Two unique indices created when using syntax `uniqueIndex:custom_index_name`, PostgreSQL

Issue:

Two indices created when using syntax uniqueIndex:custom_index_name

Expected result

Using the uniqueIndex with a custom name for the index creates just one unique index with the given name

Actual result

Both the default index (that would be created without the given name) and the named index are created:

idx_tablename_columnname
custom_index_name

Description

I was unable to make go-playground run (there's an active issue for that) but this issue is easily reproduced with e.g. the following go code

package main

import (
    "log"

    "gorm.io/driver/postgres"
    "gorm.io/gorm"
)

type User struct {
    gorm.Model
    Name  string `gorm:"uniqueIndex:uni_name_index_gorm"`
    Email string
}

func main() {
    dsn := "postgres://postgres:postgres@localhost:5432/testdb?sslmode=disable"
    db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
    if err != nil {
        log.Fatal("failed to connect database")
    }

    // Migrate the schema
    db.AutoMigrate(&User{})

}

This creates two indexes in the PostgreSQL database: idx_users_name and the index I wanted to create uni_name_index_gorm.

If I use just the tag gorm:"uniqueIndex" without a given name, only the first index idx_users_name is created

However, if I have the uniqueIndex:custom_index_name tag with the same name applied to multiple columns, then only that one named index gets created, so in that use-case it works as intended.

go-gorm / gorm