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cmd/compile: internal compiler error: panic: runtime error: invalid memory address or nil pointer dereference #51335

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dominikh opened this issue Feb 23, 2022 · 6 comments
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FrozenDueToAge NeedsFix The path to resolution is known, but the work has not been done. release-blocker
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@dominikh
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Input:

package pkg

type S1 struct{ X int }

func foo[T *S1|S1]() {
	_= []T{{1}}
}

Output:

$ go build bar.go
# command-line-arguments
<unknown line number>: internal compiler error: panic: runtime error: invalid memory address or nil pointer dereference

goroutine 1 [running]:
runtime/debug.Stack()
	/home/dominikh/prj/go/src/runtime/debug/stack.go:24 +0x65
cmd/compile/internal/base.FatalfAt({0x211d3fff?, 0x7fd0?}, {0xd22189, 0x9}, {0xc0000efec8, 0x1, 0x1})
	/home/dominikh/prj/go/src/cmd/compile/internal/base/print.go:227 +0x1d7
cmd/compile/internal/base.Fatalf(...)
	/home/dominikh/prj/go/src/cmd/compile/internal/base/print.go:196
cmd/compile/internal/gc.handlePanic()
	/home/dominikh/prj/go/src/cmd/compile/internal/gc/main.go:49 +0x85
panic({0xcaba20, 0x1311df0})
	/home/dominikh/prj/go/src/runtime/panic.go:838 +0x207
cmd/compile/internal/types2.(*Checker).handleBailout(0xc00045e000, 0xc0000f1648)
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/check.go:283 +0x8b
panic({0xcaba20, 0x1311df0})
	/home/dominikh/prj/go/src/runtime/panic.go:838 +0x207
cmd/compile/internal/types2.under({0x0?, 0x0?})
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/type.go:27 +0x4f
cmd/compile/internal/types2.coreType({0x0?, 0x0?})
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/type.go:39 +0x9a
cmd/compile/internal/types2.(*Checker).exprInternal(0xc00045e000, 0xc0000e5b40, {0xe95be8?, 0xc000451c70}, {0xe94d80?, 0xc000427380?})
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/expr.go:1370 +0x293
cmd/compile/internal/types2.(*Checker).rawExpr(0xc00045e000, 0xc0000e5b40, {0xe95be8?, 0xc000451c70?}, {0xe94d80?, 0xc000427380?}, 0x0)
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/expr.go:1225 +0x1a5
cmd/compile/internal/types2.(*Checker).exprWithHint(0xca8d40?, 0xc0000f07e8?, {0xe95be8?, 0xc000451c70?}, {0xe94d80?, 0xc000427380?})
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/expr.go:1774 +0x46
cmd/compile/internal/types2.(*Checker).indexedElts(0xe94d08?, {0xc0000bac00, 0x1, 0xc00002d07c?}, {0xe94d80, 0xc000427380}, 0xffffffffffffffff)
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/index.go:462 +0x4cc
cmd/compile/internal/types2.(*Checker).exprInternal(0xc00045e000, 0xc0000e5ac0, {0xe95be8?, 0xc000451c20}, {0x0?, 0x0?})
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/expr.go:1481 +0x645
cmd/compile/internal/types2.(*Checker).rawExpr(0xc00045e000, 0xc0000e5ac0, {0xe95be8?, 0xc000451c20?}, {0x0?, 0x0?}, 0x0)
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/expr.go:1225 +0x1a5
cmd/compile/internal/types2.(*Checker).multiExpr(0x1?, 0xc0000f0e60?, {0xe95be8?, 0xc000451c20?})
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/expr.go:1764 +0x35
cmd/compile/internal/types2.(*Checker).exprList(0x0?, {0xc0000f1198?, 0xc000000718?, 0xc0000005a0?}, 0x0)
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/call.go:250 +0x97
cmd/compile/internal/types2.(*Checker).assignVars(0xc00045e000, {0xc0000f11a8?, 0x1, 0x1}, {0xc0000f1198?, 0x1, 0x1})
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/assignments.go:392 +0x85
cmd/compile/internal/types2.(*Checker).stmt(0xc00045e000, 0x0, {0xe95a68?, 0xc0000e5880?})
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/stmt.go:452 +0x405
cmd/compile/internal/types2.(*Checker).stmtList(0xe94510?, 0x0, {0xc0000bac10?, 0x203000?, 0x203000?})
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/stmt.go:124 +0xc9
cmd/compile/internal/types2.(*Checker).funcBody(0xc00045e000, 0xc0000c7c20, {0xc00002d083?, 0xc00042fd80?}, 0xc0000e5900, 0xc0000e5840, {0x0, 0x0})
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/stmt.go:45 +0x3fb
cmd/compile/internal/types2.(*Checker).funcDecl.func1()
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/decl.go:718 +0x45
cmd/compile/internal/types2.(*Checker).processDelayed(0xc00045e000, 0x0)
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/check.go:369 +0x44
cmd/compile/internal/types2.(*Checker).checkFiles(0xc00045e000, {0xc00000e480, 0x1, 0x1})
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/check.go:316 +0x172
cmd/compile/internal/types2.(*Checker).Files(...)
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/check.go:288
cmd/compile/internal/types2.(*Config).Check(0xca95e0?, {0x7fff95b94f0f?, 0xd1db3e?}, {0xc00000e480, 0x1, 0x1}, 0x600c0003fe690?)
	/home/dominikh/prj/go/src/cmd/compile/internal/types2/api.go:420 +0x70
cmd/compile/internal/noder.checkFiles({0xc00000e450, 0x1, 0x203000?})
	/home/dominikh/prj/go/src/cmd/compile/internal/noder/irgen.go:65 +0x49c
cmd/compile/internal/noder.check2({0xc00000e450, 0x1, 0x1})
	/home/dominikh/prj/go/src/cmd/compile/internal/noder/irgen.go:78 +0x46
cmd/compile/internal/noder.LoadPackage({0xc00001e2f0, 0x1, 0x0?})
	/home/dominikh/prj/go/src/cmd/compile/internal/noder/noder.go:90 +0x335
cmd/compile/internal/gc.Main(0xd52330)
	/home/dominikh/prj/go/src/cmd/compile/internal/gc/main.go:191 +0xb13
main.main()
	/home/dominikh/prj/go/src/cmd/compile/main.go:55 +0xdd
@dominikh dominikh added the NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. label Feb 23, 2022
@dominikh dominikh added this to the Go1.18 milestone Feb 23, 2022
@dominikh
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Same crash, slightly less weird code:

package pkg

type S1 struct{ X int }
type S2 struct{ X int }

func foo[T *S1|*S2]() {
	_= []T{{1}}
}

@findleyr
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CC @griesemer

@findleyr
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Conservatively marking as a release blocker until we understand this.

@findleyr
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findleyr commented Feb 23, 2022

I looked into this superficially. This code assumes that the type hint has a core type:
https://cs.opensource.google/go/go/+/master:src/cmd/compile/internal/types2/expr.go;l=1362;drc=master

This appears straightforward to fix, and is a crasher. We should fix for 1.18.

EDIT: and thank you @dominikh for the report!

@griesemer griesemer self-assigned this Feb 23, 2022
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Agreed. Coming to the same conclusion @findleyr . Seems easy to fix.

@gopherbot
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Change https://go.dev/cl/387676 mentions this issue: go/types, types2: don't crash if comp. literal element type has no core type

@griesemer griesemer added NeedsFix The path to resolution is known, but the work has not been done. and removed NeedsInvestigation Someone must examine and confirm this is a valid issue and not a duplicate of an existing one. labels Feb 23, 2022
@golang golang locked and limited conversation to collaborators Jun 22, 2023
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