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x/tools/go/types/typeutil: stack overflow when hashing mutually recursive pointers to type parameters #51314

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dominikh opened this issue Feb 22, 2022 · 5 comments
Closed

x/tools/go/types/typeutil: stack overflow when hashing mutually recursive pointers to type parameters #51314

dominikh opened this issue Feb 22, 2022 · 5 comments
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FrozenDueToAge NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. Soon This needs to be done soon. (regressions, serious bugs, outages) Tools This label describes issues relating to any tools in the x/tools repository.
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@dominikh
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Input:


-- foo.go --
package main

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/types/typeutil"
)

const src = `
package pkg

func Fn[T1 ~*T2, T2 ~*T1](t1 T1, t2 T2) {}
`

func main() {
	fset := token.NewFileSet()
	f, _ := parser.ParseFile(fset, "foo.go", src, 0)
	pkg := types.NewPackage("pkg", "pkg")
	c := types.NewChecker(nil, fset, pkg, nil)
	c.Files([]*ast.File{f})

	obj := pkg.Scope().Lookup("Fn")
	fmt.Println(obj.Type())

	h := typeutil.MakeHasher()
	h.Hash(obj.Type())
}
-- go.mod --
module example.com

go 1.18

require golang.org/x/tools v0.1.10-0.20220218145154-897bd77cd717

(Truncated) output:

$ go run foo.go 
func[T1 ~*T2, T2 ~*T1](t1 T1, t2 T2)
runtime: goroutine stack exceeds 1000000000-byte limit
runtime: sp=0xc020180388 stack=[0xc020180000, 0xc040180000]
fatal error: stack overflow

runtime stack:
runtime.throw({0x5a061e?, 0x6ab720?})
	/home/dominikh/prj/go/src/runtime/panic.go:992 +0x71
runtime.newstack()
	/home/dominikh/prj/go/src/runtime/stack.go:1101 +0x5cc
runtime.morestack()
	/home/dominikh/prj/go/src/runtime/asm_amd64.s:547 +0x8b

goroutine 1 [running]:
runtime.typehash(0x594140, 0xc020180460, 0x756ea16a56a621?)
	/home/dominikh/prj/go/src/runtime/alg.go:144 +0x2d2 fp=0xc020180398 sp=0xc020180390 pc=0x403672
runtime.interhash(0x0?, 0x0?)
	/home/dominikh/prj/go/src/runtime/alg.go:111 +0x56 fp=0xc0201803d0 sp=0xc020180398 pc=0x4031b6
runtime.mapaccess2(0x0?, 0x0?, 0x0?)
	/home/dominikh/prj/go/src/runtime/map.go:471 +0xf9 fp=0xc020180410 sp=0xc0201803d0 pc=0x40dd79
golang.org/x/tools/go/types/typeutil.Hasher.Hash({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0x5dc400, 0xc0000b6720})
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:244 +0x67 fp=0xc020180478 sp=0xc020180410 pc=0x561ac7
golang.org/x/tools/go/types/typeutil.Hasher.hashTypeParam({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, 0x1?)
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:426 +0x66 fp=0xc0201804b8 sp=0xc020180478 pc=0x562966
golang.org/x/tools/go/types/typeutil.Hasher.hashFor({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0x5dc540?, 0xc0000ca7e0?})
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:370 +0x4e7 fp=0xc020180698 sp=0xc0201804b8 pc=0x562067
golang.org/x/tools/go/types/typeutil.Hasher.Hash({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0x5dc540, 0xc0000ca7e0})
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:246 +0x91 fp=0xc020180700 sp=0xc020180698 pc=0x561af1
golang.org/x/tools/go/types/typeutil.Hasher.hashFor({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0x5dc478?, 0xc000010450?})
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:289 +0x525 fp=0xc0201808e0 sp=0xc020180700 pc=0x5620a5
golang.org/x/tools/go/types/typeutil.Hasher.Hash({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0x5dc478, 0xc000010450})
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:246 +0x91 fp=0xc020180948 sp=0xc0201808e0 pc=0x561af1
golang.org/x/tools/go/types/typeutil.Hasher.hashTermSet({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0xc002b04f70, 0x1, 0x0?})
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:404 +0x76 fp=0xc0201809b0 sp=0xc020180948 pc=0x562856
golang.org/x/tools/go/types/typeutil.Hasher.hashFor({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0x5dc400?, 0xc0000b66c0?})
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:349 +0x7a5 fp=0xc020180b90 sp=0xc0201809b0 pc=0x562325
golang.org/x/tools/go/types/typeutil.Hasher.Hash({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0x5dc400, 0xc0000b66c0})
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:246 +0x91 fp=0xc020180bf8 sp=0xc020180b90 pc=0x561af1
golang.org/x/tools/go/types/typeutil.Hasher.hashTypeParam({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, 0x1?)
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:426 +0x66 fp=0xc020180c38 sp=0xc020180bf8 pc=0x562966
golang.org/x/tools/go/types/typeutil.Hasher.hashFor({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0x5dc540?, 0xc0000ca780?})
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:370 +0x4e7 fp=0xc020180e18 sp=0xc020180c38 pc=0x562067
golang.org/x/tools/go/types/typeutil.Hasher.Hash({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0x5dc540, 0xc0000ca780})
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:246 +0x91 fp=0xc020180e80 sp=0xc020180e18 pc=0x561af1
golang.org/x/tools/go/types/typeutil.Hasher.hashFor({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0x5dc478?, 0xc000010490?})
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:289 +0x525 fp=0xc020181060 sp=0xc020180e80 pc=0x5620a5
golang.org/x/tools/go/types/typeutil.Hasher.Hash({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0x5dc478, 0xc000010490})
	/home/dominikh/prj/pkg/mod/golang.org/x/tools@v0.1.10-0.20220218145154-897bd77cd717/go/types/typeutil/map.go:246 +0x91 fp=0xc0201810c8 sp=0xc020181060 pc=0x561af1
golang.org/x/tools/go/types/typeutil.Hasher.hashTermSet({0xc04017fbe8?, 0xc04017fdb0?, 0xc00000c120?}, {0xc002b04f48, 0x1, 0x0?})
...additional frames elided...
exit status 2

/cc @findleyr
@gopherbot gopherbot added the Tools This label describes issues relating to any tools in the x/tools repository. label Feb 22, 2022
@gopherbot gopherbot added this to the Unreleased milestone Feb 22, 2022
@findleyr findleyr added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Feb 22, 2022
@findleyr
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CC @timothy-king

@findleyr findleyr added the Soon This needs to be done soon. (regressions, serious bugs, outages) label Feb 23, 2022
@findleyr findleyr self-assigned this Feb 23, 2022
@dominikh
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Another example:

type Constraint[T any] interface{}

func Foo[T Constraint[T]]() {}

@gopherbot
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Change https://go.dev/cl/387754 mentions this issue: go/types/typeutil: don't recurse into constraints when hashing tparams

@timothy-king
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Thanks for the report @dominikh. I also encountered this on gotip/test/typeparam/issue48137.go

type Constraint[T any] interface {
	~func() T
}

func Foo[T Constraint[T]]() T {
	var t T

	t = func() T {
		return t
	}
	return t
}

Looks like the same core issue to me.

@dominikh
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My second example was in fact extracted from issue48137.go.

@golang golang locked and limited conversation to collaborators Jun 22, 2023
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