cmd/equaler: add command to generate Equal() methodss/eq

The generator is still crude and do not cover most types, but it
covers all the ones needed by the tailcfg package. It's a start.

Fixes #8077.

Signed-off-by: salman <salman@tailscale.com>

7 files changed, 436 insertions, 126 deletions

diff --git a/cmd/equaler/equaler.go b/cmd/equaler/equaler.go
new file mode 100644
index 000000000..27412bb23
--- /dev/null
+++ b/cmd/equaler/equaler.go
@@ -0,0 +1,177 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Equaler is a tool to automate the creation of an Equals method.
+//
+// This tool assumes that if a type you give it contains another named struct
+// type, that type will also have an Equal method, and that all fields are
+// comparable unless explicitly excluded.
+package main
+
+import (
+	"bytes"
+	"flag"
+	"fmt"
+	"go/token"
+	"go/types"
+	"log"
+	"os"
+	"strings"
+
+	"golang.org/x/exp/slices"
+	"tailscale.com/util/codegen"
+)
+
+var (
+	flagTypes     = flag.String("type", "", "comma-separated list of types; required")
+	flagBuildTags = flag.String("tags", "", "compiler build tags to apply")
+)
+
+func main() {
+	log.SetFlags(0)
+	log.SetPrefix("equaler: ")
+	flag.Parse()
+	if len(*flagTypes) == 0 {
+		flag.Usage()
+		os.Exit(2)
+	}
+	typeNames := strings.Split(*flagTypes, ",")
+
+	pkg, namedTypes, err := codegen.LoadTypes(*flagBuildTags, ".")
+	if err != nil {
+		log.Fatal(err)
+	}
+	it := codegen.NewImportTracker(pkg.Types)
+	buf := new(bytes.Buffer)
+	for _, typeName := range typeNames {
+		typ, ok := namedTypes[typeName]
+		if !ok {
+			log.Fatalf("could not find type %s", typeName)
+		}
+		gen(buf, it, typ, typeNames)
+	}
+
+	cloneOutput := pkg.Name + "_equal.go"
+	if err := codegen.WritePackageFile("tailscale.com/cmd/equaler", pkg, cloneOutput, it, buf); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func gen(buf *bytes.Buffer, it *codegen.ImportTracker, typ *types.Named, typeNames []string) {
+	t, ok := typ.Underlying().(*types.Struct)
+	if !ok {
+		return
+	}
+
+	name := typ.Obj().Name()
+	fmt.Fprintf(buf, "// Equal reports whether a and b are equal.\n")
+	fmt.Fprintf(buf, "func (a *%s) Equal(b *%s) bool {\n", name, name)
+	writef := func(format string, args ...any) {
+		fmt.Fprintf(buf, "\t"+format+"\n", args...)
+	}
+	writef("if a == b {")
+	writef("\treturn true")
+	writef("}")
+
+	writef("return a != nil && b != nil &&")
+	for i := 0; i < t.NumFields(); i++ {
+		fname := t.Field(i).Name()
+		ft := t.Field(i).Type()
+
+		// Fields which are explicitly ignored are skipped.
+		if codegen.HasNoEqual(t.Tag(i)) {
+			writef("\t// Skipping %s because of codegen:noequal", fname)
+			continue
+		}
+
+		// Fields which are named types that have an Equal() method, get that method used
+		if named, _ := ft.(*types.Named); named != nil {
+			if implementsEqual(ft) || slices.Contains(typeNames, named.Obj().Name()) {
+				writef("\ta.%s.Equal(b.%s) &&", fname, fname)
+				continue
+			}
+		}
+
+		// Fields which are just values are directly compared, unless they have an Equal() method.
+		if !codegen.ContainsPointers(ft) {
+			writef("\ta.%s == b.%s &&", fname, fname)
+			continue
+		}
+
+		switch ft := ft.Underlying().(type) {
+		case *types.Pointer:
+			if named, _ := ft.Elem().(*types.Named); named != nil {
+				if slices.Contains(typeNames, named.Obj().Name()) || implementsEqual(ft) {
+					writef("\t((a.%s == nil) == (b.%s == nil)) && (a.%s == nil || a.%s.Equal(b.%s)) &&", fname, fname, fname, fname, fname)
+					continue
+				}
+				if implementsEqual(ft.Elem()) {
+					writef("\t((a.%s == nil) == (b.%s == nil)) && (a.%s == nil || a.%s.Equal(*b.%s)) &&", fname, fname, fname, fname, fname)
+					continue
+				}
+			}
+			if !codegen.ContainsPointers(ft.Elem()) {
+				writef("\t((a.%s == nil) == (b.%s == nil)) && (a.%s == nil || *a.%s == *b.%s) &&", fname, fname, fname, fname, fname)
+				continue
+			}
+			log.Fatalf("unimplemented: %s (%T)", fname, ft)
+		case *types.Slice:
+			// Empty slices and nil slices are different.
+			writef("\t((a.%s == nil) == (b.%s == nil)) &&", fname, fname)
+			if named, _ := ft.Elem().(*types.Named); named != nil {
+				if implementsEqual(ft.Elem()) {
+					it.Import("golang.org/x/exp/slices")
+					writef("\tslices.EqualFunc(a.%s, b.%s, func(aa %s, bb %s) bool {return aa.Equal(bb)}) &&", fname, fname, named.Obj().Name(), named.Obj().Name())
+					continue
+				}
+				if slices.Contains(typeNames, named.Obj().Name()) || implementsEqual(types.NewPointer(ft.Elem())) {
+					it.Import("golang.org/x/exp/slices")
+					writef("\tslices.EqualFunc(a.%s, b.%s, func(aa %s, bb %s) bool {return aa.Equal(&bb)}) &&", fname, fname, named.Obj().Name(), named.Obj().Name())
+					continue
+				}
+			}
+			if !codegen.ContainsPointers(ft.Elem()) {
+				it.Import("golang.org/x/exp/slices")
+				writef("\tslices.Equal(a.%s, b.%s) &&", fname, fname)
+				continue
+			}
+			log.Fatalf("unimplemented: %s (%T)", fname, ft)
+		case *types.Map:
+			if !codegen.ContainsPointers(ft.Elem()) {
+				it.Import("golang.org/x/exp/maps")
+				writef("\tmaps.Equal(a.%s, b.%s) &&", fname, fname)
+				continue
+			}
+			log.Fatalf("unimplemented: %s (%T)", fname, ft)
+		default:
+			log.Fatalf("unimplemented: %s (%T)", fname, ft)
+		}
+	}
+	writef("\ttrue")
+	fmt.Fprintf(buf, "}\n\n")
+
+	buf.Write(codegen.AssertStructUnchanged(t, name, "Equal", it))
+}
+
+// hasBasicUnderlying reports true when typ.Underlying() is a slice or a map.
+func hasBasicUnderlying(typ types.Type) bool {
+	switch typ.Underlying().(type) {
+	case *types.Slice, *types.Map:
+		return true
+	default:
+		return false
+	}
+}
+
+// implementsEqual reports whether typ has an Equal(typ) bool method.
+func implementsEqual(typ types.Type) bool {
+	return types.Implements(typ, types.NewInterfaceType(
+		[]*types.Func{types.NewFunc(
+			token.NoPos, nil, "Equal", types.NewSignatureType(
+				types.NewVar(token.NoPos, nil, "a", typ),
+				nil, nil,
+				types.NewTuple(types.NewVar(token.NoPos, nil, "b", typ)),
+				types.NewTuple(types.NewVar(token.NoPos, nil, "", types.Typ[types.Bool])), false))},
+		[]types.Type{},
+	))
+}
diff --git a/tailcfg/tailcfg.go b/tailcfg/tailcfg.go
index b77193f2b..6efd17f80 100644
--- a/tailcfg/tailcfg.go
+++ b/tailcfg/tailcfg.go
@@ -5,8 +5,9 @@ package tailcfg
 
 //go:generate go run tailscale.com/cmd/viewer --type=User,Node,Hostinfo,NetInfo,Login,DNSConfig,RegisterResponse,DERPRegion,DERPMap,DERPNode,SSHRule,SSHAction,SSHPrincipal,ControlDialPlan --clonefunc
 
+//go:generage go run tailscale.com/cmd/equaler  --type Node,Hostinfo,NetInfo,Service
+
 import (
-	"bytes"
 	"encoding/hex"
 	"errors"
 	"fmt"
@@ -497,7 +498,7 @@ const (
 
 // Service represents a service running on a node.
 type Service struct {
-	_ structs.Incomparable
+	_ structs.Incomparable `codegen:"noequal"`
 
 	// Proto is the type of service. It's usually the constant TCP
 	// or UDP ("tcp" or "udp"), but it can also be one of the
@@ -582,9 +583,6 @@ type Hostinfo struct {
 	Cloud           string         `json:",omitempty"`
 	Userspace       opt.Bool       `json:",omitempty"` // if the client is running in userspace (netstack) mode
 	UserspaceRouter opt.Bool       `json:",omitempty"` // if the client's subnet router is running in userspace (netstack) mode
-
-	// NOTE: any new fields containing pointers in this type
-	//       require changes to Hostinfo.Equal.
 }
 
 // TailscaleSSHEnabled reports whether or not this node is acting as a
@@ -664,9 +662,7 @@ type NetInfo struct {
 	// This should only be updated rarely, or when there's a
 	// material change, as any change here also gets uploaded to
 	// the control plane.
-	DERPLatency map[string]float64 `json:",omitempty"`
-
-	// Update BasicallyEqual when adding fields.
+	DERPLatency map[string]float64 `json:",omitempty" codegen:"noequal"`
 }
 
 func (ni *NetInfo) String() string {
@@ -704,40 +700,6 @@ func conciseOptBool(b opt.Bool, trueVal string) string {
 	return ""
 }
 
-// BasicallyEqual reports whether ni and ni2 are basically equal, ignoring
-// changes in DERP ServerLatency & RegionLatency.
-func (ni *NetInfo) BasicallyEqual(ni2 *NetInfo) bool {
-	if (ni == nil) != (ni2 == nil) {
-		return false
-	}
-	if ni == nil {
-		return true
-	}
-	return ni.MappingVariesByDestIP == ni2.MappingVariesByDestIP &&
-		ni.HairPinning == ni2.HairPinning &&
-		ni.WorkingIPv6 == ni2.WorkingIPv6 &&
-		ni.OSHasIPv6 == ni2.OSHasIPv6 &&
-		ni.WorkingUDP == ni2.WorkingUDP &&
-		ni.WorkingICMPv4 == ni2.WorkingICMPv4 &&
-		ni.HavePortMap == ni2.HavePortMap &&
-		ni.UPnP == ni2.UPnP &&
-		ni.PMP == ni2.PMP &&
-		ni.PCP == ni2.PCP &&
-		ni.PreferredDERP == ni2.PreferredDERP &&
-		ni.LinkType == ni2.LinkType
-}
-
-// Equal reports whether h and h2 are equal.
-func (h *Hostinfo) Equal(h2 *Hostinfo) bool {
-	if h == nil && h2 == nil {
-		return true
-	}
-	if (h == nil) != (h2 == nil) {
-		return false
-	}
-	return reflect.DeepEqual(h, h2)
-}
-
 // HowUnequal returns a list of paths through Hostinfo where h and h2 differ.
 // If they differ in nil-ness, the path is "nil", otherwise the path is like
 // "ShieldsUp" or "NetInfo.nil" or "NetInfo.PCP".
@@ -1689,82 +1651,6 @@ func (id UserID) String() string  { return fmt.Sprintf("userid:%x", int64(id)) }
 func (id LoginID) String() string { return fmt.Sprintf("loginid:%x", int64(id)) }
 func (id NodeID) String() string  { return fmt.Sprintf("nodeid:%x", int64(id)) }
 
-// Equal reports whether n and n2 are equal.
-func (n *Node) Equal(n2 *Node) bool {
-	if n == nil && n2 == nil {
-		return true
-	}
-	return n != nil && n2 != nil &&
-		n.ID == n2.ID &&
-		n.StableID == n2.StableID &&
-		n.Name == n2.Name &&
-		n.User == n2.User &&
-		n.Sharer == n2.Sharer &&
-		n.UnsignedPeerAPIOnly == n2.UnsignedPeerAPIOnly &&
-		n.Key == n2.Key &&
-		n.KeyExpiry.Equal(n2.KeyExpiry) &&
-		bytes.Equal(n.KeySignature, n2.KeySignature) &&
-		n.Machine == n2.Machine &&
-		n.DiscoKey == n2.DiscoKey &&
-		eqPtr(n.Online, n2.Online) &&
-		eqCIDRs(n.Addresses, n2.Addresses) &&
-		eqCIDRs(n.AllowedIPs, n2.AllowedIPs) &&
-		eqCIDRs(n.PrimaryRoutes, n2.PrimaryRoutes) &&
-		eqStrings(n.Endpoints, n2.Endpoints) &&
-		n.DERP == n2.DERP &&
-		n.Cap == n2.Cap &&
-		n.Hostinfo.Equal(n2.Hostinfo) &&
-		n.Created.Equal(n2.Created) &&
-		eqTimePtr(n.LastSeen, n2.LastSeen) &&
-		n.MachineAuthorized == n2.MachineAuthorized &&
-		eqStrings(n.Capabilities, n2.Capabilities) &&
-		n.ComputedName == n2.ComputedName &&
-		n.computedHostIfDifferent == n2.computedHostIfDifferent &&
-		n.ComputedNameWithHost == n2.ComputedNameWithHost &&
-		eqStrings(n.Tags, n2.Tags) &&
-		n.Expired == n2.Expired &&
-		eqPtr(n.SelfNodeV4MasqAddrForThisPeer, n2.SelfNodeV4MasqAddrForThisPeer) &&
-		n.IsWireGuardOnly == n2.IsWireGuardOnly
-}
-
-func eqPtr[T comparable](a, b *T) bool {
-	if a == b { // covers nil
-		return true
-	}
-	if a == nil || b == nil {
-		return false
-	}
-	return *a == *b
-}
-
-func eqStrings(a, b []string) bool {
-	if len(a) != len(b) || ((a == nil) != (b == nil)) {
-		return false
-	}
-	for i, v := range a {
-		if v != b[i] {
-			return false
-		}
-	}
-	return true
-}
-
-func eqCIDRs(a, b []netip.Prefix) bool {
-	if len(a) != len(b) || ((a == nil) != (b == nil)) {
-		return false
-	}
-	for i, v := range a {
-		if v != b[i] {
-			return false
-		}
-	}
-	return true
-}
-
-func eqTimePtr(a, b *time.Time) bool {
-	return ((a == nil) == (b == nil)) && (a == nil || a.Equal(*b))
-}
-
 // Oauth2Token is a copy of golang.org/x/oauth2.Token, to avoid the
 // go.mod dependency on App Engine and grpc, which was causing problems.
 // All we actually needed was this struct on the client side.
diff --git a/tailcfg/tailcfg_equal.go b/tailcfg/tailcfg_equal.go
new file mode 100644
index 000000000..c01454890
--- /dev/null
+++ b/tailcfg/tailcfg_equal.go
@@ -0,0 +1,244 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Code generated by tailscale.com/cmd/equaler; DO NOT EDIT.
+
+package tailcfg
+
+import (
+	"net/netip"
+	"time"
+
+	"golang.org/x/exp/slices"
+	"tailscale.com/types/key"
+	"tailscale.com/types/opt"
+	"tailscale.com/types/structs"
+	"tailscale.com/types/tkatype"
+)
+
+// Equal reports whether a and b are equal.
+func (a *Node) Equal(b *Node) bool {
+	if a == b {
+		return true
+	}
+	return a != nil && b != nil &&
+		a.ID == b.ID &&
+		a.StableID == b.StableID &&
+		a.Name == b.Name &&
+		a.User == b.User &&
+		a.Sharer == b.Sharer &&
+		a.Key == b.Key &&
+		a.KeyExpiry.Equal(b.KeyExpiry) &&
+		((a.KeySignature == nil) == (b.KeySignature == nil)) &&
+		slices.Equal(a.KeySignature, b.KeySignature) &&
+		a.Machine == b.Machine &&
+		a.DiscoKey == b.DiscoKey &&
+		((a.Addresses == nil) == (b.Addresses == nil)) &&
+		slices.Equal(a.Addresses, b.Addresses) &&
+		((a.AllowedIPs == nil) == (b.AllowedIPs == nil)) &&
+		slices.Equal(a.AllowedIPs, b.AllowedIPs) &&
+		((a.Endpoints == nil) == (b.Endpoints == nil)) &&
+		slices.Equal(a.Endpoints, b.Endpoints) &&
+		a.DERP == b.DERP &&
+		a.Hostinfo.Equal(b.Hostinfo) &&
+		a.Created.Equal(b.Created) &&
+		a.Cap == b.Cap &&
+		((a.Tags == nil) == (b.Tags == nil)) &&
+		slices.Equal(a.Tags, b.Tags) &&
+		((a.PrimaryRoutes == nil) == (b.PrimaryRoutes == nil)) &&
+		slices.Equal(a.PrimaryRoutes, b.PrimaryRoutes) &&
+		((a.LastSeen == nil) == (b.LastSeen == nil)) && (a.LastSeen == nil || a.LastSeen.Equal(*b.LastSeen)) &&
+		((a.Online == nil) == (b.Online == nil)) && (a.Online == nil || *a.Online == *b.Online) &&
+		a.KeepAlive == b.KeepAlive &&
+		a.MachineAuthorized == b.MachineAuthorized &&
+		((a.Capabilities == nil) == (b.Capabilities == nil)) &&
+		slices.Equal(a.Capabilities, b.Capabilities) &&
+		a.UnsignedPeerAPIOnly == b.UnsignedPeerAPIOnly &&
+		a.ComputedName == b.ComputedName &&
+		a.computedHostIfDifferent == b.computedHostIfDifferent &&
+		a.ComputedNameWithHost == b.ComputedNameWithHost &&
+		a.DataPlaneAuditLogID == b.DataPlaneAuditLogID &&
+		a.Expired == b.Expired &&
+		((a.SelfNodeV4MasqAddrForThisPeer == nil) == (b.SelfNodeV4MasqAddrForThisPeer == nil)) && (a.SelfNodeV4MasqAddrForThisPeer == nil || *a.SelfNodeV4MasqAddrForThisPeer == *b.SelfNodeV4MasqAddrForThisPeer) &&
+		a.IsWireGuardOnly == b.IsWireGuardOnly &&
+		true
+}
+
+// A compilation failure here means this code must be regenerated, with the command at the top of this file.
+var _NodeEqualNeedsRegeneration = Node(struct {
+	ID                            NodeID
+	StableID                      StableNodeID
+	Name                          string
+	User                          UserID
+	Sharer                        UserID
+	Key                           key.NodePublic
+	KeyExpiry                     time.Time
+	KeySignature                  tkatype.MarshaledSignature
+	Machine                       key.MachinePublic
+	DiscoKey                      key.DiscoPublic
+	Addresses                     []netip.Prefix
+	AllowedIPs                    []netip.Prefix
+	Endpoints                     []string
+	DERP                          string
+	Hostinfo                      HostinfoView
+	Created                       time.Time
+	Cap                           CapabilityVersion
+	Tags                          []string
+	PrimaryRoutes                 []netip.Prefix
+	LastSeen                      *time.Time
+	Online                        *bool
+	KeepAlive                     bool
+	MachineAuthorized             bool
+	Capabilities                  []string
+	UnsignedPeerAPIOnly           bool
+	ComputedName                  string
+	computedHostIfDifferent       string
+	ComputedNameWithHost          string
+	DataPlaneAuditLogID           string
+	Expired                       bool
+	SelfNodeV4MasqAddrForThisPeer *netip.Addr
+	IsWireGuardOnly               bool
+}{})
+
+// Equal reports whether a and b are equal.
+func (a *Hostinfo) Equal(b *Hostinfo) bool {
+	if a == b {
+		return true
+	}
+	return a != nil && b != nil &&
+		a.IPNVersion == b.IPNVersion &&
+		a.FrontendLogID == b.FrontendLogID &&
+		a.BackendLogID == b.BackendLogID &&
+		a.OS == b.OS &&
+		a.OSVersion == b.OSVersion &&
+		a.Container == b.Container &&
+		a.Env == b.Env &&
+		a.Distro == b.Distro &&
+		a.DistroVersion == b.DistroVersion &&
+		a.DistroCodeName == b.DistroCodeName &&
+		a.App == b.App &&
+		a.Desktop == b.Desktop &&
+		a.Package == b.Package &&
+		a.DeviceModel == b.DeviceModel &&
+		a.PushDeviceToken == b.PushDeviceToken &&
+		a.Hostname == b.Hostname &&
+		a.ShieldsUp == b.ShieldsUp &&
+		a.ShareeNode == b.ShareeNode &&
+		a.NoLogsNoSupport == b.NoLogsNoSupport &&
+		a.WireIngress == b.WireIngress &&
+		a.AllowsUpdate == b.AllowsUpdate &&
+		a.Machine == b.Machine &&
+		a.GoArch == b.GoArch &&
+		a.GoArchVar == b.GoArchVar &&
+		a.GoVersion == b.GoVersion &&
+		((a.RoutableIPs == nil) == (b.RoutableIPs == nil)) &&
+		slices.Equal(a.RoutableIPs, b.RoutableIPs) &&
+		((a.RequestTags == nil) == (b.RequestTags == nil)) &&
+		slices.Equal(a.RequestTags, b.RequestTags) &&
+		((a.Services == nil) == (b.Services == nil)) &&
+		slices.EqualFunc(a.Services, b.Services, func(aa Service, bb Service) bool { return aa.Equal(&bb) }) &&
+		((a.NetInfo == nil) == (b.NetInfo == nil)) && (a.NetInfo == nil || a.NetInfo.Equal(b.NetInfo)) &&
+		((a.SSH_HostKeys == nil) == (b.SSH_HostKeys == nil)) &&
+		slices.Equal(a.SSH_HostKeys, b.SSH_HostKeys) &&
+		a.Cloud == b.Cloud &&
+		a.Userspace == b.Userspace &&
+		a.UserspaceRouter == b.UserspaceRouter &&
+		true
+}
+
+// A compilation failure here means this code must be regenerated, with the command at the top of this file.
+var _HostinfoEqualNeedsRegeneration = Hostinfo(struct {
+	IPNVersion      string
+	FrontendLogID   string
+	BackendLogID    string
+	OS              string
+	OSVersion       string
+	Container       opt.Bool
+	Env             string
+	Distro          string
+	DistroVersion   string
+	DistroCodeName  string
+	App             string
+	Desktop         opt.Bool
+	Package         string
+	DeviceModel     string
+	PushDeviceToken string
+	Hostname        string
+	ShieldsUp       bool
+	ShareeNode      bool
+	NoLogsNoSupport bool
+	WireIngress     bool
+	AllowsUpdate    bool
+	Machine         string
+	GoArch          string
+	GoArchVar       string
+	GoVersion       string
+	RoutableIPs     []netip.Prefix
+	RequestTags     []string
+	Services        []Service
+	NetInfo         *NetInfo
+	SSH_HostKeys    []string
+	Cloud           string
+	Userspace       opt.Bool
+	UserspaceRouter opt.Bool
+}{})
+
+// Equal reports whether a and b are equal.
+func (a *NetInfo) Equal(b *NetInfo) bool {
+	if a == b {
+		return true
+	}
+	return a != nil && b != nil &&
+		a.MappingVariesByDestIP == b.MappingVariesByDestIP &&
+		a.HairPinning == b.HairPinning &&
+		a.WorkingIPv6 == b.WorkingIPv6 &&
+		a.OSHasIPv6 == b.OSHasIPv6 &&
+		a.WorkingUDP == b.WorkingUDP &&
+		a.WorkingICMPv4 == b.WorkingICMPv4 &&
+		a.HavePortMap == b.HavePortMap &&
+		a.UPnP == b.UPnP &&
+		a.PMP == b.PMP &&
+		a.PCP == b.PCP &&
+		a.PreferredDERP == b.PreferredDERP &&
+		a.LinkType == b.LinkType &&
+		// Skipping DERPLatency because of codegen:noequal
+		true
+}
+
+// A compilation failure here means this code must be regenerated, with the command at the top of this file.
+var _NetInfoEqualNeedsRegeneration = NetInfo(struct {
+	MappingVariesByDestIP opt.Bool
+	HairPinning           opt.Bool
+	WorkingIPv6           opt.Bool
+	OSHasIPv6             opt.Bool
+	WorkingUDP            opt.Bool
+	WorkingICMPv4         opt.Bool
+	HavePortMap           bool
+	UPnP                  opt.Bool
+	PMP                   opt.Bool
+	PCP                   opt.Bool
+	PreferredDERP         int
+	LinkType              string
+	DERPLatency           map[string]float64
+}{})
+
+// Equal reports whether a and b are equal.
+func (a *Service) Equal(b *Service) bool {
+	if a == b {
+		return true
+	}
+	return a != nil && b != nil &&
+		// Skipping _ because of codegen:noequal
+		a.Proto == b.Proto &&
+		a.Port == b.Port &&
+		a.Description == b.Description &&
+		true
+}
+
+// A compilation failure here means this code must be regenerated, with the command at the top of this file.
+var _ServiceEqualNeedsRegeneration = Service(struct {
+	_           structs.Incomparable
+	Proto       ServiceProto
+	Port        uint16
+	Description string
+}{})
diff --git a/tailcfg/tailcfg_test.go b/tailcfg/tailcfg_test.go
index b0e3f982e..bc94e9843 100644
--- a/tailcfg/tailcfg_test.go
+++ b/tailcfg/tailcfg_test.go
@@ -572,7 +572,7 @@ func TestNetInfoFields(t *testing.T) {
 		"DERPLatency",
 	}
 	if have := fieldsOf(reflect.TypeOf(NetInfo{})); !reflect.DeepEqual(have, handled) {
-		t.Errorf("NetInfo.Clone/BasicallyEqually check might be out of sync\nfields: %q\nhandled: %q\n",
+		t.Errorf("NetInfo.Clone/Equal check might be out of sync\nfields: %q\nhandled: %q\n",
 			have, handled)
 	}
 }
diff --git a/tailcfg/tailcfg_view.go b/tailcfg/tailcfg_view.go
index b4ff3b738..957605255 100644
--- a/tailcfg/tailcfg_view.go
+++ b/tailcfg/tailcfg_view.go
@@ -402,6 +402,7 @@ func (v NetInfoView) LinkType() string                { return v.ж.LinkType }
 
 func (v NetInfoView) DERPLatency() views.Map[string, float64] { return views.MapOf(v.ж.DERPLatency) }
 func (v NetInfoView) String() string                          { return v.ж.String() }
+func (v NetInfoView) Equal(v2 NetInfoView) bool               { return v.ж.Equal(v2.ж) }
 
 // A compilation failure here means this code must be regenerated, with the command at the top of this file.
 var _NetInfoViewNeedsRegeneration = NetInfo(struct {
diff --git a/util/codegen/codegen.go b/util/codegen/codegen.go
index b1e012fad..277d39097 100644
--- a/util/codegen/codegen.go
+++ b/util/codegen/codegen.go
@@ -16,6 +16,7 @@ import (
 	"reflect"
 	"strings"
 
+	"golang.org/x/exp/slices"
 	"golang.org/x/tools/go/packages"
 	"golang.org/x/tools/imports"
 	"tailscale.com/util/mak"
@@ -47,12 +48,13 @@ func LoadTypes(buildTags string, pkgName string) (*packages.Package, map[string]
 // HasNoClone reports whether the provided tag has `codegen:noclone`.
 func HasNoClone(structTag string) bool {
 	val := reflect.StructTag(structTag).Get("codegen")
-	for _, v := range strings.Split(val, ",") {
-		if v == "noclone" {
-			return true
-		}
-	}
-	return false
+	return slices.Contains(strings.Split(val, ","), "noclone")
+}
+
+// HasNoEqual reports whether the provided tag has `codegen:noequal`.
+func HasNoEqual(structTag string) bool {
+	val := reflect.StructTag(structTag).Get("codegen")
+	return slices.Contains(strings.Split(val, ","), "noequal")
 }
 
 const copyrightHeader = `// Copyright (c) Tailscale Inc & AUTHORS
diff --git a/wgengine/magicsock/magicsock.go b/wgengine/magicsock/magicsock.go
index 3223441c4..e1a6a68db 100644
--- a/wgengine/magicsock/magicsock.go
+++ b/wgengine/magicsock/magicsock.go
@@ -951,7 +951,7 @@ func (c *Conn) pickDERPFallback() int {
 func (c *Conn) callNetInfoCallback(ni *tailcfg.NetInfo) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
-	if ni.BasicallyEqual(c.netInfoLast) {
+	if ni.Equal(c.netInfoLast) {
 		return
 	}
 	c.callNetInfoCallbackLocked(ni)