Merge branch '3.x'

1 files changed, 12 insertions, 9 deletions

diff --git a/sphinx/registry.py b/sphinx/registry.py
index c36671103..3dde26b67 100644
--- a/sphinx/registry.py
+++ b/sphinx/registry.py
@@ -138,9 +138,9 @@ class SphinxComponentRegistry:
             entry_points = iter_entry_points('sphinx.builders', name)
             try:
                 entry_point = next(entry_points)
-            except StopIteration:
+            except StopIteration as exc:
                 raise SphinxError(__('Builder name %s not registered or available'
-                                     ' through entry point') % name)
+                                     ' through entry point') % name) from exc
 
             self.load_extension(app, entry_point.module_name)
 
@@ -272,8 +272,8 @@ class SphinxComponentRegistry:
     def get_source_parser(self, filetype: str) -> "Type[Parser]":
         try:
             return self.source_parsers[filetype]
-        except KeyError:
-            raise SphinxError(__('Source parser for %s not registered') % filetype)
+        except KeyError as exc:
+            raise SphinxError(__('Source parser for %s not registered') % filetype) from exc
 
     def get_source_parsers(self) -> Dict[str, "Type[Parser]"]:
         return self.source_parsers
@@ -310,9 +310,11 @@ class SphinxComponentRegistry:
             try:
                 visit, depart = handlers  # unpack once for assertion
                 translation_handlers[node.__name__] = (visit, depart)
-            except ValueError:
-                raise ExtensionError(__('kwargs for add_node() must be a (visit, depart) '
-                                        'function tuple: %r=%r') % (builder_name, handlers))
+            except ValueError as exc:
+                raise ExtensionError(
+                    __('kwargs for add_node() must be a (visit, depart) '
+                       'function tuple: %r=%r') % (builder_name, handlers)
+                ) from exc
 
     def get_translator_class(self, builder: Builder) -> "Type[nodes.NodeVisitor]":
         return self.translators.get(builder.name,
@@ -406,7 +408,8 @@ class SphinxComponentRegistry:
                 mod = import_module(extname)
             except ImportError as err:
                 logger.verbose(__('Original exception:\n') + traceback.format_exc())
-                raise ExtensionError(__('Could not import extension %s') % extname, err)
+                raise ExtensionError(__('Could not import extension %s') % extname,
+                                     err) from err
 
             setup = getattr(mod, 'setup', None)
             if setup is None:
@@ -422,7 +425,7 @@ class SphinxComponentRegistry:
                         __('The %s extension used by this project needs at least '
                            'Sphinx v%s; it therefore cannot be built with this '
                            'version.') % (extname, err)
-                    )
+                    ) from err
 
             if metadata is None:
                 metadata = {}