Merging of use-implicit-booleaness-like checkers for consistency and performance

doc/user_guide/checkers/features.rst

@@ -893,14 +893,21 @@ Refactoring checker Messages
   Emitted when a single "return" or "return None" statement is found at the end
   of function or method definition. This statement can safely be removed
   because Python will implicitly return None
-:use-implicit-booleaness-not-comparison-to-zero (C1805): *"%s" can be simplified to "%s" as 0 is falsey*
-  Used when Pylint detects comparison to a 0 constant.
-:use-implicit-booleaness-not-comparison-to-string (C1804): *"%s" can be simplified to "%s" as an empty string is falsey*
-  Used when Pylint detects comparison to an empty string constant.
-:use-implicit-booleaness-not-comparison (C1803): *'%s' can be simplified to '%s' as an empty %s is falsey*
-  Used when Pylint detects that collection literal comparison is being used to
-  check for emptiness; Use implicit booleaness instead of a collection classes;
-  empty collections are considered as false
+:use-implicit-booleaness-not-comparison-to-string (C1804): *"%s" can be simplified to "%s", if it is striclty a string, as an empty string is falsey*
+  Empty string are considered false in a boolean context. Following this check
+  blindly in weakly typed code base can create hard to debug issues. If the
+  value can be something else that is falsey but not a string (for example
+  ``None``, an empty sequence, or ``0``) the code will not be equivalent.
+:use-implicit-booleaness-not-comparison (C1803): *"%s" can be simplified to "%s", if it is strictly a sequence, as an empty %s is falsey*
+  Empty sequences are considered false in a boolean context. Following this
+  check blindly in weakly typed code base can create hard to debug issues. If
+  the value can be something else that is falsey but not a sequence (for
+  example ``None``, an empty string, or ``0``) the code will not be equivalent.
+:use-implicit-booleaness-not-comparison-to-zero (C1805): *"%s" can be simplified to "%s", if it is strictly an int, as 0 is falsey*
+  0 is considered false in a boolean context. Following this check blindly in
+  weakly typed code base can create hard to debug issues. If the value can be
+  something else that is falsey but not an int (for example ``None``, an empty
+  string, or an empty sequence) the code will not be equivalent.
 :unneeded-not (C0113): *Consider changing "%s" to "%s"*
   Used when a boolean expression contains an unneeded negation.
 :consider-iterating-dictionary (C0201): *Consider iterating the dictionary directly instead of calling .keys()*
@@ -916,10 +923,9 @@ Refactoring checker Messages
   Emitted when code that iterates with range and len is encountered. Such code
   can be simplified by using the enumerate builtin.
 :use-implicit-booleaness-not-len (C1802): *Do not use `len(SEQUENCE)` without comparison to determine if a sequence is empty*
-  Used when Pylint detects that len(sequence) is being used without explicit
-  comparison inside a condition to determine if a sequence is empty. Instead of
-  coercing the length to a boolean, either rely on the fact that empty
-  sequences are false or compare the length against a scalar.
+  Empty sequences are considered false in a boolean context. You can either
+  remove the call to 'len' (``if not x``) or compare the length against ascalar
+  (``if len(x) > 1``).
 :consider-using-f-string (C0209): *Formatting a regular string which could be an f-string*
   Used when we detect a string that is being formatted with format() or % which
   could potentially be an f-string. The use of f-strings is preferred. Requires

doc/whatsnew/fragments/6871.user_action

@@ -9,7 +9,9 @@ and they now need to be enabled explicitly.
 The `pylint.extensions.emptystring`` and ``pylint.extensions.compare-to-zero`` extensions
 no longer exists and needs to be removed from the ``load-plugins`` option.
 
+Messages related to implicit booleaness were made more explicit and actionable.
+
 This permits to make their likeness explicit and will provide better performance as they share most of their
 conditions to be raised.
 
-Refs #6871
+Closes #6871

pylint/checkers/refactoring/implicit_booleaness_checker.py

@@ -66,38 +66,47 @@ class ImplicitBooleanessChecker(checkers.BaseChecker):
         "C1802": (
             "Do not use `len(SEQUENCE)` without comparison to determine if a sequence is empty",
             "use-implicit-booleaness-not-len",
-            "Used when Pylint detects that len(sequence) is being used "
-            "without explicit comparison inside a condition to determine if a sequence is empty. "
-            "Instead of coercing the length to a boolean, either "
-            "rely on the fact that empty sequences are false or "
-            "compare the length against a scalar.",
+            "Empty sequences are considered false in a boolean context. You can either"
+            " remove the call to 'len' (``if not x``) or compare the length against a"
+            "scalar (``if len(x) > 1``).",
             {"old_names": [("C1801", "len-as-condition")]},
         ),
         "C1803": (
-            "'%s' can be simplified to '%s' as an empty %s is falsey",
+            '"%s" can be simplified to "%s", if it is strictly a sequence, as an empty %s is falsey',
             "use-implicit-booleaness-not-comparison",
-            "Used when Pylint detects that collection literal comparison is being "
-            "used to check for emptiness; Use implicit booleaness instead "
-            "of a collection classes; empty collections are considered as false",
+            "Empty sequences are considered false in a boolean context. Following this"
+            " check blindly in weakly typed code base can create hard to debug issues."
+            " If the value can be something else that is falsey but not a sequence (for"
+            " example ``None``, an empty string, or ``0``) the code will not be "
+            "equivalent.",
         ),
         "C1804": (
-            '"%s" can be simplified to "%s" as an empty string is falsey',
+            '"%s" can be simplified to "%s", if it is striclty a string, as an empty string is falsey',
             "use-implicit-booleaness-not-comparison-to-string",
-            "Used when Pylint detects comparison to an empty string constant.",
+            "Empty string are considered false in a boolean context. Following this"
+            " check blindly in weakly typed code base can create hard to debug issues."
+            " If the value can be something else that is falsey but not a string (for"
+            " example ``None``, an empty sequence, or ``0``) the code will not be "
+            "equivalent.",
             {
                 "default_enabled": False,
                 "old_names": [("C1901", "compare-to-empty-string")],
             },
         ),
         "C1805": (
-            '"%s" can be simplified to "%s" as 0 is falsey',
+            '"%s" can be simplified to "%s", if it is strictly an int, as 0 is falsey',
             "use-implicit-booleaness-not-comparison-to-zero",
-            "Used when Pylint detects comparison to a 0 constant.",
+            "0 is considered false in a boolean context. Following this"
+            " check blindly in weakly typed code base can create hard to debug issues."
+            " If the value can be something else that is falsey but not an int (for"
+            " example ``None``, an empty string, or an empty sequence) the code will not be "
+            "equivalent.",
             {"default_enabled": False, "old_names": [("C2001", "compare-to-zero")]},
         ),
     }
 
     options = ()
+    _operators = {"!=", "==", "is not", "is"}
 
     @utils.only_required_for_messages("use-implicit-booleaness-not-len")
     def visit_call(self, node: nodes.Call) -> None:
@@ -177,91 +186,77 @@ def visit_unaryop(self, node: nodes.UnaryOp) -> None:
         "use-implicit-booleaness-not-comparison-to-zero",
     )
     def visit_compare(self, node: nodes.Compare) -> None:
-        self._check_use_implicit_booleaness_not_comparison(node)
-        self._check_compare_to_zero(node)
-        self._check_compare_to_string(node)
+        if self.linter.is_message_enabled("use-implicit-booleaness-not-comparison"):
+            self._check_use_implicit_booleaness_not_comparison(node)
+        if self.linter.is_message_enabled(
+            "use-implicit-booleaness-not-comparison-to-zero"
+        ) or self.linter.is_message_enabled(
+            "use-implicit-booleaness-not-comparison-to-str"
+        ):
+            self._check_compare_to_str_or_zero(node)
 
-    def _check_compare_to_zero(self, node: nodes.Compare) -> None:
-        # pylint: disable=duplicate-code
-        _operators = ["!=", "==", "is not", "is"]
+    def _check_compare_to_str_or_zero(self, node: nodes.Compare) -> None:
         # note: astroid.Compare has the left most operand in node.left
         # while the rest are a list of tuples in node.ops
         # the format of the tuple is ('compare operator sign', node)
         # here we squash everything into `ops` to make it easier for processing later
-        ops: list[tuple[str, nodes.NodeNG]] = [("", node.left)]
-        ops.extend(node.ops)
+        ops: list[tuple[str, nodes.NodeNG]] = [("", node.left), *node.ops]
         iter_ops = iter(ops)
         all_ops = list(itertools.chain(*iter_ops))
-
         for ops_idx in range(len(all_ops) - 2):
-            op_1 = all_ops[ops_idx]
             op_2 = all_ops[ops_idx + 1]
+            if op_2 not in self._operators:
+                continue
+            op_1 = all_ops[ops_idx]
             op_3 = all_ops[ops_idx + 2]
             error_detected = False
-
-            # 0 ?? X
-            if _is_constant_zero(op_1) and op_2 in _operators:
-                error_detected = True
-                op = op_3
-            # X ?? 0
-            elif op_2 in _operators and _is_constant_zero(op_3):
-                error_detected = True
-                op = op_1
-
-            if error_detected:
-                original = f"{op_1.as_string()} {op_2} {op_3.as_string()}"
-                suggestion = (
-                    op.as_string()
-                    if op_2 in {"!=", "is not"}
-                    else f"not {op.as_string()}"
-                )
-                self.add_message(
-                    "compare-to-zero",
-                    args=(original, suggestion),
-                    node=node,
-                    confidence=HIGH,
-                )
-
-    def _check_compare_to_string(self, node: nodes.Compare) -> None:
-        """Checks for comparisons to empty string.
-
-        Most of the time you should use the fact that empty strings are false.
-        An exception to this rule is when an empty string value is allowed in the program
-        and has a different meaning than None!
-        """
-        _operators = {"!=", "==", "is not", "is"}
-        # note: astroid.Compare has the left most operand in node.left while the rest
-        # are a list of tuples in node.ops the format of the tuple is
-        # ('compare operator sign', node) here we squash everything into `ops`
-        # to make it easier for processing later
-        ops: list[tuple[str, nodes.NodeNG | None]] = [("", node.left)]
-        ops.extend(node.ops)
-        iter_ops = iter(ops)
-        ops = list(itertools.chain(*iter_ops))  # type: ignore[arg-type]
-        for ops_idx in range(len(ops) - 2):
-            op_1: nodes.NodeNG | None = ops[ops_idx]
-            op_2: str = ops[ops_idx + 1]  # type: ignore[assignment]
-            op_3: nodes.NodeNG | None = ops[ops_idx + 2]
-            error_detected = False
-            if op_1 is None or op_3 is None or op_2 not in _operators:
-                continue
-            node_name = ""
-            # x ?? ""
-            if utils.is_empty_str_literal(op_1):
-                error_detected = True
-                node_name = op_3.as_string()
-            # '' ?? X
-            elif utils.is_empty_str_literal(op_3):
-                error_detected = True
-                node_name = op_1.as_string()
-            if error_detected:
-                suggestion = f"not {node_name}" if op_2 in {"==", "is"} else node_name
-                self.add_message(
-                    "compare-to-empty-string",
-                    args=(node.as_string(), suggestion),
-                    node=node,
-                    confidence=HIGH,
-                )
+            if self.linter.is_message_enabled(
+                "use-implicit-booleaness-not-comparison-to-zero"
+            ):
+                # 0 ?? X
+                if _is_constant_zero(op_1):
+                    error_detected = True
+                    op = op_3
+                # X ?? 0
+                elif _is_constant_zero(op_3):
+                    error_detected = True
+                    op = op_1
+                if error_detected:
+                    original = f"{op_1.as_string()} {op_2} {op_3.as_string()}"
+                    suggestion = (
+                        op.as_string()
+                        if op_2 in {"!=", "is not"}
+                        else f"not {op.as_string()}"
+                    )
+                    self.add_message(
+                        "use-implicit-booleaness-not-comparison-to-zero",
+                        args=(original, suggestion),
+                        node=node,
+                        confidence=HIGH,
+                    )
+                    error_detected = False
+            if self.linter.is_message_enabled(
+                "use-implicit-booleaness-not-comparison-to-str"
+            ):
+                node_name = ""
+                # x ?? ""
+                if utils.is_empty_str_literal(op_1):
+                    error_detected = True
+                    node_name = op_3.as_string()
+                # '' ?? X
+                elif utils.is_empty_str_literal(op_3):
+                    error_detected = True
+                    node_name = op_1.as_string()
+                if error_detected:
+                    suggestion = (
+                        f"not {node_name}" if op_2 in {"==", "is"} else node_name
+                    )
+                    self.add_message(
+                        "use-implicit-booleaness-not-comparison-to-string",
+                        args=(node.as_string(), suggestion),
+                        node=node,
+                        confidence=HIGH,
+                    )
 
     def _check_use_implicit_booleaness_not_comparison(
         self, node: nodes.Compare