tpl/tplimpl: Resolve fragments in link render hook

Fixes #12084

tpl/tplimpl/embedded/templates/_default/_markup/render-link.html

@@ -1,6 +1,8 @@
 {{- $u := urls.Parse .Destination -}}
 {{- $href := $u.String -}}
-{{- if not $u.IsAbs -}}
+{{- if strings.HasPrefix $u.String "#" }}
+  {{- $href = printf "%s#%s" .Page.RelPermalink $u.Fragment }}
+{{- else if not $u.IsAbs -}}
   {{- with or
     ($.Page.GetPage $u.Path)
     ($.Page.Resources.Get $u.Path)

tpl/tplimpl/render_hook_integration_test.go

@@ -0,0 +1,129 @@
+// Copyright 2024 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tplimpl_test
+
+import (
+	"testing"
+
+	"github.com/gohugoio/hugo/hugolib"
+)
+
+func TestEmbeddedLinkRenderHook(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- hugo.toml --
+disableKinds = ['rss','sitemap','taxonomy','term']
+[markup.goldmark.renderHooks.link]
+enableDefault = true
+-- layouts/_default/list.html --
+{{ .Content }}
+-- layouts/_default/single.html --
+{{ .Content }}
+-- assets/a.txt --
+irrelevant
+-- content/_index.md --
+---
+title: home
+---
+-- content/s1/_index.md --
+---
+title: s1
+---
+-- content/s1/p1.md --
+---
+title: s1/p1
+---
+-- content/s1/p2/index.md --
+---
+title: s1/p2
+---
+[500](a.txt) // global resource
+[600](b.txt) // page resource
+-- content/s1/p2/b.txt --
+irrelevant
+-- content/s1/p3.md --
+---
+title: s1/p3
+---
+// Remote
+[10](https://a.org)
+
+// fragment
+[100](/#foo)
+[110](#foo)
+[120](p1#foo)
+[130](p1/#foo)
+
+// section page
+[200](s1)
+[210](/s1)
+[220](../s1)
+[230](s1/)
+[240](/s1/)
+[250](../s1/)
+
+// regular page
+[300](p1)
+[310](/s1/p1)
+[320](../s1/p1)
+[330](p1/)
+[340](/s1/p1/)
+[350](../s1/p1/)
+
+// leaf bundle
+[400](p2)
+[410](/s1/p2)
+[420](../s1/p2)
+[430](p2/)
+[440](/s1/p2/)
+[450](../s1/p2/)
+`
+
+	b := hugolib.Test(t, files)
+
+	b.AssertFileContent("public/s1/p3/index.html",
+		`<a href="https://a.org">10</a>`,
+		`<a href="/#foo">100</a>`,
+		`<a href="/s1/p3/#foo">110</a>`,
+		`<a href="/s1/p1/#foo">120</a>`,
+		`<a href="/s1/p1/#foo">130</a>`,
+
+		`<a href="/s1/">200</a>`,
+		`<a href="/s1/">210</a>`,
+		`<a href="/s1/">220</a>`,
+		`<a href="/s1/">230</a>`,
+		`<a href="/s1/">240</a>`,
+		`<a href="/s1/">250</a>`,
+
+		`<a href="/s1/p1/">300</a>`,
+		`<a href="/s1/p1/">310</a>`,
+		`<a href="/s1/p1/">320</a>`,
+		`<a href="/s1/p1/">330</a>`,
+		`<a href="/s1/p1/">340</a>`,
+		`<a href="/s1/p1/">350</a>`,
+
+		`<a href="/s1/p2/">400</a>`,
+		`<a href="/s1/p2/">410</a>`,
+		`<a href="/s1/p2/">420</a>`,
+		`<a href="/s1/p2/">430</a>`,
+		`<a href="/s1/p2/">440</a>`,
+		`<a href="/s1/p2/">450</a>`,
+	)
+
+	b.AssertFileContent("public/s1/p2/index.html",
+		`<a href="/a.txt">500</a>`,
+		`<a href="/s1/p2/b.txt">600</a>`,
+	)
+}