Fix false-positive ``useless-suppression`` for ``line-too-long`` (#5077)

Also changes ``add_ignored_message()`` to make ``nodes`` parameter
optional.
Closes #4212

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

4 files changed, 22 insertions, 9 deletions

diff --git a/ChangeLog b/ChangeLog
index 324a5dcab..99c3c2a67 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -47,6 +47,10 @@ Release date: TBA
 
   Closes #5066
 
+* Fix false-positive ``useless-suppression`` for ``line-too-long``
+
+  Closes #4212
+
 * Fixed ``invalid-name`` not checking parameters of overwritten base ``object`` methods
 
   Closes #3614
diff --git a/pylint/checkers/format.py b/pylint/checkers/format.py
index e0d627e1c..7817dba72 100644
--- a/pylint/checkers/format.py
+++ b/pylint/checkers/format.py
@@ -673,7 +673,7 @@ class FormatChecker(BaseTokenChecker):
                 "trailing-whitespace", line=i, col_offset=len(stripped_line)
             )
 
-    def check_line_length(self, line: str, i: int) -> None:
+    def check_line_length(self, line: str, i: int, checker_off: bool) -> None:
         """
         Check that the line length is less than the authorized value
         """
@@ -681,7 +681,10 @@ class FormatChecker(BaseTokenChecker):
         ignore_long_line = self.config.ignore_long_lines
         line = line.rstrip()
         if len(line) > max_chars and not ignore_long_line.search(line):
-            self.add_message("line-too-long", line=i, args=(len(line), max_chars))
+            if checker_off:
+                self.linter.add_ignored_message("line-too-long", i)
+            else:
+                self.add_message("line-too-long", line=i, args=(len(line), max_chars))
 
     @staticmethod
     def remove_pylint_option_from_lines(options_pattern_obj) -> str:
@@ -775,16 +778,16 @@ class FormatChecker(BaseTokenChecker):
 
         # Line length check may be deactivated through `pylint: disable` comment
         mobj = OPTION_PO.search(lines)
+        checker_off = False
         if mobj:
             if not self.is_line_length_check_activated(mobj):
-                # the line length check is deactivated, we can stop here
-                return
+                checker_off = True
             # The 'pylint: disable whatever' should not be taken into account for line length count
             lines = self.remove_pylint_option_from_lines(mobj)
 
         # here we re-run specific_splitlines since we have filtered out pylint options above
         for offset, line in enumerate(self.specific_splitlines(lines)):
-            self.check_line_length(line, lineno + offset)
+            self.check_line_length(line, lineno + offset, checker_off)
 
     def check_indent_level(self, string, expected, line_num):
         """return the indent level of the string"""
diff --git a/pylint/message/message_handler_mix_in.py b/pylint/message/message_handler_mix_in.py
index 185658d4a..662a086cb 100644
--- a/pylint/message/message_handler_mix_in.py
+++ b/pylint/message/message_handler_mix_in.py
@@ -261,7 +261,7 @@ class MessagesHandlerMixIn:
         self: "PyLinter",
         msgid: str,
         line: int,
-        node: nodes.NodeNG,
+        node: Optional[nodes.NodeNG] = None,
         confidence: Optional[Confidence] = UNDEFINED,
     ) -> None:
         """Prepares a message to be added to the ignored message storage
diff --git a/tests/functional/u/useless/useless_suppression.py b/tests/functional/u/useless/useless_suppression.py
index f9bf7d490..7ca3f74ce 100644
--- a/tests/functional/u/useless/useless_suppression.py
+++ b/tests/functional/u/useless/useless_suppression.py
@@ -1,6 +1,12 @@
-"""Test for useless suppression false positive for wrong-import-order
-Reported in https://github.com/PyCQA/pylint/issues/2366"""
-# pylint: enable=useless-suppression
+"""Tests for useless suppressions"""
+# pylint: enable=useless-suppression, line-too-long
 # pylint: disable=unused-import, wrong-import-order
+
+# False positive for wrong-import-order
+# Reported in https://github.com/PyCQA/pylint/issues/2366
 from pylint import run_pylint
 import astroid
+
+# False-positive for 'line-too-long'
+# Reported in https://github.com/PyCQA/pylint/issues/4212
+VAR = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" # pylint: disable=line-too-long