When fmt.Errorf is provided with a %w verb with an error operand,
return an error implementing an Unwrap method returning that operand.
It is invalid to use %w with other formatting functions, to use %w
multiple times in a format string, or to use %w with a non-error
operand. When the Errorf format string contains an invalid use of %w,
the returned error does not implement Unwrap.
Change-Id: I534e20d3b163ab22c2b137b1c9095906dc243221
Reviewed-on: https://go-review.googlesource.com/c/go/+/176998
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>
Renaming the method makes clear, both to readers and to vet,
that this method is not the implementation of io.ByteWriter.
Working toward making the tree vet-safe instead of having
so many exceptions in cmd/vet/all/whitelist.
For #31916.
Change-Id: I79da062ca6469b62a6b9e284c6cf2413c7425249
Reviewed-on: https://go-review.googlesource.com/c/go/+/176109
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This applies only for cases where %w is not used.
The purpose of this change is to reduce test failures where tests
depend on these two being the same type, as they previously were.
Change-Id: I2dd28b93fe1d59f3cfbb4eb0875d1fb8ee699746
Reviewed-on: https://go-review.googlesource.com/c/go/+/167402
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
When formatting an error with a non-string formatting verb such as %d,
use the default formatting behavior rather than treating this as a bad
verb.
For example, this should print 42, not %!d(main.E=42):
var E int
func (E) Error() string { return "error" }
fmt.Printf("%d", E(42))
Fixes#30472
Change-Id: I62fd309c8ee9839a69052b0ec7f1808449dcee8e
Reviewed-on: https://go-review.googlesource.com/c/164557
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Baokun Lee
Damien Neil
Russ Cox
Marcel van Lohuizen