All Questions
415
questions
1
vote
1
answer
83
views
consteval member function allowed?
I have this c++20/23 code:
#include <cstddef>
template <size_t N>
class Foo {
public:
consteval size_t size() noexcept { return N; }
size_t real_size() {
...
- 2,587
4
votes
1
answer
95
views
Why does operator() copy movable temporaries in Clang?
In the following C++23 program
struct A {
A() {}
A(A&&) = default;
void f(this A) {}
void operator() (this A) {}
};
int main() {
A{}.f(); // ok
A{}(); // Clang error
...
- 19.3k
4
votes
2
answers
110
views
Move elision in explicit object member functions
If one calls explicit object member function of a temporary, must the move of the temporary be elided in the explicit object parameter?
Consider the following example, where struct A has move ...
- 19.3k
1
vote
3
answers
110
views
Is std::move_only_function thread safe?
Is it safe to call a std::move_only_function object in one thread and replace the function it points to in another thread?
My code:
#include <future>
#include <functional>
int main() {
...
- 5,679
2
votes
1
answer
95
views
Overload resolution between ordinary and explicit object member functions
In the following test program, struct B has two member functions f, which can be called using B{}.f(): one ordinary f() and another with explicit object f(this A).
struct A {
int f() { return 1; }
...
- 19.3k
3
votes
1
answer
126
views
Explicit object member function with void parameter
According to cppreference since C++23
For a non-static non-virtual member function not declared with cv-qualifier or ref-qualifier, its first parameter, if not being a function parameter pack, can be ...
- 19.3k
0
votes
1
answer
86
views
/Fo Command Does Not Output Object When Compiling C++ std Module
Context
I am using Visual Studio 2022 v17.10.4
So I am attempting to make a script to make compiling C++ programs easier for me using the Visual Studio 2022 compiler. I found a textbook about ...
- 3
4
votes
0
answers
105
views
Run time depends on code after the measured part
Consider the following C++23 program (online).
#include <chrono>
#include <cstdio>
#include <print>
constexpr size_t NWrites = 10000000000;
#define DEST_STORAGE static
#define ...
- 2,723
4
votes
1
answer
83
views
Can you call virtual methods on a base class in a union when a derived class is active?
While std::variant is great for some use cases, it's a bit analogous to std::tuple in that you can't name each individual variant. Often a struct is better than a tuple.
I'm wondering if it's legal ...
- 4,362
-4
votes
0
answers
108
views
Why std::flat_set etc. lack of the merge support?
I don't understand why std::flat_set etc. lack merge member functions. There's already a perfect algo for implementing it — std::ranges::merge. And I know that while de jure time complexity is ...
5
votes
1
answer
295
views
Explicit object member function discrepancies between different compilers
I wrote the following program in c++23. Here I've overloaded member functions. But for all cases different compilers give different result as shown below in comment. As you can see I have three cases ...
- 1,118
1
vote
0
answers
69
views
Why is Clang rejecting this coroutine code?
Here's the code:
#include <generator>
std::generator<int> foo() {
int i{};
while (true) {
co_yield i++;
}
}
Clang 18.1.8 rejects it with
/usr/bin/../lib64/gcc/x86_64-...
- 26.7k
0
votes
1
answer
74
views
Is GCC correct in rejecting overload between ref-qualified and non-ref-qualified member function? [duplicate]
If I understand this correctly, [over.load] doesn't exist in c++23, and so what I read in [over.load]/2.3 should not be true anymore, so this code
struct Foo {
int const& bar() const;
int bar()...
- 26.7k
2
votes
1
answer
108
views
In C++ std::ranges, how do I build a map out of a views::join result?
I'm using GCC 14 in C+23 mode. In the following code, I create a view of views of pairs, which I then flatten with views::join and put into a vector:
auto c = std::ranges::views::iota(1, 5)
| ...
- 478
1
vote
1
answer
71
views
Calling a consteval function within if consteval causes error in non-constexpr context
The following code does not compile with g++ 14.1 or clang++ 18.1:
#include <type_traits>
consteval int
plusone(int n)
{
return n+1;
}
constexpr int
maybeplusone(int n)
{
if (std::...
- 4,362