Merge branch '3.x' into 8183

1 files changed, 10 insertions, 3 deletions

diff --git a/sphinx/registry.py b/sphinx/registry.py
index 0aec0a9fd..d0c00b85f 100644
--- a/sphinx/registry.py
+++ b/sphinx/registry.py
@@ -259,12 +259,12 @@ class SphinxComponentRegistry:
         else:
             self.source_suffix[suffix] = filetype
 
-    def add_source_parser(self, parser: "Type[Parser]", **kwargs: Any) -> None:
+    def add_source_parser(self, parser: "Type[Parser]", override: bool = False) -> None:
         logger.debug('[app] adding search source_parser: %r', parser)
 
         # create a map from filetype to parser
         for filetype in parser.supported:
-            if filetype in self.source_parsers and not kwargs.get('override'):
+            if filetype in self.source_parsers and not override:
                 raise ExtensionError(__('source_parser for %r is already registered') %
                                      filetype)
             else:
@@ -367,7 +367,14 @@ class SphinxComponentRegistry:
         logger.debug('[app] adding js_file: %r, %r', filename, attributes)
         self.js_files.append((filename, attributes))
 
+    def has_latex_package(self, name: str) -> bool:
+        packages = self.latex_packages + self.latex_packages_after_hyperref
+        return bool([x for x in packages if x[0] == name])
+
     def add_latex_package(self, name: str, options: str, after_hyperref: bool = False) -> None:
+        if self.has_latex_package(name):
+            logger.warn("latex package '%s' already included" % name)
+
         logger.debug('[app] adding latex package: %r', name)
         if after_hyperref:
             self.latex_packages_after_hyperref.append((name, options))
@@ -394,7 +401,7 @@ class SphinxComponentRegistry:
 
     def load_extension(self, app: "Sphinx", extname: str) -> None:
         """Load a Sphinx extension."""
-        if extname in app.extensions:  # alread loaded
+        if extname in app.extensions:  # already loaded
             return
         if extname in EXTENSION_BLACKLIST:
             logger.warning(__('the extension %r was already merged with Sphinx since '