Fixed #19552 -- Enhanced makemessages handling of ``{# #}``-style template comments.

They are simply ignored now. This allows for a more correct behavior when
they are placed before translatable constructs on the same line.

Previously, the latter were wrongly ignored because the former were
preserved when converting template code to the internal Python-syntax
form later fed to xgettext but Python has no ``/* ... */``-style
comments.

Also, special comments directed to translators are now only taken in
account when they are located at the end of a line. e.g.::

  {# Translators: ignored #}{% trans "Literal A" %}{# Translators: valid, associated with "Literal B" below #}
  {% trans "Literal B" %}

Behavior of ``{% comment %}...{% endcomment %}``tags remains unchanged.

Thanks juneih at redpill-linpro dot com for the report and Claude for
his work on the issue.

3 files changed, 92 insertions, 5 deletions

diff --git a/docs/releases/1.6.txt b/docs/releases/1.6.txt
index e0c07c40fe..79fa3ffb86 100644
--- a/docs/releases/1.6.txt
+++ b/docs/releases/1.6.txt
@@ -47,6 +47,26 @@ Backwards incompatible changes in 1.6
   should review it as ``type='text'`` widgets might be now output as
   ``type='email'`` or ``type='url'`` depending on their corresponding field type.
 
+* Extraction of translatable literals from templates with the
+  :djadmin:`makemessages` command now correctly detects i18n constructs when
+  they are located after a ``{#`` / ``#}``-type comment on the same line. E.g.:
+
+  .. code-block:: html+django
+
+    {# A comment #}{% trans "This literal was incorrectly ignored. Not anymore" %}
+
+* (Related to the above item.) Validation of the placement of
+  :ref:`translator-comments-in-templates` specified using ``{#`` / ``#}`` is now
+  stricter. All translator comments not located at the end of their respective
+  lines in a template are ignored and a warning is generated by
+  :djadmin:`makemessages` when it finds them. E.g.:
+
+  .. code-block:: html+django
+
+    {# Translators: This is ignored #}{% trans "Translate me" %}
+    {{ title }}{# Translators: Extracted and associated with 'Welcome' below #}
+    <h1>{% trans "Welcome" %}</h1>
+
 .. warning::
 
     In addition to the changes outlined in this section, be sure to review the
diff --git a/docs/topics/i18n/translation.txt b/docs/topics/i18n/translation.txt
index 01f168bc10..3cf08e7ddf 100644
--- a/docs/topics/i18n/translation.txt
+++ b/docs/topics/i18n/translation.txt
@@ -142,14 +142,22 @@ preceding the string, e.g.::
         # Translators: This message appears on the home page only
         output = ugettext("Welcome to my site.")
 
-This also works in templates with the :ttag:`comment` tag:
+The comment will then appear in the resulting ``.po`` file associated with the
+translatable contruct located below it and should also be displayed by most
+translation tools.
 
-.. code-block:: html+django
+.. note:: Just for completeness, this is the corresponding fragment of the
+    resulting ``.po`` file:
+
+    .. code-block:: po
 
-    {% comment %}Translators: This is a text of the base template {% endcomment %}
+        #. Translators: This message appears on the home page only
+        # path/to/python/file.py:123
+        msgid "Welcome to my site."
+        msgstr ""
 
-The comment will then appear in the resulting ``.po`` file and should also be
-displayed by most translation tools.
+This also works in templates. See :ref:`translator-comments-in-templates` for
+more details.
 
 Marking strings as no-op
 ------------------------
@@ -620,6 +628,63 @@ markers<contextual-markers>` using the ``context`` keyword:
 
     {% blocktrans with name=user.username context "greeting" %}Hi {{ name }}{% endblocktrans %}
 
+.. _translator-comments-in-templates:
+
+Comments for translators in templates
+-------------------------------------
+
+Just like with :ref:`Python code <translator-comments>`, these notes for
+translators can be specified using comments, either with the :ttag:`comment`
+tag:
+
+.. code-block:: html+django
+
+    {% comment %}Translators: View verb{% endcomment %}
+    {% trans "View" %}
+
+    {% comment %}Translators: Short intro blurb{% endcomment %}
+    <p>{% blocktrans %}A multiline translatable
+    literal.{% endblocktrans %}</p>
+
+or with the ``{#`` ... ``#}`` :ref:`one-line comment constructs <template-comments>`:
+
+.. code-block:: html+django
+
+    {# Translators: Label of a button that triggers search{% endcomment #}
+    <button type="submit">{% trans "Go" %}</button>
+
+    {# Translators: This is a text of the base template #}
+    {% blocktrans %}Ambiguous translatable block of text{% endtransblock %}
+
+.. note:: Just for completeness, these are the corresponding fragments of the
+    resulting ``.po`` file:
+
+    .. code-block:: po
+
+        #. Translators: View verb
+        # path/to/template/file.html:10
+        msgid "View"
+        msgstr ""
+
+        #. Translators: Short intro blurb
+        # path/to/template/file.html:13
+        msgid ""
+        "A multiline translatable"
+        "literal."
+        msgstr ""
+
+        # ...
+
+        #. Translators: Label of a button that triggers search
+        # path/to/template/file.html:100
+        msgid "Go"
+        msgstr ""
+
+        #. Translators:
+        # path/to/template/file.html:103
+        msgid "Ambiguous translatable block of text"
+        msgstr ""
+
 .. _template-translation-vars:
 
 Other tags
diff --git a/docs/topics/templates.txt b/docs/topics/templates.txt
index fb2119515b..58a3ee9870 100644
--- a/docs/topics/templates.txt
+++ b/docs/topics/templates.txt
@@ -250,6 +250,8 @@ You can also create your own custom template tags; see
     tags and filters available for a given site. See
     :doc:`/ref/contrib/admin/admindocs`.
 
+.. _template-comments:
+
 Comments
 ========