Fix #7535: sphinx-autogen: crashes when custom template uses inheritance

1 files changed, 37 insertions, 1 deletions

diff --git a/sphinx/util/template.py b/sphinx/util/template.py
index 1337f407c..2449a60a1 100644
--- a/sphinx/util/template.py
+++ b/sphinx/util/template.py
@@ -10,8 +10,11 @@
 
 import os
 from functools import partial
-from typing import Dict, List, Union
+from os import path
+from typing import Callable, Dict, List, Tuple, Union
 
+from jinja2 import TemplateNotFound
+from jinja2.environment import Environment
 from jinja2.loaders import BaseLoader
 from jinja2.sandbox import SandboxedEnvironment
 
@@ -94,3 +97,36 @@ class ReSTRenderer(SphinxRenderer):
         self.env.filters['e'] = rst.escape
         self.env.filters['escape'] = rst.escape
         self.env.filters['heading'] = rst.heading
+
+
+class SphinxTemplateLoader(BaseLoader):
+    """A loader supporting template inheritance"""
+
+    def __init__(self, confdir: str, templates_paths: List[str],
+                 system_templates_paths: List[str]) -> None:
+        self.loaders = []
+        self.sysloaders = []
+
+        for templates_path in templates_paths:
+            loader = SphinxFileSystemLoader(path.join(confdir, templates_path))
+            self.loaders.append(loader)
+
+        for templates_path in system_templates_paths:
+            loader = SphinxFileSystemLoader(templates_path)
+            self.loaders.append(loader)
+            self.sysloaders.append(loader)
+
+    def get_source(self, environment: Environment, template: str) -> Tuple[str, str, Callable]:
+        if template.startswith('!'):
+            # search a template from ``system_templates_paths``
+            loaders = self.sysloaders
+            template = template[1:]
+        else:
+            loaders = self.loaders
+
+        for loader in loaders:
+            try:
+                return loader.get_source(environment, template)
+            except TemplateNotFound:
+                pass
+        raise TemplateNotFound(template)