Use shorter paths in the OUT_DIR

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

@@ -21,6 +21,11 @@ pub(crate) const INCLUDE_VERB: &str = "create symlink";
 #[cfg(not(unix))]
 pub(crate) const INCLUDE_VERB: &str = "deep copy files";
 
+pub(crate) fn gen() -> PathBuf {
+    // Use a short name due to the Windows file path limit!
+    out().join("cxxqtgen")
+}
+
 // Clean a directory by removing it and recreating it.
 pub(crate) fn clean(path: impl AsRef<Path>) -> Result<()> {
     let result = std::fs::remove_dir_all(&path);
@@ -37,14 +42,26 @@ pub(crate) fn clean(path: impl AsRef<Path>) -> Result<()> {
 
 /// The target directory, namespaced by crate
 pub(crate) fn crate_target() -> PathBuf {
-    target().join("crates").join(crate_name())
+    let path = target();
+    if is_exporting_crate() {
+        path.join("crates").join(crate_name())
+    } else {
+        // If we're not exporting, use a shortened path
+        // The paths for files in the OUT_DIR can get pretty long, especially if combined with
+        // Corrosion/CMake.
+        // This is an issue, as Windows has a maximum path length of 260 characters.
+        // The OUT_DIR is already namespaced by crate name, so we don't need to prefix again.
+        // See also: https://github.com/KDAB/cxx-qt/issues/1237
+        path
+    }
 }
 
 /// The target directory, namespaced by QML module
 pub(crate) fn module_target(module_uri: &str) -> PathBuf {
     module_export(module_uri).unwrap_or_else(|| {
         out()
-            .join("qml_modules")
+            // Use a short name due to the Windows file path limit!
+            .join("cxxqtqml")
             .join(module_name_from_uri(module_uri))
     })
 }
@@ -75,7 +92,8 @@ pub(crate) fn target() -> PathBuf {
         return export;
     }
 
-    out().join("cxx-qt-build").join("target")
+    // Use a short name due to the Windows file path limit!
+    out().join("cxxqtbuild")
 }
 
 /// The export directory, if one was specified through the environment.

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

@@ -264,7 +264,7 @@ fn generate_cxxqt_cpp_files(
     header_dir: impl AsRef<Path>,
     include_prefix: &str,
 ) -> Vec<GeneratedCppFilePaths> {
-    let cxx_qt_dir = dir::out().join("cxx-qt-gen");
+    let cxx_qt_dir = dir::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("");
 

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

@@ -80,7 +80,7 @@ fn main() {
     });
     println!("cargo::rerun-if-changed=src/assertion_utils.h");
 
-    builder
-        .include_prefix("cxx-qt-lib-extras-internals")
-        .build();
+    // Use a short name due to the Windows file path limit!
+    // We don't re-export these headers anyway.
+    builder.include_prefix("private").build();
 }

crates/cxx-qt-lib/build.rs

@@ -352,7 +352,9 @@ fn main() {
         .reexport_dependency("cxx-qt");
 
     let mut builder = CxxQtBuilder::library(interface)
-        .include_prefix("cxx-qt-lib-internals")
+        // Use a short name due to the Windows file path limit!
+        // We don't re-export these headers anyway
+        .include_prefix("private")
         .initializer(qt_build_utils::Initializer {
             file: Some("src/core/init.cpp".into()),
             ..qt_build_utils::Initializer::default_signature("init_cxx_qt_lib_core")