go/types, types2: data race to interface typeset

[findleyr]

Discovered in the trybot failures of https://go.dev/cl/512636.

There's a data race to interface type set computation. I don't know how it's gone undetected for so long: the interface type set is unguarded, and instantiated interfaces are not completed.
https://cs.opensource.google/go/go/+/master:src/go/types/interface.go;l=29;drc=97f843b51f69f392bb09b24c077aca505e519551

Whatever the fix, I think we should consider back porting to 1.21+1.20.

CC @griesemer

[findleyr]

Connecting the dots: I think this may be the cause of some confusing diagnostics users have reported in gopls. (e.g. https://gophers.slack.com/archives/C2B4L99RS/p1686512574586319)

[gopherbot]

Change https://go.dev/cl/512636 mentions this issue: gopls/internal/lsp/cache: memoize active packages after every operation

[bcmills]

race reports from the TryBot log

==================
WARNING: DATA RACE
Read at 0x00c0052140e8 by goroutine 34355:
  go/types.computeInterfaceTypeSet()
      /workdir/go/src/go/types/typeset.go:155 +0x6e
  go/types.(*Interface).typeSet()
      /workdir/go/src/go/types/interface.go:29 +0xc4f
  go/types.NewMethodSet()
      /workdir/go/src/go/types/methodset.go:158 +0x6d7
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.methodSetInfo()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:278 +0x84
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.(*indexBuilder).build()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:245 +0x704
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.NewIndex()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:82 +0x50
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1.(*syntaxPackage).methodsets.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:74 +0x7a
  sync.(*Once).doSlow()
      /workdir/go/src/sync/once.go:74 +0xf0
  sync.(*Once).Do()
      /workdir/go/src/sync/once.go:65 +0x44
  golang.org/x/tools/gopls/internal/lsp/cache.(*syntaxPackage).methodsets()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:73 +0x20f
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:661 +0x1df

Previous write at 0x00c0052140e8 by goroutine 34345:
  go/types.computeInterfaceTypeSet()
      /workdir/go/src/go/types/typeset.go:194 +0x404
  go/types.(*Interface).typeSet()
      /workdir/go/src/go/types/interface.go:29 +0xc4f
  go/types.NewMethodSet()
      /workdir/go/src/go/types/methodset.go:158 +0x6d7
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.methodSetInfo()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:278 +0x84
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.KeyOf()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:103 +0xc6e
  golang.org/x/tools/gopls/internal/lsp/source.implementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:147 +0xc30
  golang.org/x/tools/gopls/internal/lsp/source.Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:52 +0x114
  golang.org/x/tools/gopls/internal/lsp.(*Server).implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/implementation.go:25 +0x2d2
  golang.org/x/tools/gopls/internal/lsp.(*Server).Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/server_gen.go:140 +0x44
  golang.org/x/tools/gopls/internal/lsp/protocol.serverDispatch()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/tsserver.go:407 +0x5a7e
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.ServerHandler.func3()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/protocol.go:157 +0xae
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.handshaker.func4()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/lsprpc/lsprpc.go:519 +0xb83
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.MustReplyHandler.func1()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:35 +0x18b
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.AsyncHandler.func2.2()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:103 +0xb1

Goroutine 34355 (running) created at:
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:658 +0x431
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).handleSyntaxPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:512 +0x52c
  golang.org/x/tools/gopls/internal/lsp/cache.(*snapshot).forEachPackageInternal.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:374 +0x74
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76

Goroutine 34345 (running) created at:
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.AsyncHandler.func2()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:100 +0x38e
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.CancelHandler.CancelHandler.func4()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:69 +0x2a9
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.CancelHandler.func3()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/protocol.go:249 +0x136
  golang.org/x/tools/internal/jsonrpc2.(*conn).run()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/conn.go:218 +0xab9
  golang.org/x/tools/internal/jsonrpc2.(*conn).Go.func1()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/conn.go:189 +0x5d
==================
==================
WARNING: DATA RACE
Read at 0x00c0047b53c0 by goroutine 34355:
  go/types.NewMethodSet()
      /workdir/go/src/go/types/methodset.go:158 +0xc5e
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.methodSetInfo()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:278 +0x84
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.(*indexBuilder).build()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:245 +0x704
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.NewIndex()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:82 +0x50
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1.(*syntaxPackage).methodsets.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:74 +0x7a
  sync.(*Once).doSlow()
      /workdir/go/src/sync/once.go:74 +0xf0
  sync.(*Once).Do()
      /workdir/go/src/sync/once.go:65 +0x44
  golang.org/x/tools/gopls/internal/lsp/cache.(*syntaxPackage).methodsets()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:73 +0x20f
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:661 +0x1df

Previous write at 0x00c0047b53c0 by goroutine 34345:
  go/types.computeInterfaceTypeSet()
      /workdir/go/src/go/types/typeset.go:194 +0x31e
  go/types.(*Interface).typeSet()
      /workdir/go/src/go/types/interface.go:29 +0xc4f
  go/types.NewMethodSet()
      /workdir/go/src/go/types/methodset.go:158 +0x6d7
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.methodSetInfo()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:278 +0x84
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.KeyOf()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:103 +0xc6e
  golang.org/x/tools/gopls/internal/lsp/source.implementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:147 +0xc30
  golang.org/x/tools/gopls/internal/lsp/source.Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:52 +0x114
  golang.org/x/tools/gopls/internal/lsp.(*Server).implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/implementation.go:25 +0x2d2
  golang.org/x/tools/gopls/internal/lsp.(*Server).Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/server_gen.go:140 +0x44
  golang.org/x/tools/gopls/internal/lsp/protocol.serverDispatch()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/tsserver.go:407 +0x5a7e
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.ServerHandler.func3()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/protocol.go:157 +0xae
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.handshaker.func4()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/lsprpc/lsprpc.go:519 +0xb83
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.MustReplyHandler.func1()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:35 +0x18b
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.AsyncHandler.func2.2()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:103 +0xb1

Goroutine 34355 (running) created at:
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:658 +0x431
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).handleSyntaxPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:512 +0x52c
  golang.org/x/tools/gopls/internal/lsp/cache.(*snapshot).forEachPackageInternal.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:374 +0x74
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76

Goroutine 34345 (running) created at:
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.AsyncHandler.func2()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:100 +0x38e
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.CancelHandler.CancelHandler.func4()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:69 +0x2a9
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.CancelHandler.func3()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/protocol.go:249 +0x136
  golang.org/x/tools/internal/jsonrpc2.(*conn).run()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/conn.go:218 +0xab9
  golang.org/x/tools/internal/jsonrpc2.(*conn).Go.func1()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/conn.go:189 +0x5d
==================
==================
WARNING: DATA RACE
Read at 0x00c00551ca18 by goroutine 34355:
  go/types.methodSet.add()
      /workdir/go/src/go/types/methodset.go:222 +0x116
  go/types.NewMethodSet()
      /workdir/go/src/go/types/methodset.go:158 +0xca8
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.methodSetInfo()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:278 +0x84
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.(*indexBuilder).build()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:245 +0x704
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.NewIndex()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:82 +0x50
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1.(*syntaxPackage).methodsets.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:74 +0x7a
  sync.(*Once).doSlow()
      /workdir/go/src/sync/once.go:74 +0xf0
  sync.(*Once).Do()
      /workdir/go/src/sync/once.go:65 +0x44
  golang.org/x/tools/gopls/internal/lsp/cache.(*syntaxPackage).methodsets()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:73 +0x20f
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:661 +0x1df

Previous write at 0x00c00551ca18 by goroutine 34345:
  go/types.computeInterfaceTypeSet.func2()
      /workdir/go/src/go/types/typeset.go:226 +0x954
  go/types.computeInterfaceTypeSet()
      /workdir/go/src/go/types/typeset.go:257 +0x757
  go/types.(*Interface).typeSet()
      /workdir/go/src/go/types/interface.go:29 +0xc4f
  go/types.NewMethodSet()
      /workdir/go/src/go/types/methodset.go:158 +0x6d7
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.methodSetInfo()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:278 +0x84
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.KeyOf()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:103 +0xc6e
  golang.org/x/tools/gopls/internal/lsp/source.implementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:147 +0xc30
  golang.org/x/tools/gopls/internal/lsp/source.Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:52 +0x114
  golang.org/x/tools/gopls/internal/lsp.(*Server).implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/implementation.go:25 +0x2d2
  golang.org/x/tools/gopls/internal/lsp.(*Server).Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/server_gen.go:140 +0x44
  golang.org/x/tools/gopls/internal/lsp/protocol.serverDispatch()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/tsserver.go:407 +0x5a7e
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.ServerHandler.func3()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/protocol.go:157 +0xae
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.handshaker.func4()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/lsprpc/lsprpc.go:519 +0xb83
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.MustReplyHandler.func1()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:35 +0x18b
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.AsyncHandler.func2.2()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:103 +0xb1

Goroutine 34355 (running) created at:
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:658 +0x431
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).handleSyntaxPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:512 +0x52c
  golang.org/x/tools/gopls/internal/lsp/cache.(*snapshot).forEachPackageInternal.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:374 +0x74
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76

Goroutine 34345 (running) created at:
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.AsyncHandler.func2()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:100 +0x38e
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.CancelHandler.CancelHandler.func4()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:69 +0x2a9
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.CancelHandler.func3()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/protocol.go:249 +0x136
  golang.org/x/tools/internal/jsonrpc2.(*conn).run()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/conn.go:218 +0xab9
  golang.org/x/tools/internal/jsonrpc2.(*conn).Go.func1()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/conn.go:189 +0x5d
==================
==================
WARNING: DATA RACE
Read at 0x00c004ed14e8 by goroutine 34390:
  go/types.computeInterfaceTypeSet()
      /workdir/go/src/go/types/typeset.go:155 +0x6e
  go/types.(*Interface).typeSet()
      /workdir/go/src/go/types/interface.go:29 +0x64
  go/types.(*Interface).Empty()
      /workdir/go/src/go/types/interface.go:120 +0x12
  go/types.(*Checker).implements()
      /workdir/go/src/go/types/instantiate.go:224 +0x66a
  go/types.(*operand).assignableTo()
      /workdir/go/src/go/types/operand.go:284 +0x52c
  go/types.AssignableTo()
      /workdir/go/src/go/types/api.go:451 +0x108
  golang.org/x/tools/gopls/internal/lsp/source.concreteImplementsIntf()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:443 +0x12
  golang.org/x/tools/gopls/internal/lsp/source.localImplementations.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:342 +0x44b
  go/ast.inspector.Visit()
      /workdir/go/src/go/ast/walk.go:386 +0x3a
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:51 +0x82
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:344 +0x27d1
  go/ast.walkDeclList()
      /workdir/go/src/go/ast/walk.go:38 +0x2724
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:366 +0x24eb
  go/ast.Inspect()
      /workdir/go/src/go/ast/walk.go:397 +0x224
  golang.org/x/tools/gopls/internal/lsp/source.localImplementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:322 +0x1f9
  golang.org/x/tools/gopls/internal/lsp/source.implementations.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:190 +0x124
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76

Previous write at 0x00c004ed14e8 by goroutine 34387:
  go/types.computeInterfaceTypeSet()
      /workdir/go/src/go/types/typeset.go:194 +0x404
  go/types.(*Interface).typeSet()
      /workdir/go/src/go/types/interface.go:29 +0xc4f
  go/types.NewMethodSet()
      /workdir/go/src/go/types/methodset.go:158 +0x6d7
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.methodSetInfo()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:278 +0x84
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.(*indexBuilder).build()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:245 +0x704
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.NewIndex()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:82 +0x50
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1.(*syntaxPackage).methodsets.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:74 +0x7a
  sync.(*Once).doSlow()
      /workdir/go/src/sync/once.go:74 +0xf0
  sync.(*Once).Do()
      /workdir/go/src/sync/once.go:65 +0x44
  golang.org/x/tools/gopls/internal/lsp/cache.(*syntaxPackage).methodsets()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:73 +0x20f
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:661 +0x1df

Goroutine 34390 (running) created at:
  golang.org/x/sync/errgroup.(*Group).Go()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:72 +0x124
  golang.org/x/tools/gopls/internal/lsp/source.implementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:189 +0x17ba
  golang.org/x/tools/gopls/internal/lsp/source.Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:52 +0x114
  golang.org/x/tools/gopls/internal/lsp.(*Server).implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/implementation.go:25 +0x2d2
  golang.org/x/tools/gopls/internal/lsp.(*Server).Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/server_gen.go:140 +0x44
  golang.org/x/tools/gopls/internal/lsp/protocol.serverDispatch()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/tsserver.go:407 +0x5a7e
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.ServerHandler.func3()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/protocol.go:157 +0xae
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.handshaker.func4()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/lsprpc/lsprpc.go:519 +0xb83
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.MustReplyHandler.func1()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:35 +0x18b
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.AsyncHandler.func2.2()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:103 +0xb1

Goroutine 34387 (running) created at:
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:658 +0x431
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).handleSyntaxPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:512 +0x52c
  golang.org/x/tools/gopls/internal/lsp/cache.(*snapshot).forEachPackageInternal.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:374 +0x74
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76
==================
==================
WARNING: DATA RACE
Read at 0x00c004c81570 by goroutine 34390:
  go/types.(*_TypeSet).IsMethodSet()
      /workdir/go/src/go/types/typeset.go:40 +0x77
  go/types.(*_TypeSet).IsAll()
      /workdir/go/src/go/types/typeset.go:37 +0xc5
  go/types.(*Interface).Empty()
      /workdir/go/src/go/types/interface.go:120 +0x12
  go/types.(*Checker).implements()
      /workdir/go/src/go/types/instantiate.go:224 +0x66a
  go/types.(*operand).assignableTo()
      /workdir/go/src/go/types/operand.go:284 +0x52c
  go/types.AssignableTo()
      /workdir/go/src/go/types/api.go:451 +0x108
  golang.org/x/tools/gopls/internal/lsp/source.concreteImplementsIntf()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:443 +0x12
  golang.org/x/tools/gopls/internal/lsp/source.localImplementations.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:342 +0x44b
  go/ast.inspector.Visit()
      /workdir/go/src/go/ast/walk.go:386 +0x3a
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:51 +0x82
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:344 +0x27d1
  go/ast.walkDeclList()
      /workdir/go/src/go/ast/walk.go:38 +0x2724
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:366 +0x24eb
  go/ast.Inspect()
      /workdir/go/src/go/ast/walk.go:397 +0x224
  golang.org/x/tools/gopls/internal/lsp/source.localImplementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:322 +0x1f9
  golang.org/x/tools/gopls/internal/lsp/source.implementations.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:190 +0x124
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76

Previous write at 0x00c004c81570 by goroutine 34387:
  go/types.computeInterfaceTypeSet()
      /workdir/go/src/go/types/typeset.go:194 +0x31e
  go/types.(*Interface).typeSet()
      /workdir/go/src/go/types/interface.go:29 +0xc4f
  go/types.NewMethodSet()
      /workdir/go/src/go/types/methodset.go:158 +0x6d7
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.methodSetInfo()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:278 +0x84
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.(*indexBuilder).build()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:245 +0x704
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.NewIndex()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:82 +0x50
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1.(*syntaxPackage).methodsets.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:74 +0x7a
  sync.(*Once).doSlow()
      /workdir/go/src/sync/once.go:74 +0xf0
  sync.(*Once).Do()
      /workdir/go/src/sync/once.go:65 +0x44
  golang.org/x/tools/gopls/internal/lsp/cache.(*syntaxPackage).methodsets()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:73 +0x20f
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:661 +0x1df

Goroutine 34390 (running) created at:
  golang.org/x/sync/errgroup.(*Group).Go()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:72 +0x124
  golang.org/x/tools/gopls/internal/lsp/source.implementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:189 +0x17ba
  golang.org/x/tools/gopls/internal/lsp/source.Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:52 +0x114
  golang.org/x/tools/gopls/internal/lsp.(*Server).implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/implementation.go:25 +0x2d2
  golang.org/x/tools/gopls/internal/lsp.(*Server).Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/server_gen.go:140 +0x44
  golang.org/x/tools/gopls/internal/lsp/protocol.serverDispatch()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/tsserver.go:407 +0x5a7e
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.ServerHandler.func3()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/protocol.go:157 +0xae
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.handshaker.func4()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/lsprpc/lsprpc.go:519 +0xb83
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.MustReplyHandler.func1()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:35 +0x18b
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.AsyncHandler.func2.2()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:103 +0xb1

Goroutine 34387 (running) created at:
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:658 +0x431
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).handleSyntaxPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:512 +0x52c
  golang.org/x/tools/gopls/internal/lsp/cache.(*snapshot).forEachPackageInternal.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:374 +0x74
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76
==================
==================
WARNING: DATA RACE
Read at 0x00c004c81558 by goroutine 34390:
  go/types.(*_TypeSet).IsMethodSet()
      /workdir/go/src/go/types/typeset.go:40 +0x8e
  go/types.(*_TypeSet).IsAll()
      /workdir/go/src/go/types/typeset.go:37 +0xc5
  go/types.(*Interface).Empty()
      /workdir/go/src/go/types/interface.go:120 +0x12
  go/types.(*Checker).implements()
      /workdir/go/src/go/types/instantiate.go:224 +0x66a
  go/types.(*operand).assignableTo()
      /workdir/go/src/go/types/operand.go:284 +0x52c
  go/types.AssignableTo()
      /workdir/go/src/go/types/api.go:451 +0x108
  golang.org/x/tools/gopls/internal/lsp/source.concreteImplementsIntf()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:443 +0x12
  golang.org/x/tools/gopls/internal/lsp/source.localImplementations.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:342 +0x44b
  go/ast.inspector.Visit()
      /workdir/go/src/go/ast/walk.go:386 +0x3a
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:51 +0x82
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:344 +0x27d1
  go/ast.walkDeclList()
      /workdir/go/src/go/ast/walk.go:38 +0x2724
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:366 +0x24eb
  go/ast.Inspect()
      /workdir/go/src/go/ast/walk.go:397 +0x224
  golang.org/x/tools/gopls/internal/lsp/source.localImplementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:322 +0x1f9
  golang.org/x/tools/gopls/internal/lsp/source.implementations.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:190 +0x124
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76

Previous write at 0x00c004c81558 by goroutine 34387:
  go/types.computeInterfaceTypeSet()
      /workdir/go/src/go/types/typeset.go:194 +0x31e
  go/types.(*Interface).typeSet()
      /workdir/go/src/go/types/interface.go:29 +0xc4f
  go/types.NewMethodSet()
      /workdir/go/src/go/types/methodset.go:158 +0x6d7
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.methodSetInfo()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:278 +0x84
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.(*indexBuilder).build()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:245 +0x704
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.NewIndex()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:82 +0x50
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1.(*syntaxPackage).methodsets.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:74 +0x7a
  sync.(*Once).doSlow()
      /workdir/go/src/sync/once.go:74 +0xf0
  sync.(*Once).Do()
      /workdir/go/src/sync/once.go:65 +0x44
  golang.org/x/tools/gopls/internal/lsp/cache.(*syntaxPackage).methodsets()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:73 +0x20f
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:661 +0x1df

Goroutine 34390 (running) created at:
  golang.org/x/sync/errgroup.(*Group).Go()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:72 +0x124
  golang.org/x/tools/gopls/internal/lsp/source.implementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:189 +0x17ba
  golang.org/x/tools/gopls/internal/lsp/source.Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:52 +0x114
  golang.org/x/tools/gopls/internal/lsp.(*Server).implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/implementation.go:25 +0x2d2
  golang.org/x/tools/gopls/internal/lsp.(*Server).Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/server_gen.go:140 +0x44
  golang.org/x/tools/gopls/internal/lsp/protocol.serverDispatch()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/tsserver.go:407 +0x5a7e
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.ServerHandler.func3()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/protocol.go:157 +0xae
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.handshaker.func4()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/lsprpc/lsprpc.go:519 +0xb83
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.MustReplyHandler.func1()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:35 +0x18b
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.AsyncHandler.func2.2()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:103 +0xb1

Goroutine 34387 (running) created at:
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:658 +0x431
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).handleSyntaxPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:512 +0x52c
  golang.org/x/tools/gopls/internal/lsp/cache.(*snapshot).forEachPackageInternal.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:374 +0x74
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76
==================
==================
WARNING: DATA RACE
Read at 0x00c004c81540 by goroutine 34390:
  go/types.(*_TypeSet).IsAll()
      /workdir/go/src/go/types/typeset.go:37 +0x149
  go/types.(*Interface).Empty()
      /workdir/go/src/go/types/interface.go:120 +0x12
  go/types.(*Checker).implements()
      /workdir/go/src/go/types/instantiate.go:224 +0x66a
  go/types.(*operand).assignableTo()
      /workdir/go/src/go/types/operand.go:284 +0x52c
  go/types.AssignableTo()
      /workdir/go/src/go/types/api.go:451 +0x108
  golang.org/x/tools/gopls/internal/lsp/source.concreteImplementsIntf()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:443 +0x12
  golang.org/x/tools/gopls/internal/lsp/source.localImplementations.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:342 +0x44b
  go/ast.inspector.Visit()
      /workdir/go/src/go/ast/walk.go:386 +0x3a
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:51 +0x82
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:344 +0x27d1
  go/ast.walkDeclList()
      /workdir/go/src/go/ast/walk.go:38 +0x2724
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:366 +0x24eb
  go/ast.Inspect()
      /workdir/go/src/go/ast/walk.go:397 +0x224
  golang.org/x/tools/gopls/internal/lsp/source.localImplementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:322 +0x1f9
  golang.org/x/tools/gopls/internal/lsp/source.implementations.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:190 +0x124
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76

Previous write at 0x00c004c81540 by goroutine 34387:
  go/types.computeInterfaceTypeSet()
      /workdir/go/src/go/types/typeset.go:194 +0x31e
  go/types.(*Interface).typeSet()
      /workdir/go/src/go/types/interface.go:29 +0xc4f
  go/types.NewMethodSet()
      /workdir/go/src/go/types/methodset.go:158 +0x6d7
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.methodSetInfo()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:278 +0x84
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.(*indexBuilder).build()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:245 +0x704
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.NewIndex()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:82 +0x50
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1.(*syntaxPackage).methodsets.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:74 +0x7a
  sync.(*Once).doSlow()
      /workdir/go/src/sync/once.go:74 +0xf0
  sync.(*Once).Do()
      /workdir/go/src/sync/once.go:65 +0x44
  golang.org/x/tools/gopls/internal/lsp/cache.(*syntaxPackage).methodsets()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:73 +0x20f
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:661 +0x1df

Goroutine 34390 (running) created at:
  golang.org/x/sync/errgroup.(*Group).Go()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:72 +0x124
  golang.org/x/tools/gopls/internal/lsp/source.implementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:189 +0x17ba
  golang.org/x/tools/gopls/internal/lsp/source.Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:52 +0x114
  golang.org/x/tools/gopls/internal/lsp.(*Server).implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/implementation.go:25 +0x2d2
  golang.org/x/tools/gopls/internal/lsp.(*Server).Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/server_gen.go:140 +0x44
  golang.org/x/tools/gopls/internal/lsp/protocol.serverDispatch()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/tsserver.go:407 +0x5a7e
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.ServerHandler.func3()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/protocol.go:157 +0xae
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.handshaker.func4()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/lsprpc/lsprpc.go:519 +0xb83
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.MustReplyHandler.func1()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:35 +0x18b
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.AsyncHandler.func2.2()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:103 +0xb1

Goroutine 34387 (running) created at:
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:658 +0x431
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).handleSyntaxPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:512 +0x52c
  golang.org/x/tools/gopls/internal/lsp/cache.(*snapshot).forEachPackageInternal.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:374 +0x74
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76
==================
==================
WARNING: DATA RACE
Read at 0x00c000f5dd70 by goroutine 34390:
  go/types.(*Checker).missingMethod()
      /workdir/go/src/go/types/lookup.go:377 +0xecc
  go/types.(*Checker).implements()
      /workdir/go/src/go/types/instantiate.go:246 +0x9f7
  go/types.(*operand).assignableTo()
      /workdir/go/src/go/types/operand.go:284 +0x52c
  go/types.AssignableTo()
      /workdir/go/src/go/types/api.go:451 +0x108
  golang.org/x/tools/gopls/internal/lsp/source.concreteImplementsIntf()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:443 +0x12
  golang.org/x/tools/gopls/internal/lsp/source.localImplementations.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:342 +0x44b
  go/ast.inspector.Visit()
      /workdir/go/src/go/ast/walk.go:386 +0x3a
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:51 +0x82
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:344 +0x27d1
  go/ast.walkDeclList()
      /workdir/go/src/go/ast/walk.go:38 +0x2724
  go/ast.Walk()
      /workdir/go/src/go/ast/walk.go:366 +0x24eb
  go/ast.Inspect()
      /workdir/go/src/go/ast/walk.go:397 +0x224
  golang.org/x/tools/gopls/internal/lsp/source.localImplementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:322 +0x1f9
  golang.org/x/tools/gopls/internal/lsp/source.implementations.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:190 +0x124
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76

Previous write at 0x00c000f5dd70 by goroutine 34387:
  go/types.computeInterfaceTypeSet.func2()
      /workdir/go/src/go/types/typeset.go:226 +0x954
  go/types.computeInterfaceTypeSet()
      /workdir/go/src/go/types/typeset.go:257 +0x757
  go/types.(*Interface).typeSet()
      /workdir/go/src/go/types/interface.go:29 +0xc4f
  go/types.NewMethodSet()
      /workdir/go/src/go/types/methodset.go:158 +0x6d7
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.methodSetInfo()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:278 +0x84
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.(*indexBuilder).build()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:245 +0x704
  golang.org/x/tools/gopls/internal/lsp/source/methodsets.NewIndex()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/methodsets/methodsets.go:82 +0x50
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1.(*syntaxPackage).methodsets.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:74 +0x7a
  sync.(*Once).doSlow()
      /workdir/go/src/sync/once.go:74 +0xf0
  sync.(*Once).Do()
      /workdir/go/src/sync/once.go:65 +0x44
  golang.org/x/tools/gopls/internal/lsp/cache.(*syntaxPackage).methodsets()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/pkg.go:73 +0x20f
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage.func1()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:661 +0x1df

Goroutine 34390 (running) created at:
  golang.org/x/sync/errgroup.(*Group).Go()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:72 +0x124
  golang.org/x/tools/gopls/internal/lsp/source.implementations()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:189 +0x17ba
  golang.org/x/tools/gopls/internal/lsp/source.Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/source/implementation.go:52 +0x114
  golang.org/x/tools/gopls/internal/lsp.(*Server).implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/implementation.go:25 +0x2d2
  golang.org/x/tools/gopls/internal/lsp.(*Server).Implementation()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/server_gen.go:140 +0x44
  golang.org/x/tools/gopls/internal/lsp/protocol.serverDispatch()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/tsserver.go:407 +0x5a7e
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.ServerHandler.func3()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/protocol/protocol.go:157 +0xae
  golang.org/x/tools/gopls/internal/lsp/lsprpc.(*StreamServer).ServeStream.handshaker.func4()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/lsprpc/lsprpc.go:519 +0xb83
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.MustReplyHandler.func1()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:35 +0x18b
  golang.org/x/tools/gopls/internal/lsp/protocol.Handlers.AsyncHandler.func2.2()
      /workdir/gopath/src/golang.org/x/tools/internal/jsonrpc2/handler.go:103 +0xb1

Goroutine 34387 (running) created at:
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).checkPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:658 +0x431
  golang.org/x/tools/gopls/internal/lsp/cache.(*typeCheckBatch).handleSyntaxPackage()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:512 +0x52c
  golang.org/x/tools/gopls/internal/lsp/cache.(*snapshot).forEachPackageInternal.func2()
      /workdir/gopath/src/golang.org/x/tools/gopls/internal/lsp/cache/check.go:374 +0x74
  golang.org/x/sync/errgroup.(*Group).Go.func1()
      /workdir/gopath/pkg/mod/golang.org/x/sync@v0.3.0/errgroup/errgroup.go:75 +0x76
==================

[bcmills]

As I understand it, this is too recent to explain #37602?

[findleyr]

@bcmills this race has existed from the beginning (go 1.18).

I'm shocked that it hasn't been uncovered until now, though it does explain multiple confusing observations in gopls, which may be one of the few concurrent users of go/types.

[gopherbot]

Change https://go.dev/cl/512955 mentions this issue: internal/gcimporter: another workaround for race to interface type set

[findleyr]

I believe I have a fix for this. Unfortunately, these types of fixes (in go/types, at least) tend to be risky, so we must be very careful before cherry-picking.

[firelizzard18]

I’ve also seen what I believe is a related failure when running lint in CI. I’ll hunt for the logs tomorrow. I’ve only seen it fail once or twice and it went away when I retried the job.