Crate static_vcruntime 

Statically link the VCRuntime while dynamically linking the UCRT. This only applies when using the MSVC toolchain.

By default, Rust requires programs to deploy vcruntime140.dll (or equivalent) when redistributing binaries. You can use the -C target-feature=+crt-static rustc flag to statically link it but that also statically links the Universal CRT. The Universal CRT is a component of Windows so can always be dynamically linked.

See Details for more information.

Usage

Add this to your Cargo.toml:

[build-dependencies]
static_vcruntime = "3.0"

And then in your build script you can call static_vcruntime::metabuild like so:

fn main() {
    static_vcruntime::metabuild();
}

For the best compatibility it is recommended that you also set the target-feature flag to +crt-static. In the same directory as your Cargo.toml, create a folder called .cargo. In that folder create the file config.toml and add the following:

# In .cargo/config.toml
[target.'cfg(all(windows, target_env = "msvc"))']
rustflags = ["-C", "target-feature=+crt-static"]

Details

What we call the “CRT” is actually three components:

• The C startup files. This provide startup/shutdown code.
• The VC runtime. In rust this is mainly used for panic handling but also provides some fundamental functions such as memcpy.
• The Universal CRT (aka UCRT). This is where most of the C standard library lives.

Each of these can be linked either dynamically or statically, however it is usually required that if one is linked statically then they are all linked statically (and ditto for dynamica linking). There is one exceptions. If the VC runtime and C startup files are linked statically then the UCRT can be linked dynamically.

The following table summarises these options:

	C startup	VC runtime	Universal CRT
Default	dynamic	dynamic	dynamic
+crt-static	static	static	static
static_vcruntime	static	static	dynamic

Issues

If you have problems then you may need to clean the build directory before rebuilding:

cargo clean

It is possible that some C/C++ dependencies may not work in this configuration.

Note that Microsoft recommends all the runtime libraries be dynamically linked (which is the default).

Functions

metabuild

Use dynamically linked ucrt with a statically linked vcruntime.