// issue-0026: Chess game on iOS-sim with `plat.gpu_mode = .metal` crashes
// inside `[MTLTexture replaceRegion:mipmapLevel:withBytes:bytesPerRow:]`
// when uploading the 1024×1024 R8 font atlas. The 1×1 RGBA8 white tex
// through the SAME code path (metal_update_texture_region_ios in
// library/modules/gpu/metal.sx) works.
//
// Blocked on issue-0024 (NSLog inside if/else not firing — or unified-log
// buffer loss on crash; investigation pending) — without a trustworthy
// tracer we can't reliably bisect which arg arrives wrong. Most likely
// cause: this is downstream of issue-0025's ABI gaps (MTLRegion is 48
// bytes and goes through `xx objc_msgSend` cast, which is the
// call_indirect path that issue-0025 part B covers).
//
// ── Reproduction recipe ───────────────────────────────────────────────────
//
//   cd /Users/agra/projects/game
//   /Users/agra/projects/sx/zig-out/bin/sx build --target ios-sim main.sx \
//     --bundle sx-out/ios/SxChess.app --bundle-id co.swipelab.sxchess \
//     -F ~/Library/Frameworks
//   cp -R assets sx-out/ios/SxChess.app/
//   codesign --force --sign - --timestamp=none sx-out/ios/SxChess.app
//   xcrun simctl install booted sx-out/ios/SxChess.app
//   xcrun simctl launch --terminate-running-process booted co.swipelab.sxchess
//   sleep 4 && xcrun simctl io booted screenshot /tmp/sx-chess.png
//
// Expected (after fix): chess board renders via Metal.
// Observed: app launches, returns immediately to home screen, no screen
// touched. The simpler examples/63-metal-clear.sx demo still renders the
// colored triangle on the same sim, so the Metal pipeline itself works
// for small uploads.
//
// ── Candidate root causes (in priority order) ─────────────────────────────
//
// 1. issue-0025 fallout (most likely): MTLRegion (48 B by value) passed
//    via the *MTLRegion workaround. The call_indirect path (issue-0025
//    part B) doesn't ABI-coerce, so the pointer-shaped declaration may
//    not actually pass the address in the right register slot for that
//    call site shape (6 args, including the indirect aggregate).
//
// 2. iOS-sim Metal-driver limitation: `setStorageMode:.shared` may not be
//    honored for r8 textures of this size; default may be `.private`
//    which precludes CPU-side replaceRegion. Workaround would be to
//    upload via `MTLBuffer` + `MTLBlitCommandEncoder` (newBufferWithBytes
//    + copyFromBuffer:sourceOffset:sourceBytesPerRow:...:toTexture:...).
//
// 3. sx-side `xx` cast bug: bytes_per_row : u64 = xx (u32_expr) may
//    truncate or sign-extend incorrectly. Less likely (the math comes
//    out to 1024, which fits in any width).
//
// ── How to resolve ────────────────────────────────────────────────────────
//
// After issues 0024 + 0025 are landed:
//   1. Re-add the trace NSLog markers ("[metal] U1..U5" in
//      metal_update_texture_region_ios) — now they should actually print.
//   2. Re-build + relaunch chess on iOS-sim.
//   3. If U5 fires after U4 (no crash inside msg_replace), the bug was
//      ABI-related; declare success and rename this file to
//      examples/NN-metal-large-region-upload.sx (next free NN).
//   4. If U4 → crash persists, fall back to the MTLBuffer + blit
//      encoder path in metal.sx's create_texture (when pixels != null,
//      allocate a temporary MTLBuffer with newBufferWithBytes:length:options:
//      then run a one-shot command buffer with a MTLBlitCommandEncoder
//      copying the buffer into the texture). This is the Apple-recommended
//      approach for large texture initial-uploads.

#import "modules/std.sx";

main :: () -> s32 { 0; }