Fix server rebuilds when adding sub sections especially on Windows

This commit also optimizes for the case where change events for both file (e.g. `_index.md`) and the container directory comes in the same event batch.

While testing this on Windows 11 (ARM64), I notice that Windows behaves a little oddly when dumping a folder of files into the content tree; it works (at least after this commit), but it seems like the event batching behaves differently compared to other OSes (even older Win versions).

A related tip would be to try starting the server with polling, to see if that improves the situation, e.g.:

```
hugo server --poll 700ms
```

Fixes gohugoio#12230

Author: bep

hugolib/hugo_sites_build.go

@@ -595,8 +595,10 @@ func (h *HugoSites) processPartial(ctx context.Context, l logg.LevelLogger, conf
 		return sb.String()
 	}))
 
+	// For a list of events for the different OSes, see the test output in https://github.com/bep/fsnotifyeventlister/.
 	events = h.fileEventsFilter(events)
 	events = h.fileEventsTranslate(events)
+	eventInfos := h.fileEventsApplyInfo(events)
 
 	logger := h.Log
 
@@ -631,36 +633,12 @@ func (h *HugoSites) processPartial(ctx context.Context, l logg.LevelLogger, conf
 		addedContentPaths []*paths.Path
 	)
 
-	for _, ev := range events {
-		removed := false
-		added := false
-
-		if ev.Op&fsnotify.Remove == fsnotify.Remove {
-			removed = true
-		}
-
-		fi, statErr := h.Fs.Source.Stat(ev.Name)
-
-		// Some editors (Vim) sometimes issue only a Rename operation when writing an existing file
-		// Sometimes a rename operation means that file has been renamed other times it means
-		// it's been updated.
-		if ev.Op.Has(fsnotify.Rename) {
-			// If the file is still on disk, it's only been updated, if it's not, it's been moved
-			if statErr != nil {
-				removed = true
-			}
-		}
-		if ev.Op.Has(fsnotify.Create) {
-			added = true
-		}
-
-		isChangedDir := statErr == nil && fi.IsDir()
-
+	for _, ev := range eventInfos {
 		cpss := h.BaseFs.ResolvePaths(ev.Name)
 		pss := make([]*paths.Path, len(cpss))
 		for i, cps := range cpss {
 			p := cps.Path
-			if removed && !paths.HasExt(p) {
+			if ev.removed && !paths.HasExt(p) {
 				// Assume this is a renamed/removed directory.
 				// For deletes, we walk up the tree to find the container (e.g. branch bundle),
 				// so we will catch this even if it is a file without extension.
@@ -671,7 +649,7 @@ func (h *HugoSites) processPartial(ctx context.Context, l logg.LevelLogger, conf
 			}
 
 			pss[i] = h.Configs.ContentPathParser.Parse(cps.Component, p)
-			if added && !isChangedDir && cps.Component == files.ComponentFolderContent {
+			if ev.added && !ev.isChangedDir && cps.Component == files.ComponentFolderContent {
 				addedContentPaths = append(addedContentPaths, pss[i])
 			}
 
@@ -683,9 +661,9 @@ func (h *HugoSites) processPartial(ctx context.Context, l logg.LevelLogger, conf
 			}
 		}
 
-		if removed {
+		if ev.removed {
 			changedPaths.deleted = append(changedPaths.deleted, pss...)
-		} else if isChangedDir {
+		} else if ev.isChangedDir {
 			changedPaths.changedDirs = append(changedPaths.changedDirs, pss...)
 		} else {
 			changedPaths.changedFiles = append(changedPaths.changedFiles, pss...)

hugolib/pages_capture.go

@@ -161,7 +161,7 @@ func (c *pagesCollector) Collect() (collectErr error) {
 				// We always start from a directory.
 				collectErr = c.collectDir(id.p, id.isDir, func(fim hugofs.FileMetaInfo) bool {
 					if id.delete || id.isDir {
-						if id.isDir {
+						if id.isDir && fim.Meta().PathInfo.IsLeafBundle() {
 							return strings.HasPrefix(fim.Meta().PathInfo.Path(), paths.AddTrailingSlash(id.p.Path()))
 						}
 

hugolib/site.go

@@ -19,6 +19,7 @@ import (
 	"io"
 	"mime"
 	"net/url"
+	"os"
 	"path/filepath"
 	"runtime"
 	"sort"
@@ -426,6 +427,73 @@ func (h *HugoSites) fileEventsFilter(events []fsnotify.Event) []fsnotify.Event {
 	return events[:n]
 }
 
+type fileEventInfo struct {
+	fsnotify.Event
+	fi           os.FileInfo
+	added        bool
+	removed      bool
+	isChangedDir bool
+}
+
+func (h *HugoSites) fileEventsApplyInfo(events []fsnotify.Event) []fileEventInfo {
+	var infos []fileEventInfo
+	for _, ev := range events {
+		removed := false
+		added := false
+
+		if ev.Op&fsnotify.Remove == fsnotify.Remove {
+			removed = true
+		}
+
+		fi, statErr := h.Fs.Source.Stat(ev.Name)
+
+		// Some editors (Vim) sometimes issue only a Rename operation when writing an existing file
+		// Sometimes a rename operation means that file has been renamed other times it means
+		// it's been updated.
+		if ev.Op.Has(fsnotify.Rename) {
+			// If the file is still on disk, it's only been updated, if it's not, it's been moved
+			if statErr != nil {
+				removed = true
+			}
+		}
+		if ev.Op.Has(fsnotify.Create) {
+			added = true
+		}
+
+		isChangedDir := statErr == nil && fi.IsDir()
+
+		infos = append(infos, fileEventInfo{
+			Event:        ev,
+			fi:           fi,
+			added:        added,
+			removed:      removed,
+			isChangedDir: isChangedDir,
+		})
+	}
+
+	n := 0
+
+	for _, ev := range infos {
+		// Remove any directories that's also represented by a file.
+		keep := true
+		if ev.isChangedDir {
+			for _, ev2 := range infos {
+				if ev2.fi != nil && !ev2.fi.IsDir() && filepath.Dir(ev2.Name) == ev.Name {
+					keep = false
+					break
+				}
+			}
+		}
+		if keep {
+			infos[n] = ev
+			n++
+		}
+	}
+	infos = infos[:n]
+
+	return infos
+}
+
 func (h *HugoSites) fileEventsTranslate(events []fsnotify.Event) []fsnotify.Event {
 	eventMap := make(map[string][]fsnotify.Event)