go build -gcflags=-m=2 main.go
# command-line-arguments
./main.go:12:6: cannot inline escapes: function too complex: cost 87 exceeds budget 80
./main.go:13:12: can inline escapes.func1 with cost 4 as: func() { p.b = true }
./main.go:13:11: inlining call to sync.(*Once).Do
./main.go:13:11: inlining call to atomic.(*Uint32).Load
./main.go:18:6: can inline doesntescape with cost 4 as: func(*V) { p.b = true }
./main.go:22:6: can inline main with cost 73 as: func() { vv = <nil>; escapes(&vv); doesntescape(&vv) }
./main.go:25:14: inlining call to doesntescape
./main.go:12:14: escapes capturing by value: p (addr=false assign=false width=8)
./main.go:12:14: parameter p leaks to {heap} with derefs=0:
./main.go:12:14:   flow: sync.o = p:
./main.go:12:14:     from p.once (dot of pointer) at ./main.go:13:3
./main.go:12:14:     from p.once (address-of) at ./main.go:13:8
./main.go:12:14:     from sync.o, sync.f := p.once, func literal (assign-pair) at ./main.go:13:11
./main.go:12:14:   flow: {heap} = sync.o:
./main.go:12:14:     from (*sync.Once).doSlow(sync.o, sync.f) (call parameter) at ./main.go:13:11
./main.go:12:14: leaking param: p
./main.go:13:12: func literal does not escape
./main.go:18:19: p does not escape
./main.go:23:6: vv escapes to heap:
./main.go:23:6:   flow: {heap} = &vv:
./main.go:23:6:     from &vv (address-of) at ./main.go:24:10
./main.go:23:6:     from escapes(&vv) (call parameter) at ./main.go:24:9
./main.go:23:6: moved to heap: vv