gh-105184: document that marshal functions can fail and need to be checked with PyErr...

diff --git a/Doc/c-api/marshal.rst b/Doc/c-api/marshal.rst
index 8e25968c6909fd69650f04f2811d9a26c4c56b09..489f1580a414b2d7c4514b878c68a5f65e2ee377 100644 (file)
--- a/Doc/c-api/marshal.rst
+++ b/Doc/c-api/marshal.rst
@@ -25,12 +25,16 @@ unmarshalling.  Version 2 uses a binary format for floating point numbers.
    the least-significant 32 bits of *value*; regardless of the size of the
    native :c:expr:`long` type.  *version* indicates the file format.
 
+   This function can fail, in which case it sets the error indicator.
+   Use :c:func:`PyErr_Occurred` to check for that.
 
 .. c:function:: void PyMarshal_WriteObjectToFile(PyObject *value, FILE *file, int version)
 
    Marshal a Python object, *value*, to *file*.
    *version* indicates the file format.
 
+   This function can fail, in which case it sets the error indicator.
+   Use :c:func:`PyErr_Occurred` to check for that.
 
 .. c:function:: PyObject* PyMarshal_WriteObjectToString(PyObject *value, int version)
 

diff --git a/Python/marshal.c b/Python/marshal.c
index 208996b05fc484f38a8e25ef85147b8a1a81b1dd..6439503d2c687967ba70170957edf50014f282b4 100644 (file)
--- a/Python/marshal.c
+++ b/Python/marshal.c
@@ -625,6 +625,10 @@ w_clear_refs(WFILE *wf)
 }
 
 /* version currently has no effect for writing ints. */
+/* Note that while the documentation states that this function
+ * can error, currently it never does. Setting an exception in
+ * this function should be regarded as an API-breaking change.
+ */
 void
 PyMarshal_WriteLongToFile(long x, FILE *fp, int version)
 {