go/types: nil pointer exception in Checker.allowVersion

[findleyr]

From x/telemetry build failures:
https://build.golang.org/log/2d191343b496feff9fb3cd86a6e699d43127630a

panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x61d64c]

goroutine 1 [running]:
go/types.(*Checker).handleBailout(0xc0001b6000, 0xc00033ba00)
	go/types/check.go:339 +0x88
panic({0x6d5920?, 0x92a0e0?})
	runtime/panic.go:612 +0x132
go/token.(*File).Pos(...)
	go/token/position.go:268
go/types.(*Checker).allowVersion(0xc0001b6000, 0xc00007d920?, {0x7945c0?, 0x9227e0?}, {0x40d2a5?, 0x30?})

linux-amd64 at 65d4723 building telemetry at 6b1207f8206a1faf0c958750d7e9f325334576e4

:: Running /workdir/go/bin/go with args ["/workdir/go/bin/go" "test" "-short" "./..."] and env ["HOSTNAME=buildlet-linux-amd64-bullseye-rn552a163" "HOME=/root" "SHLVL=0" "DEBIAN_FRONTEND=noninteractive" "USER=root" "GO_STAGE0_NET_DELAY=0s" "GO_STAGE0_DL_DELAY=200ms" "WORKDIR=/workdir" "GOROOT_BOOTSTRAP=/workdir/go1.4" "GO_BUILDER_NAME=linux-amd64" "GO_DISABLE_OUTBOUND_NETWORK=1" "GOROOT=/workdir/go" "GOPATH=/workdir/gopath" "GOPROXY=http://gk3-services-nap-jetxd907-8f582974-u4g3.c.symbolic-datum-552.internal:30157" "TMPDIR=/workdir/tmp" "GOCACHE=/workdir/gocache" "GOPLSCACHE=/workdir/goplscache" "PATH=/workdir/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin" "PWD=/workdir/gopath/src/golang.org/x/telemetry"] in dir /workdir/gopath/src/golang.org/x/telemetry

go: downloading golang.org/x/mod v0.10.0
? golang.org/x/telemetry [no test files]

golang.org/x/telemetry/counter/countertest

panic: runtime error: invalid memory address or nil pointer dereference [recovered]
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x61d64c]

goroutine 1 [running]:
go/types.(*Checker).handleBailout(0xc0001b6000, 0xc00033ba00)
go/types/check.go:339 +0x88
panic({0x6d5920?, 0x92a0e0?})
runtime/panic.go:612 +0x132
go/token.(*File).Pos(...)
go/token/position.go:268
go/types.(*Checker).allowVersion(0xc0001b6000, 0xc00007d920?, {0x7945c0?, 0x9227e0?}, {0x40d2a5?, 0x30?})
go/types/version.go:136 +0x6c
go/types.(*Checker).verifyVersionf(0xc0001b6000, {0x7945c0, 0x9227e0}, {0xc00033a248?, 0x0?}, {0x72913c, 0x1e}, {0xc00033a2f8, 0x1, 0x1})
go/types/version.go:150 +0x68
go/types.computeInterfaceTypeSet(0xc0001b6000, 0x6172cb?, 0xc00044f860)
go/types/typeset.go:280 +0x6e5
go/types.(*Interface).typeSet(...)
go/types/interface.go:29
go/types.(*Interface).Empty(0x7951b0?)
go/types/interface.go:120 +0x25
go/types.(*Checker).implements(0xc0001b6000, 0xf73, {0x795070?, 0xc000412e90}, {0x7951b0?, 0xc00044f860}, 0x1, 0xc00033a6e0)
go/types/instantiate.go:224 +0x46d
go/types.(*Checker).verify(0xc000271cd0?, 0xc00033a7b0?, {0xc000584ce0?, 0x2, 0x6d1ec0?}, {0xc0004e12a0?, 0x2, 0x6d1ec0?}, 0x4323d9f5cd864f8f?)
go/types/instantiate.go:181 +0x145
go/types.(*Checker).instantiateSignature.func2()
go/types/call.go:159 +0x185
go/types.(*Checker).processDelayed(0xc0001b6000, 0x26)
go/types/check.go:446 +0x15c
go/types.(*Checker).stmt(0xc0001b6000, 0x0, {0x7964e0?, 0xc0001a61c0?})
go/types/stmt.go:403 +0x391
go/types.(*Checker).stmtList(0x7950e8?, 0x0, {0xc0001a4e80?, 0x0?, 0x0?})
go/types/stmt.go:124 +0x85
go/types.(*Checker).funcBody(0xc0001b6000, 0xc000101c20, {0xc000013c80?, 0xc00007ac80?}, 0xc000211200, 0xc00019f230, {0x0, 0x0})
go/types/stmt.go:44 +0x325
go/types.(*Checker).funcDecl.func1()
go/types/decl.go:826 +0x3a
go/types.(*Checker).processDelayed(0xc0001b6000, 0x0)
go/types/check.go:446 +0x15c
go/types.(*Checker).checkFiles(0xc0001b6000, {0xc0001a64b0, 0x2, 0x2})
go/types/check.go:390 +0x245
go/types.(*Checker).Files(...)
go/types/check.go:344
go/types.(*Config).Check(0xc000079a40, {0xc000016750?, 0xc000012047?}, 0xc000194d80, {0xc0001a64b0, 0x2, 0x2}, 0xc000079aa0)
go/types/api.go:436 +0x169
cmd/vendor/golang.org/x/tools/go/analysis/unitchecker.run(0xc000194d80, 0xc0001680e0, {0xc000027600, 0xa, 0x0?})
cmd/vendor/golang.org/x/tools/go/analysis/unitchecker/unitchecker.go:235 +0x4a5
cmd/vendor/golang.org/x/tools/go/analysis/unitchecker.Run({0x7fffd16c6b1d?, 0x1e?}, {0xc000027600, 0xa, 0x10})
cmd/vendor/golang.org/x/tools/go/analysis/unitchecker/unitchecker.go:133 +0xc8
cmd/vendor/golang.org/x/tools/go/analysis/unitchecker.Main({0xc000192000, 0x1e, 0x1e})
cmd/vendor/golang.org/x/tools/go/analysis/unitchecker/unitchecker.go:120 +0x337
main.main()
cmd/vet/main.go:47 +0x41c
? golang.org/x/telemetry/cmd/gotelemetry [no test files]
? golang.org/x/telemetry/counter [no test files]
? golang.org/x/telemetry/internal/mmap [no test files]
ok golang.org/x/telemetry/cmd/gotelemetry/internal/view 0.004s
FAIL golang.org/x/telemetry/counter/countertest [build failed]
ok golang.org/x/telemetry/internal/config 0.003s
ok golang.org/x/telemetry/internal/configstore 0.016s
ok golang.org/x/telemetry/internal/counter 0.063s
ok golang.org/x/telemetry/internal/proxy 0.005s
ok golang.org/x/telemetry/internal/telemetry 0.004s
ok golang.org/x/telemetry/internal/testenv 0.011s
ok golang.org/x/telemetry/internal/upload 0.004s
FAIL
:: Running /workdir/go/bin/go with args ["/workdir/go/bin/go" "test" "-short" "./..."] and env ["HOSTNAME=buildlet-linux-amd64-bullseye-rn552a163" "HOME=/root" "SHLVL=0" "DEBIAN_FRONTEND=noninteractive" "USER=root" "GO_STAGE0_NET_DELAY=0s" "GO_STAGE0_DL_DELAY=200ms" "WORKDIR=/workdir" "GOROOT_BOOTSTRAP=/workdir/go1.4" "GO_BUILDER_NAME=linux-amd64" "GO_DISABLE_OUTBOUND_NETWORK=1" "GOROOT=/workdir/go" "GOPATH=/workdir/gopath" "GOPROXY=http://gk3-services-nap-jetxd907-8f582974-u4g3.c.symbolic-datum-552.internal:30157" "TMPDIR=/workdir/tmp" "GOCACHE=/workdir/gocache" "GOPLSCACHE=/workdir/goplscache" "PATH=/workdir/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin" "PWD=/workdir/gopath/src/golang.org/x/telemetry/config"] in dir /workdir/gopath/src/golang.org/x/telemetry/config

? golang.org/x/telemetry/config [no test files]
:: Running /workdir/go/bin/go with args ["/workdir/go/bin/go" "test" "-short" "./..."] and env ["HOSTNAME=buildlet-linux-amd64-bullseye-rn552a163" "HOME=/root" "SHLVL=0" "DEBIAN_FRONTEND=noninteractive" "USER=root" "GO_STAGE0_NET_DELAY=0s" "GO_STAGE0_DL_DELAY=200ms" "WORKDIR=/workdir" "GOROOT_BOOTSTRAP=/workdir/go1.4" "GO_BUILDER_NAME=linux-amd64" "GO_DISABLE_OUTBOUND_NETWORK=1" "GOROOT=/workdir/go" "GOPATH=/workdir/gopath" "GOPROXY=http://gk3-services-nap-jetxd907-8f582974-u4g3.c.symbolic-datum-552.internal:30157" "TMPDIR=/workdir/tmp" "GOCACHE=/workdir/gocache" "GOPLSCACHE=/workdir/goplscache" "PATH=/workdir/go/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin" "PWD=/workdir/gopath/src/golang.org/x/telemetry/godev"] in dir /workdir/gopath/src/golang.org/x/telemetry/godev

go: downloading github.com/yuin/goldmark v1.5.4
go: downloading github.com/yuin/goldmark-meta v1.1.0
go: downloading google.golang.org/api v0.122.0
go: downloading github.com/google/go-cmp v0.5.9
go: downloading golang.org/x/exp v0.0.0-20230522175609-2e198f4a06a1
go: downloading cloud.google.com/go/storage v1.30.1
go: downloading github.com/fullstorydev/emulators/storage v0.0.0-20230523204811-eccb7d2267b0
go: downloading github.com/evanw/esbuild v0.17.19
go: downloading github.com/google/btree v1.0.1
go: downloading github.com/bluele/gcache v0.0.2
go: downloading gopkg.in/yaml.v2 v2.4.0
go: downloading google.golang.org/protobuf v1.30.0
go: downloading cloud.google.com/go v0.110.0
go: downloading golang.org/x/sys v0.8.0
go: downloading github.com/google/uuid v1.3.0
go: downloading cloud.google.com/go/iam v1.0.1
go: downloading cloud.google.com/go/compute/metadata v0.2.3
go: downloading github.com/googleapis/gax-go/v2 v2.8.0
go: downloading golang.org/x/oauth2 v0.8.0
go: downloading cloud.google.com/go/compute v1.19.0
go: downloading google.golang.org/genproto v0.0.0-20230410155749-daa745c078e1
go: downloading google.golang.org/grpc v1.55.0
go: downloading go.opencensus.io v0.24.0
go: downloading golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2
go: downloading golang.org/x/net v0.10.0
go: downloading github.com/golang/protobuf v1.5.3
go: downloading github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da
go: downloading golang.org/x/text v0.9.0
go: downloading github.com/googleapis/enterprise-certificate-proxy v0.2.3
go: downloading github.com/google/s2a-go v0.1.3
go: downloading google.golang.org/appengine v1.6.7
go: downloading golang.org/x/crypto v0.7.0
? golang.org/x/telemetry/godev [no test files]
? golang.org/x/telemetry/godev/cmd/worker [no test files]
? golang.org/x/telemetry/godev/devtools/cmd/esbuild [no test files]
? golang.org/x/telemetry/godev/devtools/cmd/npmdeps [no test files]
? golang.org/x/telemetry/godev/internal/middleware [no test files]
ok golang.org/x/telemetry/godev/cmd/telemetrygodev 0.014s
ok golang.org/x/telemetry/godev/internal/content 0.022s
ok golang.org/x/telemetry/godev/internal/storage 0.026s
ok golang.org/x/telemetry/godev/internal/unionfs 0.003s

I have a repro and fix.

CC @griesemer @jamalc @hyangah @bcmills

[gopherbot]

Change https://go.dev/cl/516738 mentions this issue: go/types: fix panic in allowVersion when pos is invalid