Thanks, but you are describing a solution rather than a problem. What is the real goal? What paths do you want to trim and why?

I have configuration where there are two gopaths. And both of them show local system information (e.g. my username). I want to remove these paths from the project and keep only src/... part and this is the only method which currently helps.
But trimpath supports only one path and by this default remove of $WORK directory is not working anymore.

I'm encountering this issue when I'm compiling a program using cgo (with Go 1.10). For example, for this program:

package main

// typedef int (*intFunc) ();
//
// int
// bridge_int_func(intFunc f)
// {
//		return f();
// }
//
// int fortytwo()
// {
//	    return 42;
// }
import "C"
import "fmt"

func main() {
	f := C.intFunc(C.fortytwo)
	fmt.Println(int(C.bridge_int_func(f)))
	// Output: 42
}

If I compile this program with no trimpath flags (go build fortytwo.go), the executable will have these two paths:

/home/jeff/fortytwo.go
_cgo_gotypes.go

If I compile with trimpath flags (go build -gcflags "all=-trimpath=/home/jeff" -asmflags "all=-trimpath=/home/jeff" fortytwo.go), the executable will have these two paths:

fortytwo.go
/tmp/go-build073316115/b001/_cgo_gotypes.go

Because I supplied the trimpath flags, the built-in -trimpath $WORK is overridden. Neither option is great in terms of reproducibility; ideally both paths are trimmed.

This issue should be more relevant now with modules, since the project you're building can be outside the $GOPATH while modules that your project depends on are built inside $GOPATH.

I agree with @jclc that this issue is relevant when using modules, since it is impossible to remove $GOPATH/pkg strings from your binary if you are already using -trimpath on any other location.

I suppose that there are a few of ways to solve this, and I would be curious to which one is most amenable to the Go community:

1. Teach -trimpath to respect os.PathListSeparator, so that we could say: -trimpath=$(pwd):$GOPATH/pkg, or similar.

2. Teach cmd/compile to respect multiple -trimpath arguments, which I believe would address issues like cmd/go: setting a global "-trimpath" untrims some temporary cgo files #24976, too.

3. Add additional semantics to always trim $GOPATH/pkg or others from the compiled binary. This option seems too mysterious to me, but I would defer to the judgement of others.

I'd be happy myself to write a patch for any of the above three.

Instead of multiple paths, probably we should have some mode that means “trim all paths that aren't part of the import path”. That would help with cases like #28008 where the caller doesn't actually know the full set of paths in play.

Users should not be using -trimpath. The general problem here is #16860.

FYI: https://go-review.googlesource.com/c/go/+/65233/