G2: panel-clades Zig FFI builds green under Zig 0.15

build.zig migrated to 0.15 API (addSharedLibrary/addStaticLibrary ->
addLibrary+linkage, addTest/addExecutable -> root_module via
createModule, addInstallHeader -> addInstallFileWithDir, .link_libc on
all modules). main.zig: opaque-with-fields -> struct, callconv(.C) ->
callconv(.c), removed pointless discard. zig build test now exits 0
(was: didn't compile). Same proven pattern as Axiom.jl PR #17.

Author: hyperpolymath

panel-clades/ffi/zig/build.zig

@@ -7,41 +7,49 @@ pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
 
-    // Shared library (.so, .dylib, .dll)
-    const lib = b.addSharedLibrary(.{
-        .name = "panel_clades",
+    // Root module shared by the library/test artifacts (Zig 0.15 API).
+    const root_mod = b.createModule(.{
+            .link_libc = true,
         .root_source_file = b.path("src/main.zig"),
         .target = target,
         .optimize = optimize,
     });
 
-    // Set version
-    lib.version = .{ .major = 0, .minor = 1, .patch = 0 };
+    // Shared library (.so, .dylib, .dll)
+    const lib = b.addLibrary(.{
+        .name = "panel_clades",
+        .linkage = .dynamic,
+        .root_module = root_mod,
+        .version = .{ .major = 0, .minor = 1, .patch = 0 },
+    });
 
     // Static library (.a)
-    const lib_static = b.addStaticLibrary(.{
+    const lib_static = b.addLibrary(.{
         .name = "panel_clades",
-        .root_source_file = b.path("src/main.zig"),
-        .target = target,
-        .optimize = optimize,
+        .linkage = .static,
+        .root_module = root_mod,
     });
 
     // Install artifacts
     b.installArtifact(lib);
     b.installArtifact(lib_static);
 
-    // Generate header file for C compatibility
-    const header = b.addInstallHeader(
+    // Install the C header (Zig 0.15 API).
+    const header = b.addInstallFileWithDir(
         b.path("include/panel_clades.h"),
+        .header,
         "panel_clades.h",
     );
     b.getInstallStep().dependOn(&header.step);
 
     // Unit tests
     const lib_tests = b.addTest(.{
-        .root_source_file = b.path("src/main.zig"),
-        .target = target,
-        .optimize = optimize,
+        .root_module = b.createModule(.{
+            .link_libc = true,
+            .root_source_file = b.path("src/main.zig"),
+            .target = target,
+            .optimize = optimize,
+        }),
     });
 
     const run_lib_tests = b.addRunArtifact(lib_tests);
@@ -51,9 +59,12 @@ pub fn build(b: *std.Build) void {
 
     // Integration tests
     const integration_tests = b.addTest(.{
-        .root_source_file = b.path("test/integration_test.zig"),
-        .target = target,
-        .optimize = optimize,
+        .root_module = b.createModule(.{
+            .link_libc = true,
+            .root_source_file = b.path("test/integration_test.zig"),
+            .target = target,
+            .optimize = optimize,
+        }),
     });
 
     integration_tests.linkLibrary(lib);
@@ -65,9 +76,12 @@ pub fn build(b: *std.Build) void {
 
     // Documentation
     const docs = b.addTest(.{
-        .root_source_file = b.path("src/main.zig"),
-        .target = target,
-        .optimize = .Debug,
+        .root_module = b.createModule(.{
+            .link_libc = true,
+            .root_source_file = b.path("src/main.zig"),
+            .target = target,
+            .optimize = .Debug,
+        }),
     });
 
     const docs_step = b.step("docs", "Generate documentation");
@@ -80,9 +94,12 @@ pub fn build(b: *std.Build) void {
     // Benchmark (if needed)
     const bench = b.addExecutable(.{
         .name = "panel_clades-bench",
-        .root_source_file = b.path("bench/bench.zig"),
-        .target = target,
-        .optimize = .ReleaseFast,
+        .root_module = b.createModule(.{
+            .link_libc = true,
+            .root_source_file = b.path("bench/bench.zig"),
+            .target = target,
+            .optimize = .ReleaseFast,
+        }),
     });
 
     bench.linkLibrary(lib);

panel-clades/ffi/zig/src/main.zig

@@ -59,12 +59,13 @@ pub const CladeKind = enum(u32) {
     terminal = 12,
 };
 
-/// Library handle (opaque to prevent direct access)
-pub const Handle = opaque {
+/// Library handle. A real struct internally; exposed across the C ABI as
+/// an opaque pointer (the header forward-declares it). `opaque{}` cannot
+/// have fields or be `create`d, so this must be a `struct`.
+pub const Handle = struct {
     // Internal state hidden from C
     allocator: std.mem.Allocator,
     initialized: bool,
-    // Add your fields here
 };
 
 //==============================================================================
@@ -154,8 +155,7 @@ export fn panel_clades_load_clade(handle: ?*Handle, clade_id: ?[*:0]const u8) Re
         return .invalid_param;
     }
 
-    // TODO: store clade definition internally
-    _ = id_str;
+    // TODO: store clade definition internally (id_str validated above)
 
     clearError();
     return .ok;
@@ -318,7 +318,7 @@ export fn panel_clades_build_info() [*:0]const u8 {
 //==============================================================================
 
 /// Callback function type (C ABI)
-pub const Callback = *const fn (u64, u32) callconv(.C) u32;
+pub const Callback = *const fn (u64, u32) callconv(.c) u32;
 
 /// Register a callback
 export fn panel_clades_register_callback(