cmd/vet: panic when run with -source starting at CL 38262

[josharian]

To reproduce, go to $GOROOT/src and run go tool vet -source .. Results:

panic: path must not be "" or "." [recovered]
	panic: path must not be "" or "."

goroutine 1 [running]:
go/types.(*Checker).handleBailout(0xc4200bae00, 0xc424ceb238)
	/Users/josh/go/tip/src/go/types/check.go:225 +0xa4
panic(0x12714c0, 0x1305cf0)
	/Users/josh/go/tip/src/runtime/panic.go:489 +0x26a
go/types.(*Config).Check(0xc421f7a340, 0x12d0334, 0x1, 0xc4202d4400, 0xc420333518, 0x1, 0x1, 0x0, 0x1, 0x0, ...)
	/Users/josh/go/tip/src/go/types/api.go:351 +0x31e
go/internal/srcimporter.(*Importer).ImportFrom(0xc4202cd290, 0xc42522ec31, 0x9, 0xc4250165a0, 0x15, 0x0, 0x0, 0x0, 0x0)
	/Users/josh/go/tip/src/go/internal/srcimporter/srcimporter.go:137 +0x78c
go/types.(*Checker).importPackage(0xc4200bae00, 0x16, 0xc42522ec31, 0x9, 0xc4250165a0, 0x15, 0x9)
	/Users/josh/go/tip/src/go/types/resolver.go:150 +0x185
go/types.(*Checker).collectObjects(0xc4200bae00)
	/Users/josh/go/tip/src/go/types/resolver.go:243 +0x1cd5
go/types.(*Checker).checkFiles(0xc4200bae00, 0xc42522edb0, 0x2, 0x2, 0x0, 0x0)
	/Users/josh/go/tip/src/go/types/check.go:237 +0xa1
go/types.(*Checker).Files(0xc4200bae00, 0xc42522edb0, 0x2, 0x2, 0xc422d3b650, 0x0)
	/Users/josh/go/tip/src/go/types/check.go:230 +0x49
go/types.(*Config).Check(0xc421f7a180, 0xc42522ec00, 0x4, 0xc421fdff80, 0xc42522edb0, 0x2, 0x2, 0xc4207bdb30, 0xc42086b400, 0xc424ceb468, ...)
	/Users/josh/go/tip/src/go/types/api.go:354 +0x1d2
main.(*Package).check(0xc42594fa40, 0xc421fdff80, 0xc42522edb0, 0x2, 0x2, 0xc42522edc0, 0x1)
	/Users/josh/go/tip/src/cmd/vet/types.go:93 +0x37d
main.doPackage(0xc425023ee0, 0x15, 0xc425016580, 0x2, 0x2, 0x0, 0x0)
	/Users/josh/go/tip/src/cmd/vet/main.go:340 +0x14c
main.doPackageDir(0xc425023ee0, 0x15)
	/Users/josh/go/tip/src/cmd/vet/main.go:288 +0x583
main.visit(0xc425023ee0, 0x15, 0x142be00, 0xc4259736c0, 0x0, 0x0, 0x0, 0x0)
	/Users/josh/go/tip/src/cmd/vet/main.go:375 +0xd9
path/filepath.walk(0xc425023ee0, 0x15, 0x142be00, 0xc4259736c0, 0x12e0560, 0x0, 0x0)
	/Users/josh/go/tip/src/path/filepath/path.go:351 +0x81
path/filepath.walk(0xc42523d7e0, 0xf, 0x142be00, 0xc423f87d40, 0x12e0560, 0x0, 0x0)
	/Users/josh/go/tip/src/path/filepath/path.go:376 +0x40c
path/filepath.walk(0xc424b987d8, 0x6, 0x142be00, 0xc421de3520, 0x12e0560, 0x0, 0x0)
	/Users/josh/go/tip/src/path/filepath/path.go:376 +0x40c
path/filepath.walk(0xc42184d115, 0x3, 0x142be00, 0xc42166aa90, 0x12e0560, 0x0, 0x0)
	/Users/josh/go/tip/src/path/filepath/path.go:376 +0x40c
path/filepath.walk(0x7fff5fbff8a5, 0x1, 0x142be00, 0xc420085520, 0x12e0560, 0x0, 0xc420043e78)
	/Users/josh/go/tip/src/path/filepath/path.go:376 +0x40c
path/filepath.Walk(0x7fff5fbff8a5, 0x1, 0x12e0560, 0xc, 0xc420085450)
	/Users/josh/go/tip/src/path/filepath/path.go:398 +0x14c
main.walkDir(0x7fff5fbff8a5, 0x1)
	/Users/josh/go/tip/src/cmd/vet/main.go:390 +0x41
main.main()
	/Users/josh/go/tip/src/cmd/vet/main.go:244 +0x32b

This is why the vetall builder is currently red. Haven't investigated whether the CL is the problem or whether it uncovered an existing problem.

cc @mvdan @griesemer

[mvdan]

My guess is that it uncovered a misuse of Check. Thanks for filing the bug.

[mvdan]

Perhaps related to how you're using "." as an argument. If I understand correctly, you have to give the full import path (absolute, not relative) to go/types.

Does it fail if you give it explicitly, like $(go list .)?

[josharian]

'go tool vet -source pwd' panics, the same way.

[josharian]

I traced this down a little bit.

In the packages that fails (cmd/go/testdata/local) we're passing "main" as the path to config.Check. Note that that package has an import "./easysub" in it.

In srcimporter.Importer.ImportFrom, that goes into the build.IsLocalImport(path), gets resolved using p.ctxt.ImportDir, and the resulting package has bp.ImportPath == ".".

I'm not sure where in this chain of events something has gone wrong, but I don't think vet is doing anything wrong here. I suspect that srcimporter does not correctly handle relative imports, one way or another.

[josharian]

Once this is resolved, re-submit CL 38262.

[griesemer]

@josharian Thanks for looking into this; and my apologies for not looking at the one failure more carefully.

[ALTree]

I can't reproduce this on tip go version devel +3231d4e4ef Fri Nov 10 10:56:22 2017 +0000 linux/amd64. Possibly already fixed?

[rsc]

Maybe fixed, and maybe we'll just remove -source entirely anyway.