Tonic: hello_world example is fails with environment variable `OUT_DIR` not defined

[incker]

Have tried hello world example from here

Got an error:

error: environment variable `OUT_DIR` not defined
--> src/server.rs:21:5
|
21 |     tonic::include_proto!("helloworld");
|     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

Windows 10 64bit

[dependencies]
tonic = "0.2.0"
prost = "0.6.1"
tokio = { version = "0.2.18", features = ["macros"] }

[build-dependencies]
tonic-build = "0.2.0"

Maybe it is windows-only bug?
I have made everything step by step like in example

Can you also help, explain how I need to set OUT_DIR variable and which path have to provide (If I have to)
Forward thank you

[incker]

I just have put build.rs file is src/ folder instead of root. That was a mistake.
Maybe this silly issue will help somebody as green as I am))