# Cross Compile gRPC-rs(0.2.1) to Windows under *nix
## First you need to install mingw
```bash
# macOS
brew install mingw-w64
# CentOS
yum install mingw64-openssl-static mingw64-zlib-static mingw64-winpthreads-static
```
## Fix CMake
```
# modify grpc-rs/grpc-sys/build.rs
# fix SYSTEM_PROCESSOR
"CMAKE_SYSTEM_PROCESSOR", get_env("CARGO_CFG_TARGET_ARCH").unwrap()
# fix try_run
"CMAKE_CROSSCOMPILING", "true"
```
### All diff in `fn build_grpc`
```rust
let dst = {
let mut config = Config::new("grpc");
if get_env("CARGO_CFG_TARGET_OS").map_or(false, |s| s == "macos") {
config.cxxflag("-stdlib=libc++");
}
config
.define("CMAKE_SYSTEM_PROCESSOR", get_env("CARGO_CFG_TARGET_ARCH").unwrap())
.define("CMAKE_CROSSCOMPILING", "true")
.build_target(library)
.uses_cxx11()
.build()
// config.build_target(library).uses_cxx11().build()
};
```
### Fix find zlib
```rust
// try these values
let mut zlib = "z";
let mut zlib = "zlibstatic";
let mut zlib = "zlibstaticd";
```
## Fix WIN32 API
```
# grpc-rs/grpc-sys/grpc/CMakeLists.txt
# add these code after about line number 295
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D_WIN32_WINNT=0x600")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -D_WIN32_WINNT=0x600")
set(C_CXX_FLAGS "${C_CXX_FLAGS} -D_WIN32_WINNT=0x600")
```
## Fix boringssl
Just update third_party/boringssl
```bash
cd third_party/boringssl
git checkout master
git pull
```