runtime: multiple definition of 'go:itab.runtime.errorString,error'

[wingrez]

Go version

go1.23.2

Output of go env in your module/workspace:

Doesn't matter.

What did you do?

I'm trying to customize some of the features in the runtime. However I ran into a problem.

To simplify, here is an example.

Add this function to runtime.

func Demo() error {
	return errorString("hello")
}

main.go

package main

import "C"
import (
	_ "plugin"
	"runtime"
)

func main() {
	err := runtime.Demo()
	println(err)
}

Build using go build main.go.

What did you see happen?

go/pkg/tool/linux_arm64/link: running gcc failed: exit status 1
/usr/bin/ld.gold: error: /tmp/go-link-2461440430/go.o: multiple definition of 'go:itab.runtime.errorString,error'
/usr/bin/ld.gold: /tmp/go-link-2461440430/go.o: previous definition here
collect2: error: ld returned 1 exit status

What did you expect to see?

Build success

[gabyhelp]

Related Issues and Documentation

• gollvm: multiple definition of 'runtime.nanotime..f' #53807

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[wingrez]

There are two duplicate symbols in go.o: go:itab.runtime.errorString,error, and their attributes are Global.

[seankhliao]

If you look at errorString, it's only used for panics.

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[randall77]

This is kind of odd, although I wouldn't call it a bug either. Certainly we don't support modifying the runtime like this.

I think the trigger is because Demo is being inlined. That means we get a runtime symbol defined in both the runtime .o and the main package .o.
I don't understand why that is a problem, though. Itab symbols like this should me marked DUPOK and deduplicated. Maybe something about the buildmode loses that DUPOK mark somewhere?

In any case, marking Demo with //go:noinline fixes it.