The compiler deduces U as std::string& or as std::string depending on value category of the argument:
template <class U>
void f(U&& s)
{
static_assert(std::is_same_v<U, const std::string&>);
std::cout << std::forward<U>(s) << std::endl;
}
int main()
{
const std::string& s = "abc";
f(s);
return 0;
}
There was qtquickcontrols2.conf in the root directory of my app sources with the following content:
; This file can be edited to change the style of the application
; See Styling Qt Quick Controls 2 in the documentation for details:
; https://doc.qt.io/qt-6/qtquickcontrols2-styles.html
[Controls]
;Style=Default
;Style=Universal
;Style=Material
Style=Fusion
;Style=iOS
[Universal]
Theme=Light
Accent=Steel
[Material]
;Theme=Light
Theme=Dark
;Accent=BlueGrey
;Primary=BlueGray
I built BOOST with MSVC2022 in a similar way I built it with MSVC2017 except that I did install, but not stage:
cd C:\dev\repos\boost_1_80_0
set OPENSSL_ROOT_DIR=C:/dev/libs/OpenSSL
set OPENSSL_USE_STATIC_LIBS=ON
bootstrap.bat
b2 install --prefix=C:/dev/libs/boost_1_80_0 --toolset=msvc-14.3 link=static runtime-link=static variant=release address-model=64
b2 install --prefix=C:/dev/libs/boost_1_80_0 --toolset=msvc-14.3 link=static runtime-link=static variant=debug address-model=64
I am not sure if OPENSSL_ROOT_DIR takse an effect because boost::asio is header-only (but it depends on system and thread modules).
At least this compiles and works:
#include <iostream>
#include <memory>
#include <string>
template <class T>
std::shared_ptr<T> make_instance();
template <class T> requires std::is_default_constructible_v<T>
std::shared_ptr<T> make_instance()
{
return std::make_shared<T>();
}
When I switched to PHP 7.4 I forgot to specify sendmail_path parameter in php.ini and my contact form stopped working. Today I found sendmail_path parameter in PHP 7.0:
cd /etc/php
find . -name "php.ini"
./7.0/fpm/php.ini
./7.0/cgi/php.ini
./7.0/cli/php.ini
./7.4/fpm/php.ini
./7.4/cli/php.ini
grep sendmail ./7.0/fpm/php.ini
sendmail_path = "/usr/sbin/sendmail -t -f *****@yandex.ru -i"
There is no difference between lines 82 and 92 in the code below with both MSVC2022 and GCC11:
#include <utility>
#include <stdexcept>
#include <iostream>
struct Object
{
virtual const char* name() = 0;
virtual ~Object() = default;
};
struct A : public Object
{
const char* name() override
{
return "A";
}
};
It converts only from non-virtual base class subobject:
struct B
{
virtual ~B() {};
};
struct D : public virtual B { };
int main()
{
D d;
B& br1 = d;
// cannot convert a 'B*' to a 'D*'; conversion from a virtual base class is implied
// static_cast<D&>(br1);
dynamic_cast<D&>(br1);
return 0;
}
In the vernacular they say stack and heap, but the standard call this automatic and dynamic:
The parameter or print function is a forwarding reference because the range can change while being iterated, but the current value is l-value reference:
#include <string>
#include <vector>
#include <ranges>
#include <iostream>
template <class R, class Value>
concept range_over = std::ranges::range<R> &&
std::same_as<std::ranges::range_value_t<R>, Value>;
template <range_over<std::string> Range>
void print(Range&& range)
{
for (const std::string& val : range)
{
std::cout << val << std::endl;
}
}
