type switch fails when multiple cases are put together

[bo-er]

Go version

go version go1.21.3 linux/amd64

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

GO111MODULE='on'
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/steve/.cache/go-build'
GOENV='/home/steve/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE='actiontech.cloud'
GOMODCACHE='/home/steve/go/pkg/mod'
GONOPROXY='actiontech.cloud'
GONOSUMDB='actiontech.cloud'
GOOS='linux'
GOPATH='/home/steve/go'
GOPRIVATE='actiontech.cloud'
GOPROXY='goproxy.cn,goproxy.io,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='go1.21.3'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/home/steve/actiontech/Diagno/dms-diagno/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 -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build376176395=/tmp/go-build -gno-record-gcc-switches'

What did you do?

`type Value struct {
floatValue float64
intValue int64
stringValue string
}

func NewValue(v any) *Value {
switch nv := v.(type) {
case string:
return &Value{
stringValue: nv,
}
case int64, int, uint:
return &Value{
intValue: int64(nv),
}
case float64:
return &Value{
floatValue: nv,
}
}
return &Value{}
}`

The above code fails to compile due to error:

cannot convert nv (variable of type any) to type int64: need type assertion

What did you expect to see?

I expect the case：

case int64, int, uint: return &Value{ intValue: int64(nv), }
to be treated as:

case int64: return &Value{ intValue: int64(nv), } case int: return &Value{ intValue: int64(nv), } case uint: return &Value{ intValue: int64(nv), }

What did you see instead?

The compiler complains about syntax error:

cannot convert nv (variable of type any) to type int64: need type assertion

[mateusz834]

This works as expected. Consider the spec https://go.dev/ref/spec#Type_switches and the example there.

In clauses with a case listing exactly one type, the variable has that type; otherwise, the variable has the type of the expression in the TypeSwitchGuard.