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Changed implementation of gsl::narrow to throw gsl::narrowing_error

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Implementation now behaves as described in the C++ Core Guidlines
This commit is contained in:
Nicholas Londey 2020-04-22 10:09:13 +10:00
parent 9f6a9a5807
commit 61534ca3ad
2 changed files with 9 additions and 11 deletions
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8
include/gsl/gsl_util
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@ -96,6 +96,10 @@ constexpr T narrow_cast(U&& u) noexcept
return static_cast<T>(std::forward<U>(u));
}
struct narrowing_error : public std::exception
{
};
namespace details
{
template <class T, class U>
@ -115,9 +119,9 @@ constexpr
T narrow(U u) noexcept(false)
{
T t = narrow_cast<T>(u);
if (static_cast<U>(t) != u) gsl::details::terminate();
if (static_cast<U>(t) != u) throw narrowing_error{};
if (!details::is_same_signedness<T, U>::value && ((t < T{}) != (u < U{})))
gsl::details::terminate();
throw narrowing_error{};
return t;
}

12
tests/utils_tests.cpp
View File

@ -104,11 +104,6 @@ TEST(utils_tests, narrow_cast)
TEST(utils_tests, narrow)
{
std::set_terminate([] {
std::cerr << "Expected Death. narrow";
std::abort();
});
int n = 120;
const char c = narrow<char>(n);
EXPECT_TRUE(c == 120);
@ -123,14 +118,13 @@ TEST(utils_tests, narrow)
EXPECT_TRUE(narrow<uint32_t>(int32_t(1)) == 1);
EXPECT_TRUE(narrow<uint32_t>(int32_max) == static_cast<uint32_t>(int32_max));
EXPECT_DEATH(narrow<uint32_t>(int32_t(-1)), deathstring);
EXPECT_DEATH(narrow<uint32_t>(int32_min), deathstring);
EXPECT_THROW(narrow<uint32_t>(int32_t(-1)), narrowing_error);
EXPECT_THROW(narrow<uint32_t>(int32_min), narrowing_error);
n = -42;
EXPECT_DEATH(narrow<unsigned>(n), deathstring);
EXPECT_THROW(narrow<unsigned>(n), narrowing_error);
#if GSL_CONSTEXPR_NARROW
static_assert(narrow<char>(120) == 120, "Fix GSL_CONSTEXPR_NARROW");
#endif
}