Fix false positive consider-using-dict-comprehension when creating a dict using a list of tuple where key AND value vary depending on the same condition (#5590)

Co-authored-by: Pierre Sassoulas <[email protected]>
Co-authored-by: Daniël van Noord <[email protected]>

Author: 3 people

.copyrite_aliases

@@ -108,5 +108,10 @@
     ],
     "authoritative_mail": "[email protected]",
     "name": "bot"
+  },
+  {
+    "mails": ["[email protected]", "[email protected]"],
+    "authoritative_mail": "[email protected]",
+    "name": "Tushar Sadhwani"
   }
 ]

ChangeLog

@@ -11,6 +11,11 @@ Release date: TBA
 ..
   Put new features here and also in 'doc/whatsnew/2.13.rst'
 
+* Fixed false positive ``consider-using-dict-comprehension`` when creating a dict
+  using a list of tuples where key AND value vary depending on the same condition.
+
+  Closes #5588
+
 * When run in parallel mode ``pylint`` now pickles the data passed to subprocesses with
   the ``dill`` package. The ``dill`` package has therefore been added as a dependency.
 

doc/whatsnew/2.13.rst

@@ -32,6 +32,11 @@ Extensions
 Other Changes
 =============
 
+* Fixed false positive ``consider-using-dict-comprehension`` when creating a dict
+  using a list of tuples where key AND value vary depending on the same condition.
+
+  Closes #5588
+
 * When run in parallel mode ``pylint`` now pickles the data passed to subprocesses with
   the ``dill`` package. The ``dill`` package has therefore been added as a dependency.
 

pylint/checkers/refactoring/refactoring_checker.py

@@ -934,9 +934,28 @@ def _check_consider_using_comprehension_constructor(self, node):
             and node.args
             and isinstance(node.args[0], nodes.ListComp)
         ):
-            if node.func.name == "dict" and not isinstance(
-                node.args[0].elt, nodes.Call
-            ):
+            if node.func.name == "dict":
+                element = node.args[0].elt
+                if isinstance(element, nodes.Call):
+                    return
+
+                # If we have an `IfExp` here where both the key AND value
+                # are different, then don't raise the issue. See #5588
+                if (
+                    isinstance(element, nodes.IfExp)
+                    and isinstance(element.body, (nodes.Tuple, nodes.List))
+                    and len(element.body.elts) == 2
+                    and isinstance(element.orelse, (nodes.Tuple, nodes.List))
+                    and len(element.orelse.elts) == 2
+                ):
+                    key1, value1 = element.body.elts
+                    key2, value2 = element.orelse.elts
+                    if (
+                        key1.as_string() != key2.as_string()
+                        and value1.as_string() != value2.as_string()
+                    ):
+                        return
+
                 message_name = "consider-using-dict-comprehension"
                 self.add_message(message_name, node=node)
             elif node.func.name == "set":

tests/functional/c/consider/consider_using_dict_comprehension.py

@@ -1,4 +1,4 @@
-# pylint: disable=missing-docstring, invalid-name, use-dict-literal
+# pylint: disable=missing-docstring, invalid-name, use-dict-literal, line-too-long
 
 numbers = [1, 2, 3, 4, 5, 6]
 
@@ -8,5 +8,10 @@
 
 dict([(number, number*2) for number in numbers])  # [consider-using-dict-comprehension]
 
+stuff = {1: 10, 2: -20}
+dict([(k, v) if v > 0 else (k, 0) for k, v in stuff.items()])  # [consider-using-dict-comprehension]
+dict([(k, v) if v > 0 else (k*2, v) for k, v in stuff.items()])  # [consider-using-dict-comprehension]
+dict([(k, v) if v > 0 else (k * 2, 0) for k, v in stuff.items()])
+
 # Cannot emit as this cannot be written as a comprehension
 dict([value.split("=") for value in ["a=b", "c=d"]])

tests/functional/c/consider/consider_using_dict_comprehension.txt

@@ -1 +1,3 @@
 consider-using-dict-comprehension:9:0:9:48::Consider using a dictionary comprehension:UNDEFINED
+consider-using-dict-comprehension:12:0:12:61::Consider using a dictionary comprehension:UNDEFINED
+consider-using-dict-comprehension:13:0:13:63::Consider using a dictionary comprehension:UNDEFINED