feat: constexpr_format added

src/core/CMakeLists.txt

@@ -88,6 +88,7 @@ if(NOT ${projectPrefix}API_FREESTANDING)
                BASE_DIRS
                ${CMAKE_CURRENT_SOURCE_DIR}/include
                FILES
+               include/mp-units/bits/constexpr_format.h
                include/mp-units/bits/fmt.h
                include/mp-units/bits/format.h
                include/mp-units/bits/ostream.h

src/core/include/mp-units/bits/constexpr_format.h

@@ -0,0 +1,49 @@
+// The MIT License (MIT)
+//
+// Copyright (c) 2018 Mateusz Pusz
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+#pragma once
+
+#include <mp-units/bits/hacks.h>  // IWYU pragma: keep
+
+#ifndef MP_UNITS_IN_MODULE_INTERFACE
+#include <mp-units/ext/format.h>
+#ifdef MP_UNITS_IMPORT_STD
+import std;
+#else
+#include <string>
+#endif
+#endif
+
+namespace mp_units::detail {
+
+[[nodiscard]] consteval std::string constexpr_format([[maybe_unused]] auto fmt, [[maybe_unused]] auto&&... args)
+{
+  std::string text;
+#if MP_UNITS_USE_FMTLIB
+  fmt::format_to(std::back_inserter(text), fmt, std::forward<decltype(args)>(args)...);
+#else
+  static_assert(false, "`std::format` is not `constexpr` yet");
+#endif
+  return text;
+};
+
+}  // namespace mp_units::detail

src/core/include/mp-units/ext/format.h

@@ -33,6 +33,7 @@
 MP_UNITS_DIAGNOSTIC_PUSH
 MP_UNITS_DIAGNOSTIC_IGNORE_UNREACHABLE
 MP_UNITS_DIAGNOSTIC_IGNORE_SHADOW
+#include <fmt/compile.h>
 #include <fmt/format.h>
 MP_UNITS_DIAGNOSTIC_POP
 #else  // MP_UNITS_USE_FMTLIB