[Build] Linux→Windows cross-compile toolchain (clang-cl + xwin)

New CMake preset `cross-win-clangcl` for Ninja Multi-Config on non-Windows hosts. Toolchain: clang-cl (MSVC-ABI), lld-link, xwin SDK/CRT splat. Shader compilation routes through wine fxc.exe with FXC_PATH env forwarding and unix→Windows path translation via `winepath -w`. Plus per-file build fixes (constexpr→const, llvm-rc forward-slash, zlib-ng AVX guard, /RTCsu MSVC-only). third_party/snappy bumped to fabi/sylpheed-crossbuild for the target-aware POSIX-gate header. Produces `xenia_canary.exe` (Debug MSVC) suitable for use as the audit oracle under Wine for xenia-rs work. See docs/CROSS_BUILD_SETUP.md for the full reproduction recipe. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-06-05 23:52:27 +02:00
12 changed files with 343 additions and 9 deletions
--- a/.gitignore
+++ b/.gitignore
@@ -94,6 +94,7 @@ node_modules/.bin/
 /build/
 /build-arm64/
 /build-x64/
+/build-cross/

 # ==============================================================================
 # Local-only paths
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -82,6 +82,23 @@ file(MAKE_DIRECTORY "${PROJECT_SOURCE_DIR}/scratch")
 # Python for shader compilation scripts
 find_package(Python3 REQUIRED COMPONENTS Interpreter)

+# Generate build-tree version.h via xenia-build.py's generate_version_h()
+# (normally invoked by `xb premake`/`xb build`; CMake-direct flows need it too).
+execute_process(
+  COMMAND ${Python3_EXECUTABLE} -c
+    "import importlib.util,sys; \
+     spec=importlib.util.spec_from_file_location('xb',r'${PROJECT_SOURCE_DIR}/xenia-build.py'); \
+     m=importlib.util.module_from_spec(spec); spec.loader.exec_module(m); \
+     m.generate_version_h(r'${CMAKE_BINARY_DIR}')"
+  WORKING_DIRECTORY "${PROJECT_SOURCE_DIR}"
+  RESULT_VARIABLE _xenia_version_rc
+)
+if(NOT _xenia_version_rc EQUAL 0)
+  message(WARNING "version.h generation failed (rc=${_xenia_version_rc}); writing stub.")
+  file(WRITE "${CMAKE_BINARY_DIR}/version.h"
+    "#ifndef GENERATED_VERSION_H_\n#define GENERATED_VERSION_H_\n#define XE_BUILD_BRANCH \"unknown\"\n#define XE_BUILD_COMMIT \"unknown\"\n#define XE_BUILD_COMMIT_SHORT \"unknown\"\n#define XE_BUILD_DATE __DATE__\n#endif\n")
+endif()
+
 # Include helpers
 include(cmake/XeniaHelpers.cmake)

@@ -146,8 +163,14 @@ if(MSVC)

  # --- Per-configuration MSVC flags ---
  # Checked
+  if(CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "MSVC"
+     AND NOT CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
    string(APPEND CMAKE_C_FLAGS_CHECKED " /RTCsu /fsanitize=address")
    string(APPEND CMAKE_CXX_FLAGS_CHECKED " /RTCsu /fsanitize=address")
+  else()
+    string(APPEND CMAKE_C_FLAGS_CHECKED " /fsanitize=address")
+    string(APPEND CMAKE_CXX_FLAGS_CHECKED " /fsanitize=address")
+  endif()
  string(APPEND CMAKE_EXE_LINKER_FLAGS_CHECKED " /INCREMENTAL:NO")
  add_compile_definitions($<$<CONFIG:Checked>:DEBUG>)

--- a/CMakePresets.json
+++ b/CMakePresets.json
@@ -39,6 +39,22 @@
      "cacheVariables": {
        "CMAKE_SYSTEM_PROCESSOR": "ARM64"
      }
+    },
+    {
+      "name": "cross-win-clangcl",
+      "displayName": "Cross (Linux→Win MSVC) clang-cl + xwin",
+      "generator": "Ninja Multi-Config",
+      "binaryDir": "${sourceDir}/build-cross",
+      "toolchainFile": "${sourceDir}/cmake/toolchains/linux-to-win-msvc.cmake",
+      "condition": {
+        "type": "notEquals",
+        "lhs": "${hostSystemName}",
+        "rhs": "Windows"
+      },
+      "cacheVariables": {
+        "XWIN_DIR":  "$env{HOME}/.xwin/splat",
+        "FXC_PATH":  "$env{HOME}/.local/share/xenia-cross/fxc/fxc.exe"
+      }
    }
  ],
  "buildPresets": [
@@ -89,6 +105,9 @@
      "name": "vs-arm64-checked",
      "configurePreset": "vs-arm64",
      "configuration": "Checked"
-    }
+    },
+    { "name": "cross-debug",   "configurePreset": "cross-win-clangcl", "configuration": "Debug" },
+    { "name": "cross-release", "configurePreset": "cross-win-clangcl", "configuration": "Release" },
+    { "name": "cross-checked", "configurePreset": "cross-win-clangcl", "configuration": "Checked" }
  ]
 }
--- a/cmake/XeniaHelpers.cmake
+++ b/cmake/XeniaHelpers.cmake
@@ -192,6 +192,12 @@ function(xe_shader_rules_dxbc target shader_dir)
  set(_valid_stages vs hs ds gs ps cs)
  set(_commands)
  set(_bytecode_dir "${shader_dir}/bytecode/d3d12_5_1")
+  # Propagate FXC_PATH from the configure-time env so ninja-spawned python
+  # subprocesses can find fxc.exe (CMake `set(ENV{...})` doesn't reach build).
+  set(_env_prefix "")
+  if(DEFINED ENV{FXC_PATH})
+    set(_env_prefix ${CMAKE_COMMAND} -E env "FXC_PATH=$ENV{FXC_PATH}")
+  endif()
  list(APPEND _commands COMMAND ${CMAKE_COMMAND} -E make_directory "${_bytecode_dir}")
  foreach(src ${_sources})
    get_filename_component(_name ${src} NAME)
@@ -206,7 +212,7 @@ function(xe_shader_rules_dxbc target shader_dir)
    if(NOT _stage IN_LIST _valid_stages)
      continue()
    endif()
-    list(APPEND _commands COMMAND ${Python3_EXECUTABLE} "${_script}" "${src}" "${_bytecode_dir}/${_id}.h")
+    list(APPEND _commands COMMAND ${_env_prefix} ${Python3_EXECUTABLE} "${_script}" "${src}" "${_bytecode_dir}/${_id}.h")
  endforeach()
  add_custom_command(
    OUTPUT "${_stamp}"
--- a/cmake/toolchains/linux-to-win-msvc.cmake
+++ b/cmake/toolchains/linux-to-win-msvc.cmake
@@ -0,0 +1,119 @@
+# cmake/toolchains/linux-to-win-msvc.cmake
+# Linux host -> Windows MSVC-ABI cross toolchain using clang-cl + lld-link
+# + xwin-supplied Win10 SDK/CRT. Driven by Ninja Multi-Config.
+
+set(CMAKE_SYSTEM_NAME      Windows)
+set(CMAKE_SYSTEM_PROCESSOR x86_64)
+
+if(NOT DEFINED XWIN_DIR)
+  if(DEFINED ENV{XWIN_DIR})
+    set(XWIN_DIR "$ENV{XWIN_DIR}")
+  else()
+    set(XWIN_DIR "$ENV{HOME}/.xwin/splat")
+  endif()
+endif()
+set(XWIN_DIR "${XWIN_DIR}" CACHE PATH "xwin splat root (contains crt/ and sdk/)")
+
+if(NOT EXISTS "${XWIN_DIR}/crt/include")
+  message(FATAL_ERROR "XWIN_DIR=${XWIN_DIR} missing crt/include - run xwin splat.")
+endif()
+
+set(CMAKE_C_COMPILER   clang-cl)
+set(CMAKE_CXX_COMPILER clang-cl)
+set(CMAKE_LINKER       lld-link)
+set(CMAKE_RC_COMPILER  llvm-rc)
+set(CMAKE_AR           llvm-lib)
+set(CMAKE_MT           llvm-mt)
+
+set(CMAKE_C_COMPILER_TARGET   x86_64-pc-windows-msvc)
+set(CMAKE_CXX_COMPILER_TARGET x86_64-pc-windows-msvc)
+
+set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
+
+# Force /MD (release CRT) for every config. xenia's CMakeLists.txt does a
+# `string(REPLACE "/MDd" "/MD" ...)` on CMAKE_CXX_FLAGS_DEBUG, but with
+# clang-cl, the runtime selection comes from CMAKE_MSVC_RUNTIME_LIBRARY
+# (which expands to -MDd in dash form), so the substitution misses.
+# Pinning the policy here avoids the need for non-redistributable debug
+# CRT DLLs (MSVCP140D.dll etc) at runtime, which xwin doesn't ship.
+cmake_policy(SET CMP0091 NEW)
+set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreadedDLL")
+
+# xwin's default splat is a flat layout (crt/include, sdk/include/{ucrt,um,shared,...}),
+# which clang-cl's /winsysroot does NOT understand. Use explicit -imsvc + -libpath:
+# instead. Re-running `xwin splat --use-winsysroot-style` would also work but
+# requires re-downloading ~600 MB.
+# Use SHELL: prefix so CMake doesn't deduplicate repeated -imsvc tokens.
+add_compile_options(
+  "SHELL:-imsvc \"${XWIN_DIR}/crt/include\""
+  "SHELL:-imsvc \"${XWIN_DIR}/sdk/include/ucrt\""
+  "SHELL:-imsvc \"${XWIN_DIR}/sdk/include/um\""
+  "SHELL:-imsvc \"${XWIN_DIR}/sdk/include/shared\""
+  "SHELL:-imsvc \"${XWIN_DIR}/sdk/include/winrt\""
+)
+add_link_options(
+  "/libpath:${XWIN_DIR}/crt/lib/x86_64"
+  "/libpath:${XWIN_DIR}/sdk/lib/ucrt/x86_64"
+  "/libpath:${XWIN_DIR}/sdk/lib/um/x86_64"
+)
+# xwin pulls the latest MSVC STL which now hard-asserts Clang >= 19. Our host
+# has Clang 18, which works fine in practice — opt out of the version check.
+# (See yvals_core.h STL1000 in $XWIN_DIR/crt/include.)
+add_compile_definitions(_ALLOW_COMPILER_AND_STL_VERSION_MISMATCH)
+# llvm-rc needs SDK headers explicitly + the resource file's own dir so the
+# RC's relative ICON path (../../../assets/icon/icon.ico) resolves.
+get_filename_component(_toolchain_dir "${CMAKE_CURRENT_LIST_FILE}" DIRECTORY)
+get_filename_component(_xenia_root "${_toolchain_dir}/../.." ABSOLUTE)
+set(CMAKE_RC_FLAGS_INIT
+    "/I \"${XWIN_DIR}/sdk/include/um\" /I \"${XWIN_DIR}/sdk/include/shared\" /I \"${_xenia_root}/src/xenia/app\"")
+
+# Quiet MSVC-STL false positives and xenia-specific warnings that clang-cl
+# emits but cl.exe doesn't (treated as errors under /WX).
+add_compile_options(
+  -Wno-microsoft-include
+  -Wno-unused-command-line-argument
+  -Wno-ignored-pragma-intrinsic
+  -Wno-nonportable-include-path
+  -Wno-pragma-pack
+  -Wno-tautological-pointer-compare
+  -Wno-microsoft-cast
+  -Wno-deprecated-declarations
+  # These are silenced for native Linux Clang in CMakeLists.txt's else() branch,
+  # but the if(MSVC) branch fires under clang-cl and skips them — so re-add.
+  -Wno-switch
+  -Wno-attributes
+  -Wno-deprecated-register
+  -Wno-deprecated-volatile
+  -Wno-deprecated-enum-enum-conversion
+  # cl.exe accepts __pragma(optimize("s",on)); clang-cl only knows the empty
+  # argument form. xenia gates XE_MSVC_OPTIMIZE_SMALL on _MSC_VER so the
+  # rejected pragma still emits from the clang-cl path. Treat as no-op.
+  -Wno-ignored-pragmas
+  # xenia decorates several `virtual` methods with XE_FORCEINLINE; clang-cl
+  # then complains that the inline body isn't visible in includer TUs
+  # (definitions live in command_processor.cc). cl.exe accepts this silently.
+  -Wno-undefined-inline
+  -Wno-sizeof-pointer-memaccess
+  # `'ZM'` (PE magic, stored little-endian as "MZ" in the binary) — cl.exe
+  # accepts the multi-char constant silently; clang-cl errors under /WX.
+  -Wno-multichar
+)
+# _mm_cvtsi64x_si128 is an MSVC-only alias for the standard _mm_cvtsi64_si128.
+# Used (gated on XE_PLATFORM_WIN32) in xenia/gpu/draw_util.cc.
+add_compile_definitions(_mm_cvtsi64x_si128=_mm_cvtsi64_si128)
+
+# Plumb FXC for tools/build/compile_shader_dxbc.py (wine fxc auto-prepend).
+# Use real Win10 SDK fxc.exe 10.x (supports SM 5_1, produces vkd3d-proton-
+# acceptable DXBC).
+if(DEFINED ENV{FXC_PATH})
+  set(ENV_FXC "$ENV{FXC_PATH}")
+else()
+  set(ENV_FXC "$ENV{HOME}/.local/share/xenia-cross/fxc/fxc.exe")
+endif()
+set(ENV{FXC_PATH} "${ENV_FXC}")
+
+set(CMAKE_FIND_ROOT_PATH "${XWIN_DIR}")
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
--- a/cmake/toolchains/xwin-case-symlinks.py
+++ b/cmake/toolchains/xwin-case-symlinks.py
@@ -0,0 +1,55 @@
+#!/usr/bin/env python3
+"""Scan xenia source for #include <...> directives and ensure case-aliases
+exist in xwin's flat SDK/CRT include dirs. Idempotent — safe to re-run."""
+from __future__ import annotations
+import os, re, sys
+from pathlib import Path
+
+INCLUDE_RE = re.compile(r'^\s*#\s*include\s*<([A-Za-z][A-Za-z0-9_/.\-]*\.h)>',
+                        re.MULTILINE)
+SOURCE_ROOTS = ["src", "third_party/SDL2/src", "third_party/SDL2/include",
+                "third_party/discord-rpc/src", "third_party/fmt",
+                "third_party/imgui"]
+SOURCE_EXTS = {".h", ".hpp", ".inc", ".c", ".cc", ".cpp", ".cxx"}
+
+def collect_includes(repo_root: Path) -> set[str]:
+    seen: set[str] = set()
+    for root in SOURCE_ROOTS:
+        base = repo_root / root
+        if not base.exists(): continue
+        for path in base.rglob("*"):
+            if path.suffix.lower() not in SOURCE_EXTS: continue
+            try: txt = path.read_text(encoding="utf-8", errors="ignore")
+            except OSError: continue
+            for m in INCLUDE_RE.finditer(txt):
+                seen.add(m.group(1))
+    return seen
+
+def fix_dir(target_dir: Path, want: set[str]) -> int:
+    if not target_dir.is_dir(): return 0
+    idx = {e.name.lower(): e.name for e in target_dir.iterdir()}
+    created = 0
+    for name in want:
+        if "/" in name: continue
+        actual = idx.get(name.lower())
+        if actual is None or actual == name: continue
+        link = target_dir / name
+        if link.exists() or link.is_symlink(): continue
+        try:
+            link.symlink_to(actual)
+            created += 1
+        except OSError: pass
+    return created
+
+if __name__ == "__main__":
+    if len(sys.argv) != 3:
+        sys.exit("usage: xwin-case-symlinks.py <xenia-canary-root> <xwin-splat-dir>")
+    repo = Path(sys.argv[1]).resolve()
+    xwin = Path(sys.argv[2]).resolve()
+    want = collect_includes(repo)
+    total = 0
+    for d in (xwin/"crt/include", xwin/"sdk/include/ucrt",
+              xwin/"sdk/include/um", xwin/"sdk/include/shared",
+              xwin/"sdk/include/winrt"):
+        total += fix_dir(d, want)
+    print(f"Created {total} case-symlinks across {len(want)} unique includes.")
--- a/docs/CROSS_BUILD_SETUP.md
+++ b/docs/CROSS_BUILD_SETUP.md
@@ -0,0 +1,100 @@
+# Building and Running Xenia Canary Windows Debug from Linux
+
+## What we built and why
+
+A Windows-MSVC debug `xenia_canary.exe` cross-compiled on Linux, runnable under Wine. This serves as the audit oracle for the xenia-rs Rust port: the Linux-native canary build stalls before the front-end UI, so all audit comparisons (memory entries audit_044–audit_059) need the Wine-targeted debug binary as the ground-truth reference engine.
+
+## Phase 1 — Host setup (run in your terminal)
+
+    sudo apt install -y clang-18 lld-18 llvm-18      # clang-cl driver mode + lld-link + binutils
+    sudo ln -s /usr/bin/clang-18 /usr/bin/clang-cl   # activates MSVC-compatible driver mode
+    xwin --accept-license --arch x86_64 splat --include-debug-libs --output ~/.xwin/splat
+                                                      # ~807 MB Win10 SDK + MSVC CRT sysroot
+    curl ... linkid=2361406 -o ~/winsdk.iso          # Win10 SDK ISO for real fxc.exe (SM 5_1)
+    winetricks -q vkd3d                              # vkd3d-proton d3d12core.dll (5.96 MB)
+    winetricks -q dxvk                               # DXVK dxgi.dll (2.95 MB)
+
+Ubuntu's clang-18 / lld-18 apt packages ship binutils suffixed (llvm-lib-18, lld-link-18, etc.); the toolchain expects unsuffixed names on PATH. Create 4 symlinks in `~/.local/bin/` (no sudo needed since it was already on PATH).
+
+## Phase 2 — In-tree edits
+
+### 8 build-fix patches (compile-time only; zero runtime semantics changes)
+
+| § | File | What changed |
+|---|---|---|
+| 7.1 | `src/xenia/base/mapped_memory_win.cc:30` | `constexpr` → `const` for `kFileHandleInvalid` (clang-cl rejects `reinterpret_cast` in constant expressions) |
+| 7.2 | `src/xenia/app/main_resources.rc:3` | `..\\..\\..\\assets\\icon\\icon.ico` → forward slashes (llvm-rc backslash literalism) |
+| 7.3 | `third_party/snappy/snappy-stubs-public.h` | Already in place via the `fabi/sylpheed-crossbuild` snappy fork submodule |
+| 7.4 | `third_party/zlib-ng/zconf-ng.h:113` | `#if 1` → `#if !defined(_WIN32)` for `Z_HAVE_UNISTD_H` (header was pre-generated on Linux) |
+| 7.5 | `third_party/CMakeLists.txt:335` | Extended `if(NOT MSVC)` → `if(NOT MSVC OR CMAKE_CXX_COMPILER_ID STREQUAL "Clang")` for zlib-ng AVX flags |
+| 7.6a | `CMakeLists.txt` | Wrapped `/RTCsu` appends in `CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "MSVC" AND NOT … "Clang"` |
+| 7.6b | `CMakeLists.txt:85-101` | Inserted `execute_process` block invoking `xenia-build.py:generate_version_h()` so CMake-direct flow produces `version.h` |
+| 7.7 | `cmake/XeniaHelpers.cmake` | Added `_env_prefix` to wrap per-shader commands in `cmake -E env FXC_PATH=…` (`cmake set(ENV{…})` doesn't survive ninja's subprocess spawn) |
+| 7.8 | `tools/build/compile_shader_dxbc.py:74` | Added `_wineify()` helper translating unix paths via `winepath -w` before fxc sees them (fxc parses `/home/…` as a `/h` switch) |
+
+### 3 new cross-compile config files
+
+| File | Purpose |
+|---|---|
+| `cmake/toolchains/linux-to-win-msvc.cmake` | clang-cl + lld-link + xwin sysroot driver. Forces `MultiThreadedDLL` runtime (no debug-CRT DLLs needed), feeds `-imsvc` flags via `SHELL:` prefix, suppresses 15+ clang-cl-specific warnings, defines `_mm_cvtsi64x_si128` alias, opts out of MSVC STL's Clang≥19 assertion, plumbs `FXC_PATH` |
+| `cmake/toolchains/xwin-case-symlinks.py` | Scans xenia includes for mixed-case Windows headers and creates the missing case-aliases in xwin's flat splat (5 needed: `ObjBase.h`, `Psapi.h`, etc.) |
+| `CMakePresets.json` | Added `cross-win-clangcl` configure preset + `cross-debug` / `cross-release` / `cross-checked` build presets, gated on `${hostSystemName}` ≠ Windows |
+
+## Phase 3 — Configure + build
+
+    python3 cmake/toolchains/xwin-case-symlinks.py "$PWD" "$HOME/.xwin/splat"
+    # Created 5 case-symlinks across 556 unique includes
+
+    cmake --preset cross-win-clangcl
+    # Generates build-cross/ with build-Debug.ninja + auto-generated version.h
+
+    cmake --build build-cross --preset cross-debug --target xenia-app -j6
+    # 936 ninja targets. -j6 not -j12 because host RAM is tight (~3.4 GiB free at start)
+    # Wall time ~25 min total
+
+Final output: `xenia_canary.exe` (27 MB PE32+ GUI x86-64) + `xenia_canary.pdb` (116 MB CodeView).
+
+## Phase 4 — Running the game
+
+    cd "/home/fabi/RE Project Sylpheed/xenia-canary/build-cross/bin/Windows/Debug"
+    WINEDEBUG=-all wine ./xenia_canary.exe --mute=true \
+        "/home/fabi/RE Project Sylpheed/Project Sylpheed - Arc of Deception (USA, Europe) (En,Ja).iso"
+
+Kill after the boot phase completes (the audit workflow only needs ~30 s of trajectory):
+
+    sleep 30
+    wineserver -k
+
+### Expected boot signals in `xenia.log`
+
+| Signal | Value | Meaning |
+|---|---|---|
+| Total log lines | 1091 | Healthy boot (≥1000 = passes) |
+| `^x>` fatals | 0 | No `xe::FatalError()` triggered |
+| `^!>` errors | 28 | Non-fatal (occasional pipeline misses — normal) |
+| `^w>` warnings | 28 | Normal startup |
+| `i> Setup: Initializing chain` | Memory → Exports → Processor → Audio → Graphics → HID → VFS → Kernel | All eight subsystems came up |
+| `i> Setup: Starting graphics_system + Starting audio_system` | present | Threads spawned cleanly |
+| DXGI adapter | NVIDIA GeForce GTX 1070 Ti | vkd3d-proton + DXVK loaded |
+| `K> XThread::Execute thid N count` | 29 | Guest threads spawned (game is past `XexLoadImage`) |
+| `Skipping draw - pipeline not ready: VS … PS …` repeating | yes | D3D12 backend is async-compiling pipelines — expected on cold boot |
+| `F>` channel | 321 lines | VFS is mounting and walking the disc image |
+| `K>` channel | 29 lines | Kernel dispatching XThread creation |
+
+## Audit-workflow integration
+
+The cross-build is now the sole canary oracle. The Linux-native `xenia-canary/build/bin/Linux/Debug/xenia_canary` is deprecated for audits.
+
+All canary launches must include `--mute=true` (project policy 2026-05-12). XAudio2 still initializes — same code paths, silent output. Do not substitute `--apu=nop`; that switches backend entirely.
+
+Point logs at `audit-runs` with `--log_file=`:
+
+    LOG="$XENIA_RS_ROOT/xenia-rs/audit-runs/audit_NN/canary.log" \
+    WINEDEBUG=-all wine xenia_canary.exe \
+        --mute=true --log_file="$LOG" \
+        --audit_NN_my_probe=true \
+        "$ISO_PATH"
+
+Add new audit instrumentation as cvars in `cpu_flags.h` / `gpu_flags.h` / `kernel_flags.h`, guard with `if (cvars::audit_NN_my_probe)`, emit `XELOGI("AUDIT-NN-EVENT …")`. Rebuild incrementally — only the touched TU recompiles, ≤60 s.
+
+The build is observation-only: cvars + `XELOG*()` + `#if`-gated diagnostic blocks are permitted; changing control flow, return values, struct layouts, or timing is forbidden, since that would invalidate every downstream audit comparison.
--- a/src/xenia/app/main_resources.rc
+++ b/src/xenia/app/main_resources.rc
@@ -1,3 +1,3 @@
 //{{NO_DEPENDENCIES}}

-MAINICON               ICON                    "..\\..\\..\\assets\\icon\\icon.ico"
+MAINICON               ICON                    "../../../assets/icon/icon.ico"
--- a/src/xenia/base/mapped_memory_win.cc
+++ b/src/xenia/base/mapped_memory_win.cc
@@ -26,8 +26,9 @@ namespace xe {
 class Win32MappedMemory : public MappedMemory {
 public:
  // CreateFile returns INVALID_HANDLE_VALUE in case of failure.
-  // chrispy: made inline const to get around clang error
-  static inline constexpr HANDLE kFileHandleInvalid = INVALID_HANDLE_VALUE;
+  // INVALID_HANDLE_VALUE expands to a reinterpret_cast which MSVC accepts
+  // in constexpr as an extension; clang-cl rejects it per C++ standard.
+  static inline const HANDLE kFileHandleInvalid = INVALID_HANDLE_VALUE;
  // CreateFileMapping returns nullptr in case of failure.
  static constexpr HANDLE kMappingHandleInvalid = nullptr;

--- a/third_party/CMakeLists.txt
+++ b/third_party/CMakeLists.txt
@@ -332,7 +332,7 @@ else()
    X86_AVX512VNNI
    WITH_GZFILEOP
  )
-  if(NOT MSVC)
+  if(NOT MSVC OR CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
    # GCC/Clang have native __builtin_ctz/__builtin_ctzll (MSVC gets these
    # from fallback_builtins.h). Defining these enables optimized compare256
    # and longest_match codepaths.
--- a/third_party/snappy
+++ b/third_party/snappy
--- a/tools/build/compile_shader_dxbc.py
+++ b/tools/build/compile_shader_dxbc.py
@@ -73,6 +73,16 @@ def main():

    # Start with base command — use wine on non-Windows platforms.
    if sys.platform != "win32":
+        def _wineify(p):
+            try:
+                out = subprocess.check_output(["winepath", "-w", p],
+                                              stderr=subprocess.DEVNULL)
+                return out.decode("utf-8", "replace").strip()
+            except (OSError, subprocess.CalledProcessError):
+                return p
+        input_path = _wineify(input_path)
+        output_path = _wineify(output_path)
+        src_dir = _wineify(src_dir)
        compiler_args = ["wine", fxc]
    else:
        compiler_args = [fxc]