hugofs: Fix crash in multilingual content fs

Fixes #6463

hugofs/rootmapping_fs.go

@@ -196,12 +196,12 @@ func (fs *RootMappingFs) doLstat(name string, allowMultiple bool) ([]FileMetaInf
 		fis  []FileMetaInfo
 		dirs []FileMetaInfo
 		b    bool
-		fi   os.FileInfo
 		root RootMapping
 		err  error
 	)
 
 	for _, root = range roots {
+		var fi os.FileInfo
 		fi, b, err = fs.statRoot(root, name)
 		if err != nil {
 			if os.IsNotExist(err) {
@@ -233,12 +233,16 @@ func (fs *RootMappingFs) doLstat(name string, allowMultiple bool) ([]FileMetaInf
 		return fis, dirs, b, nil
 	}
 
+	if len(fis) == 0 {
+		return nil, nil, false, os.ErrNotExist
+	}
+
 	// Open it in this composite filesystem.
 	opener := func() (afero.File, error) {
 		return fs.Open(name)
 	}
 
-	return []FileMetaInfo{decorateFileInfo(fi, fs, opener, "", "", root.Meta)}, nil, b, nil
+	return []FileMetaInfo{decorateFileInfo(fis[0], fs, opener, "", "", root.Meta)}, nil, b, nil
 
 }
 

hugofs/rootmapping_fs_test.go

@@ -209,7 +209,7 @@ func TestRootMappingFsMount(t *testing.T) {
 	blog, err := rfs.Stat(filepath.FromSlash("content/blog"))
 	c.Assert(err, qt.IsNil)
 	blogm := blog.(FileMetaInfo).Meta()
-	c.Assert(blogm.Lang(), qt.Equals, "sv") // Last match
+	c.Assert(blogm.Lang(), qt.Equals, "no") // First match
 
 	f, err := blogm.Open()
 	c.Assert(err, qt.IsNil)

hugolib/language_content_dir_test.go

@@ -319,3 +319,90 @@ Content.
 	c.Assert(nnHome.RelPermalink(), qt.Equals, "/nn/")
 
 }
+
+// https://github.com/gohugoio/hugo/issues/6463
+func TestLanguageRootSectionsMismatch(t *testing.T) {
+	t.Parallel()
+
+	config := `
+baseURL: "https://example.org/"
+languageCode: "en-us"
+title: "My New Hugo Site"
+theme: "mytheme"
+
+contentDir: "content/en"
+
+languages:
+    en:
+        weight: 1
+        languageName: "English"
+        contentDir: content/en
+    es:
+        weight: 2
+        languageName: "Español"
+        contentDir: content/es
+    fr:
+        weight: 4
+        languageName: "Française"
+        contentDir: content/fr
+
+        
+`
+	createPage := func(title string) string {
+		return fmt.Sprintf(`---
+title: %q
+---
+
+`, title)
+	}
+
+	b := newTestSitesBuilder(t)
+	b.WithConfigFile("yaml", config)
+
+	b.WithSourceFile("themes/mytheme/layouts/index.html", `MYTHEME`)
+	b.WithTemplates("index.html", `
+Lang: {{ .Lang }}
+{{ range .Site.RegularPages }}
+Page: {{ .RelPermalink }}|{{ .Title -}}
+{{ end }}
+
+`)
+	b.WithSourceFile("static/hello.txt", `hello`)
+	b.WithContent("en/_index.md", createPage("en home"))
+	b.WithContent("es/_index.md", createPage("es home"))
+	b.WithContent("fr/_index.md", createPage("fr home"))
+
+	for i := 1; i < 3; i++ {
+		b.WithContent(fmt.Sprintf("en/event/page%d.md", i), createPage(fmt.Sprintf("ev-en%d", i)))
+		b.WithContent(fmt.Sprintf("es/event/page%d.md", i), createPage(fmt.Sprintf("ev-es%d", i)))
+		b.WithContent(fmt.Sprintf("fr/event/page%d.md", i), createPage(fmt.Sprintf("ev-fr%d", i)))
+		b.WithContent(fmt.Sprintf("en/blog/page%d.md", i), createPage(fmt.Sprintf("blog-en%d", i)))
+		b.WithContent(fmt.Sprintf("es/blog/page%d.md", i), createPage(fmt.Sprintf("blog-es%d", i)))
+		b.WithContent(fmt.Sprintf("fr/other/page%d.md", i), createPage(fmt.Sprintf("other-fr%d", i)))
+	}
+
+	b.Build(BuildCfg{})
+
+	b.AssertFileContent("public/index.html", `
+Lang: en
+Page: /blog/page1/|blog-en1
+Page: /blog/page2/|blog-en2
+Page: /event/page1/|ev-en1
+Page: /event/page2/|ev-en2
+`)
+
+	b.AssertFileContent("public/es/index.html", `
+Lang: es
+Page: /es/blog/page1/|blog-es1
+Page: /es/blog/page2/|blog-es2
+Page: /es/event/page1/|ev-es1
+Page: /es/event/page2/|ev-es2
+`)
+	b.AssertFileContent("public/fr/index.html", `
+Lang: fr
+Page: /fr/event/page1/|ev-fr1
+Page: /fr/event/page2/|ev-fr2
+Page: /fr/other/page1/|other-fr1
+Page: /fr/other/page2/|other-fr2`)
+
+}