Added ``wrong-exception-operation``

Used when an operation is done against an exception, but the operation
is not valid for the exception in question. Usually emitted when having
binary operations between exceptions in except handlers.

Close #2494

4 files changed, 57 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 0768f789d..6d90cdf52 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,7 +5,7 @@ Pylint's ChangeLog
 What's New in Pylint 2.3.0?
 ===========================
 
-Release date: TB
+Release date: TBA
 
 * Refactor ``bad-reversed-sequence`` to account for more objects that can define ``__reversed__``
 
@@ -15,6 +15,14 @@ Release date: TB
 
   Close #2598
 
+* Added ``wrong-exception-operation``
+
+  Used when an operation is done against an exception, but the operation
+  is not valid for the exception in question. Usually emitted when having
+  binary operations between exceptions in except handlers.
+
+  Close #2494
+
 What's New in Pylint 2.2.2?
 ===========================
 
diff --git a/pylint/checkers/exceptions.py b/pylint/checkers/exceptions.py
index e0a449ca8..80ea98ae2 100644
--- a/pylint/checkers/exceptions.py
+++ b/pylint/checkers/exceptions.py
@@ -160,6 +160,13 @@ MSGS = {
         "constructor, the first of them a string literal containing what "
         "appears to be placeholders intended for formatting",
     ),
+    "W0716": (
+        "Invalid exception operation. %s",
+        "wrong-exception-operation",
+        "Used when an operation is done against an exception, but the operation "
+        "is not valid for the exception in question. Usually emitted when having "
+        "binary operations between exceptions in except handlers.",
+    ),
 }
 
 
@@ -448,6 +455,26 @@ class ExceptionsChecker(checkers.BaseChecker):
         if bare_raise:
             self.add_message("try-except-raise", node=handler_having_bare_raise)
 
+    @utils.check_messages("wrong-exception-operation")
+    def visit_binop(self, node):
+        if isinstance(node.parent, astroid.ExceptHandler):
+            # except (V | A)
+            suggestion = "Did you mean '(%s, %s)' instead?" % (
+                node.left.as_string(),
+                node.right.as_string(),
+            )
+            self.add_message("wrong-exception-operation", node=node, args=(suggestion,))
+
+    @utils.check_messages("wrong-exception-operation")
+    def visit_compare(self, node):
+        if isinstance(node.parent, astroid.ExceptHandler):
+            # except (V < A)
+            suggestion = "Did you mean '(%s, %s)' instead?" % (
+                node.left.as_string(),
+                ", ".join(operand.as_string() for _, operand in node.ops),
+            )
+            self.add_message("wrong-exception-operation", node=node, args=(suggestion,))
+
     @utils.check_messages(
         "bare-except",
         "broad-except",
diff --git a/pylint/test/functional/wrong_exception_operation.py b/pylint/test/functional/wrong_exception_operation.py
new file mode 100644
index 000000000..1c3c4e380
--- /dev/null
+++ b/pylint/test/functional/wrong_exception_operation.py
@@ -0,0 +1,18 @@
+# pylint: disable=missing-docstring, superfluous-parens
+
+
+try:
+    1/0
+except (ValueError | TypeError): # [wrong-exception-operation]
+    pass
+
+try:
+    1/0
+except (ValueError + TypeError): # [wrong-exception-operation]
+    pass
+
+
+try:
+    1/0
+except (ValueError < TypeError): # [wrong-exception-operation]
+    pass
diff --git a/pylint/test/functional/wrong_exception_operation.txt b/pylint/test/functional/wrong_exception_operation.txt
new file mode 100644
index 000000000..61a2e179f
--- /dev/null
+++ b/pylint/test/functional/wrong_exception_operation.txt
@@ -0,0 +1,3 @@
+wrong-exception-operation:6::Invalid exception operation. Did you mean '(ValueError, TypeError)' instead?
+wrong-exception-operation:11::Invalid exception operation. Did you mean '(ValueError, TypeError)' instead?
+wrong-exception-operation:17::Invalid exception operation. Did you mean '(ValueError, TypeError)' instead?