Fix broken +checkescape annotation in sleep package.

Make `checkescape` check for variants of `+checkescape` that would silently be
ignored. #codehealth

PiperOrigin-RevId: 436882400

pkg/metric/metric.go

@@ -798,7 +798,7 @@ type TimedOperation struct {
 // fields must be passed to TimedOperation.Finish. This is useful for cases
 // where which path an operation took is only known after it happens. This
 // path can be part of the fields passed to Finish.
-//+checkescape:all
+// +checkescape:all
 //go:nosplit
 func (t *TimerMetric) Start(fields ...string) TimedOperation {
 	return TimedOperation{
@@ -812,7 +812,7 @@ func (t *TimerMetric) Start(fields ...string) TimedOperation {
 // `extraFields` is the rest of the fields appended to the fields passed to
 // `TimerMetric.Start`. The concatenation of these two must be the exact
 // number of fields that the underlying metric has.
-//+checkescape:all
+// +checkescape:all
 //go:nosplit
 func (o TimedOperation) Finish(extraFields ...string) {
 	ended := CheapNowNano()

pkg/sleep/sleep_unsafe.go

@@ -166,6 +166,7 @@ func (s *Sleeper) AddWaker(w *Waker) {
 // block, then we will need to explicitly wake a runtime P.
 //
 // Precondition: wakepOrSleep may be true iff block is true.
+//go:nosplit
 func (s *Sleeper) nextWaker(block, wakepOrSleep bool) *Waker {
 	// Attempt to replenish the local list if it's currently empty.
 	if s.localList == nil {
@@ -282,7 +283,7 @@ func (s *Sleeper) Fetch(block bool) *Waker {
 //
 // N.B. Like Fetch, this method is *not* thread-safe. This will also yield the current
 //      P to the next goroutine, avoiding associated scheduled overhead.
-//+checkescapes:all
+// +checkescape:all
 //go:nosplit
 func (s *Sleeper) AssertAndFetch(n *Waker) *Waker {
 	n.assert(false /* wakep */)
@@ -325,6 +326,7 @@ func (s *Sleeper) Done() {
 
 // enqueueAssertedWaker enqueues an asserted waker to the "ready" circular list
 // of wakers that want to notify the sleeper.
+//go:nosplit
 func (s *Sleeper) enqueueAssertedWaker(w *Waker, wakep bool) {
 	// Add the new waker to the front of the list.
 	for {

pkg/sync/runtime_amd64.go

@@ -20,10 +20,12 @@ func addrOfSpinning() *int32
 // nmspinning caches addrOfSpinning.
 var nmspinning = addrOfSpinning()
 
+//go:nosplit
 func preGoReadyWakeSuppression() {
 	atomic.AddInt32(nmspinning, 1)
 }
 
+//go:nosplit
 func postGoReadyWakeSuppression() {
 	atomic.AddInt32(nmspinning, -1)
 }

tools/checkescape/checkescape.go

@@ -84,6 +84,10 @@ const (
 	// magic is the magic annotation.
 	magic = "// +checkescape"
 
+	// Bad versions of `magic` observed in the wilderness of the codebase.
+	badMagicNoSpace = "//+checkescape"
+	badMagicPlural  = "// +checkescapes"
+
 	// magicParams is the magic annotation with specific parameters.
 	magicParams = magic + ":"
 
@@ -573,6 +577,10 @@ func findReasons(pass *analysis.Pass, fdecl *ast.FuncDecl) ([]EscapeReason, bool
 	// Scan all lines.
 	found := false
 	for _, c := range fdecl.Doc.List {
+		if strings.HasPrefix(c.Text, badMagicNoSpace) || strings.HasPrefix(c.Text, badMagicPlural) {
+			pass.Reportf(fdecl.Pos(), "misspelled checkescape prefix: please use %q instead", magic)
+			continue
+		}
 		// Does the comment contain a +checkescape line?
 		if !strings.HasPrefix(c.Text, magic) && !strings.HasPrefix(c.Text, testMagic) {
 			continue