From f1c6bc6210332ae922042b3286d247e7fe71ce52 Mon Sep 17 00:00:00 2001
From: Light Ning <light4@users.noreply.github.com>
Date: Sat, 10 Nov 2018 00:55:45 +0800
Subject: [PATCH] cross compile grpc-rs to windows under *nix (#169)

* update for cross compile

* add cross_compile

* update cross_compile

* add cross compile link

* update

* update

* fix typo
---
 README.md         |  4 +++
 cross_compile.md  | 82 +++++++++++++++++++++++++++++++++++++++++++++++
 grpc-sys/build.rs |  6 ++--
 3 files changed, 89 insertions(+), 3 deletions(-)
 create mode 100644 cross_compile.md

diff --git a/README.md b/README.md
index 8f5910d2a..b2b8d5430 100644
--- a/README.md
+++ b/README.md
@@ -97,3 +97,7 @@ grpcio = { version = "0.4", default-features = false, features = ["protobuf-code
 ## Performance
 
 See [benchmark](https://github.com/pingcap/grpc-rs/tree/master/benchmark) to find out how to run a benchmark by yourself.
+
+Cross Compile
+-------------
+See [cross_compile](cross_compile.md)
diff --git a/cross_compile.md b/cross_compile.md
new file mode 100644
index 000000000..a3146227e
--- /dev/null
+++ b/cross_compile.md
@@ -0,0 +1,82 @@
+# 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 try_run
+
+```
+# grpc-rs/grpc-sys/grpc/third_party/benchmark/cmake/CXXFeatureCheck.cmake
+# add these code to fix try_run
+SET( RUN_HAVE_STD_REGEX
+     0
+     CACHE STRING "Result from TRY_RUN" FORCE)
+
+SET( RUN_HAVE_STEADY_CLOCK
+     0
+     CACHE STRING "Result from TRY_RUN" FORCE)
+```
+
+## 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
+```
diff --git a/grpc-sys/build.rs b/grpc-sys/build.rs
index f674c9ae9..80d17f4be 100644
--- a/grpc-sys/build.rs
+++ b/grpc-sys/build.rs
@@ -75,7 +75,7 @@ fn build_grpc(cc: &mut Build, library: &str) {
             // the unnecessary dependency.
             config.define("GO_EXECUTABLE", "fake-go-nonexist");
         }
-        if cfg!(target_os = "macos") {
+        if get_env("CARGO_CFG_TARGET_OS").map_or(false, |s| s == "macos") {
             config.cxxflag("-stdlib=libc++");
         }
         if env::var("CARGO_CFG_TARGET_ENV").unwrap_or("".to_owned()) == "musl" {
@@ -106,7 +106,7 @@ fn build_grpc(cc: &mut Build, library: &str) {
         "boringssl/ssl",
         "boringssl/crypto",
     ];
-    if cfg!(target_os = "windows") {
+    if get_env("CARGO_CFG_TARGET_OS").map_or(false, |s| s == "windows") {
         let profile = match &*env::var("PROFILE").unwrap_or("debug".to_owned()) {
             "bench" | "release" => {
                 zlib = "zlibstatic";
@@ -193,7 +193,7 @@ fn main() {
     }
     cc.file("grpc_wrap.cc");
 
-    if cfg!(target_os = "windows") {
+    if get_env("CARGO_CFG_TARGET_OS").map_or(false, |s| s == "windows") {
         // At lease win7
         cc.define("_WIN32_WINNT", Some("0x0700"));
     }