////
Copyright 2019 Peter Dimov
Distributed under the Boost Software License, Version 1.0.
http://www.boost.org/LICENSE_1_0.txt
////

[#source_location_support]
# Source Location Support, <boost/assert/source_location.hpp>
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## Description

The header `<boost/assert/source_location.hpp>` defines `source_location`,
a class representing a source location and containing file, line, function
and column information. It's similar to `std::source_location` from {cpp}20,
but only requires {cpp}03.

The macro `BOOST_CURRENT_LOCATION` creates a `source_location` object
containing information about the current source location.

## Synopsis

```
namespace boost
{

struct source_location
{
  constexpr source_location() noexcept;
  constexpr source_location(char const* file, uint_least32_t line,
    char const* function, uint_least32_t column = 0) noexcept;

  constexpr char const* file_name() const noexcept;
  constexpr char const* function_name() const noexcept;
  constexpr uint_least32_t line() const noexcept;
  constexpr uint_least32_t column() const noexcept;
};

template<class E, class T>
  std::basic_ostream<E, T> &
  operator<<( std::basic_ostream<E, T> & os, source_location const & loc );

} // namespace boost

#define BOOST_CURRENT_LOCATION \
  ::boost::source_location(__FILE__, __LINE__, BOOST_CURRENT_FUNCTION)
```

## source_location

```
constexpr source_location() noexcept;
```

Effects: :: Constructs a `source_location` object for which `file_name()`
and `function_name()` return `"(unknown)"`, and `line()` and `column()`
return `0`.

```
constexpr source_location(char const* file, uint_least32_t line,
  char const* function, uint_least32_t column = 0) noexcept;
```

Effects: :: Constructs a `source_location` object for which `file_name()`
returns `file`, `function_name()` returns `function`, `line()` returns the
`line` argument and `column()` returns the `column` argument.

## operator<<

```
template<class E, class T>
  std::basic_ostream<E, T> &
  operator<<( std::basic_ostream<E, T> & os, source_location const & loc );
```

Effects: :: Outputs a string representation of `loc` to `os`.
Returns: :: `os`.

## BOOST_CURRENT_LOCATION

When `BOOST_DISABLE_CURRENT_LOCATION` is not defined, the definition of
`BOOST_CURRENT_LOCATION` is:

```
#define BOOST_CURRENT_LOCATION \
  ::boost::source_location(__FILE__, __LINE__, BOOST_CURRENT_FUNCTION)
```

Otherwise, `BOOST_CURRENT_LOCATION` is defined as:

```
#define BOOST_CURRENT_LOCATION ::boost::source_location()
```

This allows producing executables that contain no identifying information,
for security reasons.