extract context errors with context.Cause and not ctx.Err() to suppor…

…t users using CancelCause

go.mod

@@ -1,6 +1,6 @@
 module github.com/avast/retry-go/v4
 
-go 1.18
+go 1.20
 
 require github.com/stretchr/testify v1.9.0
 

retry.go

@@ -132,7 +132,7 @@ func DoWithData[T any](retryableFunc RetryableFuncWithData[T], opts ...Option) (
 		opt(config)
 	}
 
-	if err := config.context.Err(); err != nil {
+	if err := context.Cause(config.context); err != nil {
 		return emptyT, err
 	}
 
@@ -161,9 +161,9 @@ func DoWithData[T any](retryableFunc RetryableFuncWithData[T], opts ...Option) (
 			case <-config.timer.After(delay(config, n, err)):
 			case <-config.context.Done():
 				if config.wrapContextErrorWithLastError {
-					return emptyT, Error{config.context.Err(), lastErr}
+					return emptyT, Error{context.Cause(config.context), lastErr}
 				}
-				return emptyT, config.context.Err()
+				return emptyT, context.Cause(config.context)
 			}
 		}
 	}
@@ -207,10 +207,10 @@ func DoWithData[T any](retryableFunc RetryableFuncWithData[T], opts ...Option) (
 		case <-config.timer.After(delay(config, n, err)):
 		case <-config.context.Done():
 			if config.lastErrorOnly {
-				return emptyT, config.context.Err()
+				return emptyT, context.Cause(config.context)
 			}
 
-			return emptyT, append(errorLog, config.context.Err())
+			return emptyT, append(errorLog, context.Cause(config.context))
 		}
 
 		n++