From f681fc172ca89fa3d610fe7e47aa18970aaa82fc Mon Sep 17 00:00:00 2001
From: Andrew Udvare <audvare@gmail.com>
Date: Sun, 8 Feb 2026 19:43:14 -0500
Subject: [PATCH 15/21] Add USE_SYSTEM_CXXOPTS option for system cxxopts
 (header-only)

- premake5.lua: read USE_SYSTEM_CXXOPTS on Linux; pkg-config cxxopts or
  fallback to /usr/include/cxxopts.hpp; add global includedirs from
  pkg-config --cflags or fallback; define XENIA_USE_SYSTEM_CXXOPTS;
  conditional third_party/cxxopts.lua.
- src/xenia/base/cxxopts_include.h: wrapper for cxxopts.hpp (system vs bundled).
- cvar.h: use cxxopts_include.h instead of third_party path.

Clean build tested with all USE_SYSTEM_* except glslang.

Co-authored-by: Cursor <cursoragent@cursor.com>
---
 premake5.lua                     | 41 +++++++++++++++++++++++++++++++-
 src/xenia/base/cvar.h            |  2 +-
 src/xenia/base/cxxopts_include.h | 11 +++++++++
 3 files changed, 52 insertions(+), 2 deletions(-)
 create mode 100644 src/xenia/base/cxxopts_include.h

diff --git a/premake5.lua b/premake5.lua
index b9dceed35..19af0619d 100644
--- a/premake5.lua
+++ b/premake5.lua
@@ -170,6 +170,26 @@ if os.istarget("linux") then
   end
 end
 
+-- USE_SYSTEM_CXXOPTS: use system cxxopts when set (Linux only). Header-only; fail if set and not found.
+-- Prefer pkg-config; if unavailable (e.g. Gentoo without .pc), fall back to /usr/include/cxxopts.hpp.
+use_system_cxxopts = false
+cxxopts_pkg_config_available = false
+cxxopts_system_include = nil
+if os.istarget("linux") then
+  local env = os.getenv("USE_SYSTEM_CXXOPTS") or ""
+  if env ~= "" and env ~= "0" then
+    use_system_cxxopts = true
+    cxxopts_pkg_config_available = os.execute("pkg-config --exists cxxopts")
+    if not cxxopts_pkg_config_available then
+      if os.isfile("/usr/include/cxxopts.hpp") or os.isdir("/usr/include/cxxopts") then
+        cxxopts_system_include = "/usr/include"
+      else
+        error("USE_SYSTEM_CXXOPTS is set but cxxopts was not found (no pkg-config and no /usr/include/cxxopts.hpp). Install dev-libs/cxxopts or unset USE_SYSTEM_CXXOPTS.")
+      end
+    end
+  end
+end
+
 -- Define an ARCH variable
 -- Only use this to enable architecture-specific functionality.
 if os.istarget("linux") then
@@ -183,6 +203,20 @@ includedirs({
   "src",
   "third_party",
 })
+if use_system_cxxopts then
+  if cxxopts_system_include then
+    includedirs(cxxopts_system_include)
+  else
+    local cflags = os.outputof("pkg-config --cflags cxxopts")
+    if cflags then
+      for _, flag in next, string.explode(cflags, " ") do
+        if flag and flag:sub(1, 2) == "-I" then
+          includedirs(flag:sub(3))
+        end
+      end
+    end
+  end
+end
 
 defines({
   "VULKAN_HPP_NO_TO_STRING",
@@ -220,6 +254,9 @@ end
 if use_system_zlib_ng then
   defines({ "XENIA_USE_SYSTEM_ZLIB_NG" })
 end
+if use_system_cxxopts then
+  defines({ "XENIA_USE_SYSTEM_CXXOPTS" })
+end
 
 cdialect("C17")
 cppdialect("C++20")
@@ -491,7 +528,9 @@ workspace("xenia")
   end
   include("third_party/dxbc.lua")
   include("third_party/discord-rpc.lua")
-  include("third_party/cxxopts.lua")
+  if not use_system_cxxopts then
+    include("third_party/cxxopts.lua")
+  end
   include("third_party/tomlplusplus.lua")
   include("third_party/FFmpeg/premake5.lua")
   if not use_system_fmt then
diff --git a/src/xenia/base/cvar.h b/src/xenia/base/cvar.h
index 48f0d571f..99feca1ba 100644
--- a/src/xenia/base/cvar.h
+++ b/src/xenia/base/cvar.h
@@ -15,7 +15,7 @@
 #include <string>
 #include <vector>
 
-#include "third_party/cxxopts/include/cxxopts.hpp"
+#include "xenia/base/cxxopts_include.h"
 #include "xenia/base/fmt_include.h"
 #include "third_party/tomlplusplus/include/toml++/toml.hpp"
 #include "xenia/base/assert.h"
diff --git a/src/xenia/base/cxxopts_include.h b/src/xenia/base/cxxopts_include.h
new file mode 100644
index 000000000..ee63d5065
--- /dev/null
+++ b/src/xenia/base/cxxopts_include.h
@@ -0,0 +1,11 @@
+// Wrapper so Xenia can use either bundled cxxopts or system cxxopts (XENIA_USE_SYSTEM_CXXOPTS). Header-only.
+#ifndef XENIA_BASE_CXXOPTS_INCLUDE_H_
+#define XENIA_BASE_CXXOPTS_INCLUDE_H_
+
+#ifdef XENIA_USE_SYSTEM_CXXOPTS
+#include <cxxopts.hpp>
+#else
+#include "third_party/cxxopts/include/cxxopts.hpp"
+#endif
+
+#endif  // XENIA_BASE_CXXOPTS_INCLUDE_H_
-- 
2.52.0