错误 [E0463]: can't find crate for std... 如何在 x64 Windows 机器上编译 Rust x32？

Question

I'm on Windows 10 x64. I have Visual Studio 2019 installed, which allows me to compile C and C++ for both x32 and x64 without problems.

Now, for Rust, I have the stable-x86_64-pc-windows-msvc toolchain installed through rustup, which allows me to compile x64 binaries just fine.

In an attempt to compile Rust x32, I installed the stable-i686-pc-windows-msvc , but when I run cargo test --target i686-pc-windows-msvc , it gives me error[E0463]: can't find crate for std .

How can I fix this?

Answer 1

This seems to be a misunderstanding on what is toolchain and what is target .

The code is always being built for some target triple - it's usually fully defined by the system in question (Windows systems are an exception, since they have two kinds of target triples - *-msvc and *-gnu , depending on the C compiler and linker).

When you install the toolchain, using the

rustup toolchain install toolchain-name

its name is defined as compiler_version - target_triple , eg stable-x86_64-pc-windows-msvc . The target triple here is the one which was used to build the compiler, ie it is defined by the host system - the one which runs the compilation process; therefore, almost always all the installed toolchains will differ only in version part - eg, if you need some code to use the nightly-only features, you'll install nigtly-*triple* alongside the stable-*triple* .

When you add the target, using the

rustup target add target-name

its name is just the target triple, without reference to the compiler version. In this case, the triple is what is used by the compiler, building your own code , and for the prebuilt standard library; and that's what you need to use when you're using the compiler for cross-compilation, including compilation to another processor architecture (32-bit vs 64-bit). The compiler itself will still be build for your host, but it will emit artifacts for another system.