Codechange: fmt (and std::format) do explicitly not support enums out-of-the-box

That it works for the version we have packaged it pure coincidence, as that is
one of the few versions that due to a bug allow it. So add the appropriate
template specialisations to support it out-of-the-box within OpenTTD.

CMakeLists.txt

@@ -250,7 +250,7 @@ endif()
 target_precompile_headers(openttd_lib
     PRIVATE
     src/stdafx.h
-    src/3rdparty/fmt/format.h
+    src/core/format.hpp
 )
 
 add_subdirectory(${CMAKE_SOURCE_DIR}/bin)

src/console_func.h

@@ -11,7 +11,7 @@
 #define CONSOLE_FUNC_H
 
 #include "console_type.h"
-#include "3rdparty/fmt/format.h"
+#include "core/format.hpp"
 
 /* console modes */
 extern IConsoleModes _iconsole_mode;

src/core/CMakeLists.txt

@@ -8,6 +8,7 @@ add_files(
     endian_func.hpp
     endian_type.hpp
     enum_type.hpp
+    format.hpp
     geometry_func.cpp
     geometry_func.hpp
     geometry_type.hpp

src/core/format.hpp

@@ -0,0 +1,44 @@
+/*
+ * This file is part of OpenTTD.
+ * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
+ * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** @file format.hpp String formatting functions and helpers. */
+
+#ifndef FORMAT_HPP
+#define FORMAT_HPP
+
+#include "../3rdparty/fmt/format.h"
+#include "strong_typedef_type.hpp"
+
+template <typename E, typename Char>
+struct fmt::formatter<E, Char, std::enable_if_t<std::is_enum<E>::value>> : fmt::formatter<typename std::underlying_type<E>::type> {
+	using underlying_type = typename std::underlying_type<E>::type;
+	using parent = typename fmt::formatter<underlying_type>;
+
+	constexpr fmt::format_parse_context::iterator parse(fmt::format_parse_context &ctx) {
+		return parent::parse(ctx);
+	}
+
+	fmt::format_context::iterator format(const E &e, format_context &ctx) const {
+		return parent::format(underlying_type(e), ctx);
+	}
+};
+
+template <typename T, typename Char>
+struct fmt::formatter<T, Char, std::enable_if_t<std::is_base_of<StrongTypedefBase, T>::value>> : fmt::formatter<typename T::Type> {
+	using underlying_type = typename T::Type;
+	using parent = typename fmt::formatter<underlying_type>;
+
+	constexpr fmt::format_parse_context::iterator parse(fmt::format_parse_context &ctx) {
+		return parent::parse(ctx);
+	}
+
+	fmt::format_context::iterator format(const T &t, format_context &ctx) const {
+		return parent::format(underlying_type(t), ctx);
+	}
+};
+
+#endif /* FORMAT_HPP */

src/debug.h

@@ -12,7 +12,7 @@
 
 #include "cpu.h"
 #include <chrono>
-#include "3rdparty/fmt/format.h"
+#include "core/format.hpp"
 
 /* Debugging messages policy:
  * These should be the severities used for direct Debug() calls

src/misc_gui.cpp

@@ -117,7 +117,7 @@ public:
 #else
 #	define LANDINFOD_LEVEL 1
 #endif
-		Debug(misc, LANDINFOD_LEVEL, "TILE: 0x{:x} ({},{})", tile, TileX(tile), TileY(tile));
+		Debug(misc, LANDINFOD_LEVEL, "TILE: 0x{:x} ({},{})", (TileIndex)tile, TileX(tile), TileY(tile));
 		Debug(misc, LANDINFOD_LEVEL, "type   = 0x{:x}", tile.type());
 		Debug(misc, LANDINFOD_LEVEL, "height = 0x{:x}", tile.height());
 		Debug(misc, LANDINFOD_LEVEL, "m1     = 0x{:x}", tile.m1());

src/os/unix/font_unix.cpp

@@ -148,7 +148,7 @@ bool SetFallbackFont(FontCacheSettings *settings, const char *language_isocode,
 			callback->SetFontNames(settings, (const char *)file);
 
 			bool missing = callback->FindMissingGlyphs();
-			Debug(fontcache, 1, "Font \"{}\" misses{} glyphs", file, missing ? "" : " no");
+			Debug(fontcache, 1, "Font \"{}\" misses{} glyphs", (char *)file, missing ? "" : " no");
 
 			if (!missing) {
 				best_weight = value;