cmd/pprof: starting pprof with -call_tree makes it panic on top

[ALTree]

go version devel +4775b7feb1 Thu Mar 2 23:49:32 2017 +0000 linux/amd64

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/adonizetti/gocode"
GORACE=""
GOROOT="/home/adonizetti/go"
GOTOOLDIR="/home/adonizetti/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build965176492=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"

Open any pprof (big enough) profile with the "call_tree" option activated:

$ gotip tool pprof -call_tree cpu.prof

issue a top command:

(pprof) top
panic: TrimTree only works on trees

goroutine 1 [running]:
cmd/vendor/github.com/google/pprof/internal/graph.(*Graph).TrimTree(0xc420451c40, 0xc4203d5080)
	/home/adonizetti/go/src/cmd/vendor/github.com/google/pprof/internal/graph/graph.go:431 +0x64b
cmd/vendor/github.com/google/pprof/internal/report.(*Report).newTrimmedGraph(0xc420451ac0, 0x184, 0x840ee824000a0600, 0xc42046c500, 0x0)
	/home/adonizetti/go/src/cmd/vendor/github.com/google/pprof/internal/report/report.go:139 +0x134
cmd/vendor/github.com/google/pprof/internal/report.printText(0xaa4c40, 0xc42010c000, 0xc420451ac0, 0xc42004bb08, 0x7a2570)
	/home/adonizetti/go/src/cmd/vendor/github.com/google/pprof/internal/report/report.go:682 +0x43
cmd/vendor/github.com/google/pprof/internal/report.Generate(0xaa4c40, 0xc42010c000, 0xc420451ac0, 0xaa7780, 0xc42012e8c0, 0x0, 0x0)
	/home/adonizetti/go/src/cmd/vendor/github.com/google/pprof/internal/report/report.go:94 +0x2e0
cmd/vendor/github.com/google/pprof/internal/driver.generateReport(0xc420268280, 0xc42037d950, 0x1, 0x1, 0xc4203e6e70, 0xc420071560, 0xc4203e6e70, 0x0)
	/home/adonizetti/go/src/cmd/vendor/github.com/google/pprof/internal/driver/driver.go:99 +0x246
cmd/vendor/github.com/google/pprof/internal/driver.interactive(0xc420154b40, 0xc420071560, 0xc420154b40, 0x0)
	/home/adonizetti/go/src/cmd/vendor/github.com/google/pprof/internal/driver/interactive.go:111 +0x62e
cmd/vendor/github.com/google/pprof/internal/driver.PProf(0xc42004be40, 0x0, 0x0)
	/home/adonizetti/go/src/cmd/vendor/github.com/google/pprof/internal/driver/driver.go:55 +0x154
cmd/vendor/github.com/google/pprof/driver.PProf(0xc42004bf18, 0xc42012e8b0, 0xc420156540)
	/home/adonizetti/go/src/cmd/vendor/github.com/google/pprof/driver/driver.go:32 +0x1c7
main.main()
	/home/adonizetti/go/src/cmd/pprof/pprof.go:34 +0xbe

This does not happen on go1.8

[ALTree]

(Opened google/pprof#103 for this)

[gopherbot]

CL https://golang.org/cl/46155 mentions this issue.

[ALTree]

The CL that fixed this was reverted. Re-opening for go1.10.

[gopherbot]

Change https://golang.org/cl/57370 mentions this issue: cmd/vendor/github.com/google/pprof: refresh from upstream