Possibly related: #25970

@ianlancetaylor @cherrymui

Function fmt.Printf is inlined. The actually called function is fmt.Fprintf, and the first arg is an ifcae, the data of it is os.Stdout. the tab of it is go.itab.*os.File,io.Writer.
I add flag "-dumpdep" to linker:

_ -> main.main
_ -> main..inittask
_ -> runtime.unreachableMethod
main.main -> os.Stdout
main.main -> go.itab.*os.File,io.Writer
main.main -> go.string."Hello, World!\n"
main.main -> fmt.Fprintf
main.main -> runtime.morestack_noctxt
main.main -> gclocals·33cdeccccebe80329f1fdbee7f5874cb
 -> go.info.fmt.Printf$abstract
go.itab.*os.File,io.Writer -> type.io.Writer
go.itab.*os.File,io.Writer -> type.*os.File 
main..inittask -> fmt..inittask
go.info.fmt.Printf$abstract -> go.info.string
go.info.fmt.Printf$abstract -> go.info.[]interface {}
go.info.fmt.Printf$abstract -> go.info.int
go.info.fmt.Printf$abstract -> go.info.error

It shows that type.*os.File is marked as "UsedInIface" in deadcode. But the symbol "type.*os.File" is in libstd.so. the method 'Write' of type.*os.File don't be marked as reachable. So the field fun of 'go.itab.*os.File,io.Writer' will be a weak reference. In function relocsym, the fun of 'go.itab.*os.File,io.Writer' will be reloced to "runtime.unreachableMethod"
It seems like this appears after https://go-review.googlesource.com/c/go/+/268479

Change https://golang.org/cl/350189 mentions this issue: cmd/link: disable weak reference in itab if build with "-linkshared"

Can you review this CL when you're free?
This cl is blocking our project. If this cl can be approved, we will cherry-pick this to our own golang-1.17.
@ianlancetaylor @cherrymui

@gopherbot please consider this for backport to 1.17, maybe we need fix it for 1.17.

Backport issue(s) opened: #49086 (for 1.17).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://golang.org/wiki/MinorReleases.