filepath.Abs() does not provide subdirectory in result

I have directory like:

myproject/
├─ data/
│  ├─ test.csv
├─ go.mod
├─ main.go

package main

import (
    "fmt"
    "log"
    "os"
    "path/filepath"
)

func main() {

    fullPath := `C:\myproject\data\test.csv`
    f, err := os.Open(fullPath)
    if err != nil {
        log.Fatal(err)
    }
    defer f.Close()

    fileInfo, err := f.Stat()
    if err != nil {
        log.Fatal(err)
    }

    // get full file path
    filePath, err := filepath.Abs(fileInfo.Name())
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(filePath)
}

However, filepath.Abs(fileInfo.Name()) gives me C:\myproject\test.csv. instead of what I would desire C:\myproject\data\test.csv

IIUC, fileInfo.Name() should give me the same path as what was fed into os.Open(), so why wouldn't filepath.Abs() recognize the directory that the file is in? filepath.Dir(fileInfo.Name()) gives me . as well... which I would expect to be C:\myproject\data\.

I am running my go file from within myproject directory.

go version 1.19.3 windows/amd64

fileInfo.Name() returns just the base name of the file, as documented, with no path info. So you're passing just a raw filename to filepath.Abs. As such, the function is doing exactly what the documentation says it will do:

If the path is not absolute it will be joined with the current working directory to turn it into an absolute path.