panic in related to Bind with a pointer

[gracenoah]

Describe the bug

Panic when running wire ./...

To Reproduce

Sorry, I can't give a specific repro because

1. I worked around it as soon as I ran into it
2. There's a lot of proprietary code involved and it would have been pretty hard to isolate

The error was related to a bind statement:

	wire.Bind(new(Interface), new(*Concrete)),

I don't know what was unusual about this bind statement. There was New function that returns a pointer to Concrete and *Concrete implements Interface. In 0.2.2, I was able to use new(Concrete), but I had to change that to new(*Concrete) after upgrading to 0.3.0 and that's when the panic happened.

I hope that the following stack trace helps. If not, we might want to wait for someone to run into this again and provide a repro.

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x64488d]

goroutine 1 [running]:
go/types.(*Package).Path(...)
        /home/<user>/.go/src/go/types/package.go:30
github.com/google/wire/internal/wire.(*objectCache).get(0xc03b480880, 0x76bb60, 0xc00008cc30, 0x0, 0x0, 0x0, 0x0, 0x0)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:464 +0x7d
github.com/google/wire/internal/wire.(*objectCache).processExpr(0xc03b480880, 0xc03a9324b0, 0xc000cfdce0, 0x5b, 0x766e60, 0xc03a9394c0, 0x0, 0x0, 0x0, 0x0, ...)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:523 +0xfd3
github.com/google/wire/internal/wire.(*objectCache).processNewSet(0xc03b480880, 0xc03a9324b0, 0xc000cfdce0, 0x5b, 0xc03a9c1980, 0x0, 0xc03a905620, 0xf, 0xc000656ec0, 0x58632c, ...)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:592 +0x18a
github.com/google/wire/internal/wire.(*objectCache).processExpr(0xc03b480880, 0xc03a9324b0, 0xc000cfdce0, 0x5b, 0x766a60, 0xc03a9c1980, 0xc03a905620, 0xf, 0xf, 0xc000026500, ...)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:535 +0x519
github.com/google/wire/internal/wire.(*objectCache).get(0xc03b480880, 0x76bd40, 0xc03a9331d0, 0x0, 0x0, 0x0, 0x0, 0x0)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:489 +0x42e
github.com/google/wire/internal/wire.(*objectCache).processExpr(0xc03b480880, 0xc03b4684b0, 0xc0003737a0, 0x51, 0x7671a0, 0xc03b441b60, 0x0, 0x0, 0x68c340, 0xc03b4e1320, ...)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:523 +0xfd3
github.com/google/wire/internal/wire.(*objectCache).processNewSet(0xc03b480880, 0xc03b4684b0, 0xc0003737a0, 0x51, 0xc03b466e40, 0x0, 0xc03b4432a0, 0x16, 0xc0006573e8, 0x58632c, ...)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:592 +0x18a
github.com/google/wire/internal/wire.(*objectCache).processExpr(0xc03b480880, 0xc03b4684b0, 0xc0003737a0, 0x51, 0x766a60, 0xc03b466e40, 0xc03b4432a0, 0x16, 0x16, 0xc000026500, ...)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:535 +0x519
github.com/google/wire/internal/wire.(*objectCache).get(0xc03b480880, 0x76bd40, 0xc03b468550, 0x0, 0x0, 0x0, 0x0, 0x0)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:489 +0x42e
github.com/google/wire/internal/wire.(*objectCache).processExpr(0xc03b480880, 0xc03b468e10, 0xc0002f6eb0, 0x49, 0x7671a0, 0xc03b4770a0, 0x0, 0x0, 0x6b2cc0, 0xc039982600, ...)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:523 +0xfd3
github.com/google/wire/internal/wire.(*objectCache).processNewSet(0xc03b480880, 0xc03b468e10, 0xc0002f6eb0, 0x49, 0xc03b467680, 0xc03b4808e0, 0x0, 0x0, 0x0, 0x0, ...)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:592 +0x18a
github.com/google/wire/internal/wire.generateInjectors(0xc03b469f90, 0xc000da5770, 0x2, 0xc0393f10a0, 0x69, 0x0, 0x0, 0xc00000c0b0)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/wire.go:176 +0xaaf
github.com/google/wire/internal/wire.Generate(0x767ca0, 0xc0000120d8, 0xc000020004, 0x40, 0xc000010c00, 0x59, 0x59, 0xc00000c0b0, 0x1, 0x1, ...)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/internal/wire/wire.go:99 +0x412
main.(*genCmd).Execute(0xc000047eb0, 0x767ca0, 0xc0000120d8, 0xc00005a180, 0x0, 0x0, 0x0, 0x7f97cf1e8008)
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/cmd/wire/main.go:131 +0x249
main.main()
        /home/<user>/go/pkg/mod/github.com/google/[email protected]/cmd/wire/main.go:71 +0x4a1
exit status 2

Expected behavior

No panic

Version

0.3.0

Additional context

Sorry, too much proprietary code. Hope there's something obvious that recently changed and the stack trace helps.

[vangent]

@shantuo can you take a look? Maybe add a new testcase with this?

[shantuo]

Hi @gracenoah , is your Interface a Go built-in type?

[gracenoah]

In this example Interface is an interface with some methods. I really don't know what's special about it because the panic happens in this one scenario, but I've used wire.Bind elsewhere without it panicking. Sorry that I can't be more helpful.

[shantuo]

No worries, from what I can tell in the stack trace you provided, I don't think this is a bug in Bind, but maybe in NewSet, as the panic happens while it is processing the out layer NewSet function. Also, the panic happens when it is trying to get the import path of one of the providers in your argument list you are passing into NewSet by calling "go/types".Object.Pkg().Path(), the Pkg() call returns nil "for labels and objects in the Universe scope", which means you might have some argument in the same NewSet call that is a built-in type, or a wrapper of one, maybe?

[gracenoah]

I think you might be right. I tried to reproduce the issue again by adding back the Bind an changing the constructor to return the struct type and I couldn't. Since, this is all the information we have, I'd be happy with a fix that just adds a better error message whenever this edge case is triggered. Hopefully if it happens again, the error will help me understand the source of the issue.

[anton-dessiatov]

It happened to me when I forgot a wire.Struct call. I have defined a provider like this:

wire.Build(new(CreateServiceWithMocks), "*")

instead of

wire.Build(wire.Struct(new(CreateServiceWithMocks), "*"))

[gracenoah]

Just got a very similar looking panic. This is the exact repro:

package main

import "github.com/google/wire"

type A struct {
	B string
}

func makeA(string) A {
	panic(wire.Build(wire.Struct(new(*A), "*")))
}

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x57f376]

goroutine 1 [running]:
go/types.writeType(0xc0024a15f0, 0x776540, 0x0, 0x0, 0xc0002353a8, 0x1, 0x8)
        /home/gracenoah/.go/src/go/types/typestring.go:120 +0x6a6
go/types.WriteType(...)
        /home/gracenoah/.go/src/go/types/typestring.go:75
go/types.TypeString(0x776540, 0x0, 0x0, 0xc0001ccb40, 0x25)
        /home/gracenoah/.go/src/go/types/typestring.go:67 +0xb1
github.com/google/wire/internal/wire.processStructProvider(0xc0000ea280, 0xc002486aa0, 0xc00247d100, 0x6, 0x1, 0x75)
        /home/gracenoah/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:806 +0xb11
github.com/google/wire/internal/wire.(*objectCache).processExpr(0xc0021b3880, 0xc002486aa0, 0xc0001d6450, 0x5, 0x778ec0, 0xc00247d100, 0x0, 0x0, 0x20, 0x6d88a0, ...)
        /home/gracenoah/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:556 +0xb6e
github.com/google/wire/internal/wire.(*objectCache).processNewSet(0xc0021b3880, 0xc002486aa0, 0xc0001d6450, 0x5, 0xc00247d140, 0xc0021b38c0, 0x0, 0x0, 0x0, 0x0, ...)
        /home/gracenoah/go/pkg/mod/github.com/google/[email protected]/internal/wire/parse.go:592 +0x18c
github.com/google/wire/internal/wire.generateInjectors(0xc002486f50, 0xc0001dcd20, 0x2, 0xc00113f590, 0x29, 0x0, 0x0, 0xc0000ac010)
        /home/gracenoah/go/pkg/mod/github.com/google/[email protected]/internal/wire/wire.go:176 +0x9f4
github.com/google/wire/internal/wire.Generate(0x77a080, 0xc00008e000, 0xc000016064, 0x1d, 0xc000102000, 0x60, 0x60, 0xc0000ac010, 0x1, 0x1, ...)
        /home/gracenoah/go/pkg/mod/github.com/google/[email protected]/internal/wire/wire.go:99 +0x411
main.(*genCmd).Execute(0xc000077e78, 0x77a080, 0xc00008e000, 0xc0000a4120, 0x0, 0x0, 0x0, 0x30)
        /home/gracenoah/go/pkg/mod/github.com/google/[email protected]/cmd/wire/main.go:131 +0x247
main.main()
        /home/gracenoah/go/pkg/mod/github.com/google/[email protected]/cmd/wire/main.go:71 +0x4dc
exit status 2

[zombiezen]

@gracenoah, thanks for the minimal repro! I'll try to take a look in the next week or so.

[zombiezen]

@gracenoah and @anton-dessiatov, it seems like that Struct issue is unrelated to @gracenoah's original issue with Bind. I wasn't able to find anything more on that particular failure, but I have a fix ready for the other issue. I've opened #219 to track the Struct issue.

[gracenoah]

Thanks for investigating and making a separate issue.