sx/issues/0122-whole-program-passes-ambient-source-context.md

0122 — whole-program passes resolve/diagnose under a stale ambient source

RESOLVED (2026-06-11, same session — found and fixed during the std.sx-as-pure-re-exports restructure, Agra-directed). Three whole-program passes ran under whatever current_source_file the previous pipeline phase happened to leave behind, instead of pinning the context per declaration:

1. ErrorAnalysis.convergeClosureShapeSets (error_analysis.zig) — resolves closure-literal param/return annotations; a stale context made example-declared nominal types (Point, Color) fail the E4 visibility gate with type 'X' is not visible attributed to nonsense std.sx spans. Fixed: pin setCurrentSourceFile per fn_ast_map entry from body.source_file (already stamped by resolveImports).
2. ErrorFlow.checkErrorFlow (error_flow.zig) — the flow walk resolves types via inferExprType AND emits its reject diagnostics; both used the ambient file. Fixed: pin per decl.
3. The UnknownTypeChecker unknown-type loop (semantic_diagnostics.zig) — emitted with the ambient file (checkBindingNames beside it already saved/restored per node). Fixed: pin diagnostics.current_source_file per decl.

Latent on master for all three — the ambient just happened to be the main file with the old single-file std.sx; the restructured std.sx (namespace part-file imports) reordered the pipeline's last-touched module and exposed them. Pinned coverage: examples 0129 / 1047 / 1049 / 1052 / 1053 / 1056 (closure shapes with nominal types, error-flow reject attribution) fail without the fixes once std.sx is the re-export facade. Gates: zig build test 426/426, suite 588/588.

Symptom

With a std.sx whose first declarations are namespace imports, programs using closures with user-struct parameter types failed type 'Point' is not visible; #import the module that declares it attributed to meaningless std.sx spans, and error-flow / unknown-type diagnostics for main-file code rendered against std.sx's line table (e.g. expected examples/foo.sx:22:21, got std.sx:16:25).

Reproduction

Against the pre-fix compiler with the re-export std.sx:

#import "modules/std.sx";
Point :: struct { x, y: s32; }
main :: () {
    f := closure((p: Point) -> Point => Point.{ x = p.x + 1, y = p.y });
    r := f(Point.{ x = 1, y = 2 });
    out("done\n");
}

Investigation prompt

(Resolved — kept for the record.) The root pattern: any pass that runs after module scanning and either resolves source-gated names or emits diagnostics MUST pin the visibility/rendering context per declaration (setCurrentSourceFile(decl.source_file) — syncs the lowering context and the diagnostics renderer), never inherit the ambient. Fn bodies carry body.source_file (stamped by resolveImports) for fn-keyed walks. When auditing for siblings, check every lowerRoot phase that walks fn_ast_map or the program decl list.