Proposal: make `--strace` standalone works without any dependency about xgo HOT 8 CLOSED

This may needs an extra layer of work before build: importing dependencies.

Maybe related to this project: https://github.com/xhd2015/go-inspect

from xgo.

Process overview:

from xgo.

Kwonledge of packages.Load:

import "golang.org/x/tools/go/packages"

func TestPackageLoad(t *testing.T) {
	fset := token.NewFileSet()
	cfg := &packages.Config{
		Mode: packages.NeedImports,
		Fset: fset,
	}

	pkgs, err := packages.Load(cfg, "./cmd/xgo")
	if err != nil {
		return err
	}
        t.Logf(pkgs)
}

from xgo.

Since go1.16, go build adds a -overlay flag, that was primarily added to support editors loading unsaved files: golang/go#39958.

But we can utilize it to include extra files without modifying any project files.

from xgo.

For the vendoring case, can we just use this replace:

replace github.com/xhd2015/xgo/runtime => ./local_created_runtime

We can manually parse the vendor/modules.txt, and recover the minimal go.mod for each module.
See here: https://github.com/golang/go/blob/334ce510046ad30b1be466634cf313aad3040892/src/cmd/go/internal/modload/vendor.go#L40

from xgo.

We can manually parse the vendor/modules.txt, and recover the minimal go.mod for each module.

To make it work in vendor mode, the key point is to use an alternate -modfile to allow go modify the go.mod, bypassing the vendoring check.

Because when turning -mod=vendor into -mod=mod -overlay overlay.json, if go.mod appears in overlay.json, go complains:

go: updates to go.mod needed, but go.mod is part of the overlay specified with -overlay

The solution becomes:

 -mod=mod -modfile go-tmp.mod

from xgo.

We are currently encounter a subtle bug while running tests:

• after trap_without_dep passed, future tests with stdlib, like func_list would fail
  • complaining about net/http.Get not trapped,
  • It's just that net, net/http are missing, but os, io, io/ioutil are still fine
• If run tests with -a, that problem goes away.

This may be related to build cache.

from xgo.

More edge scenarios need to be verified:

• what if the go.mod already contains github.com/xhd2015/xgo/runtime, directly or indirectly.
• when multiple args were used, what if some imports the dependency, while others not?

This leads to a more sophisticated solution:

1. check if go.mod contains the dependency directly or indirectly,

• go list -m -json github.com/xhd2015/xgo/runtime , or
• go list -m -json -mod=vendor github.com/xhd2015/xgo/runtime

2. for vendor mode, should also check if the pkg github.com/xhd2015/xgo/runtime/pkg is missing, if missing then the whole runtime should be imported and replacing the current runtime

The process is splitted into 2 phases:

• load dependency
• update each package's import to include the trace package
  

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