test_exceptions.cpp

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/*
    tests/test_custom-exceptions.cpp -- exception translation
 
    Copyright (c) 2016 Pim Schellart <P.Schellart@princeton.edu>
 
    All rights reserved. Use of this source code is governed by a
    BSD-style license that can be found in the LICENSE file.
*/
#include <pybind11/gil_safe_call_once.h>
 
#include "test_exceptions.h"
 
#include "local_bindings.h"
#include "pybind11_tests.h"
 
#include <exception>
#include <stdexcept>
#include <utility>
 
// A type that should be raised as an exception in Python
class MyException : public std::exception {
public:
    explicit MyException(const char *m) : message{m} {}
    const char *what() const noexcept override { return message.c_str(); }
 
private:
    std::string message = "";
};
 
class MyExceptionUseDeprecatedOperatorCall : public MyException {
    using MyException::MyException;
};
 
// A type that should be translated to a standard Python exception
class MyException2 : public std::exception {
public:
    explicit MyException2(const char *m) : message{m} {}
    const char *what() const noexcept override { return message.c_str(); }
 
private:
    std::string message = "";
};
 
// A type that is not derived from std::exception (and is thus unknown)
class MyException3 {
public:
    explicit MyException3(const char *m) : message{m} {}
    virtual const char *what() const noexcept { return message.c_str(); }
    // Rule of 5 BEGIN: to preempt compiler warnings.
    MyException3(const MyException3 &) = default;
    MyException3(MyException3 &&) = default;
    MyException3 &operator=(const MyException3 &) = default;
    MyException3 &operator=(MyException3 &&) = default;
    virtual ~MyException3() = default;
    // Rule of 5 END.
private:
    std::string message = "";
};
 
// A type that should be translated to MyException
// and delegated to its exception translator
class MyException4 : public std::exception {
public:
    explicit MyException4(const char *m) : message{m} {}
    const char *what() const noexcept override { return message.c_str(); }
 
private:
    std::string message = "";
};
 
// Like the above, but declared via the helper function
class MyException5 : public std::logic_error {
public:
    explicit MyException5(const std::string &what) : std::logic_error(what) {}
};
 
// Inherits from MyException5
class MyException5_1 : public MyException5 {
    using MyException5::MyException5;
};
 
// Exception that will be caught via the module local translator.
class MyException6 : public std::exception {
public:
    explicit MyException6(const char *m) : message{m} {}
    const char *what() const noexcept override { return message.c_str(); }
 
private:
    std::string message = "";
};
 
struct PythonCallInDestructor {
    explicit PythonCallInDestructor(const py::dict &d) : d(d) {}
    ~PythonCallInDestructor() { d["good"] = true; }
 
    py::dict d;
};
 
struct PythonAlreadySetInDestructor {
    explicit PythonAlreadySetInDestructor(const py::str &s) : s(s) {}
    ~PythonAlreadySetInDestructor() {
        py::dict foo;
        try {
            // Assign to a py::object to force read access of nonexistent dict entry
            py::object o = foo["bar"];
        } catch (py::error_already_set &ex) {
            ex.discard_as_unraisable(s);
        }
    }
 
    py::str s;
};
 
TEST_SUBMODULE(exceptions, m) {
    m.def("throw_std_exception",
          []() { throw std::runtime_error("This exception was intentionally thrown."); });
 
    // PLEASE KEEP IN SYNC with docs/advanced/exceptions.rst
    PYBIND11_CONSTINIT static py::gil_safe_call_once_and_store<py::object> ex_storage;
    ex_storage.call_once_and_store_result(
        [&]() { return py::exception<MyException>(m, "MyException"); });
    py::register_exception_translator([](std::exception_ptr p) {
        try {
            if (p) {
                std::rethrow_exception(p);
            }
        } catch (const MyException &e) {
            // Set MyException as the active python error
            py::set_error(ex_storage.get_stored(), e.what());
        }
    });
 
    // Same as above, but using the deprecated `py::exception<>::operator()`
    // We want to be sure it still works, until it's removed.
    static const auto *const exd = new py::exception<MyExceptionUseDeprecatedOperatorCall>(
        m, "MyExceptionUseDeprecatedOperatorCall");
    py::register_exception_translator([](std::exception_ptr p) {
        try {
            if (p) {
                std::rethrow_exception(p);
            }
        } catch (const MyExceptionUseDeprecatedOperatorCall &e) {
#if defined(__INTEL_COMPILER) || defined(__NVCOMPILER)
            // It is not worth the trouble dealing with warning suppressions for these compilers.
            // Falling back to the recommended approach to keep the test code simple.
            py::set_error(*exd, e.what());
#else
            PYBIND11_WARNING_PUSH
            PYBIND11_WARNING_DISABLE_CLANG("-Wdeprecated-declarations")
            PYBIND11_WARNING_DISABLE_GCC("-Wdeprecated-declarations")
            PYBIND11_WARNING_DISABLE_MSVC(4996)
            (*exd)(e.what());
            PYBIND11_WARNING_POP
#endif
        }
    });
 
    // register new translator for MyException2
    // no need to store anything here because this type will
    // never by visible from Python
    py::register_exception_translator([](std::exception_ptr p) {
        try {
            if (p) {
                std::rethrow_exception(p);
            }
        } catch (const MyException2 &e) {
            // Translate this exception to a standard RuntimeError
            py::set_error(PyExc_RuntimeError, e.what());
        }
    });
 
    // register new translator for MyException4
    // which will catch it and delegate to the previously registered
    // translator for MyException by throwing a new exception
    py::register_exception_translator([](std::exception_ptr p) {
        try {
            if (p) {
                std::rethrow_exception(p);
            }
        } catch (const MyException4 &e) {
            throw MyException(e.what());
        }
    });
 
    // A simple exception translation:
    auto ex5 = py::register_exception<MyException5>(m, "MyException5");
    // A slightly more complicated one that declares MyException5_1 as a subclass of MyException5
    py::register_exception<MyException5_1>(m, "MyException5_1", ex5.ptr());
 
    // py::register_local_exception<LocalSimpleException>(m, "LocalSimpleException")
 
    py::register_local_exception_translator([](std::exception_ptr p) {
        try {
            if (p) {
                std::rethrow_exception(p);
            }
        } catch (const MyException6 &e) {
            py::set_error(PyExc_RuntimeError, e.what());
        }
    });
 
    m.def("throws1",
          []() { throw MyException("this error should go to py::exception<MyException>"); });
    m.def("throws1d", []() {
        throw MyExceptionUseDeprecatedOperatorCall(
            "this error should go to py::exception<MyExceptionUseDeprecatedOperatorCall>");
    });
    m.def("throws2",
          []() { throw MyException2("this error should go to a standard Python exception"); });
    m.def("throws3", []() { throw MyException3("this error cannot be translated"); });
    m.def("throws4", []() { throw MyException4("this error is rethrown"); });
    m.def("throws5",
          []() { throw MyException5("this is a helper-defined translated exception"); });
    m.def("throws5_1", []() { throw MyException5_1("MyException5 subclass"); });
    m.def("throws6", []() { throw MyException6("MyException6 only handled in this module"); });
    m.def("throws_logic_error", []() {
        throw std::logic_error("this error should fall through to the standard handler");
    });
    m.def("throws_overflow_error", []() { throw std::overflow_error(""); });
    m.def("throws_local_error", []() { throw LocalException("never caught"); });
    m.def("throws_local_simple_error", []() { throw LocalSimpleException("this mod"); });
    m.def("exception_matches", []() {
        py::dict foo;
        try {
            // Assign to a py::object to force read access of nonexistent dict entry
            py::object o = foo["bar"];
        } catch (py::error_already_set &ex) {
            if (!ex.matches(PyExc_KeyError)) {
                throw;
            }
            return true;
        }
        return false;
    });
    m.def("exception_matches_base", []() {
        py::dict foo;
        try {
            // Assign to a py::object to force read access of nonexistent dict entry
            py::object o = foo["bar"];
        } catch (py::error_already_set &ex) {
            if (!ex.matches(PyExc_Exception)) {
                throw;
            }
            return true;
        }
        return false;
    });
    m.def("modulenotfound_exception_matches_base", []() {
        try {
            // On Python >= 3.6, this raises a ModuleNotFoundError, a subclass of ImportError
            py::module_::import("nonexistent");
        } catch (py::error_already_set &ex) {
            if (!ex.matches(PyExc_ImportError)) {
                throw;
            }
            return true;
        }
        return false;
    });
 
    m.def("throw_already_set", [](bool err) {
        if (err) {
            py::set_error(PyExc_ValueError, "foo");
        }
        try {
            throw py::error_already_set();
        } catch (const std::runtime_error &e) {
            if ((err && e.what() != std::string("ValueError: foo"))
                || (!err
                    && e.what()
                           != std::string("Internal error: pybind11::error_already_set called "
                                          "while Python error indicator not set."))) {
                PyErr_Clear();
                throw std::runtime_error("error message mismatch");
            }
        }
        PyErr_Clear();
        if (err) {
            py::set_error(PyExc_ValueError, "foo");
        }
        throw py::error_already_set();
    });
 
    m.def("python_call_in_destructor", [](const py::dict &d) {
        bool retval = false;
        try {
            PythonCallInDestructor set_dict_in_destructor(d);
            py::set_error(PyExc_ValueError, "foo");
            throw py::error_already_set();
        } catch (const py::error_already_set &) {
            retval = true;
        }
        return retval;
    });
 
    m.def("python_alreadyset_in_destructor", [](const py::str &s) {
        PythonAlreadySetInDestructor alreadyset_in_destructor(s);
        return true;
    });
 
    // test_nested_throws
    m.def("try_catch",
          [m](const py::object &exc_type, const py::function &f, const py::args &args) {
              try {
                  f(*args);
              } catch (py::error_already_set &ex) {
                  if (ex.matches(exc_type)) {
                      py::print(ex.what());
                  } else {
                      // Simply `throw;` also works and is better, but using `throw ex;`
                      // here to cover that situation (as observed in the wild).
                      throw ex; // Invokes the copy ctor.
                  }
              }
          });
 
    // Test repr that cannot be displayed
    m.def("simple_bool_passthrough", [](bool x) { return x; });
 
    m.def("throw_should_be_translated_to_key_error", []() { throw shared_exception(); });
 
    m.def("raise_from", []() {
        py::set_error(PyExc_ValueError, "inner");
        py::raise_from(PyExc_ValueError, "outer");
        throw py::error_already_set();
    });
 
    m.def("raise_from_already_set", []() {
        try {
            py::set_error(PyExc_ValueError, "inner");
            throw py::error_already_set();
        } catch (py::error_already_set &e) {
            py::raise_from(e, PyExc_ValueError, "outer");
            throw py::error_already_set();
        }
    });
 
    m.def("throw_nested_exception", []() {
        try {
            throw std::runtime_error("Inner Exception");
        } catch (const std::runtime_error &) {
            std::throw_with_nested(std::runtime_error("Outer Exception"));
        }
    });
 
    m.def("error_already_set_what", [](const py::object &exc_type, const py::object &exc_value) {
        py::set_error(exc_type, exc_value);
        std::string what = py::error_already_set().what();
        bool py_err_set_after_what = (PyErr_Occurred() != nullptr);
        PyErr_Clear();
        return py::make_tuple(std::move(what), py_err_set_after_what);
    });
 
    m.def("test_cross_module_interleaved_error_already_set", []() {
        auto cm = py::module_::import("cross_module_interleaved_error_already_set");
        auto interleaved_error_already_set
            = reinterpret_cast<void (*)()>(PyLong_AsVoidPtr(cm.attr("funcaddr").ptr()));
        interleaved_error_already_set();
    });
 
    m.def("test_error_already_set_double_restore", [](bool dry_run) {
        py::set_error(PyExc_ValueError, "Random error.");
        py::error_already_set e;
        e.restore();
        PyErr_Clear();
        if (!dry_run) {
            e.restore();
        }
    });
 
    // https://github.com/pybind/pybind11/issues/4075
    m.def("test_pypy_oserror_normalization", []() {
        try {
            py::module_::import("io").attr("open")("this_filename_must_not_exist", "r");
        } catch (const py::error_already_set &e) {
            return py::str(e.what()); // str must be built before e goes out of scope.
        }
        return py::str("UNEXPECTED");
    });
 
    m.def("test_fn_cast_int", [](const py::function &fn) {
        // function returns None instead of int, should give a useful error message
        fn().cast<int>();
    });
 
    // m.def("pass_exception_void", [](const py::exception<void>&) {}); // Does not compile.
    m.def("return_exception_void", []() { return py::exception<void>(); });
}