Proposal Details

Proposal Details

Proposed addition:

func Expired(err error) bool

Motivation

Currently, many codebases should check whether the error is context.Canceled or context.DeadlineExceeded like this.

x, err := doFunc(ctx) // call 
if err != nil {
    if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded)
        // handle
    }
    return err
}

As the above case, it's right if developer want to detect any context cancellation, but this handling is redundant.
This syntax search shows:

• 6.5k errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded): https://github.com/search?q=errors.Is%28err%2C+context.Canceled%29+%7C%7C+errors.Is%28err%2C+context.DeadlineExceeded%29&type=code&p=1
• 508 !errors.Is(err, context.Canceled) || !errors.Is(err, context.DeadlineExceeded): https://github.com/search?q=%21errors.Is%28err%2C+context.Canceled%29+%7C%7C+%21errors.Is%28err%2C+context.DeadlineExceeded%29&type=code&p=1

Of course it's fine that's only redundant, unfortunately, some bugs can be happened since the returning error is different by Cancel and Timeout.
These are example that happens bugs.

trinodb/trino-go-client#140
argoproj/argo-cd#22824

These cases tried to consider cancellation correctly, but the difference between the explicit cancellation and timeouted cancellation couldn't be considered. To reduce these subtle incorrect handling, I propose above new API.
Of course, we can use Canceled and DeadlineExceeded separately to distinguish these error.