How does the golang-crosscompile helper script work

1. Clone the Go Repository:
- The script starts by cloning the Go repository from the official GitHub repository.

2. Apply the Patch:
- It then applies a patch to the Go source code to enable cross-compilation. This patch is necessary because Go's standard `go build` command does not support cross-compilation out of the box.

3. Build Go:
- After applying the patch, the script builds the Go toolchain for the target platform.

4. Use the Cross-Compile Tool:
- The script then uses the `go-crosscompile` tool to build all the toolchains for the target platforms.

5. Cross-Compile Go Programs:
- Finally, the script sets the necessary environment variables (`CC`, `GOOS`, `GOARCH`, `GOARM`, and `-extld`) and uses the `go build` command to cross-compile Go programs for the target platforms.

Here is a detailed example of how to use the `golang-crosscompile` helper script to cross-compile Go programs for different operating systems and architectures:

bash
# Clone the Go repository
hg clone -u release https://code.google.com/p/go
cd go
hg update default

# Apply the patch
curl https://gist.github.com/steeve/6905542/raw/cross_compile_goos.patch | patch -p1

# Build Go
cd src
bash all.bash

# Use the cross-compile tool
git clone https://github.com/davecheney/golang-crosscompile.git
source golang-crosscompile/crosscompile.bash
go-crosscompile-build-all

# Cross-compile Go programs
CC=i586-mingw32-gcc GOOS=windows GOARCH=386 CGO_ENABLED=1 go build -v -o myprogram.exe -ldflags="-extld=$CC"

This script can be used to cross-compile Go programs for various platforms, including Windows, Linux, and macOS.