Make TypeErrors more informative when an optional header is missing
E.g. trying to convert a `list` to a `std::vector<int>` without
including <pybind11/stl.h> will now raise an error with a note that
suggests checking the headers.
The note is only appended if `std::` is found in the function
signature. This should only be the case when a header is missing.
E.g. when stl.h is included, the signature would contain `List[int]`
instead of `std::vector<int>` while using stl_bind.h would produce
something like `MyVector`. Similarly for `std::map`/`Dict`, `complex`,
`std::function`/`Callable`, etc.
There's a possibility for false positives, but it's pretty low.
diff --git a/docs/changelog.rst b/docs/changelog.rst
index eea15d5..1015f0c 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -35,6 +35,10 @@
that's only registered in an external module.
`#1058 <https://github.com/pybind/pybind11/pull/1058>`_.
+* Conversion errors now try to be more informative when it's likely that
+ a missing header is the cause (e.g. forgetting ``<pybind11/stl.h>``).
+ `#1077 <https://github.com/pybind/pybind11/pull/1077>`_.
+
v2.2.0 (August 31, 2017)
-----------------------------------------------------
diff --git a/include/pybind11/pybind11.h b/include/pybind11/pybind11.h
index 80102c5..613135a 100644
--- a/include/pybind11/pybind11.h
+++ b/include/pybind11/pybind11.h
@@ -694,6 +694,16 @@
return nullptr;
}
+ auto append_note_if_missing_header_is_suspected = [](std::string &msg) {
+ if (msg.find("std::") != std::string::npos) {
+ msg += "\n\n"
+ "Did you forget to `#include <pybind11/stl.h>`? Or <pybind11/complex.h>,\n"
+ "<pybind11/functional.h>, <pybind11/chrono.h>, etc. Some automatic\n"
+ "conversions are optional and require extra headers to be included\n"
+ "when compiling your pybind11 module.";
+ }
+ };
+
if (result.ptr() == PYBIND11_TRY_NEXT_OVERLOAD) {
if (overloads->is_operator)
return handle(Py_NotImplemented).inc_ref().ptr();
@@ -751,12 +761,14 @@
}
}
+ append_note_if_missing_header_is_suspected(msg);
PyErr_SetString(PyExc_TypeError, msg.c_str());
return nullptr;
} else if (!result) {
std::string msg = "Unable to convert function return value to a "
"Python type! The signature was\n\t";
msg += it->signature;
+ append_note_if_missing_header_is_suspected(msg);
PyErr_SetString(PyExc_TypeError, msg.c_str());
return nullptr;
} else {
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index d8c53c2..25e0666 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -76,6 +76,7 @@
set(PYBIND11_CROSS_MODULE_TESTS
test_exceptions.py
test_local_bindings.py
+ test_stl.py
test_stl_binders.py
)
diff --git a/tests/pybind11_cross_module_tests.cpp b/tests/pybind11_cross_module_tests.cpp
index 928b255..f705e31 100644
--- a/tests/pybind11_cross_module_tests.cpp
+++ b/tests/pybind11_cross_module_tests.cpp
@@ -114,4 +114,10 @@
// the same module (it would be an ODR violation). Therefore `bind_vector` of `bool`
// is defined here and tested in `test_stl_binders.py`.
py::bind_vector<std::vector<bool>>(m, "VectorBool");
+
+ // test_missing_header_message
+ // The main module already includes stl.h, but we need to test the error message
+ // which appears when this header is missing.
+ m.def("missing_header_arg", [](std::vector<float>) { });
+ m.def("missing_header_return", []() { return std::vector<float>(); });
}
diff --git a/tests/test_stl.py b/tests/test_stl.py
index f04eaeb..db8515e 100644
--- a/tests/test_stl.py
+++ b/tests/test_stl.py
@@ -179,3 +179,22 @@
""" # noqa: E501 line too long
assert m.stl_pass_by_pointer([1, 2, 3]) == [1, 2, 3]
+
+
+def test_missing_header_message():
+ """Trying convert `list` to a `std::vector`, or vice versa, without including
+ <pybind11/stl.h> should result in a helpful suggestion in the error message"""
+ import pybind11_cross_module_tests as cm
+
+ expected_message = ("Did you forget to `#include <pybind11/stl.h>`? Or <pybind11/complex.h>,\n"
+ "<pybind11/functional.h>, <pybind11/chrono.h>, etc. Some automatic\n"
+ "conversions are optional and require extra headers to be included\n"
+ "when compiling your pybind11 module.")
+
+ with pytest.raises(TypeError) as excinfo:
+ cm.missing_header_arg([1.0, 2.0, 3.0])
+ assert expected_message in str(excinfo.value)
+
+ with pytest.raises(TypeError) as excinfo:
+ cm.missing_header_return()
+ assert expected_message in str(excinfo.value)