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.

2 files changed, 73 insertions, 0 deletions

diff --git a/tests/regressiontests/i18n/commands/extraction.py b/tests/regressiontests/i18n/commands/extraction.py
index ac8d8c1a09..0367d23ec6 100644
--- a/tests/regressiontests/i18n/commands/extraction.py
+++ b/tests/regressiontests/i18n/commands/extraction.py
@@ -4,6 +4,7 @@ from __future__ import unicode_literals
 import os
 import re
 import shutil
+import warnings
 
 from django.core import management
 from django.test import SimpleTestCase
@@ -11,6 +12,7 @@ from django.utils.encoding import force_text
 from django.utils._os import upath
 from django.utils import six
 from django.utils.six import StringIO
+from django.utils.translation import TranslatorCommentWarning
 
 
 LOCALE='de'
@@ -120,6 +122,7 @@ class BasicExtractorTests(ExtractorTests):
         self.assertFalse(os.path.exists('./templates/template_with_error.tpl.py'))
 
     def test_extraction_warning(self):
+        """test xgettext warning about multiple bare interpolation placeholders"""
         os.chdir(self.test_dir)
         shutil.copyfile('./code.sample', './code_sample.py')
         stdout = StringIO()
@@ -172,6 +175,63 @@ class BasicExtractorTests(ExtractorTests):
             self.assertTrue('msgctxt "Special blocktrans context wrapped in double quotes"' in po_contents)
             self.assertTrue('msgctxt "Special blocktrans context wrapped in single quotes"' in po_contents)
 
+    def test_template_comments(self):
+        """Template comment tags on the same line of other constructs (#19552)"""
+        os.chdir(self.test_dir)
+        # Test detection/end user reporting of old, incorrect templates
+        # translator comments syntax
+        with warnings.catch_warnings(record=True) as ws:
+            warnings.simplefilter('always')
+            management.call_command('makemessages', locale=LOCALE, extensions=['thtml'], verbosity=0)
+            self.assertEqual(len(ws), 3)
+            for w in ws:
+                self.assertTrue(issubclass(w.category, TranslatorCommentWarning))
+            six.assertRegex(self, str(ws[0].message),
+                r"The translator-targeted comment 'Translators: ignored i18n comment #1' \(file templates/comments.thtml, line 4\) was ignored, because it wasn't the last item on the line\."
+            )
+            six.assertRegex(self, str(ws[1].message),
+                r"The translator-targeted comment 'Translators: ignored i18n comment #3' \(file templates/comments.thtml, line 6\) was ignored, because it wasn't the last item on the line\."
+            )
+            six.assertRegex(self, str(ws[2].message),
+                r"The translator-targeted comment 'Translators: ignored i18n comment #4' \(file templates/comments.thtml, line 8\) was ignored, because it wasn't the last item on the line\."
+            )
+        # Now test .po file contents
+        self.assertTrue(os.path.exists(self.PO_FILE))
+        with open(self.PO_FILE, 'r') as fp:
+            po_contents = force_text(fp.read())
+
+            self.assertMsgId('Translatable literal #9a', po_contents)
+            self.assertFalse('ignored comment #1' in po_contents)
+
+            self.assertFalse('Translators: ignored i18n comment #1' in po_contents)
+            self.assertMsgId("Translatable literal #9b", po_contents)
+
+            self.assertFalse('ignored i18n comment #2' in po_contents)
+            self.assertFalse('ignored comment #2' in po_contents)
+            self.assertMsgId('Translatable literal #9c', po_contents)
+
+            self.assertFalse('ignored comment #3' in po_contents)
+            self.assertFalse('ignored i18n comment #3' in po_contents)
+            self.assertMsgId('Translatable literal #9d', po_contents)
+
+            self.assertFalse('ignored comment #4' in po_contents)
+            self.assertMsgId('Translatable literal #9e', po_contents)
+            self.assertFalse('ignored comment #5' in po_contents)
+
+            self.assertFalse('ignored i18n comment #4' in po_contents)
+            self.assertMsgId('Translatable literal #9f', po_contents)
+            self.assertTrue('#. Translators: valid i18n comment #5' in po_contents)
+
+            self.assertMsgId('Translatable literal #9g', po_contents)
+            self.assertTrue('#. Translators: valid i18n comment #6' in po_contents)
+            self.assertMsgId('Translatable literal #9h', po_contents)
+            self.assertTrue('#. Translators: valid i18n comment #7' in po_contents)
+            self.assertMsgId('Translatable literal #9i', po_contents)
+
+            six.assertRegex(self, po_contents, r'#\..+Translators: valid i18n comment #8')
+            six.assertRegex(self, po_contents, r'#\..+Translators: valid i18n comment #9')
+            self.assertMsgId("Translatable literal #9j", po_contents)
+
 
 class JavascriptExtractorTests(ExtractorTests):
 
diff --git a/tests/regressiontests/i18n/commands/templates/comments.thtml b/tests/regressiontests/i18n/commands/templates/comments.thtml
new file mode 100644
index 0000000000..90eb5f1792
--- /dev/null
+++ b/tests/regressiontests/i18n/commands/templates/comments.thtml
@@ -0,0 +1,13 @@
+{% load i18n %}
+
+{# ignored comment #1 #}{% trans "Translatable literal #9a" %}
+{# Translators: ignored i18n comment #1 #}{% trans "Translatable literal #9b" %}
+{# Translators: ignored i18n comment #2 #}{# ignored comment #2 #}{% trans "Translatable literal #9c" %}
+{# ignored comment #3 #}{# Translators: ignored i18n comment #3 #}{% trans "Translatable literal #9d" %}
+{# ignored comment #4 #}{% trans "Translatable literal #9e" %}{# ignored comment #5 #}
+{# Translators: ignored i18n comment #4 #}{% trans "Translatable literal #9f" %}{# Translators: valid i18n comment #5 #}
+{% trans "Translatable literal #9g" %}{# Translators: valid i18n comment #6 #}
+{# ignored comment #6 #}{% trans "Translatable literal #9h" %}{# Translators: valid i18n comment #7 #}
+{% trans "Translatable literal #9i" %}
+{# Translators: valid i18n comment #8 #}{# Translators: valid i18n comment #9 #}
+{% trans "Translatable literal #9j" %}