Panic after unmarshal twice to same object

[gxsshallot]

Describe the bug

We need to parse the file content to same object many times. But the library will be panic after another unmarshal operation.

To Reproduce

package main

import (
    "github.com/pelletier/go-toml/v2"
)

type Target struct {
    Params map[string]string `toml:"params"`
}

func main() {
    content := "params = {a=\"1\",b=\"2\"}"
    var target Target
    _ = toml.Unmarshal([]byte(content), &target)
    _ = toml.Unmarshal([]byte(content), &target)
}

Run the test program got the panic:

panic: reflect.Value.SetMapIndex: value of type interface {} is not assignable to type string

goroutine 1 [running]:
reflect.Value.assignTo({0x4c76a0?, 0xc0000a62e0?, 0xc0000a62e0?}, {0x4dcb68, 0x19}, 0x4c5760, 0x0)
        /opt/go-1.19.6/src/reflect/value.go:3145 +0x2a5
reflect.Value.SetMapIndex({0x4c8a20?, 0xc0000b6018?, 0x0?}, {0x4c5760, 0xc0000a62c0, 0x98}, {0x4c76a0, 0xc0000a62e0, 0x194})
        /opt/go-1.19.6/src/reflect/value.go:2295 +0x1b6
github.com/pelletier/go-toml/v2.(*decoder).handleKeyValuePart(0xc0000c0080, {0x1, 0xc0000c6460}, 0xc0000a2990?, {0x4c8a20?, 0xc0000b6018?, 0x4d5800?})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:1058 +0x5fa
github.com/pelletier/go-toml/v2.(*decoder).handleKeyValueInner(0xc0000bc043?, {0x1, 0xc0000c6460}, 0x1?, {0x4c8a20?, 0xc0000b6018?, 0x195?})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:1000 +0x71
github.com/pelletier/go-toml/v2.(*decoder).handleKeyValue(0xc0000c0080, 0xc0000c6428, {0x4c8a20?, 0xc0000b6018?, 0x4b72a8?})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:986 +0xa5
github.com/pelletier/go-toml/v2.(*decoder).unmarshalInlineTable(0xc0000c0080?, 0xc0000c63f0, {0x4c8a20?, 0xc0000b6018?, 0x4c8660?})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:756 +0x2bc
github.com/pelletier/go-toml/v2.(*decoder).handleValue(0x0?, 0xc0000c63f0, {0x4c8a20?, 0xc0000b6018?, 0x28?})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:653 +0xe8
github.com/pelletier/go-toml/v2.(*decoder).handleKeyValueInner(0x4cab00?, {0x1, 0x0}, 0xc0000ce008?, {0x4c8a20?, 0xc0000b6018?, 0xc0000bc040?})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:1004 +0x8c
github.com/pelletier/go-toml/v2.(*decoder).handleKeyValuePart(0xc0000c0080, {0x1, 0xc0000c63b8}, 0x5950e0?, {0x4cab00?, 0xc0000b6018?, 0xffffffffffffffff?})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:1075 +0x9cc
github.com/pelletier/go-toml/v2.(*decoder).handleKeyValueInner(0x6?, {0x1, 0xc0000c63b8}, 0xc0000a2d90?, {0x4cab00?, 0xc0000b6018?, 0xc0000c6380?})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:1000 +0x71
github.com/pelletier/go-toml/v2.(*decoder).handleKeyValue(0xc0000c0080, 0xc0000c6380, {0x4cab00?, 0xc0000b6018?, 0x18?})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:986 +0xa5
github.com/pelletier/go-toml/v2.(*decoder).handleRootExpression(0xc0000c0080, 0xc0000c6380, {0x4cab00?, 0xc0000b6018?, 0x0?})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:258 +0xa9
github.com/pelletier/go-toml/v2.(*decoder).fromParser(0xc0000c0080, {0x4cab00?, 0xc0000b6018?, 0x5950e0?})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:224 +0xaa
github.com/pelletier/go-toml/v2.(*decoder).FromParser(0xc0000c0080, {0x4c2960?, 0xc0000b6018?})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:209 +0x1e7
github.com/pelletier/go-toml/v2.Unmarshal({0xc0000bc030, 0x16, 0x18}, {0x4c2960, 0xc0000b6018})
        /home/shallot/.go/pkg/mod/github.com/pelletier/go-toml/v2@v2.0.6/unmarshaler.go:28 +0x11a
main.main()
        /home/shallot/project/common/micro/main1.go:15 +0x76
exit status 2

Expected behavior

Not panic.

Versions

• go-toml: v2.0.6
• go: 1.19.6
• operating system: Linux

Additional context

No.

[apprehensions]

facing this same issue

[pelletier]

Thanks for reporting this bug! I've merged https://github.com/pelletier/go-toml/pull/854, which should fix the problem. Feel free to reopen this issue if it doesn't!