discard constant True condition in while loops

Cython/Compiler/FlowControl.py

@@ -904,7 +904,8 @@ class ControlFlowAnalysis(CythonTransform):
         next_block = self.flow.newblock()
         # Condition block
         self.flow.loops.append(LoopDescr(next_block, condition_block))
-        self._visit(node.condition)
+        if node.condition:
+            self._visit(node.condition)
         # Body block
         self.flow.nextblock()
         self._visit(node.body)

Cython/Compiler/Optimize.py

@@ -3382,6 +3382,7 @@ class ConstantFolding(Visitor.VisitorTransform, SkipDeclarations):
         self.visitchildren(node)
         if node.condition.has_constant_result():
             if node.condition.constant_result:
+                node.condition = None
                 node.else_clause = None
             else:
                 return node.else_clause

tests/run/constant_folding.py

@@ -192,6 +192,9 @@ def while_false_else():
 
 @cython.test_fail_if_path_exists(
     "//WhileStatNode//PrintStatNode",
+    "//WhileStatNode//PrimaryCmpNode",
+    "//WhileStatNode/BoolNode",
+    "//WhileStatNode/IntNode",
 )
 @cython.test_assert_path_exists(
     "//WhileStatNode",