x/tools/cmd/guru: panic after 39 minutes of pointer analysis

[rogpeppe]

go version devel +d5dc490 Thu Mar 16 02:44:16 2017 +0000 linux/amd64
golang.org/x/tools version 9862c35

with github.com/juju/juju at 223b8db274268e2ae655a71d4596f2a8f981344a.
To reproduce:

 go get -d github.com/juju/juju
 git checkout 223b8db274268e2ae655a71d4596f2a8f981344a
 cd $GOPATH/src/github.com/juju/juju
 go get github.com/rogpeppe/godeps
 godeps -u dependencies.tsv
 guru -scope github.com/juju/juju/... callers ./api/controller/controller.go:#7425,#7425

I got this result:

Internal panic in pointer analysis:
goroutine 1 [running]:
runtime/debug.Stack(0x24, 0x0, 0x0)
	/home/rog/go/src/runtime/debug/stack.go:24 +0x79
runtime/debug.PrintStack()
	/home/rog/go/src/runtime/debug/stack.go:16 +0x22
golang.org/x/tools/go/pointer.Analyze.func1(0xc420bc5c00)
	/home/rog/src/go/src/golang.org/x/tools/go/pointer/analysis.go:227 +0x124
panic(0x71bde0, 0xc5503766d0)
	/home/rog/go/src/runtime/panic.go:489 +0x26a
golang.org/x/tools/go/ssa.(*Program).LookupMethod(0xc46f403220, 0x94f3e0, 0xc4b5159ad0, 0x0, 0x796a15, 0x5, 0x64)
	/home/rog/src/go/src/golang.org/x/tools/go/ssa/methods.go:49 +0x1f3
golang.org/x/tools/go/pointer.(*invokeConstraint).solve(0xc4ec901e70, 0xc4b4f18700, 0xc60125a800)
	/home/rog/src/go/src/golang.org/x/tools/go/pointer/solve.go:326 +0x11a
golang.org/x/tools/go/pointer.(*analysis).solveConstraints(0xc4b4f18700, 0xc4d4c8cae0, 0xc60125a800)
	/home/rog/src/go/src/golang.org/x/tools/go/pointer/solve.go:165 +0x14e
golang.org/x/tools/go/pointer.(*analysis).solve(0xc4b4f18700)
	/home/rog/src/go/src/golang.org/x/tools/go/pointer/solve.go:59 +0x2ed
golang.org/x/tools/go/pointer.Analyze(0xc4851f30e0, 0x0, 0x94d6a0, 0xc5503766e0)
	/home/rog/src/go/src/golang.org/x/tools/go/pointer/analysis.go:331 +0x5da
main.ptrAnalysis(0xc4851f30e0, 0xc4988b4000)
	/home/rog/src/go/src/golang.org/x/tools/cmd/guru/guru.go:316 +0x2b
main.callers(0xc4200d0230, 0x7, 0x797178)
	/home/rog/src/go/src/golang.org/x/tools/cmd/guru/callers.go:72 +0x5c6
main.Run(0x7fffc459ef65, 0x7, 0xc4200d0230, 0x1, 0xc4200d4200)
	/home/rog/src/go/src/golang.org/x/tools/cmd/guru/guru.go:88 +0x3b5
main.main()
	/home/rog/src/go/src/golang.org/x/tools/cmd/guru/main.go:212 +0x3c8
panic: internal error in pointer analysis: *github.com/juju/juju/state/multiwatcher.MachineInfo has no method Error (please report this bug)

goroutine 1 [running]:
main.ptrAnalysis(0xc4851f30e0, 0xc4988b4000)
	/home/rog/src/go/src/golang.org/x/tools/cmd/guru/guru.go:318 +0x62
main.callers(0xc4200d0230, 0x7, 0x797178)
	/home/rog/src/go/src/golang.org/x/tools/cmd/guru/callers.go:72 +0x5c6
main.Run(0x7fffc459ef65, 0x7, 0xc4200d0230, 0x1, 0xc4200d4200)
	/home/rog/src/go/src/golang.org/x/tools/cmd/guru/guru.go:88 +0x3b5
main.main()
	/home/rog/src/go/src/golang.org/x/tools/cmd/guru/main.go:212 +0x3c8
Command exited with non-zero status 2
2622.37user 18.06system 38:50.13elapsed 113%CPU (0avgtext+0avgdata 8532512maxresident)k
77808inputs+1336outputs (6191major+3478260minor)pagefaults 0swaps

[dsnet]

\cc @alandonovan