Incorporate `relative_url` filter in `link` tag (#6727)

Merge pull request 6727

features/link_tag.feature

@@ -38,8 +38,8 @@ Feature: Link Tag
     When I run jekyll build
     Then I should get a zero exit status
     And the _site directory should exist
-    And I should see "<p><a href=\"/about.html\">About my projects</a></p>" in "_site/index.html"
+    And I should see "<p><a href=\"/blog/about.html\">About my projects</a></p>" in "_site/index.html"
-    And I should see "<p><a href=\"/\">Home</a></p>" in "_site/about.html"
+    And I should see "<p><a href=\"/blog/\">Home</a></p>" in "_site/about.html"
 
   Scenario: Basic site with two pages and custom baseurl and permalinks
     Given I have an "index.md" page that contains "[About my projects]({% link about.md %})"
@@ -52,8 +52,8 @@ Feature: Link Tag
     When I run jekyll build
     Then I should get a zero exit status
     And the _site directory should exist
-    And I should see "<p><a href=\"/about/\">About my projects</a></p>" in "_site/index.html"
+    And I should see "<p><a href=\"/blog/about/\">About my projects</a></p>" in "_site/index.html"
-    And I should see "<p><a href=\"/\">Home</a></p>" in "_site/about/index.html"
+    And I should see "<p><a href=\"/blog/\">Home</a></p>" in "_site/about/index.html"
 
   Scenario: Linking to a ghost file
     Given I have an "index.md" page that contains "[About my projects]({% link about.md %})"

jekyll.gemspec

@@ -30,6 +30,15 @@ Gem::Specification.new do |s|
   s.rdoc_options = ["--charset=UTF-8"]
   s.extra_rdoc_files = %w(README.markdown LICENSE)
 
+  s.post_install_message = <<~MSG
+    ----------------------------------------------------------------------------------
+    This version of Jekyll comes with some major changes. Most notably:
+      * Our `link` tag now comes with the `relative_url` filter incorporated into it.
+        You should no longer prepend `{{ site.baseurl }}` to `{% link foo.md %}`
+        For further details: https://github.com/jekyll/jekyll/pull/6727
+    ----------------------------------------------------------------------------------
+  MSG
+
   s.add_runtime_dependency("addressable",           "~> 2.4")
   s.add_runtime_dependency("colorator",             "~> 1.0")
   s.add_runtime_dependency("em-websocket",          "~> 0.5")

lib/jekyll/tags/link.rb

@@ -3,6 +3,8 @@
 module Jekyll
   module Tags
     class Link < Liquid::Tag
+      include Jekyll::Filters::URLFilters
+
       class << self
         def tag_name
           name.split("::").last.downcase
@@ -16,13 +18,14 @@ module Jekyll
       end
 
       def render(context)
+        @context = context
         site = context.registers[:site]
         relative_path = Liquid::Template.parse(@relative_path).render(context)
 
         site.each_site_file do |item|
-          return item.url if item.relative_path == relative_path
+          return relative_url(item) if item.relative_path == relative_path
           # This takes care of the case for static files that have a leading /
-          return item.url if item.relative_path == "/#{relative_path}"
+          return relative_url(item) if item.relative_path == "/#{relative_path}"
         end
 
         raise ArgumentError, <<~MSG