From 990d25c97d8d6b244a1d76c4d13736bdbcfb2a98 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Tue, 31 Mar 2026 18:42:46 -0700
Subject: [PATCH] go.toolchain.rev, version: bump Tailscale Go, add
 IsTailscaleGo

Reports whether the current binary was built with Tailscale's
custom Go toolchain (the "tailscale_go" build tag).

For https://github.com/tailscale/go/pull/165

Updates tailscale/corp#39430

Change-Id: Ica437582ddf55d7df48b1453bad03ce14b1c0949
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
---
 go.toolchain.next.rev       | 2 +-
 go.toolchain.rev            | 2 +-
 go.toolchain.rev.sri        | 2 +-
 version/version.go          | 4 ++++
 version/version_not_tsgo.go | 8 ++++++++
 version/version_tsgo.go     | 8 ++++++++
 6 files changed, 23 insertions(+), 3 deletions(-)
 create mode 100644 version/version_not_tsgo.go
 create mode 100644 version/version_tsgo.go

diff --git a/go.toolchain.next.rev b/go.toolchain.next.rev
index 205355c47..858ec57df 100644
--- a/go.toolchain.next.rev
+++ b/go.toolchain.next.rev
@@ -1 +1 @@
-f4de14a515221e27c0d79446b423849a6546e3a6
+179b46cade24e44f53b53a3cbcc7b7eb78469c31
diff --git a/go.toolchain.rev b/go.toolchain.rev
index 205355c47..858ec57df 100644
--- a/go.toolchain.rev
+++ b/go.toolchain.rev
@@ -1 +1 @@
-f4de14a515221e27c0d79446b423849a6546e3a6
+179b46cade24e44f53b53a3cbcc7b7eb78469c31
diff --git a/go.toolchain.rev.sri b/go.toolchain.rev.sri
index 86b2083ff..4efbc9f7c 100644
--- a/go.toolchain.rev.sri
+++ b/go.toolchain.rev.sri
@@ -1 +1 @@
-sha256-qmX68/Ml/jvf+sD9qykdx9QhSbkYaF8xJMFtd3iLHI8=
+sha256-VH+AgB1qjopwiB4w2SHrJm61O6yAl5ZaCGaDYnzb03o=
diff --git a/version/version.go b/version/version.go
index 1171ed2ff..7d8efc375 100644
--- a/version/version.go
+++ b/version/version.go
@@ -172,6 +172,10 @@ func majorMinorPatch() string {
 	return ret
 }
 
+// IsTailscaleGo reports whether the current binary was built with
+// Tailscale's custom Go toolchain.
+func IsTailscaleGo() bool { return isTailscaleGo }
+
 func isValidLongWithTwoRepos(v string) bool {
 	s := strings.Split(v, "-")
 	if len(s) != 3 {
diff --git a/version/version_not_tsgo.go b/version/version_not_tsgo.go
new file mode 100644
index 000000000..a852964ab
--- /dev/null
+++ b/version/version_not_tsgo.go
@@ -0,0 +1,8 @@
+// Copyright (c) Tailscale Inc & contributors
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !tailscale_go
+
+package version
+
+const isTailscaleGo = false
diff --git a/version/version_tsgo.go b/version/version_tsgo.go
new file mode 100644
index 000000000..fd72af7d4
--- /dev/null
+++ b/version/version_tsgo.go
@@ -0,0 +1,8 @@
+// Copyright (c) Tailscale Inc & contributors
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build tailscale_go
+
+package version
+
+const isTailscaleGo = true