Bugfix: buildFlags="-C directory" is invalid

[saffraan]

When set buildFlags="-C dir", go build failure. Because the "-C direcotry" option is filled after "go build -o xxx", for example:

go build -o main -C /root/main

but the "-C dir" option should be filled after "go build":

go build -C /root/main -o main

in go version 1.20.

[aarzilli]

I've tried it both ways (go build -o something -C somethingelse and go build -C somethingelse -o something) and they seem to both do the exact same thing. What is the build failure exactly?

[saffraan]

I've tried it both ways (go build -o something -C somethingelse and go build -C somethingelse -o something) and they seem to both do the exact same thing. What is the build failure exactly?

(base) ➜ /tmp cd go-example
(base) ➜ go-example ls
go.mod main.go
(base) ➜ go-example cat main.go
package main

import "fmt"

func main(){
fmt.Println("Hello word!")
}
(base) ➜ go-example cat go.mod
module go-example

go 1.20
(base) ➜ go-example cd ..
(base) ➜ /tmp go build -gcflags all="-N -l" -C /tmp/go-example -o main
go: go.mod file not found in current directory or any parent directory; see 'go help modules'
(base) ➜ /tmp go build -C /tmp/go-example -gcflags all="-N -l" -o main
(base) ➜ /tmp ls /tmp/go-example/
go.mod main main.go
(base) ➜ /tmp

[saffraan]

I've tried it both ways (go build -o something -C somethingelse and go build -C somethingelse -o something) and they seem to both do the exact same thing. What is the build failure exactly?

sorry, I found the bug in debug mode, I haven't try to run go build just with -C optional.

[aarzilli]

Looks like a bug in cmd/go, let's see.

[saffraan]

Looks like a bug in cmd/go, let's see.

Yes, this is a bug of golang, if fixed, the pr can be closed.

[aarzilli]

According to the release notes for 1.21 it looks like -C needs to be the first flag passed:

 The -C dir flag must now be the first flag on the command-line when used. 

so we should do something about this. However I don't like the approach in this PR, I think it's too complicated and we should just change goBuildArgs to start the args slice with the buildflags string:

func goBuildArgs(debugname string, pkgs []string, buildflags string, isTest bool) []string {
	args := []string{}
	if buildflags != "" {
		args = append(args, config.SplitQuotedFields(buildflags, '\'')...)
	}
	args = append(args, "-o", debugname)
	...