plugin: give moc qtdeclarative include path so QML attrs reach qmltyperegistrar

nix/plugin.nix

@@ -7,11 +7,14 @@
   runCommand,
 }:
 let
-  # nixpkgs splits Qt tools across packages: moc/rcc/qtpaths live in qtbase,
+  # nixpkgs splits Qt: tools (moc/rcc/qtpaths in qtbase, qmltyperegistrar/qmlcachegen
-  # qmltyperegistrar and qmlcachegen live in qtdeclarative. qt-build-utils
+  # in qtdeclarative) and headers (qtbase has Qt6Core etc., qtdeclarative has Qt6Qml
-  # finds tools via `qmake -query QT_INSTALL_LIBEXECS`, which only returns
+  # incl. qqmlregistration.h). qt-build-utils derives both from `qmake -query`, which
-  # qtbase paths, so those two tools are invisible. Fix: combine them into a
+  # only knows about qtbase. Symptom of missing headers: moc warns "Potential QML
-  # single symlink tree and point a qmake wrapper at it.
+  # registration macro was found, but no header containing it was included", silently
+  # strips QML_NAMED_ELEMENT/QML_SINGLETON from the JSON, qmltyperegistrar emits an
+  # empty qml_register_types_*, and the QML import resolves to no types. Fix: combine
+  # tools and headers into symlink trees and point a qmake wrapper at them.
   qtBuildTools = runCommand "qt6-build-tools" { } ''
     mkdir -p $out/libexec $out/bin
     for f in ${qt6.qtbase}/libexec/* ${qt6.qtbase}/bin/*; do
@@ -22,6 +25,12 @@ let
       [ -f "$src" ] && ln -sf "$src" "$out/libexec/$tool"
     done
   '';
+  qtIncludeRoots = runCommand "qt6-include-roots" { } ''
+    mkdir -p $out/include
+    for src in ${qt6.qtbase.dev}/include/* ${qt6.qtdeclarative.dev}/include/*; do
+      ln -sfn "$src" "$out/include/$(basename "$src")"
+    done
+  '';
   qmakeWrapper = writeShellScript "qmake6" ''
     if [ "$1" = "-query" ]; then
       case "$2" in
@@ -29,6 +38,8 @@ let
           echo "${qtBuildTools}/libexec"; exit 0;;
         QT_HOST_BINS|QT_HOST_BINS/get|QT_INSTALL_BINS|QT_INSTALL_BINS/get)
           echo "${qtBuildTools}/bin"; exit 0;;
+        QT_HOST_INCLUDES|QT_HOST_INCLUDES/get|QT_INSTALL_HEADERS|QT_INSTALL_HEADERS/get)
+          echo "${qtIncludeRoots}/include"; exit 0;;
       esac
     fi
     exec ${qt6.qtbase}/bin/qmake6 "$@"

plugin/build.rs

@@ -26,17 +26,9 @@ fn main() {
     // Crane's deps-only build stubs out lib.rs and removes our bridge sources to
     // build a dummy crate that only compiles dependencies. Skip cxx-qt codegen in
     // that case - we just want cxx-qt-lib (the heavy dep) cached, not our own glue.
-    // Use CARGO_MANIFEST_DIR for a robust path that doesn't depend on cargo's CWD.
     let manifest = std::path::Path::new(env!("CARGO_MANIFEST_DIR"));
     let bridge_files = ["src/system_stats.rs", "src/cpu_service.rs"];
-    let present: Vec<bool> = bridge_files
+    if !bridge_files.iter().all(|p| manifest.join(p).exists()) {
-        .iter()
-        .map(|p| manifest.join(p).exists())
-        .collect();
-    println!("cargo:warning=build.rs manifest_dir={}", manifest.display());
-    println!("cargo:warning=build.rs bridge_files present: {present:?}");
-    if !present.iter().all(|b| *b) {
-        println!("cargo:warning=build.rs bailing: bridge files missing (deps-only build?)");
         return;
     }
 

plugin/src/lib.rs

@@ -2,21 +2,7 @@ pub mod cpu_service;
 pub mod stats;
 pub mod system_stats;
 
-// cxx-qt 0.8.1's PluginType::Dynamic emits a QQmlEngineExtensionPlugin whose
-// constructor only anchors qml_register_types_NovaStats with `volatile auto X = &X`
-// (linker-keep, not a call), and the qmltyperegistrar static init doesn't call it
-// either. Net effect: types never register, NS.* stays undefined in QML. Workaround:
-// call it ourselves at .so load time. The function is mangled (returns void, no
-// extern "C"), so go through #[link_name] using the itanium-mangled symbol seen in
-// `nm libNovaStats.so | grep qml_register_types`.
-unsafe extern "C" {
-    #[link_name = "_Z28qml_register_types_NovaStatsv"]
-    fn qml_register_types_nova_stats();
-}
-
 #[ctor::ctor(unsafe)]
 fn on_dylib_load() {
     eprintln!("[nova-plugin] dylib loaded (libNovaStats.so)");
-    unsafe { qml_register_types_nova_stats() };
-    eprintln!("[nova-plugin] qml_register_types_NovaStats called");
 }