internal compiler error: bad type for ... argument: [2]string

[magisterquis]

What version of Go are you using (go version)?

$ go version
go version go1.16.3 openbsd/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE="auto"
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/stuart/.cache/go-build"
GOENV="/home/stuart/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="openbsd"
GOINSECURE=""
GOMODCACHE="/home/stuart/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="openbsd"
GOPATH="/home/stuart/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/stuart/.goroot"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/stuart/.goroot/pkg/tool/openbsd_amd64"
GOVCS=""
GOVERSION="go1.16.3"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="0"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build912392299=/tmp/go-build -gno-record-gcc-switches"

What did you do?

https://play.golang.org/p/i7aG3Eio2kF

What did you expect to see?

a b

What did you see instead?

/home/stuart/c.go:10:3: internal compiler error: bad type for ... argument: [2]string

[magisterquis]

Also happens with https://play.golang.org/p/KaRJNwngIab, not that it should compile anyways.

[ALTree]

Thanks for reporting this.

Still broken on tip:

$ gotip version
go version devel go1.17-879db69ce2 Sat May 1 11:43:19 2021 +0000 linux/amd64

$ gotip tool compile test.go
test.go:10:3: internal compiler error: bad type for ... argument: [2]string

cc @randall77 @mdempsky

[cuonglm]

The internal compiler error was added in df73945

Previously, the compiler reports:

main.go:10:3: not enough arguments in call to f
	have (...string)
	want (string, string)

which sounds wrong to me, though. It. should report that ... is used in non-variadic function.

cc @mdempsky

[gopherbot]

Change https://golang.org/cl/315796 mentions this issue: cmd/compile: make typecheckaste correctly report invalid use of "..."