ignore truthy while statements only if literals are involved

Author: tyralla

mypy/checker.py

@@ -5058,12 +5058,15 @@ def _filter(body: Block | None) -> bool:
 
         if if_map is None:
             if stmt.while_stmt:
-                self.msg.redundant_condition_in_while(expr)
+                self.msg.redundant_condition_in_while(False, expr)
             elif not _filter(body):
                 self.msg.redundant_condition_in_if(False, expr)
 
-        if else_map is None and not stmt.while_stmt:
-            if not (isinstance(body.body[0], ReturnStmt) or _filter(stmt.else_body)):
+        if else_map is None:
+            if stmt.while_stmt:
+                if not is_true_literal(expr):
+                    self.msg.redundant_condition_in_while(True, expr)
+            elif not (_filter(stmt.else_body) or isinstance(body.body[0], ReturnStmt)):
                 self.msg.redundant_condition_in_if(True, expr)
 
     def visit_while_stmt(self, s: WhileStmt) -> None:

mypy/messages.py

@@ -2091,8 +2091,8 @@ def redundant_condition_in_comprehension(self, truthiness: bool, context: Contex
     def redundant_condition_in_if(self, truthiness: bool, context: Context) -> None:
         self.redundant_expr("If condition", truthiness, context)
 
-    def redundant_condition_in_while(self, context: Context) -> None:
-        self.redundant_expr("While condition", False, context)
+    def redundant_condition_in_while(self, truthiness: bool, context: Context) -> None:
+        self.redundant_expr("While condition", truthiness, context)
 
     def redundant_expr(self, description: str, truthiness: bool, context: Context) -> None:
         self.fail(

test-data/unit/check-isinstance.test

@@ -3078,6 +3078,10 @@ while True:
 while False:  # E: While condition is always false
     ...
 
+y = None
+while y is None:  # E: While condition is always true
+    ...
+
 [builtins fixtures/bool.pyi]
 
 [case testNoRedundantExpressionWarningsForUsagesOfTYPECHECKING]