Issue #19720: Suppressed context for some exceptions in importlib.

3 files changed, 6 insertions, 5 deletions

diff --git a/Lib/importlib/__init__.py b/Lib/importlib/__init__.py
index e0fe466..e99f50e 100644
--- a/Lib/importlib/__init__.py
+++ b/Lib/importlib/__init__.py
@@ -73,7 +73,7 @@ def find_loader(name, path=None):
     except KeyError:
         pass
     except AttributeError:
-        raise ValueError('{}.__loader__ is not set'.format(name))
+        raise ValueError('{}.__loader__ is not set'.format(name)) from None
 
     spec = _bootstrap._find_spec(name, path)
     # We won't worry about malformed specs (missing attributes).
@@ -138,7 +138,8 @@ def reload(module):
                 parent = sys.modules[parent_name]
             except KeyError:
                 msg = "parent {!r} not in sys.modules"
-                raise ImportError(msg.format(parent_name), name=parent_name)
+                raise ImportError(msg.format(parent_name),
+                                  name=parent_name) from None
             else:
                 pkgpath = parent.__path__
         else:
diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index fff9eac..64aea61 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -2172,7 +2172,7 @@ def _find_and_load_unlocked(name, import_):
             path = parent_module.__path__
         except AttributeError:
             msg = (_ERR_MSG + '; {!r} is not a package').format(name, parent)
-            raise ImportError(msg, name=name)
+            raise ImportError(msg, name=name) from None
     spec = _find_spec(name, path)
     if spec is None:
         raise ImportError(_ERR_MSG.format(name), name=name)
diff --git a/Lib/importlib/util.py b/Lib/importlib/util.py
index 2424144..c42ef14 100644
--- a/Lib/importlib/util.py
+++ b/Lib/importlib/util.py
@@ -56,7 +56,7 @@ def _find_spec_from_path(name, path=None):
         try:
             spec = module.__spec__
         except AttributeError:
-            raise ValueError('{}.__spec__ is not set'.format(name))
+            raise ValueError('{}.__spec__ is not set'.format(name)) from None
         else:
             if spec is None:
                 raise ValueError('{}.__spec__ is None'.format(name))
@@ -96,7 +96,7 @@ def find_spec(name, package=None):
         try:
             spec = module.__spec__
         except AttributeError:
-            raise ValueError('{}.__spec__ is not set'.format(name))
+            raise ValueError('{}.__spec__ is not set'.format(name)) from None
         else:
             if spec is None:
                 raise ValueError('{}.__spec__ is None'.format(name))