win32: 使用go编译go自身 golang

因项目需要，需要重新编译go。
本文记录使用go编译go自身的流程，方便后面继续修改编译：
如直接自己编译自己，会出现下面的错误：

$ cd /c/go/src $ ./make.bat Building Go cmd/dist using C:\Go go tool: no such tool "compile" go tool: no such tool "compile" go tool: no such tool "compile" go tool: no such tool "compile" go tool: no such tool "compile" go tool: no such tool "compile" go tool: no such tool "compile" go tool: no such tool "compile"

查看go env发现也没任何错误：

$ go env set GOARCH=amd64 set GOBIN= set GOCACHE=C:\Users\Mike\AppData\Local\go-build set GOEXE=.exe set GOHOSTARCH=amd64 set GOHOSTOS=windows set GOOS=windows set GOPATH=E:\dev\golang set GORACE= set GOROOT=c:\go set GOTMPDIR= set GOTOOLDIR=c:\go\pkg\tool\windows_amd64 set GCCGO=gccgo set CC=gcc set CXX=g++ set CGO_ENABLED=1 set CGO_CFLAGS=-g -O2 set CGO_CPPFLAGS= set CGO_CXXFLAGS=-g -O2 set CGO_FFLAGS=-g -O2 set CGO_LDFLAGS=-g -O2 set PKG_CONFIG=pkg-config set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Users\Mike\AppData\Local\Temp\go-build976029818=/tmp/go-build -gno-record-gcc-switches

怀疑是其他地方的问题。折腾了半天，后来发现 GOTOOLDIR 为空
使用bootstrap源码编译工具链参考这里的说明，先下载 go1.4-bootstrap-20171003.tar.gz，使用已经下载的go编译，日志如下：

$ GOOS=windows GOARCH=amd64 ./make.bat # Building C bootstrap tool. cmd/dist# Building compilers and Go bootstrap tool. E:\go\src\lib9\fmt\fltfmt.c: In function '__efgfmt': E:\go\src\lib9\fmt\fltfmt.c:437:5: warning: this statement may fall through [-Wimplicit-fallthrough=] if(ndigits > prec) { ^ E:\go\src\lib9\fmt\fltfmt.c:451:2: note: here省略大部分日志 --- Installed Go for windows/amd64 in E:\go Installed commands in E:\go\bin

【win32: 使用go编译go自身】可以看到，编译时间已经更新：