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:UsersMikeAppDataLocalgo-build  
set GOEXE=.exe  
set GOHOSTARCH=amd64  
set GOHOSTOS=windows  
set GOOS=windows  
set GOPATH=E:devgolang  
set GORACE=  
set GOROOT=c:go  
set GOTMPDIR=  
set GOTOOLDIR=c:gopkgtoolwindows_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:UsersMikeAppDataLocalTempgo-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

使用bootstrap源码编译工具链

$ GOOS=windows GOARCH=amd64 ./make.bat  
# Building C bootstrap tool.  
cmd/dist  
  
# Building compilers and Go bootstrap tool.  
E:gosrclib9fmtfltfmt.c: In function '__efgfmt':  
E:gosrclib9fmtfltfmt.c:437:5: warning: this statement may fall through [-Wi                        mplicit-fallthrough=]  
   if(ndigits > prec) {  
     ^  
E:gosrclib9fmtfltfmt.c:451:2: note: here                 

省略大部分日志 

---  
Installed Go for windows/amd64 in E:go  
Installed commands in E:gobin

可以看到，编译时间已经更新：

123

修改GOROOT_BOOTSTRAP，设置为E:go，重新编译

$ GOOS=windows GOARCH=amd64 ./make.bat
# Building C bootstrap tool.

可以看到，编译时间已经更新：