26 files changed, 200 insertions, 68 deletions

diff --git a/.gitignore b/.gitignore
index bf237a7b3..4ceeab867 100644
--- a/.gitignore
+++ b/.gitignore
@@ -23,6 +23,8 @@ bld/
 [Bb]in/
 [Oo]bj/
 [Ll]og/
+vsxmake20*/
+vs20*/
 
 # Visual Studio Code options directory
 .vscode/
diff --git a/README.md b/README.md
index 055ecca3a..77dddfb80 100644
--- a/README.md
+++ b/README.md
@@ -55,11 +55,65 @@ You can then build from the command line:
 
 It's also possible to generate project files for Visual Studio via
 
-`d:\zen> xmake project -k vsxmake`
+`d:\zen> xmake project -k vsxmake -a x64`
 
 ## Building on Linux
 
-... coming soon
+The following instructions have been collated using Ubuntu 20.04.
+
+At the time of writing only GCC v11 supports the C++20 features used by Zen. As
+this version is not available in the default package repositories we need to
+get GCC from one of Ubuntu's toolchain repositories;
+
+```
+sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
+sudo apt install -y gcc-11
+gcc-11 --version
+```
+
+Next we need the `xmake` build system. For this we will download and install
+`xmake` as a `.deb` package. Check the project's release page for more up to
+date `.deb` files;
+
+```
+wget https://github.com/xmake-io/xmake/releases/download/v2.5.7/xmake-v2.5.7.amd64.deb
+sudo dpkg -i xmake-v2.5.7.amd64.deb
+xmake --version
+```
+
+For some of Zen's third party dependencies are provided by Microsoft's `vcpkg`
+C++ library manager. After cloning the project there is a initialisation step;
+
+```
+git clone https://github.com/microsoft/vcpkg.git ~/zen/vcpkg
+~/zen/vcpkg/bootstrap-vcpkg.sh
+```
+
+`xmake` uses an environment variable to find `vcpkg`. Alternatively this can be
+done by including `VCPKG_ROOT=...` on the command line when invoking `xmake`;
+
+```
+export VCPKG_ROOT=~/zen/vcpkg
+```
+
+Clone the Zen project and tell `xmake` to use the correct GCC version;
+
+```
+git clone https://github.com/EpicGames/zen.git ~/zen/main
+cd ~/zen/main
+xmake config --plat=linux --cxx=g++-11 --cc=gcc-11
+```
+
+Now we are ready to build Zen. The `--mode=debug` is optional. It has been
+included below to show how to change build variants. The `-y` skips `xmake` from
+prompting about updating `vcpkg` packages;
+
+```
+xmake config --mode=debug
+xmake build -y
+```
+
+The `xmake` flags `-vD` can be useful to diagnose `xmake` issues.
 
 ## Building on Mac
 
diff --git a/xmake.lua b/xmake.lua
index 9d44ec8d0..4f7612f72 100644
--- a/xmake.lua
+++ b/xmake.lua
@@ -46,6 +46,13 @@ if is_os("windows") then
     -- add_ldflags("/MAP")
 end
 
+if is_os("linux") then
+    add_cxxflags("-Wno-unused-variable")
+    add_cxxflags("-Wno-unused-parameter")
+    add_cxxflags("-Wno-strict-aliasing")
+    add_cxxflags("-Wno-implicit-fallthrough")
+end
+
 add_defines("USE_SENTRY=1")
 add_defines("ZEN_USE_MIMALLOC=1")
 
diff --git a/zencore/blake3.cpp b/zencore/blake3.cpp
index 663f21b6d..5869f19a3 100644
--- a/zencore/blake3.cpp
+++ b/zencore/blake3.cpp
@@ -8,7 +8,9 @@
 #include <zencore/zencore.h>
 
 #include "../3rdparty/BLAKE3/c/blake3.h"
-#pragma comment(lib, "blake3.lib")
+#if ZEN_PLATFORM_WINDOWS
+#	pragma comment(lib, "blake3.lib")
+#endif
 
 #include <string.h>
 
diff --git a/zencore/compactbinary.cpp b/zencore/compactbinary.cpp
index c4694733c..6a95ce555 100644
--- a/zencore/compactbinary.cpp
+++ b/zencore/compactbinary.cpp
@@ -87,7 +87,7 @@ TimeSpan::ToString(const char* Format) const
 
 	StringBuilder<128> Result;
 
-	Result.Append((Ticks < 0) ? '-' : '+');
+	Result.Append((int64_t(Ticks) < 0) ? '-' : '+');
 
 	while (*Format != '\0')
 	{
@@ -1838,11 +1838,11 @@ TEST_CASE("uson.json")
 			   << "ValueTwo";
 		CbObject Obj = Writer.Save();
 
-		StringBuilder<128>	   Sb;
-		const std::string_view JsonText = Obj.ToJson(Sb).ToView();
+		StringBuilder<128> Sb;
+		const char* JsonText = Obj.ToJson(Sb).Data();
 
 		std::string	 JsonError;
-		json11::Json Json = json11::Json::parse(JsonText.data(), JsonError);
+		json11::Json Json = json11::Json::parse(JsonText, JsonError);
 
 		const std::string ValueOne = Json["KeyOne"].string_value();
 		const std::string ValueTwo = Json["KeyTwo"].string_value();
@@ -1863,11 +1863,11 @@ TEST_CASE("uson.json")
 
 		CbObject Obj = Writer.Save();
 
-		StringBuilder<128>	   Sb;
-		const std::string_view JsonText = Obj.ToJson(Sb).ToView();
+		StringBuilder<128> Sb;
+		const char* JsonText = Obj.ToJson(Sb).Data();
 
 		std::string	 JsonError;
-		json11::Json Json = json11::Json::parse(JsonText.data(), JsonError);
+		json11::Json Json = json11::Json::parse(JsonText, JsonError);
 
 		const float	 FloatValue	 = float(Json["Float"].number_value());
 		const double DoubleValue = Json["Double"].number_value();
@@ -1888,11 +1888,11 @@ TEST_CASE("uson.json")
 
 		CbObject Obj = Writer.Save();
 
-		StringBuilder<128>	   Sb;
-		const std::string_view JsonText = Obj.ToJson(Sb).ToView();
+		StringBuilder<128> Sb;
+		const char* JsonText = Obj.ToJson(Sb).Data();
 
 		std::string	 JsonError;
-		json11::Json Json = json11::Json::parse(JsonText.data(), JsonError);
+		json11::Json Json = json11::Json::parse(JsonText, JsonError);
 
 		const double FloatValue	 = Json["FloatNan"].number_value();
 		const double DoubleValue = Json["DoubleNan"].number_value();
diff --git a/zencore/compactbinarybuilder.cpp b/zencore/compactbinarybuilder.cpp
index fa5b6a69b..3be24c149 100644
--- a/zencore/compactbinarybuilder.cpp
+++ b/zencore/compactbinarybuilder.cpp
@@ -985,7 +985,12 @@ TEST_CASE("usonbuilder.string")
 
 	SUBCASE("Non-ASCII String")
 	{
+#if ZEN_SIZEOF_WCHAR_T == 2
 		wchar_t Value[2] = {0xd83d, 0xde00};
+#else
+		wchar_t Value[1] = {0x1f600};
+#endif
+
 		Writer.AddString("\xf0\x9f\x98\x80"sv);
 		Writer.AddString(std::wstring_view(Value, ZEN_ARRAY_COUNT(Value)));
 		CbFieldIterator Fields = Writer.Save();
diff --git a/zencore/filesystem.cpp b/zencore/filesystem.cpp
index b8e8eff55..c3edf656e 100644
--- a/zencore/filesystem.cpp
+++ b/zencore/filesystem.cpp
@@ -505,7 +505,7 @@ WriteFile(std::filesystem::path Path, const IoBuffer* const* Data, size_t Buffer
 				ThrowSystemException(hRes, "File write failed for '{}'"_format(Path).c_str());
 			}
 #else
-			if (write(Fd, DataPtr, WriteSize) != WriteSize)
+			if (write(Fd, DataPtr, WriteSize) != int64_t(WriteSize))
 			{
 				ThrowLastError("File write failed for '{}'"_format(Path));
 			}
@@ -572,7 +572,9 @@ ReadFile(std::filesystem::path Path)
 	int Fd = open(Path.c_str(), O_RDONLY);
 	if (Fd < 0)
 	{
-		return FileContents{.ErrorCode = std::error_code(zen::GetLastError(), std::system_category())};
+		FileContents Ret;
+		Ret.ErrorCode = std::error_code(zen::GetLastError(), std::system_category());
+		return Ret;
 	}
 
 	static_assert(sizeof(decltype(stat::st_size)) == sizeof(uint64_t), "fstat() doesn't support large files");
@@ -731,7 +733,7 @@ FileSystemTraversal::TraverseFileSystem(const std::filesystem::path& RootDir, Tr
 		ThrowLastError("Failed to open directory for traversal: {}"_format(RootDir.c_str()));
 	}
 
-	for (struct dirent* Entry; Entry = readdir(Dir);)
+	for (struct dirent* Entry; (Entry = readdir(Dir));)
 	{
 		const char* FileName = Entry->d_name;
 
@@ -787,14 +789,15 @@ PathFromHandle(void* NativeHandle)
 
 	return FullPath;
 #elif ZEN_PLATFORM_LINUX
-	char Buffer[256];
-	sprintf(Buffer, "/proc/%d/fd/%d", getpid(), int(uintptr_t(NativeHandle)));
-	ssize_t BytesRead = readlink(Buffer, Buffer, sizeof(Buffer) - 1);
+	char Link[256];
+	char Path[64];
+	sprintf(Path, "/proc/%d/fd/%d", getpid(), int(uintptr_t(NativeHandle)));
+	ssize_t BytesRead = readlink(Path, Link, sizeof(Link) - 1);
 	if (BytesRead <= 0)
 		return std::filesystem::path();
 
-	Buffer[BytesRead] = '\0';
-	return Buffer;
+	Link[BytesRead] = '\0';
+	return Link;
 #else
 #	error Unimplemented platform
 #endif	// ZEN_PLATFORM_WINDOWS
@@ -809,14 +812,15 @@ GetRunningExecutablePath()
 
 	return {std::wstring_view(ExePath, PathLength)};
 #elif ZEN_PLATFORM_LINUX
-	char Buffer[256];
-	sprintf(Buffer, "/proc/%d/exe", getpid());
-	ssize_t BytesRead = readlink(Buffer, Buffer, sizeof(Buffer) - 1);
+	char Link[256];
+	char Path[64];
+	sprintf(Path, "/proc/%d/exe", getpid());
+	ssize_t BytesRead = readlink(Path, Link, sizeof(Link) - 1);
 	if (BytesRead < 0)
 		return {};
 
-	Buffer[BytesRead] = '\0';
-	return Buffer;
+	Link[BytesRead] = '\0';
+	return Link;
 #else
 #	error Unimplemented platform
 #endif	// ZEN_PLATFORM_WINDOWS
diff --git a/zencore/include/zencore/intmath.h b/zencore/include/zencore/intmath.h
index 7619e1950..0d0ceff16 100644
--- a/zencore/include/zencore/intmath.h
+++ b/zencore/include/zencore/intmath.h
@@ -107,7 +107,7 @@ FloorLog2(uint32_t Value)
 static inline uint32_t
 CountLeadingZeros(uint32_t Value)
 {
-	unsigned long Log2;
+	unsigned long Log2 = 0;
 	_BitScanReverse64(&Log2, (uint64_t(Value) << 1) | 1);
 	return 32 - Log2;
 }
@@ -115,7 +115,7 @@ CountLeadingZeros(uint32_t Value)
 static inline uint64_t
 FloorLog2_64(uint64_t Value)
 {
-	unsigned long Log2;
+	unsigned long Log2 = 0;
 	long		  Mask = -long(_BitScanReverse64(&Log2, Value) != 0);
 	return Log2 & Mask;
 }
@@ -123,7 +123,7 @@ FloorLog2_64(uint64_t Value)
 static inline uint64_t
 CountLeadingZeros64(uint64_t Value)
 {
-	unsigned long Log2;
+	unsigned long Log2 = 0;
 	long		  Mask = -long(_BitScanReverse64(&Log2, Value) != 0);
 	return ((63 - Log2) & Mask) | (64 & ~Mask);
 }
diff --git a/zencore/include/zencore/refcount.h b/zencore/include/zencore/refcount.h
index 1873ce48e..325863051 100644
--- a/zencore/include/zencore/refcount.h
+++ b/zencore/include/zencore/refcount.h
@@ -160,7 +160,7 @@ public:
 private:
 	T* m_Ref = nullptr;
 
-	template<class T>
+	template<class U>
 	friend class Ref;
 };
 
diff --git a/zencore/include/zencore/string.h b/zencore/include/zencore/string.h
index c205b199d..9f1bc39d0 100644
--- a/zencore/include/zencore/string.h
+++ b/zencore/include/zencore/string.h
@@ -424,7 +424,7 @@ public:
 	inline std::wstring_view ToView() const { return std::wstring_view{Data(), Size()}; }
 	inline std::wstring		 toString() const { return std::wstring{Data(), Size()}; }
 
-	inline StringBuilderImpl& operator<<(const std::u16string_view str) { return Append((const wchar_t*)str.data(), str.size()); }
+	inline StringBuilderImpl& operator<<(const std::wstring_view str) { return Append((const wchar_t*)str.data(), str.size()); }
 	inline StringBuilderImpl& operator<<(const wchar_t* str) { return Append(str); }
 	using StringBuilderImpl:: operator<<;
 };
diff --git a/zencore/include/zencore/thread.h b/zencore/include/zencore/thread.h
index 410ffbd1e..f677113a0 100644
--- a/zencore/include/zencore/thread.h
+++ b/zencore/include/zencore/thread.h
@@ -140,7 +140,7 @@ public:
 	ZENCORE_API bool			   Wait(int TimeoutMs = -1);
 	ZENCORE_API void			   Terminate(int ExitCode);
 	ZENCORE_API void			   Reset();
-	inline [[nodiscard]] int	   Pid() const { return m_Pid; }
+	[[nodiscard]] inline int	   Pid() const { return m_Pid; }
 
 private:
 	void* m_ProcessHandle = nullptr;
diff --git a/zencore/include/zencore/uid.h b/zencore/include/zencore/uid.h
index f4e9ab65a..d25aa8059 100644
--- a/zencore/include/zencore/uid.h
+++ b/zencore/include/zencore/uid.h
@@ -74,7 +74,7 @@ struct Oid
 		size_t operator()(const Oid& id) const
 		{
 			const size_t seed = id.OidBits[0];
-			return (seed << 6) + (seed >> 2) + 0x9e3779b9 + uint64_t(id.OidBits[1]) | (uint64_t(id.OidBits[2]) << 32);
+			return ((seed << 6) + (seed >> 2) + 0x9e3779b9 + uint64_t(id.OidBits[1])) | (uint64_t(id.OidBits[2]) << 32);
 		}
 	};
 
diff --git a/zencore/include/zencore/zencore.h b/zencore/include/zencore/zencore.h
index 136ed2944..3f92d7ac4 100644
--- a/zencore/include/zencore/zencore.h
+++ b/zencore/include/zencore/zencore.h
@@ -94,6 +94,13 @@
 
 #define ZEN_PLATFORM_SUPPORTS_UNALIGNED_LOADS 1
 
+#if defined(__SIZEOF_WCHAR_T__) && __SIZEOF_WCHAR_T__ == 4
+#	define ZEN_SIZEOF_WCHAR_T 4
+#else
+	static_assert(sizeof(wchar_t) == 2, "wchar_t is expected to be two bytes in size");
+#	define ZEN_SIZEOF_WCHAR_T 2
+#endif
+
 //////////////////////////////////////////////////////////////////////////
 // Assert
 //
@@ -213,9 +220,15 @@ ZENCORE_API void zencore_forcelinktests();
 //////////////////////////////////////////////////////////////////////////
 
 #if ZEN_COMPILER_MSC
-#	define ZEN_DISABLE_OPTIMIZATION_ACTUAL __pragma(optimize("", off))
+#	define ZEN_DISABLE_OPTIMIZATION_ACTUAL	__pragma(optimize("", off))
 #	define ZEN_ENABLE_OPTIMIZATION_ACTUAL	__pragma(optimize("", on))
-#else
+#elif ZEN_COMPILER_GCC
+#	define ZEN_DISABLE_OPTIMIZATION_ACTUAL	_Pragma( "GCC push_options" ) \
+											_Pragma( "GCC optimize (\"O0\")" )
+#	define ZEN_ENABLE_OPTIMIZATION_ACTUAL	_Pragma( "GCC pop_options" )
+#elif ZEN_COMPILER_CLANG
+#	define ZEN_DISABLE_OPTIMIZATION_ACTUAL	_Pragma("clang optimize off")
+#	define ZEN_ENABLE_OPTIMIZATION_ACTUAL	_Pragma("clang optimize on")
 #endif
 
 // Set up optimization control macros, now that we have both the build settings and the platform macros
diff --git a/zencore/stats.cpp b/zencore/stats.cpp
index 0c0647999..1bb6f6de0 100644
--- a/zencore/stats.cpp
+++ b/zencore/stats.cpp
@@ -227,7 +227,7 @@ UniformSample::Snapshot() const
 	uint64_t			ValuesSize = Size();
 	std::vector<double> Values(ValuesSize);
 
-	for (int i = 0; i < ValuesSize; ++i)
+	for (int i = 0, n = int(ValuesSize); i < n; ++i)
 	{
 		Values[i] = double(m_Values[i]);
 	}
diff --git a/zencore/string.cpp b/zencore/string.cpp
index 49824a910..7acdc16f0 100644
--- a/zencore/string.cpp
+++ b/zencore/string.cpp
@@ -30,6 +30,17 @@ utf16to8_impl(u16bit_iterator StartIt, u16bit_iterator EndIt, ::zen::StringBuild
 	}
 }
 
+template<typename u32bit_iterator>
+void
+utf32to8_impl(u32bit_iterator StartIt, u32bit_iterator EndIt, ::zen::StringBuilderBase& OutString)
+{
+	for (; StartIt != EndIt; ++StartIt)
+	{
+		wchar_t cp = *StartIt;
+		OutString.AppendCodepoint(cp);
+	}
+}
+
 //////////////////////////////////////////////////////////////////////////
 
 namespace zen {
@@ -76,7 +87,7 @@ FilepathFindExtension(const std::string_view& Path, const char* ExtensionToMatch
 
 	// Look for extension introducer ('.')
 
-	for (size_t i = PathLen - 1; i >= 0; --i)
+	for (int64_t i = PathLen - 1; i >= 0; --i)
 	{
 		if (Path[i] == '.')
 			return Path.data() + i;
@@ -164,26 +175,24 @@ Utf8ToWide(const std::u8string_view& Str8, WideStringBuilderBase& OutString)
 void
 WideToUtf8(const wchar_t* Wstr, StringBuilderBase& OutString)
 {
-	WideToUtf8(std::u16string_view{(char16_t*)Wstr}, OutString);
+	WideToUtf8(std::wstring_view{Wstr}, OutString);
 }
 
 void
 WideToUtf8(const std::wstring_view& Wstr, StringBuilderBase& OutString)
 {
-	WideToUtf8(std::u16string_view{(char16_t*)Wstr.data(), Wstr.size()}, OutString);
-}
-
-void
-WideToUtf8(const std::u16string_view& Wstr, StringBuilderBase& OutString)
-{
+#if ZEN_SIZEOF_WCHAR_T == 2
 	utf16to8_impl(begin(Wstr), end(Wstr), OutString);
+#else
+	utf32to8_impl(begin(Wstr), end(Wstr), OutString);
+#endif
 }
 
 std::string
 WideToUtf8(const wchar_t* Wstr)
 {
 	ExtendableStringBuilder<128> String;
-	WideToUtf8(std::u16string_view{(char16_t*)Wstr}, String);
+	WideToUtf8(std::wstring_view{Wstr}, String);
 
 	return String.c_str();
 }
@@ -192,7 +201,7 @@ std::string
 WideToUtf8(const std::wstring_view Wstr)
 {
 	ExtendableStringBuilder<128> String;
-	WideToUtf8(std::u16string_view{(char16_t*)Wstr.data(), Wstr.size()}, String);
+	WideToUtf8(std::wstring_view{Wstr.data(), Wstr.size()}, String);
 
 	return String.c_str();
 }
diff --git a/zencore/thread.cpp b/zencore/thread.cpp
index 20ab19f56..5aa0f2688 100644
--- a/zencore/thread.cpp
+++ b/zencore/thread.cpp
@@ -5,6 +5,7 @@
 #include <fmt/format.h>
 #include <zencore/except.h>
 #include <zencore/string.h>
+#include <zencore/testing.h>
 
 #if ZEN_PLATFORM_WINDOWS
 #	include <zencore/windows.h>
@@ -360,7 +361,9 @@ IsProcessRunning(int pid)
 
 	return true;
 #else
-	ZEN_NOT_IMPLEMENTED();
+	char Buffer[64];
+	sprintf(Buffer, "/proc/%d", pid);
+	return access(Buffer, F_OK) == 0;
 #endif
 }
 
@@ -389,9 +392,20 @@ Sleep(int ms)
 // Testing related code follows...
 //
 
+#if ZEN_WITH_TESTS
+
 void
 thread_forcelink()
 {
 }
 
+TEST_CASE("Thread")
+{
+	int Pid = GetCurrentProcessId();
+	CHECK(Pid > 0);
+	CHECK(IsProcessRunning(Pid));
+}
+
+#endif // ZEN_WITH_TESTS
+
 }  // namespace zen
diff --git a/zencore/xmake.lua b/zencore/xmake.lua
index 5de7f476d..1abd86b7b 100644
--- a/zencore/xmake.lua
+++ b/zencore/xmake.lua
@@ -2,13 +2,24 @@ target('zencore')
     set_kind("static")
     add_files("**.cpp")
     add_includedirs("include", {public=true})
-    add_includedirs("..\\3rdparty\\utfcpp\\source")
-    add_linkdirs("$(projectdir)/3rdparty/BLAKE3/lib/Win64", "$(projectdir)/3rdparty/Oodle/lib/Win64")
+    add_includedirs("$(projectdir)/3rdparty/utfcpp/source")
+    if is_os("windows") then
+        add_linkdirs("$(projectdir)/3rdparty/BLAKE3/lib/Win64")
+        add_linkdirs("$(projectdir)/3rdparty/Oodle/lib/Win64")
+    elseif is_os("linux") then
+        add_linkdirs("$(projectdir)/3rdparty/BLAKE3/lib/Linux_x64")
+        add_linkdirs("$(projectdir)/3rdparty/Oodle/lib/Linux_x64")
+        add_links("blake3")
+        add_links("oo2corelinux64")
+        add_links("pthread")
+    end
     add_packages(
         "vcpkg::spdlog", 
         "vcpkg::fmt",
         "vcpkg::doctest", 
         "vcpkg::lz4",
+        "vcpkg::mimalloc",
+        "vcpkg::json11",
         "vcpkg::cpr",
         "vcpkg::curl",  -- required by cpr
         "vcpkg::zlib",  -- required by curl
diff --git a/zenstore/CAS.cpp b/zenstore/CAS.cpp
index a4bbfa340..a26e9710f 100644
--- a/zenstore/CAS.cpp
+++ b/zenstore/CAS.cpp
@@ -1,6 +1,6 @@
 // Copyright Epic Games, Inc. All Rights Reserved.
 
-#include <zenstore/cas.h>
+#include <zenstore/CAS.h>
 
 #include "compactcas.h"
 #include "filecas.h"
diff --git a/zenstore/caslog.cpp b/zenstore/caslog.cpp
index 2bac6affd..c1cb68379 100644
--- a/zenstore/caslog.cpp
+++ b/zenstore/caslog.cpp
@@ -1,8 +1,8 @@
 // Copyright Epic Games, Inc. All Rights Reserved.
 
-#include <zenstore/cas.h>
+#include <zenstore/CAS.h>
 
-#include "CompactCas.h"
+#include "compactcas.h"
 
 #include <zencore/except.h>
 #include <zencore/filesystem.h>
diff --git a/zenstore/compactcas.cpp b/zenstore/compactcas.cpp
index 612f87c7c..3631722d4 100644
--- a/zenstore/compactcas.cpp
+++ b/zenstore/compactcas.cpp
@@ -1,8 +1,8 @@
 // Copyright Epic Games, Inc. All Rights Reserved.
 
-#include <zenstore/cas.h>
+#include <zenstore/CAS.h>
 
-#include "CompactCas.h"
+#include "compactcas.h"
 
 #include <zencore/except.h>
 #include <zencore/logging.h>
diff --git a/zenstore/compactcas.h b/zenstore/compactcas.h
index a512c3d93..47e989fe9 100644
--- a/zenstore/compactcas.h
+++ b/zenstore/compactcas.h
@@ -9,11 +9,14 @@
 #include <zencore/string.h>
 #include <zencore/thread.h>
 #include <zencore/uid.h>
-#include <zencore/windows.h>
 #include <zenstore/basicfile.h>
-#include <zenstore/cas.h>
+#include <zenstore/CAS.h>
 #include <zenstore/caslog.h>
 
+#if ZEN_PLATFORM_WINDOWS
+#	include <zencore/windows.h>
+#endif
+
 namespace zen {
 
 //////////////////////////////////////////////////////////////////////////
diff --git a/zenstore/filecas.cpp b/zenstore/filecas.cpp
index f69ed6bdb..b63cd4ba7 100644
--- a/zenstore/filecas.cpp
+++ b/zenstore/filecas.cpp
@@ -1,6 +1,6 @@
 // Copyright Epic Games, Inc. All Rights Reserved.
 
-#include "FileCas.h"
+#include "filecas.h"
 
 #include <zencore/except.h>
 #include <zencore/filesystem.h>
@@ -23,12 +23,14 @@
 #include <unordered_map>
 
 // clang-format off
-#include <zencore/prewindows.h>
+#if ZEN_PLATFORM_WINDOWS
+#	include <zencore/prewindows.h>
 
-struct IUnknown;  // Workaround for "combaseapi.h(229): error C2187: syntax error: 'identifier' was unexpected here" when using /permissive-
-#include <atlfile.h>
+	struct IUnknown;  // Workaround for "combaseapi.h(229): error C2187: syntax error: 'identifier' was unexpected here" when using /permissive-
+#	include <atlfile.h>
 
-#include <zencore/postwindows.h>
+#	include <zencore/postwindows.h>
+#endif
 // clang-format on
 
 namespace zen {
diff --git a/zenstore/filecas.h b/zenstore/filecas.h
index 14314ce52..8f36c0170 100644
--- a/zenstore/filecas.h
+++ b/zenstore/filecas.h
@@ -8,7 +8,7 @@
 #include <zencore/iohash.h>
 #include <zencore/string.h>
 #include <zencore/thread.h>
-#include <zenstore/cas.h>
+#include <zenstore/CAS.h>
 
 #include <functional>
 
diff --git a/zenstore/include/zenstore/CAS.h b/zenstore/include/zenstore/CAS.h
index 86e7e78d9..7f8b5bfa2 100644
--- a/zenstore/include/zenstore/CAS.h
+++ b/zenstore/include/zenstore/CAS.h
@@ -41,9 +41,9 @@ public:
 	void						AddChunksToSet(std::span<const IoHash> HashesToAdd);
 	void						RemoveChunksIf(std::function<bool(const IoHash& CandidateHash)>&& Predicate);
 	void						IterateChunks(std::function<void(const IoHash& ChunkHash)>&& Callback);
-	inline [[nodiscard]] bool	ContainsChunk(const IoHash& Hash) const { return m_ChunkSet.find(Hash) != m_ChunkSet.end(); }
-	inline [[nodiscard]] bool	IsEmpty() const { return m_ChunkSet.empty(); }
-	inline [[nodiscard]] size_t GetSize() const { return m_ChunkSet.size(); }
+	[[nodiscard]] inline bool	ContainsChunk(const IoHash& Hash) const { return m_ChunkSet.find(Hash) != m_ChunkSet.end(); }
+	[[nodiscard]] inline bool	IsEmpty() const { return m_ChunkSet.empty(); }
+	[[nodiscard]] inline size_t GetSize() const { return m_ChunkSet.size(); }
 
 private:
 	// Q: should we protect this with a lock, or is that a higher level concern?
diff --git a/zenstore/include/zenstore/basicfile.h b/zenstore/include/zenstore/basicfile.h
index 7ae35dea6..87fec16c6 100644
--- a/zenstore/include/zenstore/basicfile.h
+++ b/zenstore/include/zenstore/basicfile.h
@@ -5,7 +5,10 @@
 #include "zenstore.h"
 
 #include <zencore/iobuffer.h>
-#include <zencore/windows.h>
+
+#if ZEN_PLATFORM_WINDOWS
+#	include <zencore/windows.h>
+#endif
 
 #include <filesystem>
 #include <functional>
diff --git a/zenstore/include/zenstore/caslog.h b/zenstore/include/zenstore/caslog.h
index 00b987383..8189da87e 100644
--- a/zenstore/include/zenstore/caslog.h
+++ b/zenstore/include/zenstore/caslog.h
@@ -8,9 +8,12 @@
 #include <zencore/string.h>
 #include <zencore/thread.h>
 #include <zencore/uid.h>
-#include <zencore/windows.h>
 #include <zenstore/basicfile.h>
-#include <zenstore/cas.h>
+#include <zenstore/CAS.h>
+
+#if ZEN_PLATFORM_WINDOWS
+#	include <zencore/windows.h>
+#endif
 
 #include <functional>