.

I hope that clears my complaint up.