fix(build): Try to fix windows file sync issues

crates/cxx-qt-build/src/lib.rs

@@ -16,7 +16,8 @@ mod cfg_evaluator;
 mod diagnostics;
 use diagnostics::{Diagnostic, GeneratedError};
 
-pub mod dir;
+mod dir;
+mod out;
 
 mod dependencies;
 pub use dependencies::Interface;
@@ -244,7 +245,7 @@ fn generate_cxxqt_cpp_files(
 ) -> Vec<GeneratedCppFilePaths> {
     let cxx_qt_dir = dir::out().join("cxx-qt-gen");
     std::fs::create_dir_all(&cxx_qt_dir).expect("Failed to create cxx-qt-gen directory!");
-    std::fs::write(cxx_qt_dir.join("include-prefix.txt"), include_prefix).expect("");
+    out::write_file(cxx_qt_dir.join("include-prefix.txt"), include_prefix).expect("");
 
     let header_dir = header_dir.as_ref().join(include_prefix);
     let manifest_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
@@ -576,7 +577,7 @@ impl CxxQtBuilder {
         // Wrap the File in a block scope so the file is closed before the compiler is run.
         // Otherwise MSVC fails to open cxx.h because the process for this build script already has it open.
         {
-            std::fs::write(h_path, cxx_gen::HEADER).expect("Failed to write cxx.h");
+            out::write_file(h_path, cxx_gen::HEADER).expect("Failed to write cxx.h");
         }
     }
 
@@ -837,7 +838,7 @@ impl CxxQtBuilder {
         std::fs::create_dir_all(&initializers_path).expect("Failed to create initializers path!");
 
         let initializers_path = initializers_path.join(format!("{}.cpp", crate_name()));
-        std::fs::write(&initializers_path, self.generate_init_code(initializers))
+        out::write_file(&initializers_path, self.generate_init_code(initializers))
             .expect("Could not write initializers file");
         Self::build_object_file(
             init_builder,
@@ -895,7 +896,7 @@ impl CxxQtBuilder {
             let manifest_path = dir::crate_target().join("manifest.json");
             let manifest_json = serde_json::to_string_pretty(&manifest)
                 .expect("Failed to convert Manifest to JSON!");
-            std::fs::write(&manifest_path, manifest_json).expect("Failed to write manifest.json!");
+            out::write_file(&manifest_path, manifest_json).expect("Failed to write manifest.json!");
             println!(
                 "cargo::metadata=CXX_QT_MANIFEST_PATH={}",
                 manifest_path.to_string_lossy()

crates/cxx-qt-build/src/out.rs

@@ -0,0 +1,28 @@
+// SPDX-FileCopyrightText: 2024 Klarälvdalens Datakonsult AB, a KDAB Group company <info@kdab.com>
+// SPDX-FileContributor: Leon Matthes <leon.matthes@kdab.com>
+//
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+//! A module for handling anything output related
+
+#[cfg(windows)]
+use std::path::Path;
+
+#[cfg(windows)]
+pub(crate) fn write_file(
+    path: impl AsRef<Path>,
+    contents: impl AsRef<[u8]>,
+) -> std::io::Result<()> {
+    use std::fs::File;
+    use std::io::Write;
+
+    // On Windows we're experiencing some issues with file locking and possibly
+    // synchronization, especially when combined with cc::Build
+    // So force a synchronization here with sync_all()
+    let mut file = File::create(path)?;
+    file.write_all(contents.as_ref())?;
+    file.sync_all()
+}
+
+#[cfg(not(windows))]
+pub(crate) use std::fs::write as write_file;

crates/cxx-qt/src/lib.rs

@@ -391,5 +391,11 @@ pub fn write_headers(directory: impl AsRef<Path>) {
         let h_path = format!("{}/{file_name}", directory.display());
         let mut header = File::create(h_path).expect("Could not create cxx-qt header");
         write!(header, "{file_contents}").expect("Could not write cxx-qt header");
+        // On Windows, we're often experiencing issues with file synchronization, try forcing a
+        // synchronization here.
+        #[cfg(windows)]
+        header
+            .sync_all()
+            .expect("Failed to synchronize cxx-qt header file");
     }
 }