slint-ui/slint · error · std::io::Error

path not found

Error message

path not found

What it means

In the preview's file-load callback (editor-side), the requested path is looked up in the `code` map of known sources. If the map has no entry for that `PathBuf`, the loader returns `NotFound` with the message "path not found", aborting compilation of that dependency.

Solutions

  1. Add the missing file's source to the `code` map before compiling, keyed by the same canonical PathBuf the loader will request
  2. Normalize both map keys and lookup paths (canonicalize) so they match exactly
  3. Verify the import path in the .slint file points to a file that exists and is registered with the preview

Example fix

// before
let Some(source) = code.get(&path) else { return Err(NotFound) };
// after
let canonical = path.canonicalize()?;
let Some(source) = code.get(&canonical) else { /* register or return NotFound */ };
Defensive patterns

Strategy: fallback

Validate before calling

if !code.contains_key(&path) {
    // read the file from disk instead of the cache, or fail early with a clear message
    let source = std::fs::read_to_string(&path)?;
}

Type guard

fn has_cached_source(code: &HashMap<PathBuf, String>, path: &Path) -> bool {
    code.contains_key(path)
}

Try / catch

match code.get(&path) {
    Some(source) => Ok((Some(24u32), source.clone())),
    None => match std::fs::read_to_string(&path) {
        Ok(src) => Ok((None, src)), // fallback to disk
        Err(_) => Err(std::io::Error::new(std::io::ErrorKind::NotFound, "path not found")),
    },
}

Prevention

When it happens

Trigger: The compiler's file loader requests a path that is not a key in the captured `code` map — e.g. an imported .slint file whose path was never added to the map, or a path whose format differs (relative vs absolute, different separators).

Common situations: An import references a file outside the set of files the editor registered; path normalization differences (e.g. `./x.slint` vs `x.slint`) make the map lookup miss; file was deleted or moved after the map was built.

Understand the failure class

Background: "File not found" and ENOENT errors: why libraries can't find a file that should exist — this error's family across 50 libraries.

Related errors

AI-assisted analysis of slint-ui/slint@3a7e700487 (2026-09-16). Data as JSON: /api/errors/5da9a06867592b44. Report an issue: GitHub.

Appendix: source

Thrown at tools/editor/preview.rs:2864

    ) -> ComponentInstance {
        let code = Rc::new(code);

        let path = main_test_file_name();
        let source_code = code.get(&path).unwrap().clone();
        let (diagnostics, component_definition, _, _) = spin_on::spin_on(super::parse_source(
            Default::default(),
            path,
            Some(24),
            source_code.to_string(),
            style.to_string(),
            None,
            move |path| {
                let code = code.clone();
                let path = PathBuf::from(&path);

                Box::pin(async move {
                    let Some(source) = code.get(&path) else {
                        return Some(Result::Err(std::io::Error::new(
                            std::io::ErrorKind::NotFound,
                            "path not found",
                        )));
                    };
                    Some(Ok((Some(24), source.clone())))
                })
            },
        ));

        assert!(diagnostics.is_empty());

        component_definition.unwrap().create().unwrap()
    }

    #[track_caller]
    pub fn interpret_test(style: &str, source_code: &str) -> ComponentInstance {
        let code = HashMap::from([(main_test_file_name(), source_code.to_string())]);
        interpret_test_with_sources(style, code)

View on GitHub (pinned to 3a7e700487)