Variadic parameters are mangled passed down the function stack

[markdiener10]

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

$ go version

1.17.8

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=""

GOARCH="arm64"

GOBIN=""

GOCACHE="/Users/marco/Library/Caches/go-build"

GOENV="/Users/marco/Library/Application Support/go/env"

GOEXE=""

GOEXPERIMENT=""

GOFLAGS=""

GOHOSTARCH="arm64"

GOHOSTOS="darwin"

GOINSECURE=""

GOMODCACHE="/Users/marco/go/pkg/mod"

GONOPROXY=""

GONOSUMDB=""

GOOS="darwin"

GOPATH="/Users/marco/go"

GOPRIVATE=""

GOPROXY="https://proxy.golang.org,direct"

GOROOT="/opt/homebrew/Cellar/go/1.17.8/libexec"

GOSUMDB="sum.golang.org"

GOTMPDIR=""

GOTOOLDIR="/opt/homebrew/Cellar/go/1.17.8/libexec/pkg/tool/darwin_arm64"

GOVCS=""

GOVERSION="go1.17.8"

GCCGO="gccgo"

AR="ar"

CC="clang"

CXX="clang++"

CGO_ENABLED="1"

GOMOD="/Users/sdev/golang/abds-go/go.mod"

CGO_CFLAGS="-g -O2"

CGO_CPPFLAGS=""

CGO_CXXFLAGS="-g -O2"

CGO_FFLAGS="-g -O2"

CGO_LDFLAGS="-g -O2"

PKG_CONFIG="pkg-config"

GOGCCFLAGS="-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/03/csncw3x15h54rjwv14wsf6x40000gn/T/go-build2466302340=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Passing variadic parameters further down the function call stack mangles the parameter.

Run this in the Go Playground:

package main

import (
"fmt"
)

func one(parms ...interface{}) {

fmt.Println("One#######")

for idx,parm := range parms {
	fmt.Println(idx,parm)	
}
two(parms)

}

func two(parms ...interface{}) {

fmt.Println("Two#######")

for idx,parm := range parms {
	fmt.Println(idx,parm)	
}

}

func main() {
one(11,12,13)
}

What did you expect to see?

One#######
0 11
1 12
2 13
Two#######
0 11
1 12
2 13

What did you see instead?

One#######
0 11
1 12
2 13
Two#######
0 [11 12 13]

[mpx]

The code is working correctly. The example has a bug given your intent: two(parms) needs to be two(parms...).

Otherwise you are passing the slice of arguments as the first parameter to two. Hence you see the slice output [11 12 13].

[markdiener10]

When calling the two( ) function, you must add the spread operator

two(parms...)

Then it works ok.