build: libc++ support added

conanfile.py

@@ -103,7 +103,7 @@ class UnitsConan(ConanFile):
     #         del self.options.build_docs
 
     def requirements(self):
-        if self.settings.compiler == "clang":
+        if self.settings.compiler == "clang" and self.settings.compiler.libcxx == "libc++":
             self.requires("range-v3/0.11.0")
 
     def build_requirements(self):

example/CMakeLists.txt

@@ -43,6 +43,7 @@ add_example(avg_speed)
 add_example(hello_units)
 add_example(total_energy)
 
+if(NOT UNITS_LIBCXX)
     add_executable(glide_computer
         geographic.cpp geographic.h
         glide_computer.cpp glide_computer.h
@@ -50,13 +51,12 @@ add_executable(glide_computer
     )
     target_link_libraries(glide_computer PRIVATE mp-units::mp-units)
 
-# TODO "atomic constraint should be a constant expression" error in std::invocable
-
     find_package(linear_algebra CONFIG REQUIRED)
     add_example(linear_algebra)
     target_link_libraries(linear_algebra
         PRIVATE
             linear_algebra::linear_algebra
     )
+endif()
 
 add_subdirectory(alternative_namespaces)

src/CMakeLists.txt

@@ -30,8 +30,21 @@ project(mp-units
 set(UNITS_DOWNCAST_MODE ON CACHE STRING "Select downcasting mode")
 set_property(CACHE UNITS_DOWNCAST_MODE PROPERTY STRINGS AUTO ON OFF)
 
-# set path to custom cmake modules
-list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/../cmake")
+# check if libc++ is being used
+if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    message(CHECK_START "Checking if libc++ is being used")
+    list(APPEND CMAKE_MESSAGE_INDENT "  ")
+
+    include(CheckSymbolExists)
+    check_symbol_exists(_LIBCPP_VERSION "ciso646" UNITS_LIBCXX)
+
+    list(POP_BACK CMAKE_MESSAGE_INDENT)
+    if(UNITS_LIBCXX)
+        message(CHECK_PASS "found")
+    else()
+        message(CHECK_FAIL "not found")
+    endif()
+endif()
 
 find_package(fmt CONFIG REQUIRED)
 find_package(gsl-lite CONFIG REQUIRED)
@@ -51,11 +64,13 @@ target_include_directories(mp-units
 )
 
 if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+    if(UNITS_LIBCXX)
         find_package(range-v3)
         target_link_libraries(mp-units
             INTERFACE
                 range-v3::range-v3
         )
+    endif()
 elseif(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
     target_compile_options(mp-units
         INTERFACE

src/include/units/bits/external/hacks.h

@@ -31,15 +31,24 @@
 #define COMP_MSVC _MSC_VER
 #endif
 
-#if defined(COMP_CLANG) && !defined(UNITS_LIBCXX)
-#define UNITS_LIBCXX 0
+#if COMP_CLANG
+
+#include <ciso646>
+#if _LIBCPP_VERSION
+#define UNITS_LIBCXX _LIBCPP_VERSION
 #endif
 
-#if COMP_CLANG && UNITS_LIBCXX
+#endif
+
+#if COMP_CLANG == 12 && UNITS_LIBCXX
 
 #include <concepts/compare.hpp>
 #include <concepts/concepts.hpp>
 #include <range/v3/functional/comparisons.hpp>
+#include <range/v3/iterator.hpp>
+#include <range/v3/range/concepts.hpp>
+#include <range/v3/algorithm/lower_bound.hpp>
+#include <range/v3/algorithm/transform.hpp>
 
 #endif
 
@@ -67,35 +76,46 @@ concept default_constructible = constructible_from<T>;
 #elif COMP_CLANG && UNITS_LIBCXX
 
 // concepts
-using concepts::three_way_comparable;
-using concepts::three_way_comparable_with;
-// using concepts::common_reference_with;
 using concepts::common_with;
 using concepts::constructible_from;
 using concepts::convertible_to;
-// using concepts::default_constructible;
+using concepts::copy_constructible;
 using concepts::derived_from;
-// using concepts::equality_comparable;
+using concepts::equality_comparable;
 using concepts::equality_comparable_with;
-// // using concepts::floating_point;
-// using concepts::integral;
+using concepts::integral;
+using concepts::move_constructible;
 using concepts::regular;
-// using concepts::same_as;
-// using concepts::totally_ordered;
-// using concepts::totally_ordered_with;
+using concepts::three_way_comparable;
+using concepts::three_way_comparable_with;
+using concepts::totally_ordered;
 
 using ranges::compare_three_way;
 
-// namespace ranges {
+namespace ranges {
 
-// using ::ranges::forward_range;
-// using ::ranges::range_value_t;
+using ::ranges::begin;
+using ::ranges::end;
+using ::ranges::distance;
 
-// }
+using ::ranges::forward_range;
+using ::ranges::input_range;
+using ::ranges::range_value_t;
 
-// // missing in Range-v3
-// template<class T>
-// concept floating_point = std::is_floating_point_v<T>;
+using ::ranges::lower_bound;
+using ::ranges::transform;
+
+}
+
+// missing in Range-v3
+template<class T>
+concept floating_point = std::is_floating_point_v<T>;
+
+template<class T>
+concept default_initializable =
+    std::constructible_from<T> &&
+    requires { T{}; } &&
+    requires { ::new (static_cast<void*>(nullptr)) T; };
 
 template<class F, class... Args>
 concept invocable =

test/unit_test/static/CMakeLists.txt

@@ -24,9 +24,13 @@ cmake_minimum_required(VERSION 3.2)
 
 add_library(unit_tests_static_truncating
     quantity_test.cpp
+)
+if(NOT UNITS_LIBCXX)
+    target_sources(unit_tests_static_truncating PRIVATE
         quantity_kind_test.cpp
         quantity_point_kind_test.cpp
     )
+endif()
 target_link_libraries(unit_tests_static_truncating
     PRIVATE
         mp-units::mp-units
@@ -41,7 +45,6 @@ add_library(unit_tests_static
     chrono_test.cpp
     concepts_test.cpp
     custom_rep_test_min_expl.cpp
-    custom_rep_test_min_impl.cpp
     custom_unit_test.cpp
     data_test.cpp
     dimension_op_test.cpp
@@ -50,7 +53,6 @@ add_library(unit_tests_static
     fps_test.cpp
     kind_test.cpp
     math_test.cpp
-    quantity_point_test.cpp
     ratio_test.cpp
     si_test.cpp
     si_cgs_test.cpp
@@ -61,6 +63,14 @@ add_library(unit_tests_static
     unit_test.cpp
     us_test.cpp
 )
+
+if(NOT UNITS_LIBCXX)
+    target_sources(unit_tests_static PRIVATE
+        custom_rep_test_min_impl.cpp
+        quantity_point_test.cpp
+    )
+endif()
+
 target_link_libraries(unit_tests_static
     PRIVATE
         unit_tests_static_truncating