lab/sx

Files

agra 34819f05de issues: relocate legacy examples/issue-* repros into issues/

Clear the examples/issue-* namespace (new layout keeps open-issue repros under
issues/, co-located with their .md). Two legacy files:

- issue-0030 was a feature-request placeholder (trivial main, no real test).
  `extern G : T;` cross-file sx globals are still unimplemented (parse error),
  so it's an open feature request: issues/0030-extern-global-declarations.{md,sx}.
- issue-0019 was a broken/superseded multi-file fixture (relative imports, not
  runnable from root; the non-transitive-#import scenario is covered by the
  passing 0706-modules-import-non-transitive). Moved to
  issues/0019-import-non-transitive-c-scope/ with a status note; safe to delete.

Suite unchanged: 324 passed.

2026-06-01 19:38:09 +03:00

2.4 KiB

Raw Blame History

0030 — `extern G : T;` cross-file sx global declarations (feature request)

Status: OPEN feature request (not a bug). Relocated from the old examples/issue-0030.sx placeholder during the test-layout migration. Repro: issues/0030-extern-global-declarations.sx (currently a parse error — the syntax doesn't exist yet).

Symptom / request

Support an extern G : T; top-level form so a global defined in one sx source file can be referenced from another without threading it through parameters — mirroring how #foreign function declarations work (declared in one place, defined elsewhere, resolved at link time).

// game/main.sx
g_metal_gpu : *MetalGPU = null;

// game/chess/pieces.sx
extern g_metal_gpu : *MetalGPU;          // ← parse error today

load :: (self: *ChessPieces, path: [:0]u8) {
    inline if OS == .ios {
        tex := g_metal_gpu.create_texture(w, h, .rgba8, xx pixels);
    }
}

Today pieces.load takes has_gpu: bool, gpu: GPU params and main.sx threads them through; cross-file extern globals would drop that ceremony. Distinct from the existing name : T #foreign; form (an external C data symbol from libsystem etc. — see examples/1205-ffi-foreign-global.sx); this request is for sx-defined globals shared across sx modules.

Reproduction

issues/0030-extern-global-declarations.sx:

#import "modules/std.sx";
extern g_x : *void;          // want: a reference to a global defined elsewhere
main :: () -> s32 { 0; }

./zig-out/bin/sx run … → error: expected '::', ':=', or ':' after identifier (the extern keyword/form is unparsed).

Implementation sketch

parser — surface syntax for extern G : T;. Must not clash with G :: T; (type alias), G : T = ---; (uninitialized global), G : T; (typed global). Reject extern G : T = expr; (an extern can't carry an initializer).
src/ir/lower.zig — record an extern-global stub that resolves at module-link time.
src/ir/emit_llvm.zig — emit an external LLVM global (no storage, just a reference). Globals already have first-class IR addresses; this adds an "extern" flag meaning "emit a reference, not storage."

Caveat

Encourages process-global state. Steer callers toward explicit parameter passing where reasonable; reserve for genuine process singletons (active GPU, active platform) where threading through every call site is more noise than signal.

2.4 KiB Raw Blame History

0030 — extern G : T; cross-file sx global declarations (feature request)