Memory safety is a hot topic, but what do we mean by it?
"This post presents a lot of code as screenshots."
Does substack not provide a way to include fixed with code blocks at all? If the only limitation is not supporting syntax highlighting I'd probably give it up to be more accessible.
Cppcheck already warns for this code:
test.cpp:16:45: error: Using object that is a temporary. [danglingTemporaryLifetime]
assert((std::vector<int>{1, 2, 3, 4} == append34({1, 2}))); // FAIL: UB
^
test.cpp:3:12: note: Return lambda.
return [&](std::vector<int>&& items) {
test.cpp:2:50: note: Passed to reference.
auto make_appender(std::vector<int> const& suffix) {
test.cpp:4:36: note: Lambda captures variable by reference here.
return append(move(items), suffix);
test.cpp:15:35: note: Passed to 'make_appender'.
auto append34 = make_appender({3, 4});
test.cpp:15:35: note: Temporary created here.
test.cpp:16:45: note: Using object that is a temporary.
Would love to see Ada added to the comparison.
Yes, c++ is a footgun :-) , but saying "just a weirdness" is a bit unfair to c++:
You can get a runtime warning by compiling with -fsanitize=address, undefined.
Moreover, you can actually make a proper make_appender using perfect forwarding:
template<typename S>
auto make_appender(S&& suffix)
{
return [perf_fwd_suffix = std::tuple{std::forward<S>(suffix)}](std::vector<int>&& items)
return append(std::move(items), std::get<0>(perf_fwd_suffix));
};
}
The closure pattern in C++ is a very bad thing.
If you want to close over values, copy it.
Moving out of named objects is also a recipe for disaster.
I'm blind and posting just the screenshots without the code in at least alt text or caption means that I'm not part of the audience.
"This post presents a lot of code as screenshots."
Does substack not provide a way to include fixed with code blocks at all? If the only limitation is not supporting syntax highlighting I'd probably give it up to be more accessible.
Cppcheck already warns for this code:
test.cpp:16:45: error: Using object that is a temporary. [danglingTemporaryLifetime]
assert((std::vector<int>{1, 2, 3, 4} == append34({1, 2}))); // FAIL: UB
^
test.cpp:3:12: note: Return lambda.
return [&](std::vector<int>&& items) {
^
test.cpp:2:50: note: Passed to reference.
auto make_appender(std::vector<int> const& suffix) {
^
test.cpp:4:36: note: Lambda captures variable by reference here.
return append(move(items), suffix);
^
test.cpp:15:35: note: Passed to 'make_appender'.
auto append34 = make_appender({3, 4});
^
test.cpp:15:35: note: Temporary created here.
auto append34 = make_appender({3, 4});
^
test.cpp:16:45: note: Using object that is a temporary.
assert((std::vector<int>{1, 2, 3, 4} == append34({1, 2}))); // FAIL: UB
Would love to see Ada added to the comparison.
Yes, c++ is a footgun :-) , but saying "just a weirdness" is a bit unfair to c++:
You can get a runtime warning by compiling with -fsanitize=address, undefined.
Moreover, you can actually make a proper make_appender using perfect forwarding:
template<typename S>
auto make_appender(S&& suffix)
{
return [perf_fwd_suffix = std::tuple{std::forward<S>(suffix)}](std::vector<int>&& items)
{
return append(std::move(items), std::get<0>(perf_fwd_suffix));
};
}
The closure pattern in C++ is a very bad thing.
If you want to close over values, copy it.
Moving out of named objects is also a recipe for disaster.
I'm blind and posting just the screenshots without the code in at least alt text or caption means that I'm not part of the audience.