Omit no-member error if guarded behind if stmt (#4764)

* Omit no-member error if guarded behind if stmt

Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>

2 files changed, 82 insertions, 0 deletions

diff --git a/tests/functional/n/no/no_member_if_statements.py b/tests/functional/n/no/no_member_if_statements.py
new file mode 100644
index 000000000..ad87e9950
--- /dev/null
+++ b/tests/functional/n/no/no_member_if_statements.py
@@ -0,0 +1,79 @@
+# pylint: disable=invalid-name,missing-docstring,pointless-statement
+from datetime import datetime
+from typing import Union
+
+value = "Hello World"
+value.isoformat()  # [no-member]
+
+
+if isinstance(value, datetime):
+    value.isoformat()
+else:
+    value.isoformat()  # [no-member]
+
+
+def func():
+    if hasattr(value, "load"):
+        value.load()
+
+    if getattr(value, "load", None):
+        value.load
+
+
+if value.none_existent():  # [no-member]
+    pass
+
+res = value.isoformat() if isinstance(value, datetime) else value
+
+
+class Base:
+    _attr_state: Union[str, datetime] = "Unknown"
+
+    @property
+    def state(self) -> Union[str, datetime]:
+        return self._attr_state
+
+    def some_function(self) -> str:
+        state = self.state
+        if isinstance(state, datetime):
+            return state.isoformat()
+        return str(state)
+
+
+# https://github.com/PyCQA/pylint/issues/1990
+# Attribute access after 'isinstance' should not cause 'no-member' error
+import subprocess  # pylint: disable=wrong-import-position  # noqa: E402
+
+try:
+    subprocess.check_call(['ls', '-'])  # Deliberately made error in this line
+except Exception as err:
+    if isinstance(err, subprocess.CalledProcessError):
+        print(f'Subprocess error occured. Return code: {err.returncode}')
+    else:
+        print(f'An error occured: {str(err)}')
+    raise
+
+
+# https://github.com/PyCQA/pylint/issues/4168
+# 'encode' for 'arg' should not cause 'no-member' error
+mixed_tuple = (b"a", b"b", b"c", b"d")
+byte_tuple = [arg.encode('utf8') if isinstance(arg, str) else arg for arg in mixed_tuple]
+
+for arg in mixed_tuple:
+    if isinstance(arg, str):
+        print(arg.encode('utf8'))
+    else:
+        print(arg)
+
+
+# https://github.com/PyCQA/pylint/issues/1162
+# Attribute access after 'isinstance' should not cause 'no-member' error
+class FoobarException(Exception):
+    foobar = None
+
+try:  # noqa: E305
+    pass
+except Exception as ex:
+    if isinstance(ex, FoobarException):
+        ex.foobar
+    raise
diff --git a/tests/functional/n/no/no_member_if_statements.txt b/tests/functional/n/no/no_member_if_statements.txt
new file mode 100644
index 000000000..2bc673b49
--- /dev/null
+++ b/tests/functional/n/no/no_member_if_statements.txt
@@ -0,0 +1,3 @@
+no-member:6:0::Instance of 'str' has no 'isoformat' member:INFERENCE
+no-member:12:4::Instance of 'str' has no 'isoformat' member:INFERENCE
+no-member:23:3::Instance of 'str' has no 'none_existent' member:INFERENCE