[red-knot] Add basic WASM API (#12654)

2025-08-03 18:28:24 +00:00 · 2024-08-06 09:21:42 +02:00 · 2024-08-06 09:21:42 +02:00 · 10e977d5f5
commit 10e977d5f5
parent f0318ff889
11 changed files with 473 additions and 31 deletions
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@ -111,7 +111,7 @@ jobs:
      - name: "Clippy"
        run: cargo clippy --workspace --all-targets --all-features --locked -- -D warnings
      - name: "Clippy (wasm)"
-        run: cargo clippy -p ruff_wasm --target wasm32-unknown-unknown --all-features --locked -- -D warnings
+        run: cargo clippy -p ruff_wasm -p red_knot_wasm --target wasm32-unknown-unknown --all-features --locked -- -D warnings

  cargo-test-linux:
    name: "cargo test (linux)"
@ -191,10 +191,14 @@ jobs:
          cache-dependency-path: playground/package-lock.json
      - uses: jetli/wasm-pack-action@v0.4.0
      - uses: Swatinem/rust-cache@v2
-      - name: "Run wasm-pack"
+      - name: "Test ruff_wasm"
        run: |
          cd crates/ruff_wasm
          wasm-pack test --node
+      - name: "Test red_knot_wasm"
+        run: |
+          cd crates/red_knot_wasm
+          wasm-pack test --node

  cargo-build-release:
    name: "cargo build (release)"
--- a/Cargo.lock
+++ b/Cargo.lock
@ -20,7 +20,7 @@ version = "0.8.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e89da841a80418a9b391ebaea17f5c112ffaaa96f621d2c285b5174da76b9011"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "getrandom",
 "once_cell",
 "version_check",
@ -270,6 +270,12 @@ dependencies = [
 "once_cell",
 ]

+[[package]]
+name = "cfg-if"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
+
 [[package]]
 name = "cfg-if"
 version = "1.0.0"
@ -459,7 +465,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6050c3a16ddab2e412160b31f2c871015704239bca62f72f6e5f0be631d3f644"
 dependencies = [
 "castaway",
- "cfg-if",
+ "cfg-if 1.0.0",
 "itoa",
 "rustversion",
 "ryu",
@ -486,7 +492,7 @@ version = "0.1.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a06aeb73f470f66dcdbf7223caeebb85984942f22f1adb2a088cf9668146bbbc"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "wasm-bindgen",
 ]

@ -523,7 +529,7 @@ version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b3855a8a784b474f333699ef2bbca9db2c4a1f6d9088a90a2d25b1eb53111eaa"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 ]

 [[package]]
@ -673,7 +679,7 @@ version = "5.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "978747c1d849a7d2ee5e8adc0159961c48fb7e5db2f06af6723b80123bb53856"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "hashbrown",
 "lock_api",
 "once_cell",
@ -686,7 +692,7 @@ version = "6.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "804c8821570c3f8b70230c2ba75ffa5c0f9a4189b9a432b6656c536712acae28"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "crossbeam-utils",
 "hashbrown",
 "lock_api",
@ -810,7 +816,7 @@ version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "136d1b5283a1ab77bd9257427ffd09d8667ced0570b6f938942bc7568ed5b943"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "home",
 "windows-sys 0.48.0",
 ]
@ -836,7 +842,7 @@ version = "0.2.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1ee447700ac8aa0b2f2bd7bc4462ad686ba06baa6727ac149a2d6277f0d240fd"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "libc",
 "redox_syscall",
 "windows-sys 0.52.0",
@ -900,7 +906,7 @@ version = "0.2.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "94b22e06ecb0110981051723910cbf0b5f5e09a2062dd7663334ee79a9d1286c"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "js-sys",
 "libc",
 "wasi",
@ -932,7 +938,7 @@ version = "2.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6dd08c532ae367adf81c312a4580bc67f1d0fe8bc9c460520283f4c0ff277888"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "crunchy",
 ]

@ -1141,7 +1147,7 @@ version = "0.1.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7a5bbe824c507c5da5956355e86a746d82e0e1464f65d862cc5e71da70e94b2c"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 ]

 [[package]]
@ -1390,6 +1396,12 @@ version = "2.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"

+[[package]]
+name = "memory_units"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8452105ba047068f40ff7093dd1d9da90898e63dd61736462e9cdda6a90ad3c3"
+
 [[package]]
 name = "mimalloc"
 version = "0.1.43"
@ -1448,7 +1460,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ab2156c4fce2f8df6c499cc1c763e4394b7482525bf2a9701c9d79d215f519e4"
 dependencies = [
 "bitflags 2.6.0",
- "cfg-if",
+ "cfg-if 1.0.0",
 "cfg_aliases",
 "libc",
 ]
@ -1574,7 +1586,7 @@ version = "0.9.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4c42a9226546d68acdd9c0a280d17ce19bfe27a46bf68784e4066115788d008e"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "libc",
 "redox_syscall",
 "smallvec",
@ -1928,6 +1940,22 @@ dependencies = [
 "tracing",
 ]

+[[package]]
+name = "red_knot_wasm"
+version = "0.0.0"
+dependencies = [
+ "console_error_panic_hook",
+ "console_log",
+ "js-sys",
+ "log",
+ "red_knot_workspace",
+ "ruff_db",
+ "ruff_notebook",
+ "wasm-bindgen",
+ "wasm-bindgen-test",
+ "wee_alloc",
+]
+
 [[package]]
 name = "red_knot_workspace"
 version = "0.0.0"
@ -2016,7 +2044,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c17fa4cb658e3583423e915b9f3acc01cceaee1860e33d59ebae66adc3a2dc0d"
 dependencies = [
 "cc",
- "cfg-if",
+ "cfg-if 1.0.0",
 "getrandom",
 "libc",
 "spin",
@ -2134,6 +2162,7 @@ dependencies = [
 "salsa",
 "tempfile",
 "tracing",
+ "web-time",
 "zip",
 ]

@ -2989,7 +3018,7 @@ version = "3.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b8fcd239983515c23a32fb82099f97d0b11b8c72f654ed659363a95c3dad7a53"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "fastrand",
 "once_cell",
 "rustix",
@ -3034,7 +3063,7 @@ version = "3.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "adcb7fd841cd518e279be3d5a3eb0636409487998a4aff22f3de87b81e88384f"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "proc-macro2",
 "quote",
 "syn",
@ -3078,7 +3107,7 @@ version = "1.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8b9ef9bad013ada3808854ceac7b46812a6465ba368859a37e2100283d2d719c"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "once_cell",
 ]

@ -3480,7 +3509,7 @@ version = "0.2.92"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4be2531df63900aeb2bca0daaaddec08491ee64ceecbee5076636a3b026795a8"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "wasm-bindgen-macro",
 ]

@ -3505,7 +3534,7 @@ version = "0.4.42"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "76bc14366121efc8dbb487ab05bcc9d346b3b5ec0eaa76e46594cabbe51762c0"
 dependencies = [
- "cfg-if",
+ "cfg-if 1.0.0",
 "js-sys",
 "wasm-bindgen",
 "web-sys",
@ -3575,6 +3604,16 @@ dependencies = [
 "wasm-bindgen",
 ]

+[[package]]
+name = "web-time"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a6580f308b1fad9207618087a65c04e7a10bc77e02c8e84e9b00dd4b12fa0bb"
+dependencies = [
+ "js-sys",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "webpki-roots"
 version = "0.26.1"
@ -3584,6 +3623,18 @@ dependencies = [
 "rustls-pki-types",
 ]

+[[package]]
+name = "wee_alloc"
+version = "0.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dbb3b5a6b2bb17cb6ad44a2e68a43e8d2722c997da10e928665c72ec6c0a0b8e"
+dependencies = [
+ "cfg-if 0.1.10",
+ "libc",
+ "memory_units",
+ "winapi",
+]
+
 [[package]]
 name = "which"
 version = "6.0.1"
@ -3858,6 +3909,7 @@ dependencies = [
 "byteorder",
 "crc32fast",
 "crossbeam-utils",
+ "flate2",
 "zstd",
 ]

--- a/Cargo.toml
+++ b/Cargo.toml
@ -152,7 +152,7 @@ walkdir = { version = "2.3.2" }
 wasm-bindgen = { version = "0.2.92" }
 wasm-bindgen-test = { version = "0.3.42" }
 wild = { version = "2" }
-zip = { version = "0.6.6", default-features = false, features = ["zstd"] }
+zip = { version = "0.6.6", default-features = false }

 [workspace.lints.rust]
 unsafe_code = "warn"
--- a/crates/red_knot_module_resolver/Cargo.toml
+++ b/crates/red_knot_module_resolver/Cargo.toml
@ -25,7 +25,7 @@ zip = { workspace = true }
 [build-dependencies]
 path-slash = { workspace = true }
 walkdir = { workspace = true }
-zip = { workspace = true }
+zip = { workspace = true, features = ["zstd", "deflate"] }

 [dev-dependencies]
 ruff_db = { workspace = true, features = ["os"] }
--- a/crates/red_knot_module_resolver/build.rs
+++ b/crates/red_knot_module_resolver/build.rs
@ -23,8 +23,21 @@ const TYPESHED_ZIP_LOCATION: &str = "/zipped_typeshed.zip";
 fn zip_dir(directory_path: &str, writer: File) -> ZipResult<File> {
    let mut zip = ZipWriter::new(writer);

+    // Use deflated compression for WASM builds because compiling `zstd-sys` requires clang
+    // [source](https://github.com/gyscos/zstd-rs/wiki/Compile-for-WASM) which complicates the build
+    // by a lot. Deflated compression is slower but it shouldn't matter much for the WASM use case
+    // (WASM itself is already slower than a native build for a specific platform).
+    // We can't use `#[cfg(...)]` here because the target-arch in a build script is the
+    // architecture of the system running the build script and not the architecture of the build-target.
+    // That's why we use the `TARGET` environment variable here.
+    let method = if std::env::var("TARGET").unwrap().contains("wasm32") {
+        CompressionMethod::Deflated
+    } else {
+        CompressionMethod::Zstd
+    };
+
    let options = FileOptions::default()
-        .compression_method(CompressionMethod::Zstd)
+        .compression_method(method)
        .unix_permissions(0o644);

    for entry in walkdir::WalkDir::new(directory_path) {
--- a/crates/red_knot_wasm/Cargo.toml
+++ b/crates/red_knot_wasm/Cargo.toml
@ -0,0 +1,38 @@
+[package]
+name = "red_knot_wasm"
+version = "0.0.0"
+publish = false
+authors = { workspace = true }
+edition = { workspace = true }
+rust-version = { workspace = true }
+homepage = { workspace = true }
+documentation = { workspace = true }
+repository = { workspace = true }
+license = { workspace = true }
+description = "WebAssembly bindings for Red Knot"
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+doctest = false
+
+[features]
+default = ["console_error_panic_hook"]
+
+[dependencies]
+red_knot_workspace = { workspace = true }
+
+ruff_db = { workspace = true }
+ruff_notebook = { workspace = true }
+
+console_error_panic_hook = { workspace = true, optional = true }
+console_log = { workspace = true }
+js-sys = { workspace = true }
+log = { workspace = true }
+wasm-bindgen = { workspace = true }
+wee_alloc = "0.4.5"
+
+[dev-dependencies]
+wasm-bindgen-test = { workspace = true }
+
+[lints]
+workspace = true
--- a/crates/red_knot_wasm/src/lib.rs
+++ b/crates/red_knot_wasm/src/lib.rs
@ -0,0 +1,284 @@
+use std::any::Any;
+
+use js_sys::Error;
+use wasm_bindgen::prelude::*;
+
+use red_knot_workspace::db::RootDatabase;
+use red_knot_workspace::workspace::WorkspaceMetadata;
+use ruff_db::files::{system_path_to_file, File};
+use ruff_db::program::{ProgramSettings, SearchPathSettings};
+use ruff_db::system::walk_directory::WalkDirectoryBuilder;
+use ruff_db::system::{
+    DirectoryEntry, MemoryFileSystem, Metadata, System, SystemPath, SystemPathBuf,
+    SystemVirtualPath,
+};
+use ruff_notebook::Notebook;
+
+// Use `wee_alloc` as the global allocator.
+#[global_allocator]
+static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;
+
+#[wasm_bindgen(start)]
+pub fn run() {
+    use log::Level;
+
+    // When the `console_error_panic_hook` feature is enabled, we can call the
+    // `set_panic_hook` function at least once during initialization, and then
+    // we will get better error messages if our code ever panics.
+    //
+    // For more details see
+    // https://github.com/rustwasm/console_error_panic_hook#readme
+    #[cfg(feature = "console_error_panic_hook")]
+    console_error_panic_hook::set_once();
+
+    console_log::init_with_level(Level::Debug).expect("Initializing logger went wrong.");
+}
+
+#[wasm_bindgen]
+pub struct Workspace {
+    db: RootDatabase,
+    system: WasmSystem,
+}
+
+#[wasm_bindgen]
+impl Workspace {
+    #[wasm_bindgen(constructor)]
+    pub fn new(root: &str, settings: &Settings) -> Result<Workspace, Error> {
+        let system = WasmSystem::new(SystemPath::new(root));
+        let workspace =
+            WorkspaceMetadata::from_path(SystemPath::new(root), &system).map_err(into_error)?;
+
+        let program_settings = ProgramSettings {
+            target_version: settings.target_version.into(),
+            search_paths: SearchPathSettings::default(),
+        };
+
+        let db = RootDatabase::new(workspace, program_settings, system.clone());
+
+        Ok(Self { db, system })
+    }
+
+    #[wasm_bindgen(js_name = "openFile")]
+    pub fn open_file(&mut self, path: &str, contents: &str) -> Result<FileHandle, Error> {
+        self.system
+            .fs
+            .write_file(path, contents)
+            .map_err(into_error)?;
+
+        let file = system_path_to_file(&self.db, path).expect("File to exist");
+        file.sync(&mut self.db);
+
+        self.db.workspace().open_file(&mut self.db, file);
+
+        Ok(FileHandle {
+            file,
+            path: SystemPath::new(path).to_path_buf(),
+        })
+    }
+
+    #[wasm_bindgen(js_name = "updateFile")]
+    pub fn update_file(&mut self, file_id: &FileHandle, contents: &str) -> Result<(), Error> {
+        if !self.system.fs.exists(&file_id.path) {
+            return Err(Error::new("File does not exist"));
+        }
+
+        self.system
+            .fs
+            .write_file(&file_id.path, contents)
+            .map_err(into_error)?;
+
+        file_id.file.sync(&mut self.db);
+
+        Ok(())
+    }
+
+    #[wasm_bindgen(js_name = "closeFile")]
+    pub fn close_file(&mut self, file_id: &FileHandle) -> Result<(), Error> {
+        let file = file_id.file;
+
+        self.db.workspace().close_file(&mut self.db, file);
+        self.system
+            .fs
+            .remove_file(&file_id.path)
+            .map_err(into_error)?;
+
+        file.sync(&mut self.db);
+
+        Ok(())
+    }
+
+    /// Checks a single file.
+    #[wasm_bindgen(js_name = "checkFile")]
+    pub fn check_file(&self, file_id: &FileHandle) -> Result<Vec<String>, Error> {
+        let result = self.db.check_file(file_id.file).map_err(into_error)?;
+
+        Ok(result.to_vec())
+    }
+
+    /// Checks all open files
+    pub fn check(&self) -> Result<Vec<String>, Error> {
+        let result = self.db.check().map_err(into_error)?;
+
+        Ok(result.clone())
+    }
+
+    /// Returns the parsed AST for `path`
+    pub fn parsed(&self, file_id: &FileHandle) -> Result<String, Error> {
+        let parsed = ruff_db::parsed::parsed_module(&self.db, file_id.file);
+
+        Ok(format!("{:#?}", parsed.syntax()))
+    }
+
+    /// Returns the token stream for `path` serialized as a string.
+    pub fn tokens(&self, file_id: &FileHandle) -> Result<String, Error> {
+        let parsed = ruff_db::parsed::parsed_module(&self.db, file_id.file);
+
+        Ok(format!("{:#?}", parsed.tokens()))
+    }
+
+    #[wasm_bindgen(js_name = "sourceText")]
+    pub fn source_text(&self, file_id: &FileHandle) -> Result<String, Error> {
+        let source_text = ruff_db::source::source_text(&self.db, file_id.file);
+
+        Ok(source_text.to_string())
+    }
+}
+
+pub(crate) fn into_error<E: std::fmt::Display>(err: E) -> Error {
+    Error::new(&err.to_string())
+}
+
+#[derive(Debug, Eq, PartialEq)]
+#[wasm_bindgen(inspectable)]
+pub struct FileHandle {
+    path: SystemPathBuf,
+    file: File,
+}
+
+#[wasm_bindgen]
+impl FileHandle {
+    #[wasm_bindgen(js_name = toString)]
+    pub fn js_to_string(&self) -> String {
+        format!("file(id: {:?}, path: {})", self.file, self.path)
+    }
+}
+
+#[wasm_bindgen]
+pub struct Settings {
+    pub target_version: TargetVersion,
+}
+#[wasm_bindgen]
+impl Settings {
+    #[wasm_bindgen(constructor)]
+    pub fn new(target_version: TargetVersion) -> Self {
+        Self { target_version }
+    }
+}
+
+#[wasm_bindgen]
+#[derive(Copy, Clone, Hash, PartialEq, Eq, PartialOrd, Ord, Default)]
+pub enum TargetVersion {
+    Py37,
+    #[default]
+    Py38,
+    Py39,
+    Py310,
+    Py311,
+    Py312,
+    Py313,
+}
+
+impl From<TargetVersion> for ruff_db::program::TargetVersion {
+    fn from(value: TargetVersion) -> Self {
+        match value {
+            TargetVersion::Py37 => Self::Py37,
+            TargetVersion::Py38 => Self::Py38,
+            TargetVersion::Py39 => Self::Py39,
+            TargetVersion::Py310 => Self::Py310,
+            TargetVersion::Py311 => Self::Py311,
+            TargetVersion::Py312 => Self::Py312,
+            TargetVersion::Py313 => Self::Py313,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+struct WasmSystem {
+    fs: MemoryFileSystem,
+}
+
+impl WasmSystem {
+    fn new(root: &SystemPath) -> Self {
+        Self {
+            fs: MemoryFileSystem::with_current_directory(root),
+        }
+    }
+}
+
+impl System for WasmSystem {
+    fn path_metadata(&self, path: &SystemPath) -> ruff_db::system::Result<Metadata> {
+        self.fs.metadata(path)
+    }
+
+    fn canonicalize_path(&self, path: &SystemPath) -> ruff_db::system::Result<SystemPathBuf> {
+        Ok(self.fs.canonicalize(path))
+    }
+
+    fn read_to_string(&self, path: &SystemPath) -> ruff_db::system::Result<String> {
+        self.fs.read_to_string(path)
+    }
+
+    fn read_to_notebook(
+        &self,
+        path: &SystemPath,
+    ) -> Result<ruff_notebook::Notebook, ruff_notebook::NotebookError> {
+        let content = self.read_to_string(path)?;
+        Notebook::from_source_code(&content)
+    }
+
+    fn virtual_path_metadata(
+        &self,
+        _path: &SystemVirtualPath,
+    ) -> ruff_db::system::Result<Metadata> {
+        Err(not_found())
+    }
+
+    fn read_virtual_path_to_string(
+        &self,
+        _path: &SystemVirtualPath,
+    ) -> ruff_db::system::Result<String> {
+        Err(not_found())
+    }
+
+    fn read_virtual_path_to_notebook(
+        &self,
+        _path: &SystemVirtualPath,
+    ) -> Result<ruff_notebook::Notebook, ruff_notebook::NotebookError> {
+        Err(ruff_notebook::NotebookError::Io(not_found()))
+    }
+
+    fn current_directory(&self) -> &SystemPath {
+        self.fs.current_directory()
+    }
+
+    fn read_directory<'a>(
+        &'a self,
+        path: &SystemPath,
+    ) -> ruff_db::system::Result<
+        Box<dyn Iterator<Item = ruff_db::system::Result<DirectoryEntry>> + 'a>,
+    > {
+        Ok(Box::new(self.fs.read_directory(path)?))
+    }
+
+    fn walk_directory(&self, path: &SystemPath) -> WalkDirectoryBuilder {
+        self.fs.walk_directory(path)
+    }
+
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+}
+
+fn not_found() -> std::io::Error {
+    std::io::Error::new(std::io::ErrorKind::NotFound, "No such file or directory")
+}
--- a/crates/red_knot_wasm/tests/api.rs
+++ b/crates/red_knot_wasm/tests/api.rs
@ -0,0 +1,21 @@
+#![cfg(target_arch = "wasm32")]
+
+use wasm_bindgen_test::wasm_bindgen_test;
+
+use red_knot_wasm::{Settings, TargetVersion, Workspace};
+
+#[wasm_bindgen_test]
+fn check() {
+    let settings = Settings {
+        target_version: TargetVersion::Py312,
+    };
+    let mut workspace = Workspace::new("/", &settings).expect("Workspace to be created");
+
+    let test = workspace
+        .open_file("test.py", "import random22\n")
+        .expect("File to be opened");
+
+    let result = workspace.check_file(&test).expect("Check to succeed");
+
+    assert_eq!(result, vec!["Unresolved import 'random22'"]);
+}
--- a/crates/ruff_db/Cargo.toml
+++ b/crates/ruff_db/Cargo.toml
@ -29,7 +29,13 @@ salsa = { workspace = true }
 path-slash = { workspace = true }
 tracing = { workspace = true }
 rustc-hash = { workspace = true }
-zip = { workspace = true }
+
+[target.'cfg(not(target_arch="wasm32"))'.dependencies]
+zip = { workspace = true, features = ["zstd"] }
+
+[target.'cfg(target_arch="wasm32")'.dependencies]
+web-time = { version = "1.1.0" }
+zip = { workspace = true, features = ["deflate"] }

 [dev-dependencies]
 insta = { workspace = true }
--- a/crates/ruff_db/src/program.rs
+++ b/crates/ruff_db/src/program.rs
@ -77,7 +77,7 @@ impl std::fmt::Debug for TargetVersion {
 }

 /// Configures the search paths for module resolution.
-#[derive(Eq, PartialEq, Debug, Clone)]
+#[derive(Eq, PartialEq, Debug, Clone, Default)]
 pub struct SearchPathSettings {
    /// List of user-provided paths that should take first priority in the module resolution.
    /// Examples in other type checkers are mypy's MYPYPATH environment variable,
--- a/crates/ruff_db/src/system/memory_fs.rs
+++ b/crates/ruff_db/src/system/memory_fs.rs
@ -213,7 +213,7 @@ impl MemoryFileSystem {

        let file = get_or_create_file(&mut by_path, &normalized)?;
        file.content = content.to_string();
-        file.last_modified = FileTime::now();
+        file.last_modified = now();

        Ok(())
    }
@ -229,7 +229,7 @@ impl MemoryFileSystem {
            std::collections::hash_map::Entry::Vacant(entry) => {
                entry.insert(File {
                    content: content.to_string(),
-                    last_modified: FileTime::now(),
+                    last_modified: now(),
                });
            }
            std::collections::hash_map::Entry::Occupied(mut entry) => {
@ -284,7 +284,7 @@ impl MemoryFileSystem {
        let mut by_path = self.inner.by_path.write().unwrap();
        let normalized = self.normalize_path(path.as_ref());

-        get_or_create_file(&mut by_path, &normalized)?.last_modified = FileTime::now();
+        get_or_create_file(&mut by_path, &normalized)?.last_modified = now();

        Ok(())
    }
@ -449,7 +449,7 @@ fn create_dir_all(
        path.push(component);
        let entry = paths.entry(path.clone()).or_insert_with(|| {
            Entry::Directory(Directory {
-                last_modified: FileTime::now(),
+                last_modified: now(),
            })
        });

@ -472,7 +472,7 @@ fn get_or_create_file<'a>(
    let entry = paths.entry(normalized.to_path_buf()).or_insert_with(|| {
        Entry::File(File {
            content: String::new(),
-            last_modified: FileTime::now(),
+            last_modified: now(),
        })
    });

@ -654,6 +654,30 @@ enum WalkerState {
    Nested { path: SystemPathBuf, depth: usize },
 }

+#[cfg(not(target_arch = "wasm32"))]
+fn now() -> FileTime {
+    FileTime::now()
+}
+
+#[cfg(target_arch = "wasm32")]
+fn now() -> FileTime {
+    // Copied from FileTime::from_system_time()
+    let time = web_time::SystemTime::now();
+
+    time.duration_since(web_time::UNIX_EPOCH)
+        .map(|d| FileTime::from_unix_time(d.as_secs() as i64, d.subsec_nanos()))
+        .unwrap_or_else(|e| {
+            let until_epoch = e.duration();
+            let (sec_offset, nanos) = if until_epoch.subsec_nanos() == 0 {
+                (0, 0)
+            } else {
+                (-1, 1_000_000_000 - until_epoch.subsec_nanos())
+            };
+
+            FileTime::from_unix_time(-(until_epoch.as_secs() as i64) + sec_offset, nanos)
+        })
+}
+
 #[cfg(test)]
 mod tests {
    use std::io::ErrorKind;