cmd/link: DTrace fails on macOS

[shibukawa]

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

1.7.3

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

amd64 on macOS 10.11.6 (El Capitan) and 10.12.1 (Sierra)
(System Integrity Protection is turned off to use DTrace)

What did you do?

package main

func main() {
}

$ sudo dtruss ./mycode

What did you expect to see?

Appears system call information

What did you see instead?

The panic message thrown at the following place appears.

https://github.com/golang/go/blob/master/src/runtime/os_darwin.go#L108

@moriyoshi researched this issue I met and he found the following facts:

The following codes works.

package main
import (
    "C"
)
func main() {
}

package main
import (
    "time"
)
func main() {
    // attach with $ sudo dtruss -p PID 
    // during this term
    time.Sleep(10 * time.Second)
}

bsdthread_register() function may be designed to be called only once (call twice returns error), but /usr/lib/dtrace/libdtrace_dyld.dylib calls this function before loading and then Go runtime calls at initialization process too (if the go program was not built in cgo mode).

[minux]

You don't need to import "C", just force external linking suffice. go build -linkmode=external I think this is working as intended unless we switch darwin binary to always use libSystem.dylib. See #17200 and #17490.

[quentinmit]

/cc @rsc

[rsc]

Dup of #17490.

[rsc]

#18171 is about linking with at least runtime/cgo by default, to avoid this kind of bsdthread_register issue. So dup of #18171.

Although #17490 would solve this too, it's more than is necessary. (It's about not just linking with runtime/cgo by default but then using the system dylib for all system calls.)