[4.1.x] Fixed #33317 -- Added note about unconditional evaluation of {% block %} tags.

Backport of 2fac0a18081dcc77fc860c801e5d727dc90435b3 from main

1 files changed, 9 insertions, 0 deletions

diff --git a/docs/ref/templates/language.txt b/docs/ref/templates/language.txt
index f80d2a52f6..5a4cce379b 100644
--- a/docs/ref/templates/language.txt
+++ b/docs/ref/templates/language.txt
@@ -431,6 +431,15 @@ Here are some tips for working with inheritance:
   In larger templates, this technique helps you see which ``{% block %}``
   tags are being closed.
 
+* :ttag:`{% block %}<block>` tags are evaluated first. That's why the content
+  of a block is always overridden, regardless of the truthiness of surrounding
+  tags. For example, this template will *always* override the content of the
+  ``title`` block::
+
+      {% if change_title %}
+          {% block title %}Hello!{% endblock title %}
+      {% endif %}
+
 Finally, note that you can't define multiple :ttag:`block` tags with the same
 name in the same template. This limitation exists because a block tag works in
 "both" directions. That is, a block tag doesn't just provide a hole to fill --