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go/types: gopls crash due to monoGraph assertion failure (generics) #53794

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474420502 opened this issue Jul 8, 2022 · 9 comments
Closed

go/types: gopls crash due to monoGraph assertion failure (generics) #53794

474420502 opened this issue Jul 8, 2022 · 9 comments
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FrozenDueToAge gopls Issues related to the Go language server, gopls. Tools This label describes issues relating to any tools in the x/tools repository.
Milestone
Go1.21

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@474420502
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gopls version: v0.9.0 (go1.18.3)
gopls flags:
update flags: proxy
extension version: 0.34.1
go version: 1.18.3
environment: Visual Studio Code linux
initialization error: undefined
issue timestamp: Fri, 08 Jul 2022 20:17:06 GMT
restart history:
Fri, 08 Jul 2022 20:16:56 GMT: activation (enabled: true)

ATTENTION: PLEASE PROVIDE THE DETAILS REQUESTED BELOW.

Describe what you observed.

panic: assertion failed

goroutine 1212 [running]:
go/types.(*Checker).handleBailout(0xc0029fa380, 0xc003279528)
	  check.go:303  0x8b
panic({0xcc9180, 0x106a6c0})
	  panic.go:838  0x207
go/types.assert(...)
	  errors.go:21
go/types.(*monoGraph).assign.func2({0x106fe68%3F, 0xc003c1bbc0%3F})
	  mono.go:213  0x4ea
go/types.(*monoGraph).assign(0xc00004c2a0%3F, 0x7f37b84d7fff%3F, 0x1%3F, 0x1%3F, {0x106fe68%3F, 0xc003c1bbc0%3F})
	  mono.go:258  0xd1
go/types.(*monoGraph).recordInstance(0x2%3F, 0x5cf957%3F, 0xabd1e5, {0xc002cc62d0, 0x2, 0xcfd2c0%3F}, {0xc0023f2fc0, 0x2, 0x106fd00%3F}, {0x0, ...})
	  mono.go:176  0x69
go/types.(*Checker).instantiateSignature.func2()
	  call.go:90  0x1f5
go/types.(*Checker).processDelayed(0xc0029fa380, 0x11)
	  check.go:388  0x39
panic({0xcc9180, 0x106a6c0})
	  panic.go:844  0x258
go/types.assert(...)
	  errors.go:21
go/types.(*monoGraph).assign.func2({0x106fe68%3F, 0xc003c1bbc0%3F})
	  mono.go:213  0x4ea
go/types.(*monoGraph).assign(0xc00004c2a0%3F, 0xc004337ae0%3F, 0x1%3F, 0x1%3F, {0x106fe68%3F, 0xc003c1bbc0%3F})
	  mono.go:258  0xd1
go/types.(*monoGraph).recordInstance(0x2%3F, 0x5cf957%3F, 0xabd1e5, {0xc002cc62d0, 0x2, 0x106fdc8%3F}, {0xc0023f2fc0, 0x2, 0x106fd00%3F}, {0x0, ...})
	  mono.go:176  0x69
go/types.(*Checker).instantiateSignature.func2()
	  call.go:90  0x1f5
go/types.(*Checker).processDelayed(0xc0029fa380, 0x11)
	  check.go:388  0x39
panic({0xcc9180, 0x106a6c0})
	  panic.go:844  0x258
go/types.assert(...)
	  errors.go:21
go/types.(*monoGraph).assign.func2({0x106fe68%3F, 0xc003c1bbc0%3F})
	  mono.go:213  0x4ea
go/types.(*monoGraph).assign(0xc00004c2a0%3F, 0x0%3F, 0x1%3F, 0x1%3F, {0x106fe68%3F, 0xc003c1bbc0%3F})
	  mono.go:258  0xd1
go/types.(*monoGraph).recordInstance(0x2%3F, 0x404476%3F, 0xabd1e5, {0xc002cc62d0, 0x2, 0xc00333aa00%3F}, {0xc0023f2fc0, 0x2, 0x4105cb%3F}, {0x0, ...})
	  mono.go:176  0x69
go/types.(*Checker).instantiateSignature.func2()
	  call.go:90  0x1f5
go/types.(*Checker).processDelayed(0xc0029fa380, 0x11)
	  check.go:388  0x39
go/types.(*Checker).stmt(0xc0029fa380, 0x3, {0x1071e68%3F, 0xc00333aa40%3F})
	  stmt.go:935  0x28a5
go/types.(*Checker).stmtList(0xc0029fa380%3F, 0x3, {0xc002acb440%3F, 0xdf484a%3F, 0x5%3F})
	  stmt.go:125  0xc9
go/types.(*Checker).stmt(0xc0029fa380, 0x3, {0x1071f88%3F, 0xc003a2a750%3F})
	  stmt.go:559  0x23c6
go/types.(*Checker).stmt(0xc0029fa380, 0x0, {0x10724f8%3F, 0xc003294ff0%3F})
	  stmt.go:930  0x2b97
go/types.(*Checker).stmtList(0xc0029fa380%3F, 0x0, {0xc00333aa80%3F, 0xc0029fa380%3F, 0x106de60%3F})
	  stmt.go:125  0xc9
go/types.(*Checker).funcBody(0xc0029fa380, 0xc002c9dec0, {0x0%3F, 0xc003e45bd8%3F}, 0xc004166d00, 0xc003a2a780, {0x0, 0x0})
	  stmt.go:46  0x285
go/types.(*Checker).funcDecl.func1()
	  decl.go:807  0x45
go/types.(*Checker).processDelayed(0xc0029fa380, 0x0)
	  check.go:388  0x39
go/types.(*Checker).checkFiles(0xc0029fa380, {0xc003148fc0%3F, 0xc003294c80%3F, 0x0%3F})
	  check.go:336  0xcb
go/types.(*Checker).Files(...)
	  check.go:308
golang.org/x/tools/internal/lsp/cache.doTypeCheck({0x1073668, 0xc003298e40}, 0xc000255e60, 0xc000641950, 0x2, 0xc000d87590, 0x0%3F)
	  check.go:552  0x97b
golang.org/x/tools/internal/lsp/cache.typeCheck({0x1073668, 0xc003298e40}, 0xc000255e60, 0xc000641950, 0x2, 0xc000d87590%3F)
	  check.go:318  0xe5
golang.org/x/tools/internal/lsp/cache.(*snapshot).buildPackageHandle.func1({0x1073668%3F, 0xc003298e40}, {0x106ce00%3F, 0xc000255e60})
	  check.go:125  0x233
golang.org/x/tools/internal/memoize.(*Handle).run.func1.1()
	  memoize.go:407  0xa9
runtime/trace.WithRegion({0x1073668%3F, 0xc003298e40%3F}, {0xc0007217d0, 0x21}, 0xc00118b790)
	  annotation.go:141  0xe3
golang.org/x/tools/internal/memoize.(*Handle).run.func1()
	  memoize.go:400  0x135
created by golang.org/x/tools/internal/memoize.(*Handle).run
	  memoize.go:399  0x1aa
[Error - 04:16:58]

OPTIONAL: If you would like to share more information, you can attach your complete gopls logs.

NOTE: THESE MAY CONTAIN SENSITIVE INFORMATION ABOUT YOUR CODEBASE.
DO NOT SHARE LOGS IF YOU ARE WORKING IN A PRIVATE REPOSITORY.

<OPTIONAL: ATTACH LOGS HERE>
@findleyr
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Hi, thanks for the report! Do you recall what you were typing / working on when you encountered this panic?

@474420502
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@findleyr I remember just ctrl+s, then it panic!

@suzmue suzmue changed the title gopls: automated issue report (crash) x/tools/gopls: gopls crashed on save Jul 11, 2022
@suzmue suzmue transferred this issue from golang/vscode-go Jul 11, 2022
@suzmue suzmue added this to the gopls/v0.9.1 milestone Jul 11, 2022
@gopherbot gopherbot added Tools This label describes issues relating to any tools in the x/tools repository. gopls Issues related to the Go language server, gopls. labels Jul 11, 2022
@gopherbot gopherbot modified the milestones: gopls/v0.9.1, Unreleased Jul 11, 2022
@suzmue suzmue modified the milestones: Unreleased, gopls/v0.9.1 Jul 11, 2022
@findleyr
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@474420502 is this reproducible? This crash is in the type checker, so any details you could share about the generic code you were editing would be very helpful.

@findleyr findleyr changed the title x/tools/gopls: gopls crashed on save x/tools/gopls: type-checking crash on save (generics) Jul 13, 2022
@findleyr
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findleyr commented Jul 13, 2022 •
edited

CC @griesemer @mdempsky

@474420502 any additional information you could share would be incredibly helpful. A crash in the type-checker may be a big deal, and potentially something that we would try to fix for the 1.19 release.

I briefly investigated this crashing stack, and don't yet see how this assertion failure is possible: the assertion suggests that a generic function is somehow instantiated with a type parameter from another package, but I observe:

  1. We panic on the first call to do, which is checking the targ: https://cs.opensource.google/go/go/+/master:src/go/types/mono.go;l=213;drc=bc32dd1b69b0629a54cfe50626e42eb4b75eb017
  2. Unless I'm missing something, we always construct type parameters with check.pkg (search for callers of [nN]ewTypeParam)
  3. Type parameters should always be declared in an inner scope.

With these constraints, I don't see how we could pass a type parameter from another package as a type argument. My best guess is that there may be a bug in type inference allowing a type parameter from the function declaration to be inferred as a type argument.

@474420502
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@findleyr i can't reproducible this. It probably came up when I converted the tree structure to a generic type.

@findleyr findleyr modified the milestones: gopls/v0.9.1, gopls/v0.9.2 Jul 13, 2022
@findleyr findleyr changed the title x/tools/gopls: type-checking crash on save (generics) go/types: gopls crash due to monoGraph assertion failure (generics) Jul 13, 2022
@findleyr findleyr modified the milestones: gopls/v0.9.2, Go1.20 Jul 13, 2022
@findleyr
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Tentatively marking this for 1.20. We should get to the bottom of this crash, but since it is a crash (and not a miscompilation), and this code has not changed recently, I think it is probably OK to address in 1.20.

@findleyr
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@mdempsky do you have any bandwidth to look at this (or any ideas of how to start)? If not, I think it is safe to bump to 1.21.

I haven't really investigated.

@mdempsky
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@findleyr Is there a repro case? I didn't see any.

If not and the reporter can't reproduce anymore either, I think it's fine to just close this and wait for someone else to hit the same issue and give us steps to reproduce.

@findleyr findleyr modified the milestones: Go1.20, Go1.21 Nov 10, 2022
@findleyr
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Sounds good to me. Closing as not actionable.

@findleyr findleyr closed this as not planned Won't fix, can't repro, duplicate, stale Nov 10, 2022
@golang golang locked and limited conversation to collaborators Nov 10, 2023
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