std::source_location::current

 

C++

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Technical Specifications

 

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std::source_location

Member functions

Creation

source_location::source_location

source_location::current

Field Access

source_location::line

source_location::column

source_location::file_name

source_location::function_name

 

static consteval source_location current() noexcept;		(since C++20)

Constructs a new source_location object corresponding to the location of the call site.

Parameters

(none)

Return value

If current() is invoked directly (via a function call that names current()), it returns a source_location object with implementation-defined values representing the location of the call. The values should be affected by the #line preprocessor directive in the same manner as the predefined macros __LINE__ and __FILE__.

If current() is used in a default member initializer, the return value corresponds to the location of the constructor or aggregate initialization that initializes the data member.

If current() is used in a default argument, the return value will correspond to the location of the call to current() at the call site.

If current() is invoked in any other manner, the return value is unspecified.

Notes

std::source_location::current typically requires compiler's built-in implementation.

Example

Run this code

#include <source_location>
#include <iostream>
 
struct src_rec {
    std::source_location srcl = std::source_location::current();
    int dummy = 0;
 
    src_rec(std::source_location loc = std::source_location::current()) :
        srcl(loc)    // values of member refer to the location of the calling function
    {}
    src_rec(int i) : // values of member refer to this location
        dummy(i)
    {}
    src_rec(double)  // values of member refer to this location
    {}
};
 
std::source_location src_clone(std::source_location a = std::source_location::current())
{
    return a;
}
 
std::source_location src_make()
{
    std::source_location b = std::source_location::current();
    return b;
}
 
int main()
{
    src_rec srec0;
    src_rec srec1(0);
    src_rec srec2(0.0);
    auto s0 = std::source_location::current();
    auto s1 = src_clone(s0);
    auto s2 = src_clone();
    auto s3 = src_make();
 
    std::cout
        << srec0.srcl.line() << ' ' << srec0.srcl.function_name() << '\n'
        << srec1.srcl.line() << ' ' << srec1.srcl.function_name() << '\n'
        << srec2.srcl.line() << ' ' << srec2.srcl.function_name() << '\n'
        << s0.line() << ' ' << s0.function_name() << '\n'
        << s1.line() << ' ' << s1.function_name() << '\n'
        << s2.line() << ' ' << s2.function_name() << '\n'
        << s3.line() << ' ' << s3.function_name() << '\n';
}

Possible output:

31 main
12 src_rec
15 src_rec
34 main
34 main
36 main
25 src_make

See also

(constructor)

constructs a new source_location with implementation-defined values (public member function)