Why Does `==` Return `false` for Identical Go `time.Time` Structs?

Why does == return false for time structs with identical dates and times?

In Go, time.Time is a struct with fields representing the date, time, and time zone. When comparing two time.Time values using ==, it's important to note that not only the date and time but also the location are compared.

The == operator compares all non-blank fields of a struct, including the pointer to the location field (*Location). While two locations may represent the same time zone, they may reside at different memory addresses.

As a result, when comparing two time.Time values that share the same date and time but were created in different locations, this results in == returning false even though the time instants are equivalent.

Example:

Consider the following code:

import (
    "fmt"
    "time"
)

func main() {
    t1 := time.Date(2016, 4, 14, 1, 30, 30, 222000000, time.UTC)
    t2 := time.Date(2016, 4, 14, 1, 30, 30, 222000000, time.Local)

    fmt.Println(t1.Equal(t2)) // true (compares date and time only)
    fmt.Println(t1 == t2)      // false (also compares location pointers)
}

Here, t1 and t2 represent the same moment in time, but t1 is in UTC while t2 is in the local time zone. When comparing t1 and t2 using .Equal(), which ignores the location, true is returned. However, using == produces false due to the different location pointers.

Workaround:

To compare time.Time values strictly based on date and time, the time.Equal() method should be used instead of ==. Alternatively, you can manually ensure that both time.Time values share the same location pointer by calling t.In(t.Location()) on them.

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