embed: embed path on different OS cannot open file

[kesuskim]

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

$ go version
1.16.2

Does this issue reproduce with the latest release?

Yes

Tested OS

Windows, Linux

What did you do?

//go:embed dir/myfile1.txt dir/myfile2.txt
var embedDir embed.FS

func init() {
    entries, _ := embedDir.ReadDir("dir")
    for _, entry := range entries {
        fmt.Println(embedDir.Name())  // this works
        fmt.Println(embedDir.Info())  // this works, too
        fmt.Println(embedDir.ReadFile(filepath.Join("dir", entry.Name()))) // this fails on Windows
    }
}

This works perfectly okay with Linux as it follows notation of Linux filesystem, but on Windows, even though it can fetch fs.dirEntry, it cannot read file with error given; open dir/myfile1.txt: file does not exist.

I can change embed notation with double backslash \\ and it will work.

//go:embed dir\\myfile1.txt dir\\myfile2.txt
var embedDir embed.FS // now it will work on Windows!!

So I can make that compile only on Windows, but somehow I think this is bug, because it can anyway fetch meta information of file, just cannot open it.

[kesuskim]

From documentation of embed, it clearly says The path separator is a forward slash, even on Windows systems., so this seems bug.

[nanokatze]

filepath.Join will join using backward slash on Windows, path.Join will use forward slash

[kesuskim]

Oh, so filepath.Join should not be used at all :( Previous implementation should also be little adjusted to that, thank you for clarification @nanokatze .