macOS: don't use built-in filesystem implementation on Xcode 12 so we can support older macOS versions

src/CompilerSupport/filesystem.h

@@ -1,9 +1,11 @@
 #pragma once
 
-#if defined(__cplusplus) && __cplusplus >= 201703L && defined(__has_include) && __has_include(<filesystem>)
+#if !__APPLE__ /* don't use built-in filesystem implementation so we can support older macOS versions */ && \
+defined(__cplusplus) && __cplusplus >= 201703L && defined(__has_include) && __has_include(<filesystem>)
     #include <filesystem>
     namespace fs = std::filesystem;
 #else
+	#define LEGACY_FILESYSTEM_IMPLEMENTATION 1
     #include "CompilerSupport/filesystem_implementation.hpp"
     namespace fs = ghc::filesystem;
 #endif

src/Files/Files.cpp

@@ -19,7 +19,7 @@ using namespace Pomme::Files;
 
 #define LOG POMME_GENLOG(POMME_DEBUG_FILES, "FILE")
 
-constexpr int MAX_VOLUMES = 32767;  // vRefNum is a signed short
+//constexpr int MAX_VOLUMES = 32767;  // vRefNum is a signed short -- commented out for now because we only have one volume
 
 //-----------------------------------------------------------------------------
 // State

src/Files/HostVolume.cpp

@@ -151,6 +151,18 @@ OSErr HostVolume::OpenFork(const FSSpec* spec, ForkType forkType, char permissio
 			bool isAppleDoubleFile;
 		} candidates[] =
 		{
+#if LEGACY_FILESYSTEM_IMPLEMENTATION
+			// "._NAME": ADF contained in zips created by macOS's built-in archiver
+			{ "._" + specName, true },
+
+			// "NAME.rsrc": ADF extracted from StuffIt/CompactPro archives by unar
+			{ specName + ".rsrc", true },
+
+#if __APPLE__
+			// "NAME/..namedfork/rsrc": macOS-specific way to access true resource forks (not ADF)
+			{ specName + "/..namedfork/rsrc", false },
+#endif
+#else
 			// "._NAME": ADF contained in zips created by macOS's built-in archiver
 			{ u8"._" + specName, true },
 
@@ -160,6 +172,7 @@ OSErr HostVolume::OpenFork(const FSSpec* spec, ForkType forkType, char permissio
 #if __APPLE__
 			// "NAME/..namedfork/rsrc": macOS-specific way to access true resource forks (not ADF)
 			{ specName + u8"/..namedfork/rsrc", false },
+#endif
 #endif
 		};