Closed
Description
What version of Go are you using (go version
)?
$ go version go version devel go1.18-df4c625d88 Thu Sep 2 01:06:17 2021 +0000 windows/amd64
Does this issue reproduce with the latest release?
No
What operating system and processor architecture are you using (go env
)?
go env
Output
$ go env set GO111MODULE= set GOARCH=amd64 set GOBIN= set GOCACHE=C:\Users\reus\AppData\Local\go-build set GOENV=C:\Users\reus\AppData\Roaming\go\env set GOEXE=.exe set GOEXPERIMENT= set GOFLAGS= set GOHOSTARCH=amd64 set GOHOSTOS=windows set GOINSECURE= set GOMODCACHE=C:\Users\reus\go\pkg\mod set GONOPROXY=github.com/reusee/* set GONOSUMDB=github.com/reusee/* set GOOS=windows set GOPATH=C:\Users\reus\go set GOPRIVATE=github.com/reusee/* set GOPROXY=https://goproxy.cn,direct set GOROOT=C:\Users\reus\gotip set GOSUMDB=sum.golang.org set GOTMPDIR= set GOTOOLDIR=C:\Users\reus\gotip\pkg\tool\windows_amd64 set GOVCS= set GOVERSION=devel go1.18-df4c625d88 Thu Sep 2 01:06:17 2021 +0000 set GCCGO=gccgo set AR=ar set CC=gcc set CXX=g++ set CGO_ENABLED=1 set GOMOD=NUL set CGO_CFLAGS=-g -O2 set CGO_CPPFLAGS= set CGO_CXXFLAGS=-g -O2 set CGO_FFLAGS=-g -O2 set CGO_LDFLAGS=-g -O2 set PKG_CONFIG=pkg-config set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Users\reus\AppData\Local\Temp\go-build2732815147=/tmp/go-build -gno-record-gcc-switches GOROOT/bin/go version: go version devel go1.18-df4c625d88 Thu Sep 2 01:06:17 2021 +0000 windows/amd64 GOROOT/bin/go tool compile -V: compile version devel go1.18-df4c625d88 Thu Sep 2 01:06:17 2021 +0000
What did you do?
go build
package main
func Foo[
Src interface {
func() Src
},
]() Src {
return Foo[Src]
}
func main() {
Foo()
}
What did you expect to see?
Compile OK
What did you see instead?
# command-line-arguments
runtime: goroutine stack exceeds 1000000000-byte limit
runtime: sp=0xc01ce01528 stack=[0xc01ce00000, 0xc03ce00000]
fatal error: stack overflow
runtime stack:
runtime.throw({0x143863c, 0x1a3afc0})
C:/Users/reus/gotip/src/runtime/panic.go:965 +0x76
runtime.newstack()
C:/Users/reus/gotip/src/runtime/stack.go:1085 +0x5cc
runtime.morestack()
C:/Users/reus/gotip/src/runtime/asm_amd64.s:422 +0x93
goroutine 1 [running]:
cmd/compile/internal/types2.(*subster).typ(0xc03cdfde18, {0x1598640, 0xc004cc2a00})
C:/Users/reus/gotip/src/cmd/compile/internal/types2/subst.go:87 +0x19e5 fp=0xc01ce01538 sp=0xc01ce01530 pc=0x12ac0c5
cmd/compile/internal/types2.(*subster).var_(0xc00ce017e8, 0xc004cc19e0)
C:/Users/reus/gotip/src/cmd/compile/internal/types2/subst.go:297 +0x32 fp=0xc01ce01578 sp=0xc01ce01538 pc=0x12ac432
cmd/compile/internal/types2.(*subster).varList(0x0, {0xc004cb2a98, 0x1, 0x0})
C:/Users/reus/gotip/src/cmd/compile/internal/types2/subst.go:318 +0x90 fp=0xc01ce015e8 sp=0xc01ce01578 pc=0x12ac690
cmd/compile/internal/types2.(*subster).tuple(0xc0085fde18, 0xc004cbb248)
C:/Users/reus/gotip/src/cmd/compile/internal/types2/subst.go:308 +0x35 fp=0xc01ce01630 sp=0xc01ce015e8 pc=0x12ac555
cmd/compile/internal/types2.(*subster).typ(0xc03cdfde18, {0x1598640, 0xc004cc2a40})
C:/Users/reus/gotip/src/cmd/compile/internal/types2/subst.go:127 +0x5df fp=0xc01ce01898 sp=0xc01ce01630 pc=0x12aacbf
cmd/compile/internal/types2.(*subster).var_(0xc00ce01b48, 0xc004cc1a40)
C:/Users/reus/gotip/src/cmd/compile/internal/types2/subst.go:297 +0x32 fp=0xc01ce018d8 sp=0xc01ce01898 pc=0x12ac432
cmd/compile/internal/types2.(*subster).varList(0x0, {0xc004cb2aa0, 0x1, 0x0})
C:/Users/reus/gotip/src/cmd/compile/internal/types2/subst.go:318 +0x90 fp=0xc01ce01948 sp=0xc01ce018d8 pc=0x12ac690
cmd/compile/internal/types2.(*subster).tuple(0xc0085fde18, 0xc004cbb260)
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danscales commentedon Sep 2, 2021
Infinite loop in types2 substituter. @griesemer
[-]cmd/compile: infinite loop in both -G=3 and unified mode[/-][+]cmd/compile: infinite loop in types2[/+]findleyr commentedon Sep 2, 2021
Related: #45550 and #48098.
FWIW, I don't think this function can reasonably compile without errors. What is the type of
Foo()
? We'd need a type name to define this kind of recursive data type (e.g. https://play.golang.org/p/JMlAom-VMOt).griesemer commentedon Sep 2, 2021
Nice! Thanks for reporting @reusee .
griesemer commentedon Sep 2, 2021
Simpler reproducer:
griesemer commentedon Sep 2, 2021
The issue here is that constraint type inference tries to unify
P
and*P
which then leads to an infinite expansion loop (P = *P
,P = **P
, etc.). The fix requires detection of arbitrary cycles from (all) inferred types trough (all) type parameters. CL forthcoming.6 remaining items