testing: b.Cleanup(nil) panics

[cuonglm]

What version of Go are you using (go version)?

$ go version
go version devel +7c0ee1127b Thu Apr 9 16:15:34 2020 +0000 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env

What did you do?

func BenchmarkNewEmptyMap(b *testing.B) {
        b.ReportAllocs()
        b.Cleanup(func() { b.Log("Start logginng") })
        for i := 0; i < b.N; i++ {
                _ = make(map[int]int)
                if i == 1000 {
                        b.Cleanup(nil)
                }
        }
}

What did you expect to see?

Run benchmark ok.

What did you see instead?

go test -run=NONE -bench='BenchmarkNewEmptyMap$' -count=10
goos: darwin
goarch: amd64
pkg: runtime
BenchmarkNewEmptyMap-12    	       0	              NaN ns/op	       0 B/op	       0 allocs/op
--- BENCH: BenchmarkNewEmptyMap-12
    map_benchmark_test.go:312: Start logginng
    map_benchmark_test.go:312: Start logginng
    map_benchmark_test.go:312: Start logginng
BenchmarkNewEmptyMap-12    	panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x10e6f3a]

goroutine 7 [running]:
panic(0x123cd40, 0x146fcc0)
	/Users/cuonglm/sources/go/src/runtime/panic.go:1064 +0x43a fp=0xc000059e58 sp=0xc000059da0 pc=0x103521a
runtime.panicmem(...)
	/Users/cuonglm/sources/go/src/runtime/panic.go:212
runtime.sigpanic()
	/Users/cuonglm/sources/go/src/runtime/signal_unix.go:719 +0x3ca fp=0xc000059e88 sp=0xc000059e58 pc=0x104af4a
testing.(*common).Cleanup.func1()
	/Users/cuonglm/sources/go/src/testing/testing.go:796 +0x4a fp=0xc000059eb0 sp=0xc000059e88 pc=0x10e6f3a
testing.(*common).runCleanup(0xc00000c1e0, 0x0, 0x0, 0x0)
	/Users/cuonglm/sources/go/src/testing/testing.go:850 +0xa7 fp=0xc000059ee8 sp=0xc000059eb0 pc=0x10e2ba7
testing.(*B).runN(0xc00000c1e0, 0x2710)
	/Users/cuonglm/sources/go/src/testing/benchmark.go:199 +0x139 fp=0xc000059f58 sp=0xc000059ee8 pc=0x10da3d9
testing.(*B).launch(0xc00000c1e0)
	/Users/cuonglm/sources/go/src/testing/benchmark.go:321 +0xea fp=0xc000059fd8 sp=0xc000059f58 pc=0x10daa1a
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc000059fe0 sp=0xc000059fd8 pc=0x1070d21
created by testing.(*B).doBench
	/Users/cuonglm/sources/go/src/testing/benchmark.go:276 +0x55

goroutine 1 [chan receive]:
runtime.gopark(0x129c318, 0xc00008e1d8, 0x80012170e, 0x2)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc0001237c8 sp=0xc0001237a8 pc=0x1038010
runtime.chanrecv(0xc00008e180, 0x0, 0xc000000101, 0x10da4dd)
	/Users/cuonglm/sources/go/src/runtime/chan.go:567 +0x33d fp=0xc000123858 sp=0xc0001237c8 pc=0x1007a1d
runtime.chanrecv1(0xc00008e180, 0x0)
	/Users/cuonglm/sources/go/src/runtime/chan.go:434 +0x2b fp=0xc000123888 sp=0xc000123858 pc=0x100768b
testing.(*B).run1(0xc00000c3c0, 0xc00000c3c0)
	/Users/cuonglm/sources/go/src/testing/benchmark.go:233 +0x9e fp=0xc000123950 sp=0xc000123888 pc=0x10da4fe
testing.(*benchContext).processBench(0xc0000b4180, 0xc00000c3c0)
	/Users/cuonglm/sources/go/src/testing/benchmark.go:566 +0x1ee fp=0xc000123a78 sp=0xc000123950 pc=0x10dc13e
testing.(*B).run(0xc00000c1e0)
	/Users/cuonglm/sources/go/src/testing/benchmark.go:268 +0x63 fp=0xc000123ad0 sp=0xc000123a78 pc=0x10da833
testing.(*B).Run(0xc00010c000, 0x128d08a, 0x14, 0x129d138, 0x10da000)
	/Users/cuonglm/sources/go/src/testing/benchmark.go:652 +0x3fd fp=0xc000123bb8 sp=0xc000123ad0 pc=0x10dcd5d
testing.runBenchmarks.func1(0xc00010c000)
	/Users/cuonglm/sources/go/src/testing/benchmark.go:533 +0x78 fp=0xc000123c08 sp=0xc000123bb8 pc=0x10e6868
testing.(*B).runN(0xc00010c000, 0x1)
	/Users/cuonglm/sources/go/src/testing/benchmark.go:191 +0xe8 fp=0xc000123c78 sp=0xc000123c08 pc=0x10da388
testing.runBenchmarks(0x12875cc, 0x7, 0xc0000b4160, 0x1477c80, 0xf2, 0xf2, 0x147c900)
	/Users/cuonglm/sources/go/src/testing/benchmark.go:539 +0x390 fp=0xc000123d70 sp=0xc000123c78 pc=0x10dbc40
testing.(*M).Run(0xc0000e0000, 0x0)
	/Users/cuonglm/sources/go/src/testing/testing.go:1256 +0x511 fp=0xc000123e80 sp=0xc000123d70 pc=0x10e3ea1
runtime_test.TestMain(0xc0000e0000)
	/Users/cuonglm/sources/go/src/runtime/crash_test.go:28 +0x2f fp=0xc000123ed0 sp=0xc000123e80 pc=0x117b39f
main.main()
	_testmain.go:1195 +0x15f fp=0xc000123f88 sp=0xc000123ed0 pc=0x12021bf
runtime.main()
	/Users/cuonglm/sources/go/src/runtime/proc.go:204 +0x212 fp=0xc000123fe0 sp=0xc000123f88 pc=0x1037c32
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc000123fe8 sp=0xc000123fe0 pc=0x1070d21

goroutine 2 [force gc (idle)]:
runtime.gopark(0x129c660, 0x147c0f0, 0x1411, 0x1)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000048fb0 sp=0xc000048f90 pc=0x1038010
runtime.goparkunlock(...)
	/Users/cuonglm/sources/go/src/runtime/proc.go:312
runtime.forcegchelper()
	/Users/cuonglm/sources/go/src/runtime/proc.go:255 +0xbc fp=0xc000048fe0 sp=0xc000048fb0 pc=0x1037ebc
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc000048fe8 sp=0xc000048fe0 pc=0x1070d21
created by runtime.init.6
	/Users/cuonglm/sources/go/src/runtime/proc.go:243 +0x35

goroutine 3 [GC sweep wait]:
runtime.gopark(0x129c660, 0x147c500, 0x140c, 0x1)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc0000497a8 sp=0xc000049788 pc=0x1038010
runtime.goparkunlock(...)
	/Users/cuonglm/sources/go/src/runtime/proc.go:312
runtime.bgsweep(0xc000070000)
	/Users/cuonglm/sources/go/src/runtime/mgcsweep.go:90 +0x135 fp=0xc0000497d8 sp=0xc0000497a8 pc=0x1025085
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc0000497e0 sp=0xc0000497d8 pc=0x1070d21
created by runtime.gcenable
	/Users/cuonglm/sources/go/src/runtime/mgc.go:217 +0x5c

goroutine 4 [sleep]:
runtime.gopark(0x129c660, 0x147c4c0, 0x1313, 0x2)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000049f20 sp=0xc000049f00 pc=0x1038010
runtime.goparkunlock(...)
	/Users/cuonglm/sources/go/src/runtime/proc.go:312
runtime.scavengeSleep(0x17c21f, 0x3f53b)
	/Users/cuonglm/sources/go/src/runtime/mgcscavenge.go:214 +0xc0 fp=0xc000049f78 sp=0xc000049f20 pc=0x10235a0
runtime.bgscavenge(0xc000070000)
	/Users/cuonglm/sources/go/src/runtime/mgcscavenge.go:316 +0x193 fp=0xc000049fd8 sp=0xc000049f78 pc=0x1023763
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc000049fe0 sp=0xc000049fd8 pc=0x1070d21
created by runtime.gcenable
	/Users/cuonglm/sources/go/src/runtime/mgc.go:218 +0x7e

goroutine 18 [finalizer wait]:
runtime.gopark(0x129c660, 0x14a69a0, 0x81410, 0x1)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000048758 sp=0xc000048738 pc=0x1038010
runtime.goparkunlock(...)
	/Users/cuonglm/sources/go/src/runtime/proc.go:312
runtime.runfinq()
	/Users/cuonglm/sources/go/src/runtime/mfinal.go:175 +0xa4 fp=0xc0000487e0 sp=0xc000048758 pc=0x101ac04
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc0000487e8 sp=0xc0000487e0 pc=0x1070d21
created by runtime.createfing
	/Users/cuonglm/sources/go/src/runtime/mfinal.go:156 +0x61

goroutine 29 [GC worker (idle)]:
runtime.gopark(0x129c438, 0xc000180000, 0xc000081418, 0x0)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000044760 sp=0xc000044740 pc=0x1038010
runtime.gcBgMarkWorker(0xc000026000)
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1891 +0xff fp=0xc0000447d8 sp=0xc000044760 pc=0x101e64f
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc0000447e0 sp=0xc0000447d8 pc=0x1070d21
created by runtime.gcBgMarkStartWorkers
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1839 +0x77

goroutine 34 [GC worker (idle)]:
runtime.gopark(0x129c438, 0xc00001c0d0, 0x1418, 0x0)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000188760 sp=0xc000188740 pc=0x1038010
runtime.gcBgMarkWorker(0xc000028800)
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1891 +0xff fp=0xc0001887d8 sp=0xc000188760 pc=0x101e64f
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc0001887e0 sp=0xc0001887d8 pc=0x1070d21
created by runtime.gcBgMarkStartWorkers
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1839 +0x77

goroutine 30 [GC worker (idle)]:
runtime.gopark(0x129c438, 0xc000180010, 0x1418, 0x0)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000044f60 sp=0xc000044f40 pc=0x1038010
runtime.gcBgMarkWorker(0xc00002b000)
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1891 +0xff fp=0xc000044fd8 sp=0xc000044f60 pc=0x101e64f
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc000044fe0 sp=0xc000044fd8 pc=0x1070d21
created by runtime.gcBgMarkStartWorkers
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1839 +0x77

goroutine 31 [GC worker (idle)]:
runtime.gopark(0x129c438, 0xc0000a64d0, 0x1418, 0x0)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000045760 sp=0xc000045740 pc=0x1038010
runtime.gcBgMarkWorker(0xc00002d800)
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1891 +0xff fp=0xc0000457d8 sp=0xc000045760 pc=0x101e64f
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc0000457e0 sp=0xc0000457d8 pc=0x1070d21
created by runtime.gcBgMarkStartWorkers
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1839 +0x77

goroutine 32 [GC worker (idle)]:
runtime.gopark(0x129c438, 0xc00001c0e0, 0x1418, 0x0)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000045f60 sp=0xc000045f40 pc=0x1038010
runtime.gcBgMarkWorker(0xc000030000)
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1891 +0xff fp=0xc000045fd8 sp=0xc000045f60 pc=0x101e64f
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc000045fe0 sp=0xc000045fd8 pc=0x1070d21
created by runtime.gcBgMarkStartWorkers
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1839 +0x77

goroutine 35 [GC worker (idle)]:
runtime.gopark(0x129c438, 0xc00001c0f0, 0x1418, 0x0)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000188f60 sp=0xc000188f40 pc=0x1038010
runtime.gcBgMarkWorker(0xc000032800)
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1891 +0xff fp=0xc000188fd8 sp=0xc000188f60 pc=0x101e64f
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc000188fe0 sp=0xc000188fd8 pc=0x1070d21
created by runtime.gcBgMarkStartWorkers
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1839 +0x77

goroutine 33 [GC worker (idle)]:
runtime.gopark(0x129c438, 0xc000180020, 0x1418, 0x0)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000046760 sp=0xc000046740 pc=0x1038010
runtime.gcBgMarkWorker(0xc000035000)
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1891 +0xff fp=0xc0000467d8 sp=0xc000046760 pc=0x101e64f
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc0000467e0 sp=0xc0000467d8 pc=0x1070d21
created by runtime.gcBgMarkStartWorkers
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1839 +0x77

goroutine 36 [GC worker (idle)]:
runtime.gopark(0x129c438, 0xc00001c100, 0x1418, 0x0)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000189760 sp=0xc000189740 pc=0x1038010
runtime.gcBgMarkWorker(0xc000037800)
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1891 +0xff fp=0xc0001897d8 sp=0xc000189760 pc=0x101e64f
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc0001897e0 sp=0xc0001897d8 pc=0x1070d21
created by runtime.gcBgMarkStartWorkers
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1839 +0x77

goroutine 50 [GC worker (idle)]:
runtime.gopark(0x129c438, 0xc000180030, 0x1418, 0x0)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000046f60 sp=0xc000046f40 pc=0x1038010
runtime.gcBgMarkWorker(0xc00003a000)
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1891 +0xff fp=0xc000046fd8 sp=0xc000046f60 pc=0x101e64f
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc000046fe0 sp=0xc000046fd8 pc=0x1070d21
created by runtime.gcBgMarkStartWorkers
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1839 +0x77

goroutine 5 [GC worker (idle)]:
runtime.gopark(0x129c438, 0xc000180040, 0x1418, 0x0)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc00004a760 sp=0xc00004a740 pc=0x1038010
runtime.gcBgMarkWorker(0xc00003c800)
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1891 +0xff fp=0xc00004a7d8 sp=0xc00004a760 pc=0x101e64f
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc00004a7e0 sp=0xc00004a7d8 pc=0x1070d21
created by runtime.gcBgMarkStartWorkers
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1839 +0x77

goroutine 37 [GC worker (idle)]:
runtime.gopark(0x129c438, 0xc0000a64e0, 0x1418, 0x0)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc000189f60 sp=0xc000189f40 pc=0x1038010
runtime.gcBgMarkWorker(0xc00003f000)
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1891 +0xff fp=0xc000189fd8 sp=0xc000189f60 pc=0x101e64f
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc000189fe0 sp=0xc000189fd8 pc=0x1070d21
created by runtime.gcBgMarkStartWorkers
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1839 +0x77

goroutine 6 [GC worker (idle)]:
runtime.gopark(0x129c438, 0xc000180050, 0x1418, 0x0)
	/Users/cuonglm/sources/go/src/runtime/proc.go:306 +0xe0 fp=0xc00004af60 sp=0xc00004af40 pc=0x1038010
runtime.gcBgMarkWorker(0xc000041800)
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1891 +0xff fp=0xc00004afd8 sp=0xc00004af60 pc=0x101e64f
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc00004afe0 sp=0xc00004afd8 pc=0x1070d21
created by runtime.gcBgMarkStartWorkers
	/Users/cuonglm/sources/go/src/runtime/mgc.go:1839 +0x77

goroutine 66 [runnable]:
testing.(*B).run1.func1(0xc00000c3c0)
	/Users/cuonglm/sources/go/src/testing/benchmark.go:224 fp=0xc00018afd8 sp=0xc00018afd0 pc=0x10e6560
runtime.goexit()
	/Users/cuonglm/sources/go/src/runtime/asm_amd64.s:1374 +0x1 fp=0xc00018afe0 sp=0xc00018afd8 pc=0x1070d21
created by testing.(*B).run1
	/Users/cuonglm/sources/go/src/testing/benchmark.go:224 +0x7d
exit status 2
FAIL	runtime	0.073s

[gopherbot]

Change https://golang.org/cl/227800 mentions this issue: testing: check f is not nil before calling in Cleanup

[ianlancetaylor]

I'm not really seeing why this is a problem. fmt.Fprintln(nil, "") also crashes. Some standard library functions will panic if you pass nil. That seems OK.