Multiple Packages in Same Directory

Why This Happens

Go requires all non-test .go files in a directory to declare the same package name. If two files in the same directory have different package declarations, the compiler cannot determine which package the directory represents. Test files may use packagename_test for black-box testing.

The Problem

// main.go
package main

// utils.go
package utils // different package in same directory!

The Fix

// main.go
package main

// utils.go
package main // same package

// Or move utils.go to a separate directory:
// utils/utils.go
package utils

Step-by-Step Fix

1. 1

   Identify the conflicting packages

   Read the error to see which files declare different package names.

2. 2

   Decide on the package

   Determine which package name the directory should use.

3. 3

   Move or rename

   Either change the package declaration to match, or move the file to its own directory.