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Joe Tsai c700c23cef reflect: make Value.IsZero identical to v == zero
The upcoming built-in zero value provides an idiomatic way
to test for zero by comparing to the zero literal: v == zero.

The reflect package is meant to provide a programmatic way to perform
operations that the Go language itself provides.
Thus, it seems prudent that reflect.ValueOf(&v).Elem().IsZero() is
identical to v == zero.

This change alters the behavior of Value.IsZero in two concrete ways:
* negative zero is identical to zero
* blank fields in a struct are ignored

Prior to this change, we were already in an inconsistent state
due to a regression introduced by CL 411478.
The new behavior was already the case for comparable composite types.
This change makes it consistent for all other types
(in particular incomparable composite types and standalone numbers).

Updates #61372
Fixes #61827

Change-Id: Id23fb97eb3b8921417cc75a1d3ead963e22dc3d9
Reviewed-on: https://go-review.googlesource.com/c/go/+/517777
Reviewed-by: Russ Cox <rsc@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
2023-09-01 23:20:30 +00:00
.github .github: fix templates with multiple labels 2023-07-31 18:28:27 +00:00
api encoding: add AppendEncode and AppendDecode 2023-08-17 16:23:42 +00:00
doc reflect: make Value.IsZero identical to v == zero 2023-09-01 23:20:30 +00:00
lib/time lib/time: update to 2023c/2023c 2023-05-03 20:14:11 +00:00
misc os: add tests for UserCacheDir and UserConfigDir 2023-08-21 17:46:57 +00:00
src reflect: make Value.IsZero identical to v == zero 2023-09-01 23:20:30 +00:00
test Revert "cmd/compile: use shorter ANDL/TESTL if upper 32 bits are known to be zero" 2023-08-30 15:15:28 +00:00
.gitattributes
.gitignore internal/platform,cmd/dist: export the list of supported platforms 2023-06-22 19:44:52 +00:00
CONTRIBUTING.md doc: normalize proposal-process links 2023-03-29 22:00:27 +00:00
LICENSE
PATENTS
README.md README: update from CC-BY-3.0 to CC-BY-4.0 2022-11-02 20:14:56 +00:00
SECURITY.md SECURITY.md: replace golang.org with go.dev 2022-04-26 19:59:47 +00:00
codereview.cfg
go.env cmd/go: additional doc-inspired tests and bug fixes 2023-06-06 19:18:46 +00:00

README.md

The Go Programming Language

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