fixes

examples/issue-0019.sx

@@ -0,0 +1,42 @@
+// issue-0019: #import c symbols are globally visible instead of scoped to the importing file
+//
+// When a file uses `#import c { #include "foo.h"; #source "foo.c"; }`,
+// the C symbols become available to ALL files in the compilation unit,
+// not just the file that imported them.
+//
+// This means a file can call C functions without importing the module
+// that declares them, as long as some other file in the project does.
+//
+// Expected: C symbols from `#import c` should only be visible in files
+// that directly (or transitively via SX #import) import the module.
+//
+// Repro:
+//   - a.sx: `#import c { #include "some_lib.h"; #source "some_lib.c"; };`
+//   - b.sx: does NOT import a.sx, but calls some_lib_function() — compiles successfully
+//
+// In the game project:
+//   - main.sx imports modules/stb_truetype.sx (which has #import c for kbts/stbtt)
+//   - ui/glyph_cache.sx does NOT import modules/stb_truetype.sx
+//   - ui/glyph_cache.sx calls kbts_ShapeRun, stbtt_InitFont, etc. — compiles fine
+//   - If main.sx removed the import, glyph_cache.sx would break
+
+// Minimal repro structure (two files):
+
+// --- module_with_c.sx ---
+// #import c {
+//     #include "vendors/some_lib.h";
+//     #source "vendors/some_lib.c";
+// };
+//
+// uses_c :: () -> s32 {
+//     some_lib_function();
+// }
+
+// --- main.sx (this file) ---
+// #import "module_with_c.sx";
+//
+// main :: () -> s32 {
+//     // This should fail because we never imported the C module directly,
+//     // but currently it compiles:
+//     some_lib_function();
+// }