Fail static_assert when trying to reference non-referencable types
The previous commit to address #392 triggers a compiler warning about
returning a reference to a local variable, which is *not* a false alarm:
the following:
py::cast<int &>(o)
(which happens internally in an overload declaration) really is
returning a reference to a local, because the cast operators for the
type_caster for numeric types returns a reference to its own member.
This commit adds a static_assert to make that a compilation failure
rather than returning a reference into about-to-be-freed memory.
Incidentally, this is also a fix for #219, which is exactly the same
issue: we can't reference numeric primitives that are cast from
wrappers around python numeric types.
diff --git a/tests/test_issues.py b/tests/test_issues.py
index 056737a..86bd6a5 100644
--- a/tests/test_issues.py
+++ b/tests/test_issues.py
@@ -171,9 +171,10 @@
from pybind11_tests.issues import OverrideTest
o = OverrideTest(42)
- i = o.int_ref()
+ # Not allowed (see associated .cpp comment)
+ #i = o.int_ref()
+ #assert o.int_ref() == 42
assert o.int_value() == 42
- assert o.int_ref() == 42
assert o.A_value().value == 99
a = o.A_ref()