[libcxx] Add C++20 source_location header

[andreasfertig]

Summary

This patch adds the C++20 header <source_location>.

[mclow.lists]

A couple of quick comments, more to come.

libcxx/test/libcxx/support/source_location.pass.cpp

8

This test needs an XFAIL for pre-c++20 tests

10

tests that are not libc++ specific go into test/std, not test/libcxx

[andreasfertig]

Add XFAIL and move test from test/libcxx to test/std.

[andreasfertig]

Correct copy&paste left-over in header regex -> source_location.

[curdeius]

Please take a look at the discussion in https://reviews.llvm.org/D80376 that has been put on standby because the desired ABI needs compiler support.

[andreasfertig]

In D85466#2202008, @curdeius wrote:

Please take a look at the discussion in https://reviews.llvm.org/D80376 that has been put on standby because the desired ABI needs compiler support.

Thanks! I didn't knew that. I looked at your version which comes with even more tests and more feedback. It doesn't make sense to proceed this one here. How can I abandon this?

libcxx/docs/FeatureTestMacroTable.rst

.. table:: Current Status
     ``__cpp_lib_is_constant_evaluated``               ``201811L``      
     ------------------------------------------------- -----------------
     ``__cpp_lib_list_remove_return_type``             ``201806L``      
     ------------------------------------------------- -----------------
     ``__cpp_lib_math_constants``                      ``201907L``      
     ------------------------------------------------- -----------------
     ``__cpp_lib_ranges``                              *unimplemented*  
     ------------------------------------------------- -----------------
+    ``__cpp_lib_source_location``                     ``201907L``
+    ------------------------------------------------- -----------------
     ``__cpp_lib_span``                                ``202002L``      
     ------------------------------------------------- -----------------
     ``__cpp_lib_three_way_comparison``                *unimplemented*  
     ------------------------------------------------- -----------------
     ``__cpp_lib_to_array``                            ``201907L``      
     ================================================= =================
 
 

libcxx/include/CMakeLists.txt

set(files
   random
   ratio
   regex
   scoped_allocator
   semaphore
   set
   setjmp.h
   shared_mutex
+  source_location
   span
   sstream
   stack
   stdbool.h
   stddef.h
   stdexcept
   stdint.h
   stdio.h

libcxx/include/module.modulemap

module semaphore {
     header "semaphore"
     export *
   }
   module set {
     header "set"
     export initializer_list
     export *
   }
+  module source_location {
+    requires cplusplus20
+    header "source_location"
+    export *
+  }
   module sstream {
     header "sstream"
     // FIXME: should re-export istream, ostream, ios, streambuf, string?
     export *
   }
   module stack {
     header "stack"
     export initializer_list

libcxx/include/source_location

+// -*- C++ -*-
+//===--------------------------- regex ------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_SOURCE_LOCATION
+#define _LIBCPP_SOURCE_LOCATION
+
+/*
+    source_location synopsis
+
+namespace std {
+struct source_location 
+{
+    // source_location construction
+    static consteval source_location current() noexcept;
+    constexpr source_location() noexcept;
+
+    // source_location field access
+    constexpr uint_least32_t line() const noexcept;
+    constexpr uint_least32_t column() const noexcept;
+    constexpr const char* file_name() const noexcept;
+    constexpr const char* function_name() const noexcept;
+
+private:
+    uint_least32_t line_;
+    uint_least32_t column_;
+    const char* file_name_;
+    const char* function_name_;
+};
+
+}   // std
+
+*/
+
+#include <__config>
+
+#if _LIBCPP_STD_VER > 17
+
+#include <cstdint>
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+struct source_location {
+  // source_location construction
+  static consteval source_location
+  current(uint_least32_t line = __builtin_LINE(),
+          uint_least32_t column = __builtin_COLUMN(),
+          const char* file_name = __builtin_FILE(),
+          const char* function_name = __builtin_FUNCTION()) noexcept {
+    source_location loc{};
+    loc.line_ = line;
+    loc.column_ = column;
+    loc.file_name_ = file_name;
+    loc.function_name_ = function_name;
+
+    return loc;
+  }
+
+  constexpr source_location() noexcept = default;
+
+  // source_location field access
+  constexpr uint_least32_t line() const noexcept { return line_; }
+  constexpr uint_least32_t column() const noexcept { return column_; }
+  constexpr const char* file_name() const noexcept { return file_name_; }
+  constexpr const char* function_name() const noexcept {
+    return function_name_;
+  }
+
+private:
+  uint_least32_t line_;
+  uint_least32_t column_;
+  const char* file_name_{""};
+  const char* function_name_{""};
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER > 17
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP_SOURCE_LOCATION

libcxx/include/version

 __cpp_lib_result_of_sfinae                              201210L <functional> <type_traits>
 __cpp_lib_robust_nonmodifying_seq_ops                   201304L <algorithm>
 __cpp_lib_sample                                        201603L <algorithm>
 __cpp_lib_scoped_lock                                   201703L <mutex>
 __cpp_lib_shared_mutex                                  201505L <shared_mutex>
 __cpp_lib_shared_ptr_arrays                             201611L <memory>
 __cpp_lib_shared_ptr_weak_type                          201606L <memory>
 __cpp_lib_shared_timed_mutex                            201402L <shared_mutex>
+__cpp_lib_source_location                               201907L <source_location>
 __cpp_lib_span                                          202002L <span>
 __cpp_lib_string_udls                                   201304L <string>
 __cpp_lib_string_view                                   201606L <string> <string_view>
 __cpp_lib_three_way_comparison                          201711L <compare>
 __cpp_lib_to_array                                      201907L <array>
 __cpp_lib_to_chars                                      201611L <utility>
 __cpp_lib_transformation_trait_aliases                  201304L <type_traits>
 __cpp_lib_transparent_operators                         201510L <functional>

 # if !defined(_LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED)
 #   define __cpp_lib_is_constant_evaluated              201811L
 # endif
 # define __cpp_lib_list_remove_return_type              201806L
 # if defined(__cpp_concepts) && __cpp_concepts >= 201811L
 #   define __cpp_lib_math_constants                     201907L
 # endif
 // # define __cpp_lib_ranges                               201811L
+# define __cpp_lib_source_location                      201907L
 # define __cpp_lib_span                                 202002L
 // # define __cpp_lib_three_way_comparison                 201711L
 # define __cpp_lib_to_array                             201907L
 #endif
 
 #endif // _LIBCPP_VERSIONH

libcxx/test/libcxx/double_include.sh.cpp

 #include <ratio>
 #include <regex>
 #include <scoped_allocator>
 #include <set>
 #include <setjmp.h>
 #ifndef _LIBCPP_HAS_NO_THREADS
 #include <shared_mutex>
 #endif
+#if __cplusplus >= 202002L
+#include <source_location>
+#endif
 #include <span>
 #include <sstream>
 #include <stack>
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdexcept>
 #include <stdint.h>
 #include <stdio.h>

libcxx/test/libcxx/support/source_location.pass.cpp

+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+
+// <source_location>
+
+#include <source_location>
+#include <type_traits>
+#include <cassert>
+
+#include "test_macros.h"
+
+#include <cassert>
+#include <cstring>
+#include <string>
+#include <type_traits>
+
+#include "source_location"
+
+// [support.srcloc.class] p1.1
+static_assert(std::is_nothrow_move_constructible_v<std::source_location>);
+// [support.srcloc.class] p1.2
+static_assert(std::is_nothrow_move_assignable_v<std::source_location>);
+// [support.srcloc.class] p1.3
+static_assert(std::is_nothrow_swappable_v<std::source_location>);
+
+constexpr auto f(std::source_location a = std::source_location::current()) {
+  return a;
+}
+
+int main(int, char**) {
+  // [support.srcloc.class] p1 Cpp17DefaultConstructible
+  {
+    std::source_location t;
+    std::source_location u{};
+    std::source_location tt = std::source_location();
+    std::source_location uu = std::source_location{};
+  }
+
+  // [support.srcloc.class] p1 Cpp17CopyConstructible
+  {
+    std::source_location v;
+    [[maybe_unused]] std::source_location t = v;
+    [[maybe_unused]] std::source_location u(v);
+  }
+
+  // [support.srcloc.class] p1 Cpp17CopyAssignable
+  {
+    std::source_location t;
+    std::source_location v;
+    t = v;
+    assert(t.line() == v.line());
+    assert(t.column() == v.column());
+    assert(strcmp(t.file_name(), v.file_name()) == 0);
+    assert(strcmp(t.function_name(), v.function_name()) == 0);
+  }
+
+  // [support.srcloc.class] p1 Cpp17Destructible
+  {
+    std::source_location u;
+    u.~source_location();
+  }
+
+  // [support.srcloc.class] p3
+  {
+    std::source_location rhs;
+    const auto line = rhs.line();
+    const auto column = rhs.column();
+    const std::string file_name =
+        rhs.file_name(); // This covers  [support.srcloc.class] p2
+    const std::string function_name =
+        rhs.function_name(); // This covers  [support.srcloc.class] p2
+    std::source_location lhs = std::move(rhs);
+
+    // [support.srcloc.class] p3.1
+    assert(strcmp(lhs.file_name(), file_name.c_str()) == 0);
+    // [support.srcloc.class] p3.2
+    assert(strcmp(lhs.function_name(), function_name.c_str()) == 0);
+    // [support.srcloc.class] p3.3
+    assert(lhs.line() == line);
+    // [support.srcloc.class] p3.4
+    assert(lhs.column() == column);
+  }
+
+  // [support.srcloc.cons] 3 ensure at least line matches
+  {
+    constexpr auto line = __LINE__ + 1;
+    constexpr auto sLocLine = f();
+    static_assert(line == sLocLine.line());
+  }
+
+  // [support.srcloc.cons] 3 ensure at least line matches
+  {
+    constexpr std::source_location c = std::source_location::current();
+    constexpr auto sLocLine = f(c);
+    static_assert(c.line() == sLocLine.line());
+  }
+
+  return 0;
+}

libcxx/utils/generate_feature_test_macro_components.py

feature_test_macros = sorted([ add_version_header(x) for x in [
    "headers": ["bit"],
    },
   {"name": "__cpp_lib_to_array",
    "values": {
      "c++2a": int(201907),
    },
    "headers": ["array"],
    },
+  {"name": "__cpp_lib_source_location",
+   "values": {
+     "c++2a": int(201907),
+   },
+   "headers": ["span"],
+   },
   {"name": "__cpp_lib_span",
    "values": {
      "c++2a": int(202002),
    },
    "headers": ["span"],
    },
   {"name": "__cpp_lib_math_constants",
    "values": {