What version of Go are you using (go version)?

$ go version
go version go1.13.4 darwin/amd64

Does this issue reproduce with the latest release?

Yes, judging by the contents of the master branch.

What operating system and processor architecture are you using (go env)?

$ go env
O111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/alex/Library/Caches/go-build"
GOENV="/Users/alex/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/alex/programming/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/Users/alex/.go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/Users/alex/.go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/alex/programming/go-mod/0x-mesh/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/h1/vhbpm31925nd0whbv4qd8mr00000gn/T/go-build550535634=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Related to #36561, I came across another unexpected error
from the TypeScript compiler.

this should usually be avoided in anonymous functions, due to its often unexpected behavior. It's possible that this is intended, but I wanted to point it out for two reasons:

1. It looks like it could be a bug. At the very least it is not following JavaScript best practices.
2. The current version doesn't compile in TypeScript so I wanted to get confirmation about the intended behavior so I can write a version that behaves the same way but does work in TypeScript.

As a quick reminder about the behavior of this inside anonymous functions:

1. If you are not running in strict mode, this defaults to the global scope (e.g. window). In strict mode it defaults to undefined.
2. You can set the value of this by using bind. In order to do this, you need a reference to the function. So if we have a function called myFunc, you could call it this way: myFunc.bind(myObj).call(). This would result in this being set to myObj.

It was difficult for me to find where the function was called, but if you are not calling it via bind, it means that this is always undefined. This might be a bug that should be addressed. On the other hand if everything still works, this could simply be removed:

            return function() {
-                const event = { id: id, this: this, args: arguments };
+                const event = { id: id, args: arguments };
                go._pendingEvent = event;
                go._resume();
                return event.result;
            };

If you are using bind, I would suggest simply passing in an argument to the function in order to adhere to JavaScript best practices. I'm not sure what the argument should be called since I don't have the full context of how this function is being used, but it would look something like this:

            return function(myObj) {
-                const event = { id: id, this: this, args: arguments };
+                const event = { id: id, myObj: myObj, args: arguments };
                go._pendingEvent = event;
                go._resume();
                return event.result;
            };

Maybe there is some reason the function can't be written that way? I'm not sure.

What did you expect to see?

Again, I don't expect this file to compile without making changes since it wasn't written with TypeScript in mind. I was surprised by this particular error and I think it points to a potential bug.

What did you see instead?

The TypeScript compiler complains about the usage of this inside an anonymous function.