[1.8.x] Fixed #25079 -- Added warning if both TEMPLATES and TEMPLATE_* settings are defined.

Django ignores the value of the TEMPLATE_* settings if TEMPLATES is also
set, which is confusing for users following older tutorials. This change
adds a system check that warns if any of the TEMPLATE_* settings have
changed from their defaults but the TEMPLATES dict is also non-empty.

Removed the TEMPLATE_DIRS from the test settings file; this was marked
for removal in 1.10 but no tests fail if it is removed now.

Backport of 24620d71f2116da31abe6c9391f7bc807ac23c0b from master

2 files changed, 32 insertions, 0 deletions

diff --git a/django/core/checks/__init__.py b/django/core/checks/__init__.py
index e446bdc099..5b665d23c1 100644
--- a/django/core/checks/__init__.py
+++ b/django/core/checks/__init__.py
@@ -8,6 +8,7 @@ from .registry import register, run_checks, tag_exists, Tags
 
 # Import these to force registration of checks
 import django.core.checks.compatibility.django_1_7_0  # NOQA
+import django.core.checks.compatibility.django_1_8_0  # NOQA
 import django.core.checks.model_checks  # NOQA
 import django.core.checks.security.base  # NOQA
 import django.core.checks.security.csrf  # NOQA
diff --git a/django/core/checks/compatibility/django_1_8_0.py b/django/core/checks/compatibility/django_1_8_0.py
new file mode 100644
index 0000000000..c0d8d0a779
--- /dev/null
+++ b/django/core/checks/compatibility/django_1_8_0.py
@@ -0,0 +1,31 @@
+from __future__ import unicode_literals
+
+from django.conf import global_settings, settings
+
+from .. import Tags, Warning, register
+
+
+@register(Tags.compatibility)
+def check_duplicate_template_settings(app_configs, **kwargs):
+    if settings.TEMPLATES:
+        values = [
+            'TEMPLATE_DIRS',
+            'ALLOWED_INCLUDE_ROOTS',
+            'TEMPLATE_CONTEXT_PROCESSORS',
+            'TEMPLATE_DEBUG',
+            'TEMPLATE_LOADERS',
+            'TEMPLATE_STRING_IF_INVALID',
+        ]
+        duplicates = [
+            value for value in values
+            if getattr(settings, value) != getattr(global_settings, value)
+        ]
+        if duplicates:
+            return [Warning(
+                "The standalone TEMPLATE_* settings were deprecated in Django "
+                "1.8 and the TEMPLATES dictionary takes precedence. You must "
+                "put the values of the following settings into your default "
+                "TEMPLATES dict: %s." % ", ".join(duplicates),
+                id='1_8.W001',
+            )]
+    return []