x/tools/go/packages: panic loading with LoadTypes

[mmcloughlin]

This issue appears to be a recurrence of #26834.

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

$ go version
go version go1.12 darwin/amd64

Does this issue reproduce with the latest release?

Haven't tried.

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

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/michaelmcloughlin/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/michaelmcloughlin/gocode"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/Cellar/go/1.12/libexec"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.12/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/p5/84p384bs42v7pbgfx0db9gq80000gn/T/go-build218012741=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

$ gopackages -mode=types math

What did you expect to see?

Successful package load and some related output.

What did you see instead?

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=0x0 pc=0x1182b2c]

goroutine 33 [running]:
go/types.(*Checker).handleBailout(0xc0000d40f0, 0xc00051bd08)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/check.go:240 +0x98
panic(0x126a0a0, 0x14b9aa0)
	/usr/local/Cellar/go/1.12/libexec/src/runtime/panic.go:522 +0x1b5
go/types.(*StdSizes).Sizeof(0x0, 0x13089c0, 0x14ba700, 0x113818e)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/sizes.go:154 +0x1bc
go/types.(*Config).sizeof(0xc000485d40, 0x13089c0, 0x14ba700, 0xc000018101)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/sizes.go:245 +0x51
go/types.representableConst(0x130c140, 0xc000018120, 0xc0000d40f0, 0x14ba700, 0xc0000f9fe8, 0x43b1300)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/expr.go:230 +0x29a
go/types.(*Checker).representable(0xc0000d40f0, 0xc0000f9fc0, 0x14ba700)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/expr.go:335 +0x69
go/types.(*Checker).convertUntyped(0xc0000d40f0, 0xc0000f9fc0, 0x13089c0, 0x14ba700)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/expr.go:517 +0x977
go/types.(*Checker).shift(0xc0000d40f0, 0xc0000f9ec0, 0xc0000f9fc0, 0xc00031e480, 0x14)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/expr.go:665 +0xa39
go/types.(*Checker).binary(0xc0000d40f0, 0xc0000f9ec0, 0xc00031e480, 0x130ae00, 0xc000315840, 0x130ae00, 0xc000315860, 0x14)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/expr.go:792 +0xb59
go/types.(*Checker).exprInternal(0xc0000d40f0, 0xc0000f9ec0, 0x130ae40, 0xc00031e480, 0x0, 0x0, 0x1)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/expr.go:1503 +0x1f1f
go/types.(*Checker).rawExpr(0xc0000d40f0, 0xc0000f9ec0, 0x130ae40, 0xc00031e480, 0x0, 0x0, 0x0)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/expr.go:982 +0x81
go/types.(*Checker).multiExpr(0xc0000d40f0, 0xc0000f9ec0, 0x130ae40, 0xc00031e480)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/expr.go:1599 +0x58
go/types.(*Checker).expr(0xc0000d40f0, 0xc0000f9ec0, 0x130ae40, 0xc00031e480)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/expr.go:1593 +0x49
go/types.(*Checker).constDecl(0xc0000d40f0, 0xc00007fb00, 0x0, 0x0, 0x130ae40, 0xc00031e480)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/decl.go:360 +0x129
go/types.(*Checker).objDecl(0xc0000d40f0, 0x130f240, 0xc00007fb00, 0x0)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/decl.go:201 +0x719
go/types.(*Checker).packageObjects(0xc0000d40f0)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/resolver.go:588 +0x25d
go/types.(*Checker).checkFiles(0xc0000d40f0, 0xc000178480, 0x2d, 0x2d, 0x0, 0x0)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/check.go:254 +0xa5
go/types.(*Checker).Files(...)
	/usr/local/Cellar/go/1.12/libexec/src/go/types/check.go:245
golang.org/x/tools/go/packages.(*loader).loadPackage(0xc0000c6500, 0xc0001488c0)
	/Users/michaelmcloughlin/gocode/src/golang.org/x/tools/go/packages/packages.go:811 +0x52f
golang.org/x/tools/go/packages.(*loader).loadRecursive.func1()
	/Users/michaelmcloughlin/gocode/src/golang.org/x/tools/go/packages/packages.go:669 +0x17f
sync.(*Once).Do(0xc0001488d0, 0xc000031f80)
	/usr/local/Cellar/go/1.12/libexec/src/sync/once.go:44 +0xb3
golang.org/x/tools/go/packages.(*loader).loadRecursive(0xc0000c6500, 0xc0001488c0)
	/Users/michaelmcloughlin/gocode/src/golang.org/x/tools/go/packages/packages.go:656 +0x67
golang.org/x/tools/go/packages.(*loader).refine.func2(0xc0000c6500, 0xc00012b030, 0xc0001488c0)
	/Users/michaelmcloughlin/gocode/src/golang.org/x/tools/go/packages/packages.go:594 +0x35
created by golang.org/x/tools/go/packages.(*loader).refine
	/Users/michaelmcloughlin/gocode/src/golang.org/x/tools/go/packages/packages.go:593 +0xd83

[mmcloughlin]

I noticed this due to a panic in my CI tests. Based on when the CI job failed and a basic test on my machine I think golang/tools@dbeab5a may have introduced a problem.

[gopherbot]

Change https://golang.org/cl/170016 mentions this issue: go/packages: add NeedTypesSizes to LoadTypes

[ianthehat]

I think there is a second related bug, it should be possible to set any of the Need bits and the system will make sure it collects the pre-requisites, the Need bits only say what should be filled in in the output. For this panic to occur it was not correctly getting the sizes when asked for types, like it should.

[gopherbot]

Change https://golang.org/cl/170342 mentions this issue: go/packages: make sure TypesSizes are requested when Types are