From 5bfa940c971b0955bd192e22e5c19ba39c8b0fea Mon Sep 17 00:00:00 2001
From: yuhan6665 <1588741+yuhan6665@users.noreply.github.com>
Date: Sun, 12 Apr 2026 22:19:58 -0400
Subject: [PATCH] all: replace calls to errors.As with errors.AsType This
 change replaces most occurrences (in code as well as in comments) of
 errors.As with errors.AsType. It leaves the errors package and vendored code
 untouched.

Change-Id: I3bde73f318a0b408bdb8f5a251494af15a13118a
GitHub-Last-Rev: 8aaaa36
GitHub-Pull-Request: #75698
Reviewed-on: https://go-review.googlesource.com/c/go/+/708495
Auto-Submit: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
---
 conn.go             | 4 ++--
 handshake_server.go | 5 ++---
 quic.go             | 7 +++----
 3 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/conn.go b/conn.go
index 30707e0..73267f9 100644
--- a/conn.go
+++ b/conn.go
@@ -1645,9 +1645,9 @@ func (c *Conn) handshakeContext(ctx context.Context) (ret error) {
 			// the handshake (RFC 9001, Section 5.7).
 			c.quicSetReadSecret(QUICEncryptionLevelApplication, c.cipherSuite, c.in.trafficSecret)
 		} else {
-			var a alert
 			c.out.Lock()
-			if !errors.As(c.out.err, &a) {
+			a, ok := errors.AsType[alert](c.out.err)
+			if !ok {
 				a = alertInternalError
 			}
 			c.out.Unlock()
diff --git a/handshake_server.go b/handshake_server.go
index ad30acf..63ebfc0 100644
--- a/handshake_server.go
+++ b/handshake_server.go
@@ -948,10 +948,9 @@ func (c *Conn) processCertsFromClient(certificate Certificate) error {
 
 		chains, err := certs[0].Verify(opts)
 		if err != nil {
-			var errCertificateInvalid x509.CertificateInvalidError
-			if errors.As(err, &x509.UnknownAuthorityError{}) {
+			if _, ok := errors.AsType[x509.UnknownAuthorityError](err); ok {
 				c.sendAlert(alertUnknownCA)
-			} else if errors.As(err, &errCertificateInvalid) && errCertificateInvalid.Reason == x509.Expired {
+			} else if errCertificateInvalid, ok := errors.AsType[x509.CertificateInvalidError](err); ok && errCertificateInvalid.Reason == x509.Expired {
 				c.sendAlert(alertCertificateExpired)
 			} else {
 				c.sendAlert(alertBadCertificate)
diff --git a/quic.go b/quic.go
index 3d3693b..286afe8 100644
--- a/quic.go
+++ b/quic.go
@@ -363,12 +363,11 @@ func quicError(err error) error {
 	if err == nil {
 		return nil
 	}
-	var ae AlertError
-	if errors.As(err, &ae) {
+	if _, ok := errors.AsType[AlertError](err); ok {
 		return err
 	}
-	var a alert
-	if !errors.As(err, &a) {
+	a, ok := errors.AsType[alert](err)
+	if !ok {
 		a = alertInternalError
 	}
 	// Return an error wrapping the original error and an AlertError.