Ignore import errors if in guarded import block (#4702)

* Ignore import errors if in guarded import block
* Use new astroid helper methods

ChangeLog

@@ -62,6 +62,12 @@ Release date: TBA
 
   Closes #4698
 
+* Don't emit ``import-error``, ``no-name-in-module``, and ``ungrouped-imports``
+  for imports guarded by ``sys.version_info`` or ``typing.TYPE_CHECKING``.
+
+  Closes #3285
+  Closes #3382
+
 * Fix ``invalid-overridden-method`` with nested property
 
   Closes #4368

pylint/checkers/imports.py

@@ -49,7 +49,7 @@
 import os
 import sys
 from distutils import sysconfig
-from typing import Dict, List, Union
+from typing import Dict, List, Set, Union
 
 import astroid
 
@@ -58,6 +58,7 @@
     check_messages,
     get_import_name,
     is_from_fallback_block,
+    is_node_in_guarded_import_block,
     node_ignores_exception,
 )
 from pylint.exceptions import EmptyReportError
@@ -119,18 +120,10 @@ def _ignore_import_failure(node, modname, ignored_modules):
         if submodule in ignored_modules:
             return True
 
-    # ignore import failure if guarded by `sys.version_info` test
-    if isinstance(node.parent, astroid.If) and isinstance(
-        node.parent.test, astroid.Compare
-    ):
-        value = node.parent.test.left
-        if isinstance(value, astroid.Subscript):
-            value = value.value
-        if (
-            isinstance(value, astroid.Attribute)
-            and value.as_string() == "sys.version_info"
-        ):
-            return True
+    if is_node_in_guarded_import_block(node):
+        # Ignore import failure if part of guarded import block
+        # I.e. `sys.version_info` or `typing.TYPE_CHECKING`
+        return True
 
     return node_ignores_exception(node, ImportError)
 
@@ -556,25 +549,30 @@ def visit_importfrom(self, node):
                 self._add_imported_module(node, imported_module.name)
 
     @check_messages(*MSGS)
-    def leave_module(self, node):
+    def leave_module(self, node: astroid.Module) -> None:
         # Check imports are grouped by category (standard, 3rd party, local)
         std_imports, ext_imports, loc_imports = self._check_imports_order(node)
 
         # Check that imports are grouped by package within a given category
-        met_import = set()  # set for 'import x' style
-        met_from = set()  # set for 'from x import y' style
+        met_import: Set[str] = set()  # set for 'import x' style
+        met_from: Set[str] = set()  # set for 'from x import y' style
         current_package = None
         for import_node, import_name in std_imports + ext_imports + loc_imports:
             if not self.linter.is_message_enabled(
                 "ungrouped-imports", import_node.fromlineno
             ):
                 continue
-            if isinstance(import_node, astroid.node_classes.ImportFrom):
+            if isinstance(import_node, astroid.ImportFrom):
                 met = met_from
             else:
                 met = met_import
             package, _, _ = import_name.partition(".")
-            if current_package and current_package != package and package in met:
+            if (
+                current_package
+                and current_package != package
+                and package in met
+                and is_node_in_guarded_import_block(import_node) is False
+            ):
                 self.add_message("ungrouped-imports", node=import_node, args=package)
             current_package = package
             met.add(package)

pylint/checkers/utils.py

@@ -1552,3 +1552,12 @@ def get_import_name(
                     modname, level=importnode.level
                 )
     return modname
+
+
+def is_node_in_guarded_import_block(node: astroid.NodeNG) -> bool:
+    """Return True if node is part for guarded if block.
+    I.e. `sys.version_info` or `typing.TYPE_CHECKING`
+    """
+    return isinstance(node.parent, astroid.If) and (
+        node.parent.is_sys_guard() or node.parent.is_typing_guard()
+    )

pylint/checkers/variables.py

@@ -1173,12 +1173,16 @@ def visit_name(self, node):
                     self.add_message("undefined-variable", args=name, node=node)
 
     @utils.check_messages("no-name-in-module")
-    def visit_import(self, node):
+    def visit_import(self, node: astroid.Import) -> None:
         """check modules attribute accesses"""
         if not self._analyse_fallback_blocks and utils.is_from_fallback_block(node):
             # No need to verify this, since ImportError is already
             # handled by the client code.
             return
+        if utils.is_node_in_guarded_import_block(node) is True:
+            # Don't verify import if part of guarded import block
+            # I.e. `sys.version_info` or `typing.TYPE_CHECKING`
+            return
 
         for name, _ in node.names:
             parts = name.split(".")
@@ -1191,12 +1195,16 @@ def visit_import(self, node):
             self._check_module_attrs(node, module, parts[1:])
 
     @utils.check_messages("no-name-in-module")
-    def visit_importfrom(self, node):
+    def visit_importfrom(self, node: astroid.ImportFrom) -> None:
         """check modules attribute accesses"""
         if not self._analyse_fallback_blocks and utils.is_from_fallback_block(node):
             # No need to verify this, since ImportError is already
             # handled by the client code.
             return
+        if utils.is_node_in_guarded_import_block(node) is True:
+            # Don't verify import if part of guarded import block
+            # I.e. `sys.version_info` or `typing.TYPE_CHECKING`
+            return
 
         name_parts = node.modname.split(".")
         try:

tests/functional/i/import_error.py

@@ -24,14 +24,36 @@
 except ImportError:
     pass
 
-# pylint: disable=no-name-in-module
-from functional.s.syntax_error import toto # [syntax-error]
 
-# Don't emit import-error if guarded behind `sys.version_info`
+from functional.s.syntax_error import toto  # [no-name-in-module,syntax-error]
+
+
+# Don't emit `import-error` or `no-name-in-module`
+# if guarded behind `sys.version_info` or `typing.TYPE_CHECKING`
 import sys
+import typing
+import typing as tp  # pylint: disable=reimported
+from typing import TYPE_CHECKING
+
 
 if sys.version_info >= (3, 9):
-    import zoneinfo
+    import some_module
+    from some_module import some_class
+else:
+    import some_module_alt
 
 if sys.version_info[:2] >= (3, 9):
-    import zoneinfo
+    import some_module
+else:
+    import some_module_alt
+
+
+if typing.TYPE_CHECKING:
+    import stub_import
+
+if tp.TYPE_CHECKING:
+    import stub_import
+
+if TYPE_CHECKING:
+    import stub_import
+    from stub_import import stub_class

tests/functional/i/import_error.txt

@@ -1,3 +1,4 @@
 import-error:3:0::Unable to import 'totally_missing'
 import-error:16:4::Unable to import 'maybe_missing_2'
+no-name-in-module:28:0::No name 'syntax_error' in module 'functional.s'
 syntax-error:28:0::Cannot import 'functional.s.syntax_error' due to syntax error 'invalid syntax (<unknown>, line 1)'

tests/functional/u/ungrouped_imports.py

@@ -24,3 +24,11 @@
 import unittest
 from unittest import TestCase
 from unittest.mock import MagicMock
+
+
+# https://github.com/PyCQA/pylint/issues/3382
+# Imports in a `if TYPE_CHECKING` block should not trigger `ungrouped-imports`
+from typing import TYPE_CHECKING
+if TYPE_CHECKING:
+    import re
+    from typing import List