cmd/compile: global variable assignment implicit type conversion error

[deelawn]

Go version

go1.22.4 darwin/amd64

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/Users/dylan/Library/Caches/go-build'
GOENV='/Users/dylan/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMODCACHE='/Users/dylan/go/pkg/mod'
GONOPROXY='github.com/deelawn'
GONOSUMDB='github.com/deelawn'
GOOS='darwin'
GOPATH='/Users/dylan/go'
GOPRIVATE='github.com/deelawn'
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/darwin_amd64'
GOVCS=''
GOVERSION='go1.22.4'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='clang'
CXX='clang++'
CGO_ENABLED='1'
GOMOD='/Users/dylan/deelawn/gnoland/gno2/gno/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/6v/ptrk49k16l32ftg2l8x0q8j40000gn/T/go-build4157790115=/tmp/go-build -gno-record-gcc-switches -fno-common'

What did you do?

https://go.dev/play/p/AwgUrKVlv9_Z

package main

import "fmt"

type nat []int

var a, b nat = y()

func y() (nat, []int) {
	return nat{0}, nat{1}
}

func main() {
	fmt.Println(a, b)
}

What did you see happen?

./prog.go:7:5: internal compiler error: unexpected initialization statement: a, b = .autotmp_0, .autotmp_1

Please file a bug report including a short program that triggers the error.
https://go.dev/issue/new

What did you expect to see?

Expected output of [0] [1], identical to what is output when doing the same assignment to local variables:

package main

import "fmt"

type nat []int

func y() (nat, []int) {
	return nat{0}, nat{1}
}

func main() {
	var a, b nat = y()
	fmt.Println(a, b)
}

[gabyhelp]

Related Issues

• cmd/compile: global variable initialization done in unexpected order #51913 (closed)
• cmd/compile: internal compiler error: unexpected untyped type: untyped int #50635 (closed)
• cmd/compile, go/types, types2: unclear error message on initialization loop and invalid parameter type #47059
• cmd/compile: internal compiler error: got untyped bool for autotmp #17551 (closed)
• cmd/compile: cannot use s (type [][]Typ) as type []go.shape.[]int_0 in assignment #55964 (closed)
• internal compiler error: bad type for ... argument #46195 (closed)
• cmd/compile: internal compiler error with zero-size types #65808 (closed)
• cmd/compile: internal compiler error: found illegal assignment FUNC-func() T₁ -> main.T₁; #48137 (closed)
• cmd/compile: internal compiler error: 'main': Value live at entry. It shouldn't be #52590 (closed)
• internal compiler error: bad type for ... argument: [2]string #45913 (closed)

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

[thanm]

Thanks for the report.

Interestingly, this problem appears to have been around for quite some time; I can reproduce it at tip, then in 1.22 all the way back to 1.16 (works ok in 1.15).

@golang/compiler

[dr2chase]

I have a nasty suspicion this is something in expand_calls.

[cherrymui]

Actually, this panics in the frontend
https://go.dev/play/p/AwgUrKVlv9_Z?v=gotip

./prog.go:7:5: internal compiler error: unexpected initialization statement: a, b = .autotmp_0, .autotmp_1

goroutine 1 [running]:
runtime/debug.Stack()
	/usr/local/go/src/runtime/debug/stack.go:26 +0x5e
cmd/compile/internal/base.FatalfAt({0x479e91?, 0x0?}, {0xe4cd0e, 0x27}, {0xc00045b728, 0x1, 0x1})
	/usr/local/go/src/cmd/compile/internal/base/print.go:230 +0x1ea
cmd/compile/internal/staticinit.(*Schedule).tryStaticInit(0xc00045b880, {0xfa51a0, 0xc000437aa0})
	/usr/local/go/src/cmd/compile/internal/staticinit/sched.go:106 +0x1f7
cmd/compile/internal/staticinit.(*Schedule).StaticInit(0xc00045b880, {0xfa51a0, 0xc000437aa0})
	/usr/local/go/src/cmd/compile/internal/staticinit/sched.go:58 +0x26
cmd/compile/internal/pkginit.MakeTask()
	/usr/local/go/src/cmd/compile/internal/pkginit/init.go:99 +0x945
cmd/compile/internal/gc.Main(0xe66fe8)
	/usr/local/go/src/cmd/compile/internal/gc/main.go:244 +0xffd
main.main()
	/usr/local/go/src/cmd/compile/main.go:57 +0xf9

[gopherbot]

Change https://go.dev/cl/596055 mentions this issue: cmd/compile: fix ICE when compiling global a, b = f()