diff --git a/bare-arm/mpconfigport.h b/bare-arm/mpconfigport.h
index 41fe5dacef637767dd37a764bee294b5be655d3e..cae27cfd9bbff8dfa095e4dd665ab75c4007c6fa 100644
--- a/bare-arm/mpconfigport.h
+++ b/bare-arm/mpconfigport.h
@@ -18,6 +18,7 @@
#define MICROPY_ENABLE_SOURCE_LINE (0)
#define MICROPY_ENABLE_DOC_STRING (0)
#define MICROPY_ERROR_REPORTING (MICROPY_ERROR_REPORTING_TERSE)
+#define MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG (0)
#define MICROPY_PY_BUILTINS_BYTEARRAY (0)
#define MICROPY_PY_BUILTINS_MEMORYVIEW (0)
#define MICROPY_PY_BUILTINS_FROZENSET (0)
diff --git a/minimal/mpconfigport.h b/minimal/mpconfigport.h
index ef4fc00b4050ce1efdc64ac6ba9888a4628f7d23..49f380ea094032d452bd3fcf2e3157c289e88789 100644
--- a/minimal/mpconfigport.h
+++ b/minimal/mpconfigport.h
@@ -19,6 +19,7 @@
#define MICROPY_ENABLE_SOURCE_LINE (0)
#define MICROPY_ENABLE_DOC_STRING (0)
#define MICROPY_ERROR_REPORTING (MICROPY_ERROR_REPORTING_TERSE)
+#define MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG (0)
#define MICROPY_PY_BUILTINS_BYTEARRAY (0)
#define MICROPY_PY_BUILTINS_MEMORYVIEW (0)
#define MICROPY_PY_BUILTINS_ENUMERATE (0)
diff --git a/py/mpconfig.h b/py/mpconfig.h
index 2d9288f32b6792cec0b914b0f363270cabaad389..9f541ef705d315cdca9ff47962d40d9a64532e52 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -393,6 +393,15 @@ typedef double mp_float_t;
#define MICROPY_CAN_OVERRIDE_BUILTINS (0)
#endif
+// Whether to check that the "self" argument of a builtin method has the
+// correct type. Such an explicit check is only needed if a builtin
+// method escapes to Python land without a first argument, eg
+// list.append([], 1). Without this check such calls will have undefined
+// behaviour (usually segfault) if the first argument is the wrong type.
+#ifndef MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG
+#define MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG (1)
+#endif
+
/*****************************************************************************/
/* Fine control over Python builtins, classes, modules, etc */
diff --git a/py/runtime.c b/py/runtime.c
index 501ca435a046ee41f65ef9ec5e3c44c41501d39e..4959617eff6b12275c90e3b73a923ea173dd30ce 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -887,6 +887,51 @@ mp_obj_t mp_load_attr(mp_obj_t base, qstr attr) {
}
}
+#if MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG
+
+// The following "checked fun" type is local to the mp_convert_member_lookup
+// function, and serves to check that the first argument to a builtin function
+// has the correct type.
+
+typedef struct _mp_obj_checked_fun_t {
+ mp_obj_base_t base;
+ const mp_obj_type_t *type;
+ mp_obj_t fun;
+} mp_obj_checked_fun_t;
+
+STATIC mp_obj_t checked_fun_call(mp_obj_t self_in, mp_uint_t n_args, mp_uint_t n_kw, const mp_obj_t *args) {
+ mp_obj_checked_fun_t *self = self_in;
+ if (n_args > 0) {
+ const mp_obj_type_t *arg0_type = mp_obj_get_type(args[0]);
+ if (arg0_type != self->type) {
+ if (MICROPY_ERROR_REPORTING != MICROPY_ERROR_REPORTING_DETAILED) {
+ nlr_raise(mp_obj_new_exception_msg(&mp_type_TypeError,
+ "argument has wrong type"));
+ } else {
+ nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError,
+ "argument should be a '%q' not a '%q'", self->type->name, arg0_type->name));
+ }
+ }
+ }
+ return mp_call_function_n_kw(self->fun, n_args, n_kw, args);
+}
+
+STATIC const mp_obj_type_t mp_type_checked_fun = {
+ { &mp_type_type },
+ .name = MP_QSTR_function,
+ .call = checked_fun_call,
+};
+
+STATIC mp_obj_t mp_obj_new_checked_fun(const mp_obj_type_t *type, mp_obj_t fun) {
+ mp_obj_checked_fun_t *o = m_new_obj(mp_obj_checked_fun_t);
+ o->base.type = &mp_type_checked_fun;
+ o->type = type;
+ o->fun = fun;
+ return o;
+}
+
+#endif // MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG
+
// Given a member that was extracted from an instance, convert it correctly
// and put the result in the dest[] array for a possible method call.
// Conversion means dealing with static/class methods, callables, and values.
@@ -903,9 +948,18 @@ void mp_convert_member_lookup(mp_obj_t self, const mp_obj_type_t *type, mp_obj_t
// Don't try to bind types (even though they're callable)
dest[0] = member;
} else if (mp_obj_is_callable(member)) {
- // return a bound method, with self being this object
- dest[0] = member;
- dest[1] = self;
+ #if MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG
+ if (self == MP_OBJ_NULL && mp_obj_get_type(member) == &mp_type_fun_builtin) {
+ // we extracted a builtin method without a first argument, so we must
+ // wrap this function in a type checker
+ dest[0] = mp_obj_new_checked_fun(type, member);
+ } else
+ #endif
+ {
+ // return a bound method, with self being this object
+ dest[0] = member;
+ dest[1] = self;
+ }
} else {
// class member is a value, so just return that value
dest[0] = member;
diff --git a/tests/basics/class_use_other.py b/tests/basics/class_use_other.py
new file mode 100644
index 0000000000000000000000000000000000000000..c6aa94ad25b2ac57c23307754e53dfe9b9e971cd
--- /dev/null
+++ b/tests/basics/class_use_other.py
@@ -0,0 +1,12 @@
+# check that we can use an instance of B in a method of A
+
+class A:
+ def store(a, b):
+ a.value = b
+
+class B:
+ pass
+
+b = B()
+A.store(b, 1)
+print(b.value)
diff --git a/tests/basics/self_type_check.py b/tests/basics/self_type_check.py
new file mode 100644
index 0000000000000000000000000000000000000000..947e362cdbd78f43557f8cea72212e862bcb7875
--- /dev/null
+++ b/tests/basics/self_type_check.py
@@ -0,0 +1,31 @@
+# make sure type of first arg (self) to a builtin method is checked
+
+list.append
+
+try:
+ list.append()
+except TypeError as e:
+ print("TypeError")
+
+try:
+ list.append(1)
+except TypeError as e:
+ print("TypeError")
+
+try:
+ list.append(1, 2)
+except TypeError as e:
+ print("TypeError")
+
+l = []
+list.append(l, 2)
+print(l)
+
+try:
+ getattr(list, "append")(1, 2)
+except TypeError as e:
+ print("TypeError")
+
+l = []
+getattr(list, "append")(l, 2)
+print(l)
diff --git a/unix/mpconfigport_minimal.h b/unix/mpconfigport_minimal.h
index 078f5a1d1bef891727502a9a35d2ce69a0aa983b..770188a60842cb9afbac0b4fd9db5f573e1dfbe8 100644
--- a/unix/mpconfigport_minimal.h
+++ b/unix/mpconfigport_minimal.h
@@ -44,6 +44,7 @@
#define MICROPY_OPT_COMPUTED_GOTO (0)
#define MICROPY_OPT_CACHE_MAP_LOOKUP_IN_BYTECODE (0)
#define MICROPY_CAN_OVERRIDE_BUILTINS (0)
+#define MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG (0)
#define MICROPY_CPYTHON_COMPAT (0)
#define MICROPY_PY_BUILTINS_BYTEARRAY (0)
#define MICROPY_PY_BUILTINS_MEMORYVIEW (0)