27 questions
2
votes
1
answer
149
views
Compile-time manipulation of std::source_location::current()
I want to write a function that can obtain caller's function name, or at least its length, at compile time. I think obtaining std::source_location::current() is close to what I want and currently I'm ...
- 578
0
votes
0
answers
18
views
Printing std::source_location attributes in __cyg_profile_func_enter causes segfault?
I'm playing around with -finstrument-functions, and I'm running into things I don't understand
Let's take the following dead-simple program
// main.cc
#include <iostream>
#include <...
- 1
5
votes
2
answers
188
views
Is std::source_location guaranteed to reuse the same object?
My question is: If std::source_location::current() is called multiple times for the same location, is the std::source_location object guaranteed to be the same for every call?
In other words, given ...
- 479
-1
votes
1
answer
208
views
How to get data member names with source_location::function_name
After reading this source (and also my answer) and this source, I got the impression that we can use std::source_location::function_name to extract names of data members.
Let's say we are given some ...
- 713
-1
votes
2
answers
284
views
c++ string formatting function requiring constant expression to be used inside a logging function
I'm trying to create a logging function, that will write formatted string to a buffer. The function should automatically add source code location to the formatted string using std::source_location. ...
- 11
0
votes
0
answers
85
views
C++ correct usage of std::source_location [duplicate]
I'm trying to use std::source_location in combination with a logging mechanism.
However it turns out that std::source_location points to the wrong location.
For reference the compiler explorer link
...
- 1,041
3
votes
3
answers
939
views
constructing std::source_location with custom values
I am integrating a third-party library into my project. The library provides hooks to redirect its log messages and provides a struct with file, line, severity, message, etc. My project uses std::...
- 123
1
vote
0
answers
266
views
C++20 source_location template non-type parameter
I was trying to figure out ways to use std::source_location::current(), when I stumbled upon this particular answer for a thread.
I tried running the code on godbolt with x86-64 gcc 13.1 and -O3 -std=...
- 718
0
votes
2
answers
3k
views
How can I pass CMake's CMAKE_SOURCE_DIR to C++ source files?
In my C++ program I use std::source_location for log output. The printed path is currently absolute. The project is built with CMake. I want to shorten the std::source_location path according to the ...
- 6,415
4
votes
1
answer
150
views
Source location at call site and nttps: strange results and possible compiler bug?
Consider the following code that uses source_location:
// Preamble
#include <iostream>
#include <source_location>
// Using a function
constexpr std::size_t function(
std::size_t line =...
- 61.1k
0
votes
1
answer
277
views
Replacing __LINE__ and __FUNCSIG__ with the new std::source_location in a macro
C++20 added std::source_location as a replacement for the debugging macros __LINE__, __FILE__, etc.
This is great. I have a macro that builds up a variable declaration in order to log and profile a ...
- 11k
0
votes
1
answer
587
views
operator[] caller's site source location current workaround
sadly, the current source location can't be used directly in the parameter list of operator[], as this operator has to have only one argument. However, is there a workaround so I can get the callers ...
- 101
0
votes
1
answer
471
views
How to disable copy elision for constructors with std::source_location?
I am trying to add instrumentation to a widely used template class in my product. I am currently on VS 2019 (16.10.4) with /std:c++17. The new feature of std::source_location is a great addition for ...
- 4,471
2
votes
1
answer
407
views
Combining ranges adaptors and std::source_location got strange results
Consider the following useless code:
#include <ranges>
#include <source_location>
#include <iostream>
int main() {
auto lines = std::views::iota(0, 5)
| std::views::...
- 46.7k
1
vote
0
answers
50
views
source_location is not a member of std [duplicate]
I'm getting this error "source_location is not a member of std" in this simple program and I have no idea why. I'm trying to work with source location but cannot get the header included ...
2
votes
1
answer
786
views
How to get a source location from the function as argument without using static member function `current`?
I want to my function get_source to return a std::source_location type by taking a another function as an argument.
For example, I have a function named helloMessage and sumOf with the following ...
- 2,278
6
votes
1
answer
347
views
C++20 std::source_location yield different column numbers between free function and template functions
Consider the template function g() and free function f():
#include <iostream>
#include <source_location>
auto g(auto...) {
std::cout << std::source_location::current().column() <&...
- 46.7k
4
votes
1
answer
1k
views
std::source_location as non type template parameter
In my infinite quest to push limits of what can be used as non type template parameter I was trying to see if I can use std::source_location as non type template parameter.
That failed with a weird ...
- 30.9k
1
vote
0
answers
553
views
source_location::current() evaluated as default non-type template argument
[support.srcloc] introduces source_location::current:
Any call to current that appears as a default argument ([dcl.fct.default]), or as a subexpression thereof, should correspond to the location of ...
- 2,399
3
votes
2
answers
672
views
consteval wrapper vs. source_location
I tried the following first variant using GCC10 in C++20 mode:
consteval std::experimental::source_location there()
{
return std::experimental::source_location::current(); // Line 3
}
void f(const ...
- 9,384
0
votes
0
answers
35
views
Why are std::source_location's getters not marked as [[nodiscard]]? [duplicate]
According to:
https://en.cppreference.com/w/cpp/utility/source_location
the getters aren't marked as [[nodiscard]].
constexpr uint_least32_t line() const noexcept;
constexpr uint_least32_t ...
110
votes
2
answers
12k
views
Does C++20 mandate source code being stored in files?
A slightly strange question, however, if I remember correctly, C++ source code doesn't require a file system to store its files.
Having a compiler that scans handwritten papers via a camera would be ...
- 11.5k
80
votes
8
answers
10k
views
How to use source_location in a variadic template function?
The C++20 feature std::source_location is used to capture information about the context in which a function is called.
When I try to use it with a variadic template function, I encountered a problem: ...
- 20.9k
1
vote
3
answers
333
views
Is it possible to make macros that are default arguments expand at call site?
#include <stdio.h>
void print(int a = __LINE__){printf("hello %d\n", a);}
void main(){
print();
print();
print();
print();
}
The __LINE__ macro in this case expands to 3, so the print ...
- 2,866
8
votes
1
answer
2k
views
std::experimental::source_location at compile time
std::experimental::source_location will probably be added to the C++ standard at some point. I'm wondering if it possible to get the location information into the compile-time realm. Essentially, I ...
- 3,062
2
votes
1
answer
2k
views
std::experimental::source_location implementation in visual studio
A reasonably conforming version of std::experimental::source_location can be implemented in gcc with __builtin_FILE(), __builtin_LINE(), etc. Do similar intrinsics exist in Visual Studio 2017? Or is ...
- 702
16
votes
1
answer
7k
views
How could std::experimental::source_location be implemented?
C++ Extensions for Library Fundamentals, Version 2 (N4564) introduces the type std::experimental::source_location.
§ 14.1.2 [reflection.src_loc.creation] says:
static constexpr source_location ...
- 25.5k