Fixed #33701 -- Added fine-grained error locations to the technical 500 debug page.

3 files changed, 25 insertions, 4 deletions

diff --git a/django/views/debug.py b/django/views/debug.py
index b93afa5737..53b4125716 100644
--- a/django/views/debug.py
+++ b/django/views/debug.py
@@ -1,4 +1,5 @@
 import functools
+import itertools
 import re
 import sys
 import types
@@ -15,7 +16,7 @@ from django.utils.datastructures import MultiValueDict
 from django.utils.encoding import force_str
 from django.utils.module_loading import import_string
 from django.utils.regex_helper import _lazy_re_compile
-from django.utils.version import get_docs_version
+from django.utils.version import PY311, get_docs_version
 
 # Minimal Django templates engine to render the error templates
 # regardless of the project's TEMPLATES setting. Templates are
@@ -546,6 +547,24 @@ class ExceptionReporter:
                 pre_context = []
                 context_line = "<source code not available>"
                 post_context = []
+
+            colno = tb_area_colno = ""
+            if PY311:
+                _, _, start_column, end_column = next(
+                    itertools.islice(
+                        tb.tb_frame.f_code.co_positions(), tb.tb_lasti // 2, None
+                    )
+                )
+                if start_column and end_column:
+                    underline = "^" * (end_column - start_column)
+                    spaces = " " * (start_column + len(str(lineno + 1)) + 2)
+                    colno = f"\n{spaces}{underline}"
+                    tb_area_spaces = " " * (
+                        4
+                        + start_column
+                        - (len(context_line) - len(context_line.lstrip()))
+                    )
+                    tb_area_colno = f"\n{tb_area_spaces}{underline}"
             yield {
                 "exc_cause": exc_cause,
                 "exc_cause_explicit": exc_cause_explicit,
@@ -562,6 +581,8 @@ class ExceptionReporter:
                 "context_line": context_line,
                 "post_context": post_context,
                 "pre_context_lineno": pre_context_lineno + 1,
+                "colno": colno,
+                "tb_area_colno": tb_area_colno,
             }
             tb = tb.tb_next
 
diff --git a/django/views/templates/technical_500.html b/django/views/templates/technical_500.html
index ae0411729a..a5c187147b 100644
--- a/django/views/templates/technical_500.html
+++ b/django/views/templates/technical_500.html
@@ -242,7 +242,7 @@
                 </ol>
               {% endif %}
               <ol start="{{ frame.lineno }}" class="context-line">
-                <li onclick="toggle('pre{{ frame.id }}', 'post{{ frame.id }}')"><pre>{{ frame.context_line }}</pre>{% if not is_email %} <span>…</span>{% endif %}</li>
+                <li onclick="toggle('pre{{ frame.id }}', 'post{{ frame.id }}')"><pre>{{ frame.context_line }}{{ frame.colno }}</pre>{% if not is_email %} <span>…</span>{% endif %}</li>
               </ol>
               {% if frame.post_context and not is_email  %}
                 <ol start='{{ frame.lineno|add:"1" }}' class="post-context" id="post{{ frame.id }}">
@@ -327,7 +327,7 @@ The above exception ({{ frame.exc_cause|force_escape }}) was the direct cause of
 {% else %}
 During handling of the above exception ({{ frame.exc_cause|force_escape }}), another exception occurred:
 {% endif %}{% endif %}{% endifchanged %}  {% if frame.tb %}File "{{ frame.filename }}"{% if frame.context_line %}, line {{ frame.lineno }}{% endif %}, in {{ frame.function }}
-{% if frame.context_line %}    {% spaceless %}{{ frame.context_line }}{% endspaceless %}{% endif %}{% elif forloop.first %}None{% else %}Traceback: None{% endif %}{% endfor %}
+{% if frame.context_line %}    {% spaceless %}{{ frame.context_line }}{% endspaceless %}{{ frame.tb_area_colno }}{% endif %}{% elif forloop.first %}None{% else %}Traceback: None{% endif %}{% endfor %}
 
 Exception Type: {{ exception_type }}{% if request %} at {{ request.path_info }}{% endif %}
 Exception Value: {{ exception_value|force_escape }}{% if exception_notes %}{{ exception_notes }}{% endif %}
diff --git a/django/views/templates/technical_500.txt b/django/views/templates/technical_500.txt
index a481c5db0d..5a75324ebc 100644
--- a/django/views/templates/technical_500.txt
+++ b/django/views/templates/technical_500.txt
@@ -31,7 +31,7 @@ Traceback (most recent call last):
 {% for frame in frames %}{% ifchanged frame.exc_cause %}{% if frame.exc_cause %}
 {% if frame.exc_cause_explicit %}The above exception ({{ frame.exc_cause }}) was the direct cause of the following exception:{% else %}During handling of the above exception ({{ frame.exc_cause }}), another exception occurred:{% endif %}
 {% endif %}{% endifchanged %}  {% if frame.tb %}File "{{ frame.filename }}"{% if frame.context_line %}, line {{ frame.lineno }}{% endif %}, in {{ frame.function }}
-{% if frame.context_line %}    {% spaceless %}{{ frame.context_line }}{% endspaceless %}{% endif %}{% elif forloop.first %}None{% else %}Traceback: None{% endif %}
+{% if frame.context_line %}    {% spaceless %}{{ frame.context_line }}{% endspaceless %}{{ frame.tb_area_colno }}{% endif %}{% elif forloop.first %}None{% else %}Traceback: None{% endif %}
 {% endfor %}
 {% if exception_type %}Exception Type: {{ exception_type }}{% if request %} at {{ request.path_info }}{% endif %}
 {% if exception_value %}Exception Value: {{ exception_value }}{% endif %}{% if exception_notes %}{{ exception_notes }}{% endif %}{% endif %}{% endif %}