cmd/link: linkname to runtime.addmoduledata is not forbidden

[wdvxdr1123]

package main

import (
	_ "unsafe"
)

//go:linkname addmoduledata runtime.addmoduledata
func addmoduledata()

func main() {
	addmoduledata()
}

This program can compile ok. However, comment said do NOT call from Go.

go/src/runtime/stubs.go

Lines 427 to 428 in ebc763f

	// Called from linker-generated .initarray; declared for go vet; do NOT call from Go.
	func addmoduledata()

And using linkname on this function will cause a linker crash when building with buildmode=plugin.

package main

import (
	_ "unsafe"
)

//go:linkname addmoduledata runtime.addmoduledata
func addmoduledata()

func FOO() {
	addmoduledata()
}

go build -buildmode=plugin a.go
# command-line-arguments
runtime.gcWriteBarrier1: phase error: addr=0x63750 but val=0x5dc00 sym=runtime.gcWriteBarrier1 type=STEXT sect=.text sect.addr=0x0 prev=runtime.addmoduledata

[gopherbot]

Change https://go.dev/cl/699655 mentions this issue: cmd/link: disallow linkname of runtime.addmoduledata

[gabyhelp]

Related Code Changes

• cmd/link: disallow linkname of runtime.addmoduledata

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