lab/sx

Files

agra b9cfe2554f refactor(ffi-linkage): Phase 9.3/9.4 — purge 'foreign' from issues/*.md; GATE PASS

Rewrote 20 issue writeups to the extern/runtime-class vocabulary (#foreign→extern,
foreign_class_map→runtime_class_map, parseForeignClassDecl→parseRuntimeClassDecl,
findForeignMethodInChain→findRuntimeMethodInChain, dedupeForeignSymbol→
dedupeExternSymbol, is_foreign_c_api→is_extern_c_api, stale filename refs to the
renamed examples, foreign-class→runtime-class, bare foreign→extern). Renamed
issues/0043-…-foreign-class-…→…-runtime-class-….

PHASE 9 COMPLETE — 9.4 GATE PASSES: zero 'foreign' across src/library/examples/
issues/docs/editors/specs/readme/CLAUDE, excluding only the SQLite API constant
SQLITE_CONSTRAINT_FOREIGNKEY + vendored sqlite3.c/.h (upstream third-party).
Suite green (644 corpus / 443 unit, 0 failed).

2026-06-15 11:18:35 +03:00

2.4 KiB

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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 extern 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 extern; form (an external C data symbol from libsystem etc. — see examples/1205-ffi-extern-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 :: () -> i32 { 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.

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