Merge use implicit booleaness like checks

doc/data/messages/u/use-implicit-booleaness-not-comparison-to-string/bad.py

@@ -0,0 +1,6 @@
+def important_string_manipulation(x: str, y: str) -> None:
+    if x == "":  # [use-implicit-booleaness-not-comparison-to-string]
+        print("x is an empty string")
+
+    if y != "":  # [use-implicit-booleaness-not-comparison-to-string]
+        print("y is not an empty string")

doc/data/messages/u/use-implicit-booleaness-not-comparison-to-string/details.rst

@@ -0,0 +1,3 @@
+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.

doc/data/messages/u/use-implicit-booleaness-not-comparison-to-string/good.py

@@ -0,0 +1,6 @@
+def important_string_manipulation(x: str, y: str) -> None:
+    if not x:
+        print("x is an empty string")
+
+    if y:
+        print("y is not an empty string")

doc/data/messages/u/use-implicit-booleaness-not-comparison-to-string/pylintrc

@@ -0,0 +1,2 @@
+[main]
+enable=use-implicit-booleaness-not-comparison-to-string

doc/data/messages/u/use-implicit-booleaness-not-comparison-to-zero/bad.py

@@ -0,0 +1,6 @@
+def important_math(x: int, y: int) -> None:
+    if x == 0:  # [use-implicit-booleaness-not-comparison-to-zero]
+        print("x is equal to zero")
+
+    if y != 0:  # [use-implicit-booleaness-not-comparison-to-zero]
+        print("y is not equal to zero")

doc/data/messages/u/use-implicit-booleaness-not-comparison-to-zero/details.rst

@@ -0,0 +1,3 @@
+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 sequence,
+or an empty string), the code will not be equivalent.

doc/data/messages/u/use-implicit-booleaness-not-comparison-to-zero/good.py

@@ -0,0 +1,6 @@
+def important_math(x: int, y: int) -> None:
+    if not x:
+        print("x is equal to zero")
+
+    if y:
+        print("y is not equal to zero")

doc/data/messages/u/use-implicit-booleaness-not-comparison-to-zero/pylintrc

@@ -0,0 +1,2 @@
+[main]
+enable=use-implicit-booleaness-not-comparison-to-zero

doc/data/messages/u/use-implicit-booleaness-not-comparison/details.rst

@@ -0,0 +1,3 @@
+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.

doc/user_guide/checkers/extensions.rst

@@ -10,7 +10,6 @@ Pylint provides the following optional plugins:
 - :ref:`pylint.extensions.broad_try_clause`
 - :ref:`pylint.extensions.check_elif`
 - :ref:`pylint.extensions.code_style`
-- :ref:`pylint.extensions.comparetozero`
 - :ref:`pylint.extensions.comparison_placement`
 - :ref:`pylint.extensions.confusing_elif`
 - :ref:`pylint.extensions.consider_refactoring_into_while_condition`
@@ -20,7 +19,6 @@ Pylint provides the following optional plugins:
 - :ref:`pylint.extensions.docstyle`
 - :ref:`pylint.extensions.dunder`
 - :ref:`pylint.extensions.empty_comment`
-- :ref:`pylint.extensions.emptystring`
 - :ref:`pylint.extensions.eq_without_hash`
 - :ref:`pylint.extensions.for_any_all`
 - :ref:`pylint.extensions.magic_value`
@@ -88,34 +86,6 @@ Code Style checker Messages
   to. This can be changed to be an augmented assign. Disabled by default!
 
 
-.. _pylint.extensions.emptystring:
-
-Compare-To-Empty-String checker
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-This checker is provided by ``pylint.extensions.emptystring``.
-Verbatim name of the checker is ``compare-to-empty-string``.
-
-Compare-To-Empty-String checker Messages
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-:compare-to-empty-string (C1901): *"%s" can be simplified to "%s" as an empty string is falsey*
-  Used when Pylint detects comparison to an empty string constant.
-
-
-.. _pylint.extensions.comparetozero:
-
-Compare-To-Zero checker
-~~~~~~~~~~~~~~~~~~~~~~~
-
-This checker is provided by ``pylint.extensions.comparetozero``.
-Verbatim name of the checker is ``compare-to-zero``.
-
-Compare-To-Zero checker Messages
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-:compare-to-zero (C2001): *"%s" can be simplified to "%s" as 0 is falsey*
-  Used when Pylint detects comparison to a 0 constant.
-
-
 .. _pylint.extensions.comparison_placement:
 
 Comparison-Placement checker

doc/user_guide/checkers/features.rst

@@ -893,6 +893,10 @@ 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;

doc/user_guide/configuration/all-options.rst

@@ -233,7 +233,7 @@ Standard Checkers
 
    confidence = ["HIGH", "CONTROL_FLOW", "INFERENCE", "INFERENCE_FAILURE", "UNDEFINED"]
 
-   disable = ["raw-checker-failed", "bad-inline-option", "locally-disabled", "file-ignored", "suppressed-message", "useless-suppression", "deprecated-pragma", "use-symbolic-message-instead", "consider-using-augmented-assign"]
+   disable = ["raw-checker-failed", "bad-inline-option", "locally-disabled", "file-ignored", "suppressed-message", "useless-suppression", "deprecated-pragma", "use-implicit-booleaness-not-comparison-to-string", "use-implicit-booleaness-not-comparison-to-zero", "use-symbolic-message-instead", "consider-using-augmented-assign"]
 
    enable = []
 

doc/user_guide/messages/messages_overview.rst

@@ -390,8 +390,6 @@ All messages in the convention category:
    convention/bad-file-encoding
    convention/bad-mcs-classmethod-argument
    convention/bad-mcs-method-argument
-   convention/compare-to-empty-string
-   convention/compare-to-zero
    convention/consider-iterating-dictionary
    convention/consider-using-any-or-all
    convention/consider-using-dict-items
@@ -433,6 +431,8 @@ All messages in the convention category:
    convention/unnecessary-lambda-assignment
    convention/unneeded-not
    convention/use-implicit-booleaness-not-comparison
+   convention/use-implicit-booleaness-not-comparison-to-string
+   convention/use-implicit-booleaness-not-comparison-to-zero
    convention/use-implicit-booleaness-not-len
    convention/use-maxsplit-arg
    convention/use-sequence-for-iteration
@@ -449,6 +449,8 @@ All renamed messages in the convention category:
    :titlesonly:
 
    convention/blacklisted-name
+   convention/compare-to-empty-string
+   convention/compare-to-zero
    convention/len-as-condition
    convention/missing-docstring
    convention/old-misplaced-comparison-constant

doc/whatsnew/fragments/6871.user_action

@@ -0,0 +1,15 @@
+The compare to empty string checker (``pylint.extensions.emptystring``) and the compare to
+zero checker (``pylint.extensions.compare-to-zero``) have been removed and their checks are
+now part of the implicit booleaness checker:
+
+``compare-to-zero`` was renamed ``use-implicit-booleaness-not-comparison-to-zero`` and
+``compare-to-empty-string`` was renamed ``use-implicit-booleaness-not-comparison-to-string``
+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.
+
+This permits to make their likeness explicit and will provide better performance as they share most of their
+conditions to be raised.
+
+Refs #6871

examples/pylintrc

@@ -428,13 +428,15 @@ disable=raw-checker-failed,
         suppressed-message,
         useless-suppression,
         deprecated-pragma,
+        use-implicit-booleaness-not-comparison-to-string,
+        use-implicit-booleaness-not-comparison-to-zero,
         use-symbolic-message-instead
 
 # Enable the message, report, category or checker with the given id(s). You can
 # either give multiple identifier separated by comma (,) or put this option
 # multiple time (only on the command line, not in the configuration file where
 # it should appear only once). See also the "--disable" option for examples.
-enable=c-extension-no-member
+enable=
 
 
 [METHOD_ARGS]

examples/pyproject.toml

@@ -365,13 +365,13 @@ confidence = ["HIGH", "CONTROL_FLOW", "INFERENCE", "INFERENCE_FAILURE", "UNDEFIN
 # --enable=similarities". If you want to run only the classes checker, but have
 # no Warning level messages displayed, use "--disable=all --enable=classes
 # --disable=W".
-disable = ["raw-checker-failed", "bad-inline-option", "locally-disabled", "file-ignored", "suppressed-message", "useless-suppression", "deprecated-pragma", "use-symbolic-message-instead"]
+disable = ["raw-checker-failed", "bad-inline-option", "locally-disabled", "file-ignored", "suppressed-message", "useless-suppression", "deprecated-pragma", "use-implicit-booleaness-not-comparison-to-string", "use-implicit-booleaness-not-comparison-to-zero", "use-symbolic-message-instead"]
 
 # Enable the message, report, category or checker with the given id(s). You can
 # either give multiple identifier separated by comma (,) or put this option
 # multiple time (only on the command line, not in the configuration file where it
 # should appear only once). See also the "--disable" option for examples.
-enable = ["c-extension-no-member"]
+# enable =
 
 [tool.pylint.method_args]
 # List of qualified names (i.e., library.method) which require a timeout

pylint/checkers/refactoring/implicit_booleaness_checker.py

@@ -4,6 +4,8 @@
 
 from __future__ import annotations
 
+import itertools
+
 import astroid
 from astroid import bases, nodes, util
 
@@ -12,6 +14,14 @@
 from pylint.interfaces import HIGH, INFERENCE
 
 
+def _is_constant_zero(node: str | nodes.NodeNG) -> bool:
+    # We have to check that node.value is not False because node.value == 0 is True
+    # when node.value is False
+    return (
+        isinstance(node, astroid.Const) and node.value == 0 and node.value is not False
+    )
+
+
 class ImplicitBooleanessChecker(checkers.BaseChecker):
     """Checks for incorrect usage of comparisons or len() inside conditions.
 
@@ -70,6 +80,21 @@ class ImplicitBooleanessChecker(checkers.BaseChecker):
             "used to check for emptiness; Use implicit booleaness instead "
             "of a collection classes; empty collections are considered as false",
         ),
+        "C1804": (
+            '"%s" can be simplified to "%s" as an empty string is falsey',
+            "use-implicit-booleaness-not-comparison-to-string",
+            "Used when Pylint detects comparison to an empty string constant.",
+            {
+                "default_enabled": False,
+                "old_names": [("C1901", "compare-to-empty-string")],
+            },
+        ),
+        "C1805": (
+            '"%s" can be simplified to "%s" as 0 is falsey',
+            "use-implicit-booleaness-not-comparison-to-zero",
+            "Used when Pylint detects comparison to a 0 constant.",
+            {"default_enabled": False, "old_names": [("C2001", "compare-to-zero")]},
+        ),
     }
 
     options = ()
@@ -146,9 +171,97 @@ def visit_unaryop(self, node: nodes.UnaryOp) -> None:
                 "use-implicit-booleaness-not-len", node=node, confidence=HIGH
             )
 
-    @utils.only_required_for_messages("use-implicit-booleaness-not-comparison")
+    @utils.only_required_for_messages(
+        "use-implicit-booleaness-not-comparison",
+        "use-implicit-booleaness-not-comparison-to-string",
+        "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)
+
+    def _check_compare_to_zero(self, node: nodes.Compare) -> None:
+        # pylint: disable=duplicate-code
+        _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]] = [("", node.left)]
+        ops.extend(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]
+            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,
+                )
 
     def _check_use_implicit_booleaness_not_comparison(
         self, node: nodes.Compare