From 4534e03a40c70dcac56bcdc274c9116a7f5d4791 Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Fri, 26 Jun 2026 22:04:05 +0000
Subject: [PATCH] P1: fix Zig FFI to compile and match the Idris2 ABI

The Zig FFI reference implementation (src/interface/ffi/src/main.zig)
failed to compile under Zig 0.14.0. Two fixes, both confined to the FFI
layer; the Idris2 ABI remains the source of truth.

1. Syntax error (the reported `expected statement, found ';'`): the
   `if (!h.initialized) { ... }` block at the end of
   anvomidaviser_get_string was terminated with a stray `;`. An `if`
   used as a statement takes no trailing semicolon, so the `};`
   following the block body was parsed as an empty statement. Removed
   the spurious semicolon.

2. `Handle` was declared as a Zig `opaque {}` type but given fields
   (`allocator`, `initialized`) and instantiated with `handle.* = .{...}`
   plus field access (`h.allocator`, `h.initialized`). Zig `opaque`
   types are unsized and cannot hold or expose fields, so this could
   never compile once the parser advanced past the syntax error.
   Changed `Handle` to a concrete `struct`, matching the house idiom
   in alloyiser's exemplar (its `Model` struct). It is still only ever
   handed to C as a pointer, so it stays opaque across the C ABI.

No exported C symbol names changed and no Result codes changed: every
`C:anvomidaviser_*` symbol in Foreign.idr still has a matching
`export fn`, and the Result enum integer values (ok=0, error=1,
invalid_param=2, out_of_memory=3, null_pointer=4, rule_violation=5)
match Types.idr's resultToInt exactly.

Verification:
- zig test src/main.zig -lc  -> all 3 tests pass, 0 errors/warnings
- idris2 --build anvomidaviser-abi.ipkg  -> exit 0

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019xMKB3T4Vo5FYC7Czx3JSH
---
 src/interface/ffi/src/main.zig | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/interface/ffi/src/main.zig b/src/interface/ffi/src/main.zig
index 950c5e3..901d307 100644
--- a/src/interface/ffi/src/main.zig
+++ b/src/interface/ffi/src/main.zig
@@ -38,12 +38,12 @@ pub const Result = enum(c_int) {
     rule_violation = 5,
 };
 
-/// Library handle (opaque to prevent direct access)
-pub const Handle = opaque {
-    // Internal state hidden from C
+/// Library handle. Opaque to C (passed as a pointer); fields are private to
+/// this module. A concrete struct (not Zig `opaque`) so internal state can be
+/// stored and accessed here.
+pub const Handle = struct {
     allocator: std.mem.Allocator,
     initialized: bool,
-    // Add your fields here
 };
 
 //==============================================================================
@@ -285,7 +285,7 @@ export fn anvomidaviser_get_string(handle: ?*Handle) ?[*:0]const u8 {
     if (!h.initialized) {
         setError("Handle not initialized");
         return null;
-    };
+    }
 
     const result = h.allocator.dupeZ(u8, "Anvomidaviser score pending") catch {
         setError("Failed to allocate string");