chore: build with Go 1.26; use Go 1.25 features (#10570)

WaitGroup.Go and built-in gomaxprocs handling.

Signed-off-by: Jakob Borg <jakob@kastelo.net>

lib/automaxprocs/automaxprocs.go

@@ -1,15 +0,0 @@
-// Copyright (C) 2024 The Syncthing Authors.
-//
-// This Source Code Form is subject to the terms of the Mozilla Public
-// License, v. 2.0. If a copy of the MPL was not distributed with this file,
-// You can obtain one at https://mozilla.org/MPL/2.0/.
-
-package automaxprocs
-
-import (
-	"go.uber.org/automaxprocs/maxprocs"
-)
-
-func init() {
-	maxprocs.Set()
-}

lib/config/wrapper.go

@@ -329,12 +329,10 @@ func (w *wrapper) replaceLocked(to Configuration) (Waiter, error) {
 
 func (w *wrapper) notifyListeners(from, to Configuration) Waiter {
 	wg := new(sync.WaitGroup)
-	wg.Add(len(w.subs))
 	for _, sub := range w.subs {
-		go func(committer Committer) {
-			w.notifyListener(committer, from, to)
-			wg.Done()
-		}(sub)
+		wg.Go(func() {
+			w.notifyListener(sub, from, to)
+		})
 	}
 	return wg
 }

lib/connections/connections_test.go

@@ -337,23 +337,20 @@ func BenchmarkConnections(b *testing.B) {
 						b.ResetTimer()
 						for i := 0; i < b.N; i++ {
 							var wg sync.WaitGroup
-							wg.Add(2)
 							errC := make(chan error, 2)
-							go func() {
+							wg.Go(func() {
 								if _, err := client.Write(data); err != nil {
 									errC <- err
 									return
 								}
-								wg.Done()
-							}()
-							go func() {
+							})
+							wg.Go(func() {
 								if _, err := io.ReadFull(server, data); err != nil {
 									errC <- err
 									return
 								}
 								total += sz
-								wg.Done()
-							}()
+							})
 							wg.Wait()
 							close(errC)
 							err := <-errC

lib/connections/service.go

@@ -605,15 +605,13 @@ func (s *service) dialDevices(ctx context.Context, now time.Time, cfg config.Con
 		dialWG.Wait()
 		dialCancel()
 	}()
-	for i := range queue {
+	for _, entry := range queue {
 		select {
 		case <-dialCtx.Done():
 			return
 		default:
 		}
-		dialWG.Add(1)
-		go func(entry dialQueueEntry) {
-			defer dialWG.Done()
+		dialWG.Go(func() {
 			conn, ok := s.dialParallel(dialCtx, entry.id, entry.targets, dialSemaphore)
 			if !ok {
 				return
@@ -630,7 +628,7 @@ func (s *service) dialDevices(ctx context.Context, now time.Time, cfg config.Con
 				}
 			}
 			numConnsMut.Unlock()
-		}(queue[i])
+		})
 	}
 }
 
@@ -1118,12 +1116,8 @@ func (s *service) dialParallel(ctx context.Context, deviceID protocol.DeviceID,
 		wg := sync.WaitGroup{}
 		for _, tgt := range tgts {
 			sema.Take(1)
-			wg.Add(1)
-			go func(tgt dialTarget) {
-				defer func() {
-					wg.Done()
-					sema.Give(1)
-				}()
+			wg.Go(func() {
+				defer sema.Give(1)
 				conn, err := tgt.Dial(ctx)
 				if err == nil {
 					// Closes the connection on error
@@ -1136,7 +1130,7 @@ func (s *service) dialParallel(ctx context.Context, deviceID protocol.DeviceID,
 					l.Debugln("dialing", deviceID, tgt.uri, "success:", conn)
 					res <- conn
 				}
-			}(tgt)
+			})
 		}
 
 		// Spawn a routine which will unblock main routine in case we fail

lib/events/events_test.go

@@ -378,11 +378,8 @@ func TestUnsubscribeContention(t *testing.T) {
 
 	stopListeners := make(chan struct{})
 	var listenerWg sync.WaitGroup
-	listenerWg.Add(listeners)
 	for i := 0; i < listeners; i++ {
-		go func() {
-			defer listenerWg.Done()
-
+		listenerWg.Go(func() {
 			s := l.Subscribe(AllEvents)
 			defer s.Unsubscribe()
 
@@ -394,7 +391,7 @@ func TestUnsubscribeContention(t *testing.T) {
 					return
 				}
 			}
-		}()
+		})
 	}
 
 	// Start senders. These send pointless events until the stop channel is
@@ -403,11 +400,8 @@ func TestUnsubscribeContention(t *testing.T) {
 	stopSenders := make(chan struct{})
 	defer close(stopSenders)
 	var senderWg sync.WaitGroup
-	senderWg.Add(senders)
 	for i := 0; i < senders; i++ {
-		go func() {
-			defer senderWg.Done()
-
+		senderWg.Go(func() {
 			t := time.NewTicker(time.Millisecond)
 
 			for {
@@ -419,7 +413,7 @@ func TestUnsubscribeContention(t *testing.T) {
 					return
 				}
 			}
-		}()
+		})
 	}
 
 	// Give everything time to start up.

lib/model/folder_sendrecv.go

@@ -256,36 +256,28 @@ func (f *sendReceiveFolder) pullerIteration(ctx context.Context, scanChan chan<-
 
 	f.sl.DebugContext(ctx, "Starting puller iteration", "copiers", f.Copiers, "pullerPendingKiB", f.PullerMaxPendingKiB)
 
-	updateWg.Add(1)
 	var changed int // only read after updateWg closes
-	go func() {
+	updateWg.Go(func() {
 		// dbUpdaterRoutine finishes when dbUpdateChan is closed
 		changed = f.dbUpdaterRoutine(dbUpdateChan)
-		updateWg.Done()
-	}()
+	})
 
 	for range f.Copiers {
-		copyWg.Add(1)
-		go func() {
+		copyWg.Go(func() {
 			// copierRoutine finishes when copyChan is closed
 			f.copierRoutine(ctx, copyChan, pullChan, finisherChan)
-			copyWg.Done()
-		}()
+		})
 	}
 
-	pullWg.Add(1)
-	go func() {
+	pullWg.Go(func() {
 		// pullerRoutine finishes when pullChan is closed
 		f.pullerRoutine(ctx, pullChan, finisherChan)
-		pullWg.Done()
-	}()
+	})
 
-	doneWg.Add(1)
 	// finisherRoutine finishes when finisherChan is closed
-	go func() {
+	doneWg.Go(func() {
 		f.finisherRoutine(ctx, finisherChan, dbUpdateChan, scanChan)
-		doneWg.Done()
-	}()
+	})
 
 	fileDeletions, dirDeletions, err := f.processNeeded(ctx, dbUpdateChan, copyChan, scanChan)
 
@@ -1534,14 +1526,10 @@ func (f *sendReceiveFolder) pullerRoutine(ctx context.Context, in <-chan pullBlo
 			continue
 		}
 
-		wg.Add(1)
-
-		go func() {
-			defer wg.Done()
+		wg.Go(func() {
 			defer requestLimiter.Give(bytes)
-
 			f.pullBlock(ctx, state, out)
-		}()
+		})
 	}
 	wg.Wait()
 }

lib/model/folder_sendrecv_test.go

@@ -463,11 +463,9 @@ func TestDeregisterOnFailInPull(t *testing.T) {
 
 	copyChan, copyWg := startCopier(t.Context(), f, pullChan, finisherBufferChan)
 	var pullWg sync.WaitGroup
-	pullWg.Add(1)
-	go func() {
+	pullWg.Go(func() {
 		f.pullerRoutine(t.Context(), pullChan, finisherBufferChan)
-		pullWg.Done()
-	}()
+	})
 	go f.finisherRoutine(t.Context(), finisherChan, dbUpdateChan, make(chan string))
 	defer func() {
 		// Unblock copier and puller
@@ -1246,10 +1244,8 @@ func cleanupSharedPullerState(s *sharedPullerState) {
 func startCopier(ctx context.Context, f *sendReceiveFolder, pullChan chan<- pullBlockState, finisherChan chan<- *sharedPullerState) (chan copyBlocksState, *sync.WaitGroup) {
 	copyChan := make(chan copyBlocksState)
 	wg := new(sync.WaitGroup)
-	wg.Add(1)
-	go func() {
+	wg.Go(func() {
 		f.copierRoutine(ctx, copyChan, pullChan, finisherChan)
-		wg.Done()
-	}()
+	})
 	return copyChan, wg
 }

lib/model/model_test.go

@@ -993,15 +993,13 @@ func TestIssue5063(t *testing.T) {
 		if fcfg, ok := m.cfg.Folder(id); !ok || !fcfg.SharedWith(device1) {
 			t.Error("expected shared", id)
 		}
-		wg.Done()
 	}
 
 	reps := 10
 	ids := make([]string, reps)
 	for i := 0; i < reps; i++ {
-		wg.Add(1)
 		ids[i] = srand.String(8)
-		go addAndVerify(ids[i])
+		wg.Go(func() { addAndVerify(ids[i]) })
 	}
 
 	finished := make(chan struct{})
@@ -2945,16 +2943,14 @@ func TestFolderRestartZombies(t *testing.T) {
 	// for the commit to complete, but there are many of them.
 	var wg sync.WaitGroup
 	for i := 0; i < 25; i++ {
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
+		wg.Go(func() {
 			t0 := time.Now()
 			for time.Since(t0) < time.Second {
 				fcfg := folderCfg.Copy()
 				fcfg.MaxConflicts = mrand.Int() // safe change that should cause a folder restart
 				setFolder(t, wrapper, fcfg)
 			}
-		}()
+		})
 	}
 
 	// Wait for the above to complete and check how many folders we have

lib/protocol/bufferpool_test.go

@@ -82,9 +82,7 @@ func TestStressBufferPool(t *testing.T) {
 	var wg sync.WaitGroup
 	fail := make(chan struct{}, routines)
 	for i := 0; i < routines; i++ {
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
+		wg.Go(func() {
 			for time.Since(t0) < runtime {
 				blocks := make([][]byte, 10)
 				for i := range blocks {
@@ -102,7 +100,7 @@ func TestStressBufferPool(t *testing.T) {
 					bp.Put(blocks[i])
 				}
 			}
-		}()
+		})
 	}
 
 	wg.Wait()

lib/protocol/protocol_test.go

@@ -110,24 +110,18 @@ func TestCloseOnBlockingSend(t *testing.T) {
 
 	wg := sync.WaitGroup{}
 
-	wg.Add(1)
-	go func() {
+	wg.Go(func() {
 		c.ClusterConfig(&ClusterConfig{}, nil)
-		wg.Done()
-	}()
+	})
 
-	wg.Add(1)
-	go func() {
+	wg.Go(func() {
 		c.Close(errManual)
-		wg.Done()
-	}()
+	})
 
 	// This simulates an error from ping timeout
-	wg.Add(1)
-	go func() {
+	wg.Go(func() {
 		c.internalClose(ErrTimeout)
-		wg.Done()
-	}()
+	})
 
 	done := make(chan struct{})
 	go func() {

lib/syncthing/utils.go

@@ -198,10 +198,8 @@ func TryMigrateDatabase(ctx context.Context, deleteRetention time.Duration) erro
 		fis := make(chan protocol.FileInfo, 50)
 		var writeErr error
 		var wg sync.WaitGroup
-		wg.Add(1)
 		writerDone := make(chan struct{})
-		go func() {
-			defer wg.Done()
+		wg.Go(func() { //nolint:contextcheck
 			defer close(writerDone)
 			var batch []protocol.FileInfo
 			files, blocks := 0, 0
@@ -238,7 +236,7 @@ func TryMigrateDatabase(ctx context.Context, deleteRetention time.Duration) erro
 			slog.Info("Migrated folder", "folder", folder, "files", files, "blocks", blocks, "duration", d.Truncate(time.Second), "filesrate", float64(files)/d.Seconds())
 			totFiles += files
 			totBlocks += blocks
-		}()
+		})
 
 		// Iterate the existing files
 		fs, err := olddb.NewFileSet(folder, ll)

lib/syncutil/timeoutcond_test.go

@@ -48,16 +48,13 @@ func TestTimeoutCond(t *testing.T) {
 	var results [routines][2]int
 	var wg sync.WaitGroup
 	for i := 0; i < routines; i++ {
-		i := i
-		wg.Add(1)
-		go func() {
+		wg.Go(func() {
 			d := time.Duration(i) * timeMult * time.Millisecond
 			t.Logf("Routine %d waits for %v\n", i, d)
 			succ, fail := runLocks(t, iterations, c, d)
 			results[i][0] = succ
 			results[i][1] = fail
-			wg.Done()
-		}()
+		})
 	}
 
 	wg.Wait()

lib/upnp/upnp.go

@@ -123,28 +123,26 @@ func Discover(ctx context.Context, _, timeout time.Duration) []nat.Device {
 			continue
 		}
 
-		wg.Add(1)
 		// Discovery is done sequentially per interface because we discovered that
 		// FritzBox routers return a broken result sometimes if the IPv4 and IPv6
 		// request arrive at the same time.
-		go func(iface net.Interface) {
-			defer wg.Done()
-			hasGUA, err := interfaceHasGUAIPv6(iface)
+		wg.Go(func() {
+			hasGUA, err := interfaceHasGUAIPv6(intf)
 			if err != nil {
-				l.Debugf("Couldn't check for IPv6 GUAs on %s: %s", iface.Name, err)
+				l.Debugf("Couldn't check for IPv6 GUAs on %s: %s", intf.Name, err) //nolint:contextcheck
 			} else if hasGUA {
 				// Discover IPv6 gateways on interface. Only discover IGDv2, since IGDv1
 				// + IPv6 is not standardized and will lead to duplicates on routers.
 				// Only do this when a non-link-local IPv6 is available. if we can't
 				// enumerate the interface, the IPv6 code will not work anyway
-				discover(ctx, &iface, urnIgdV2, timeout, resultChan, true)
+				discover(ctx, &intf, urnIgdV2, timeout, resultChan, true)
 			}
 
 			// Discover IPv4 gateways on interface.
 			for _, deviceType := range []string{urnIgdV2, urnIgdV1} {
-				discover(ctx, &iface, deviceType, timeout, resultChan, false)
+				discover(ctx, &intf, deviceType, timeout, resultChan, false)
 			}
-		}(intf)
+		})
 	}
 
 	go func() {