cmd/compile: deadlock importing composite type including generic methods of the same type on go 1.27

[lauro-santana]

As this could be caused by the new 1.27 generic functions features (described here: https://go.dev/doc/go1.27#language), I am letting a new issue just to register. On the mentioned issue there is others deadlock mutex on different go verisons. I made a simple fix for this deadlock, will see if all is working and made a pull request.

I have faced the same error but with a different mutex deadlock call (could be caused by a different action):

Go version

go version go1.27rc1 linux/amd64

Go env output

AR='ar'
CC='gcc'
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_ENABLED='1'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
CXX='g++'
GCCGO='gccgo'
GO111MODULE=''
GOAMD64='v1'
GOARCH='amd64'
GOAUTH='netrc'
GOBIN='/home/lauro/go/bin'
GOCACHE='/home/lauro/.cache/go-build'
GOCACHEPROG=''
GODEBUG=''
GOENV='/home/lauro/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFIPS140='off'
GOFLAGS=''
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build2815077223=/tmp/go-build -gno-record-gcc-switches'
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMOD='/home/lauro/repos/go/bin/teste/go.mod'
GOMODCACHE='/home/lauro/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPACKAGESDRIVER=''
GOPATH='/home/lauro/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/home/lauro/sdk/go1.27rc1'
GOSUMDB='sum.golang.org'
GOTELEMETRY='local'
GOTELEMETRYDIR='/home/lauro/.config/go/telemetry'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/lauro/sdk/go1.27rc1/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.27rc1'
GOWORK=''
PKG_CONFIG='pkg-config'

What did you do?

package main

import "example/p"

var T p.I

func main() {
}

-- go.mod --
module example

go 1.27
-- p/p.go --

package p

type I int

func (i *I) M[V I]() {}

What did you see happen?

# command-line-arguments
fatal error: all goroutines are asleep - deadlock!

goroutine 1 [sync.Mutex.Lock]:
internal/sync.runtime_SemacquireMutex(0x7f4b7acd8328?, 0xe0?, 0x1ac3890?)
        runtime/sema.go:95 +0x25
internal/sync.(*Mutex).lockSlow(0x9da9b95ca20)
        internal/sync/mutex.go:149 +0x15a
internal/sync.(*Mutex).Lock(...)
        internal/sync/mutex.go:70
sync.(*Mutex).Lock(...)
        sync/mutex.go:46
cmd/compile/internal/types2.(*Named).resolveUnderlying.func1(0x19ee598?, 0x9da9b9121e0)
        cmd/compile/internal/types2/named.go:672 +0x49
cmd/compile/internal/types2.(*Named).resolveUnderlying(0x9da9b95ca00)
        cmd/compile/internal/types2/named.go:681 +0x275
cmd/compile/internal/types2.(*Named).Underlying(0x9da9b95ca00)
        cmd/compile/internal/types2/named.go:604 +0x32
cmd/compile/internal/types2.computeInterfaceTypeSet(0x0, {0x9da9b9cf2c0?, 0x0?, 0x0?}, 0x9da9bc1f810)
        cmd/compile/internal/types2/typeset.go:267 +0x4e6
cmd/compile/internal/types2.(*TypeParam).iface(0x9da9b9cf2f0)
        cmd/compile/internal/types2/typeparam.go:145 +0x206
cmd/compile/internal/types2.(*TypeParam).SetConstraint(...)
        cmd/compile/internal/types2/typeparam.go:89
cmd/compile/internal/importer.(*reader).typeParamNames.func1()
        cmd/compile/internal/importer/ureader.go:597 +0x45
cmd/compile/internal/types2.(*Named).unpack(0x9da9b95ca00)
        cmd/compile/internal/types2/named.go:276 +0x3a2
cmd/compile/internal/types2.(*Named).TypeParams(...)
        cmd/compile/internal/types2/named.go:387
cmd/compile/internal/types2.isGeneric({0x1ac0fb0?, 0x9da9b95ca00?})
        cmd/compile/internal/types2/predicates.go:146 +0xb6
cmd/compile/internal/types2.(*Checker).declaredType(0x9da9b9aa600, {0x1ac2f78, 0x9da9bc1f6d0}, 0x4a1be7?)
        cmd/compile/internal/types2/typexpr.go:186 +0x7e
cmd/compile/internal/types2.(*Checker).varType(0x9da9b9aa600, {0x1ac2f78, 0x9da9bc1f6d0})
        cmd/compile/internal/types2/typexpr.go:148 +0x31
cmd/compile/internal/types2.(*Checker).varDecl(0x9da9b9aa600, 0x9da9b95f810, {0x9da9b902740, 0x1, 0x1}, {0x1ac2f78, 0x9da9bc1f6d0}, {0x0, 0x0})
        cmd/compile/internal/types2/decl.go:362 +0x85
cmd/compile/internal/types2.(*Checker).objDecl(0x9da9b9aa600, {0x1ac39b0, 0x9da9b95f810})
        cmd/compile/internal/types2/decl.go:155 +0x97d
cmd/compile/internal/types2.(*Checker).packageObjects(0x9da9b9aa600)
        cmd/compile/internal/types2/resolver.go:699 +0x465
cmd/compile/internal/types2.(*Checker).checkFiles(0x9da9b9aa600, {0x9da9b912e38?, 0x425e45?, 0x1d079e0?})
        cmd/compile/internal/types2/check.go:443 +0x3f7
cmd/compile/internal/types2.(*Checker).Files(0x7fffb1be17e7?, {0x9da9b912e38?, 0x0?, 0x0?})
        cmd/compile/internal/types2/check.go:414 +0x75
cmd/compile/internal/types2.(*Config).Check(0x9da9bc20480, {0x7fffb1be17e7?, 0x9da9b8320c7?}, {0x9da9b912e38, 0x1, 0x1}, 0x9da9bc204e0)
        cmd/compile/internal/types2/api.go:478 +0x19d
cmd/compile/internal/noder.checkFiles({0x0, {0x0, 0x0}}, {0x9da9b9026d0, 0x1, 0x9?})
        cmd/compile/internal/noder/irgen.go:100 +0x65f
cmd/compile/internal/noder.writePkgStub({0x0?, {0x0?, 0x0?}}, {0x9da9b9026d0, 0x1, 0x1})
        cmd/compile/internal/noder/unified.go:322 +0x6a
cmd/compile/internal/noder.unified({0x0?, {0x0?, 0x0?}}, {0x9da9b9026d0?, 0x19ba430?, 0x1ba0718?})
        cmd/compile/internal/noder/unified.go:198 +0xb6
cmd/compile/internal/noder.LoadPackage({0x9da9b948130, 0x1, 0x1})
        cmd/compile/internal/noder/noder.go:76 +0x529
cmd/compile/internal/gc.Main(0x1ac7768)
        cmd/compile/internal/gc/main.go:218 +0xd05
main.main()
        cmd/compile/main.go:57 +0x105

What did you expect to see?

Compilation successful

Observation

If try the same example without using a package, the compiler works fine

Originally posted by @lauro-santana in #79711

[gabyhelp]

Related Issues

• cmd/compile/internal/importer: deadlock in recursion through type parameter #63285 (closed)
• cmd/compile: deadlock importing generic alias in recursive struct field #78343
• cmd/compile: deadlock #73539 (closed)
• cmd/compile: deadlock importing composite type including a recursive generic alias #79711
• cmd/compile: cannot use generic type alias as method receiver #77249
• cmd/compile/internal/types2: deadlock using type alias #75757
• cmd/compile: deadlock while typechecking self-referential constraint #49439 (closed)
• go/types, types2: inconsistent behavior with recursive generic types that produces deadlock, invalid recursive, unknown field error #60817 (closed)
• cmd/compile: infinite loop with recursive generic types #56665 (closed)
• cmd/compile: compiler hang involving recursive generic type instantiation #78341

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[gopherbot]

Change https://go.dev/cl/796960 mentions this issue: cmd/compile: fix for deadlock on delayed function inside named unpack