Pick the latest value from the inferred values when looking for ``rai…

…sing-non-exception``

Close #2431

ChangeLog

@@ -7,6 +7,10 @@ What's New in Pylint 2.2?
 
 Release date: TBA
 
+   * Pick the latest value from the inferred values when looking for ``raising-non-exception``
+
+     Close #2431
+
    * Extend the TYPE_CHECKING guard to TYPE_CHECKING name as well, not just the attribute
 
      Close #2411

doc/whatsnew/2.2.rst

@@ -24,3 +24,10 @@ Other Changes
 * Fix false positive ``undefined-variable`` and ``used-before-assignment`` with nonlocal keyword usage.
 
 * Fix exceptions being raised when one of the params is not a ClassDef for :func:`checkers.utils.is_subclass_of`.
+
+* ``pylint`` now picks the latest value from the inferred values of the exception that gets
+  raised, when looking for ``raising-non-exception``. This helps when reusing a variable name
+  for multiple types, since ``pylint`` was picking just the first inferred value, leading
+  to spurious false positives.
+
+  Close #2431

pylint/checkers/exceptions.py

@@ -264,15 +264,15 @@ def visit_raise(self, node):
             self._check_bad_exception_context(node)
 
         expr = node.exc
-        try:
-            inferred_value = next(expr.infer())
-        except astroid.InferenceError:
-            inferred_value = None
-
         ExceptionRaiseRefVisitor(self, node).visit(expr)
 
-        if inferred_value:
-            ExceptionRaiseLeafVisitor(self, node).visit(inferred_value)
+        try:
+            inferred_value = expr.inferred()[-1]
+        except astroid.InferenceError:
+            pass
+        else:
+            if inferred_value:
+                ExceptionRaiseLeafVisitor(self, node).visit(inferred_value)
 
     def _check_misplaced_bare_raise(self, node):
         # Filter out if it's present in __exit__.

pylint/test/functional/invalid_exceptions_raised.py

@@ -89,3 +89,17 @@ def exception_instance_regression():
         int("9a")
     except ValueError as exc:
         raise exc
+
+
+def reusing_same_name_picks_the_latest_raised_value():
+    class Error(Exception):
+        """some error"""
+
+    exceptions = tuple([ValueError, TypeError])
+    try:
+        raise ValueError
+    except exceptions as exc:  # pylint: disable=catching-non-exception
+        # https://github.com/PyCQA/pylint/issues/1756
+        exc = Error(exc)
+        if exc:
+            raise exc