Detailed explanation of Go tool chain (1): go tool fix without worrying about upgrading version

go tool fix function

go tool fix is ​​a command in the Go tool chain. Its function is to fix all the old version codes in the specified Go program code package to the new version codes (the version mentioned here is the Golang version). After upgrading the Go version, use this command to automatically make the necessary changes to the program.

During the evolution of Golang, it is inevitable to improve some functions and standard libraries. Compatibility problems may arise during the improvement process. Once compatibility problems occur, the cost of upgrading from the old version to the new version will be relatively high. And go tool fix can automatically correct the compatibility problems caused by the upgrade, and minimize the cost of the upgrade version.

How to use go tool fix and examples

The basic usage of the go tool fix command is as follows:

go tool fix [-r name,...] [path ...]

If no path is specified, standard input is read and results are written to standard output. If the specified path is a file, the specified file is rewritten in-place (the rewrite operation is idempotent). If the specified path is a directory, all files with a .go suffix in the directory will be overwritten. When a file is rewritten, a line is output to standard error giving the name of the file and the rewrites applied. Look at an example:

package main

import (
	"golang.org/x/net/context"
)

func main() {
	var ctx context.Context
	ctx.Value("luduoxin")
}

Run the command:

$ go tool fix main.go          

reader.go: fixed context

Then the content of the source file becomes the following:

package main

import (
	"context"
)

func main() {
	var ctx context.Context
	ctx.Value("luduoxin")
}

If the -diff flag is set, the file will not be rewritten, and the difference before and after the correction will be printed. Take the above code before correction as an example, run the command to view the effect:

$ go tool fix -diff main.go      
main.go: fixed context
diff main.go fixed/main.go
--- /var/folders/_6/ftdrl7pd4f34ndx_mkzv2zxh0000gn/T/go-fix3344770880   2023-07-17 21:59:08
+++ /var/folders/_6/ftdrl7pd4f34ndx_mkzv2zxh0000gn/T/go-fix273913435    2023-07-17 21:59:08
@@ -1,7 +1,7 @@
 package main
 
 import (
-       "golang.org/x/net/context"
+       "context"
 )
 
 func main() {
   
   

The function of the -r flag is to only perform the specified correction operation on the target source file. The value of the flag is the name of the allowed correction operation, and multiple names are separated by commas. For example:

 $ go tool fix -r=context main.go 

Correction operations include buildtag, cftype, context, egl, eglconf, gotypes, jni, netipv6zone.

The function of the -force flag is to force the specified correction operation even if the code in the source file already matches the Go version used.

$ go tool fix -force=context main.go

For more detailed usage of go tool fix, you can use the command run go tool fix -help to view.

go tool fix usage scenarios

• After the Go version is upgraded, the import path of some software packages may be adjusted, a function, method or constant name may be adjusted, or a new function or method may be used to replace the old function or method. Use go tool fix to automatically fix these problems in the old code.
• go tool fix can automatically fix some formatting problems in the code, such as missing spaces, repeated imports, etc.

It should be noted that go tool fix cannot solve all problems, and in many cases it is still necessary to manually change the code. Before using go tool fix for code repair, it is recommended to make a backup first.

summary

go tool fix can help to automatically fix some common problems and compatibility problems, especially after upgrading the Go version, it can automatically fix the compatibility problems caused by the upgrade, which perfectly solves the worries of the upgraded version.