[GR-75364] Handle native float subtype allocation failure

graalpython/com.oracle.graal.python.cext/src/floatobject.c

@@ -1,4 +1,4 @@
-/* Copyright (c) 2018, 2025, Oracle and/or its affiliates.
+/* Copyright (c) 2018, 2026, Oracle and/or its affiliates.
  * Copyright (C) 1996-2017 Python Software Foundation
  *
  * Licensed under the PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2
@@ -2689,7 +2689,6 @@ GraalPyPrivate_Float_SubtypeNew(PyTypeObject *type, double x)
 {
     PyObject* newobj = type->tp_alloc(type, 0);
     if (newobj == NULL) {
-        Py_DECREF(newobj);
         return NULL;
     }
     ((PyFloatObject *)newobj)->ob_fval = x;

graalpython/com.oracle.graal.python.test/src/tests/cpyext/test_float.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2018, 2025, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2018, 2026, Oracle and/or its affiliates. All rights reserved.
 # DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 #
 # The Universal Permissive License (UPL), Version 1.0
@@ -245,6 +245,25 @@ class ManagedSubclass(NativeFloatSubclass):
         f = ManagedSubclass(1.0)
         assert is_native_object(f)
 
+    def test_alloc_failure(self):
+        """A native float subtype must propagate tp_alloc failure instead of crashing on NULL."""
+        FailingAllocFloatSubclass = CPyExtType(
+            'FailingAllocFloatSubclass',
+            r'''
+            static PyObject* fail_alloc(PyTypeObject *type, Py_ssize_t nitems) {
+                PyErr_NoMemory();
+                return NULL;
+            }
+            ''',
+            struct_base='PyFloatObject base;',
+            tp_base='&PyFloat_Type',
+            tp_new='0',
+            tp_alloc='fail_alloc',
+            tp_free='0',
+        )
+        with self.assertRaises(MemoryError):
+            FailingAllocFloatSubclass(1.0)
+
     def test_methods(self):
         f = NativeFloatSubclass(1.1)
         zero = NativeFloatSubclass(0.0)

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/cext/capi/CExtNodes.java

@@ -205,15 +205,18 @@ public abstract static class FloatSubtypeNew extends Node {
         static Object doGeneric(Object object, double arg,
                         @Bind Node inliningTarget,
                         @Cached PythonToNativeNode toNativeNode,
-                        @Cached NativeToPythonTransferNode toJavaNode) {
+                        @Cached NativeToPythonTransferNode toJavaNode,
+                        @Cached PyObjectCheckFunctionResultNode checkFunctionResultNode) {
             assert TypeNodes.NeedsNativeAllocationNode.executeUncached(object);
             NativeFunctionPointer callable = CApiContext.getNativeSymbol(inliningTarget, NativeCAPISymbol.FUN_FLOAT_SUBTYPE_NEW);
+            long result;
             try {
-                long result = ExternalFunctionInvoker.invokeFLOAT_SUBTYPE_NEW(callable.getAddress(), toNativeNode.executeLong(object), arg);
-                return toJavaNode.execute(result);
+                result = ExternalFunctionInvoker.invokeFLOAT_SUBTYPE_NEW(callable.getAddress(), toNativeNode.executeLong(object), arg);
             } catch (Throwable e) {
                 throw CompilerDirectives.shouldNotReachHere(e);
             }
+            return checkFunctionResultNode.execute(PythonContext.get(inliningTarget), NativeCAPISymbol.FUN_FLOAT_SUBTYPE_NEW.getTsName(),
+                            toJavaNode.execute(result));
         }
     }