Stream: git-wasmtime

Topic: wasmtime / issue #11627 bindgen! macro WIT Package resolu...

Wasmtime GitHub notifications bot (Sep 05 2025 at 18:42):

fuzing opened issue #11627:

I'm trying to share types across packages in WIT definitions. The functionality defined in the WIT files is provided by an embedded wasmtime host (Rust). There is also a wasm guest that consumes the functionality.

I have 2 projects that consume the WIT definitions, namely:

• a rust project that provides the embedded wasmtime runtime (I'll refer to this as host)
• a project that generates wasm bytecode that will run inside the wasmtime host (I'll refer to this as guest)

On the guest side, the component builds fine using the following steps:

1. cargo component bindings
2. cargo component build --release --target wasm32-unknown-unknown

Step 1 above seems to parse the WIT files as I'd anticipate, and the resulting bindings.rs contains the definition for Bytes (2 definitions, namely scoped to: abc::types::types::Bytes and abc::compression::compression::Bytes) that can be used by the local rust code.

On the wasmtime embedded host side, the bindgen! macro seems unable to find/resolve the shared types across packages (in this case, between package abc:compression@0.1.0 and package abc:types@0.1.0, where abc:types@0.1.0 contains a type bytes that should be shared across other packages, including to the abc:compression@0.1.0 package.

I have the following file structure

  wit/package.wit
  wit/deps/types/world.wit
  wit/deps/types/types.wit
  wit/deps/compression/compression.wit
  wit/deps/compression/world.wit

My shared types WIT files look like these:

wit/deps/types/world.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import types;
}

wit/deps/types/types.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    type bytes = list<u8>;
}

Note that it's the bytes type that I need to share with (in this case) the compression package

The package attempting to access the above shared types look like these:

wit/deps/compression.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface compression {
    @since(version = 0.1.0)
    use abc:types/types@0.1.0.{bytes};

    @since(version = 0.1.0)
    use types.{compression-level, compression-type};

    @since(version = 0.1.0)
    compress: func(compression-type: compression-type, compression-level: compression-level, data: bytes) -> bytes;

    @since(version = 0.1.0)
    decompress: func(compression-type: compression-type, data: bytes) -> bytes;
}

wit/deps/world.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import abc:types/types@0.1.0;

    @since(version = 0.1.0)
    import compression;
}

On the host, the bindgen! looks like:

bindgen!({
    path: "wit/deps/compression",
    world: "imports",
});

The error coming from the compilation of the host is as follows:

   Compiling wasmtime-test v1.0.0 (/home/abc/Projects/abc-project/bin/wasmtime-test)
error: failed to resolve directory while parsing WIT for path [/home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression]

       Caused by:
           package 'abc:types@0.1.0' not found. known packages:
               abc:compression@0.1.0

                --> /home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression/compression.wit:6:9
                 |
               6 |     use fusing:types/types@0.1.0.{bytes};
                 |         ^-----------
  --> bin/wasmtime-test/src/platform_implementations/compression/compression.rs:15:1
   |
15 | / bindgen!({
16 | |     path: "wit/deps/compression",
17 | |     world: "imports",
...  |
26 | | });
   | |__^

Notes:

On the guest wasm bytecode project side, the following had to be included in the Cargo.toml file:

[package.metadata.component.target.dependencies]
"abc:compression" = { path = "../../bin/wasmtime-test/wit/deps/compression" }
"abc:types" = { path = "../../bin/wasmtime-test/wit/deps/types" }

I've tried adding these to the Cargo.toml inside the host wasmtime embedding project but to no avail (I'm guessing that the bindgen! macro doesn't use these).

Also for the guest, a single world.wit WIT file, defined as:

package component:wasm-component;

interface run {
    run: func();
}

world client {
    import abc:compression/compression@0.1.0;
    import abc:types/types@0.1.0;
    export run;
}

Is there something I'm missing for the bindgen! macro options (or for the Cargo.toml on the host side)?

Wasmtime GitHub notifications bot (Sep 05 2025 at 18:42):

fuzing added the bug label to Issue #11627.

Wasmtime GitHub notifications bot (Sep 05 2025 at 18:45):

fuzing edited issue #11627:

I'm trying to share types across packages in WIT definitions. The functionality defined in the WIT files is provided by an embedded wasmtime host (Rust). There is also a wasm guest that consumes the functionality.

I have 2 projects that consume the WIT definitions, namely:

• a rust project that provides the embedded wasmtime runtime (I'll refer to this as host)
• a project that generates wasm bytecode that will run inside the wasmtime host (I'll refer to this as guest)

I have the following file structure for my WIT files (WIT files are defined within the host project)

  wit/package.wit
  wit/deps/types/world.wit
  wit/deps/types/types.wit
  wit/deps/compression/compression.wit
  wit/deps/compression/world.wit

My shared types WIT files look like these:

wit/deps/types/world.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import types;
}

wit/deps/types/types.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    type bytes = list<u8>;
}

Note that it's the bytes type that I need to share with (in this case) the compression package

The package attempting to access the above shared types look like these:

wit/deps/compression.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface compression {
    @since(version = 0.1.0)
    use abc:types/types@0.1.0.{bytes};

    @since(version = 0.1.0)
    use types.{compression-level, compression-type};

    @since(version = 0.1.0)
    compress: func(compression-type: compression-type, compression-level: compression-level, data: bytes) -> bytes;

    @since(version = 0.1.0)
    decompress: func(compression-type: compression-type, data: bytes) -> bytes;
}

wit/deps/world.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import abc:types/types@0.1.0;

    @since(version = 0.1.0)
    import compression;
}

On the guest side, the component builds fine using the following steps:

1. cargo component bindings
2. cargo component build --release --target wasm32-unknown-unknown

Step 1 above seems to parse the WIT files as I'd anticipate, and the resulting bindings.rs contains the definition for Bytes (2 definitions, namely scoped to: abc::types::types::Bytes and abc::compression::compression::Bytes) that can be used by the local rust code.

On the wasmtime embedded host side, the bindgen! macro seems unable to find/resolve the shared types across packages (in this case, between package abc:compression@0.1.0 and package abc:types@0.1.0, where abc:types@0.1.0 contains a type bytes that should be shared across other packages, including to the abc:compression@0.1.0 package.

On the host, the bindgen! looks like:

bindgen!({
    path: "wit/deps/compression",
    world: "imports",
});

The error coming from the compilation of the host is as follows:

   Compiling wasmtime-test v1.0.0 (/home/abc/Projects/abc-project/bin/wasmtime-test)
error: failed to resolve directory while parsing WIT for path [/home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression]

       Caused by:
           package 'abc:types@0.1.0' not found. known packages:
               abc:compression@0.1.0

                --> /home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression/compression.wit:6:9
                 |
               6 |     use fusing:types/types@0.1.0.{bytes};
                 |         ^-----------
  --> bin/wasmtime-test/src/platform_implementations/compression/compression.rs:15:1
   |
15 | / bindgen!({
16 | |     path: "wit/deps/compression",
17 | |     world: "imports",
...  |
26 | | });
   | |__^

Notes:

On the guest wasm bytecode project side, the following had to be included in the Cargo.toml file:

[package.metadata.component.target.dependencies]
"abc:compression" = { path = "../../bin/wasmtime-test/wit/deps/compression" }
"abc:types" = { path = "../../bin/wasmtime-test/wit/deps/types" }

I've tried adding these to the Cargo.toml inside the host wasmtime embedding project but to no avail (I'm guessing that the bindgen! macro doesn't use these).

Also for the guest, a single world.wit WIT file, defined as:

package component:wasm-component;

interface run {
    run: func();
}

world client {
    import abc:compression/compression@0.1.0;
    import abc:types/types@0.1.0;
    export run;
}

Is there something I'm missing for the bindgen! macro options (or for the Cargo.toml on the host side)?

Wasmtime GitHub notifications bot (Sep 05 2025 at 18:47):

fuzing edited issue #11627:

I'm trying to share types across packages in WIT definitions. The functionality defined in the WIT files is provided by an embedded wasmtime host (Rust). There is also a wasm guest that consumes the functionality.

I have 2 projects that consume the WIT definitions, namely:

• a rust project that provides the embedded wasmtime runtime (I'll refer to this as host)
• a project that generates wasm bytecode that will run inside the wasmtime host (I'll refer to this as guest)

I have the following file structure for my WIT files (WIT files are defined within the host project)

  wit/package.wit
  wit/deps/types/world.wit
  wit/deps/types/types.wit
  wit/deps/compression/compression.wit
  wit/deps/compression/world.wit

My shared types WIT files look like these:

wit/deps/types/world.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import types;
}

wit/deps/types/types.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    type bytes = list<u8>;
}

Note that it's the bytes type that I need to share with (in this case) the compression package

The package attempting to access the above shared types look like these:

wit/deps/compression/compression.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface compression {
    @since(version = 0.1.0)
    use abc:types/types@0.1.0.{bytes};

    @since(version = 0.1.0)
    use types.{compression-level, compression-type};

    @since(version = 0.1.0)
    compress: func(compression-type: compression-type, compression-level: compression-level, data: bytes) -> bytes;

    @since(version = 0.1.0)
    decompress: func(compression-type: compression-type, data: bytes) -> bytes;
}

wit/deps/compression/world.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import abc:types/types@0.1.0;

    @since(version = 0.1.0)
    import compression;
}

On the guest side, the component builds fine using the following steps:

1. cargo component bindings
2. cargo component build --release --target wasm32-unknown-unknown

Step 1 above seems to parse the WIT files as I'd anticipate, and the resulting bindings.rs contains the definition for Bytes (2 definitions, namely scoped to: abc::types::types::Bytes and abc::compression::compression::Bytes) that can be used by the local rust code.

On the wasmtime embedded host side, the bindgen! macro seems unable to find/resolve the shared types across packages (in this case, between package abc:compression@0.1.0 and package abc:types@0.1.0, where abc:types@0.1.0 contains a type bytes that should be shared across other packages, including to the abc:compression@0.1.0 package.

On the host, the bindgen! looks like:

bindgen!({
    path: "wit/deps/compression",
    world: "imports",
});

The error coming from the compilation of the host is as follows:

   Compiling wasmtime-test v1.0.0 (/home/abc/Projects/abc-project/bin/wasmtime-test)
error: failed to resolve directory while parsing WIT for path [/home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression]

       Caused by:
           package 'abc:types@0.1.0' not found. known packages:
               abc:compression@0.1.0

                --> /home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression/compression.wit:6:9
                 |
               6 |     use fusing:types/types@0.1.0.{bytes};
                 |         ^-----------
  --> bin/wasmtime-test/src/platform_implementations/compression/compression.rs:15:1
   |
15 | / bindgen!({
16 | |     path: "wit/deps/compression",
17 | |     world: "imports",
...  |
26 | | });
   | |__^

Notes:

On the guest wasm bytecode project side, the following had to be included in the Cargo.toml file:

[package.metadata.component.target.dependencies]
"abc:compression" = { path = "../../bin/wasmtime-test/wit/deps/compression" }
"abc:types" = { path = "../../bin/wasmtime-test/wit/deps/types" }

I've tried adding these to the Cargo.toml inside the host wasmtime embedding project but to no avail (I'm guessing that the bindgen! macro doesn't use these).

Also for the guest, a single world.wit WIT file, defined as:

package component:wasm-component;

interface run {
    run: func();
}

world client {
    import abc:compression/compression@0.1.0;
    import abc:types/types@0.1.0;
    export run;
}

Is there something I'm missing for the bindgen! macro options (or for the Cargo.toml on the host side)?

Wasmtime GitHub notifications bot (Sep 05 2025 at 18:49):

fuzing edited issue #11627:

I'm trying to share types across packages in WIT definitions. The functionality defined in the WIT files is provided by an embedded wasmtime host (Rust). There is also a wasm guest that consumes the functionality.

I have 2 projects that consume the WIT definitions, namely:

• a rust project that provides the embedded wasmtime runtime (I'll refer to this as host)
• a project that generates wasm bytecode that will run inside the wasmtime host (I'll refer to this as guest)

I have the following file structure for my WIT files (WIT files are defined within the host project)

  wit/package.wit
  wit/deps/types/world.wit
  wit/deps/types/types.wit
  wit/deps/compression/compression.wit
  wit/deps/compression/world.wit

My shared types WIT files look like these:

wit/deps/types/world.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import types;
}

wit/deps/types/types.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    type bytes = list<u8>;
}

Note that it's the bytes type that I need to share with (in this case) the compression package

The package attempting to access the above shared types look like these:

wit/deps/compression/compression.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface compression {
    @since(version = 0.1.0)
    use abc:types/types@0.1.0.{bytes};

    @since(version = 0.1.0)
    use types.{compression-level, compression-type};

    @since(version = 0.1.0)
    compress: func(compression-type: compression-type, compression-level: compression-level, data: bytes) -> bytes;

    @since(version = 0.1.0)
    decompress: func(compression-type: compression-type, data: bytes) -> bytes;
}

wit/deps/compression/world.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import abc:types/types@0.1.0;

    @since(version = 0.1.0)
    import compression;
}

wit/deps/compression/types.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    enum compression-level {
        ultra-low,
        low,
        medium,
        high,
        ultra-high,
    }

    @since(version = 0.1.0)
    enum compression-type {
        zstd,
        deflate,
    }
}

On the guest side, the component builds fine using the following steps:

1. cargo component bindings
2. cargo component build --release --target wasm32-unknown-unknown

Step 1 above seems to parse the WIT files as I'd anticipate, and the resulting bindings.rs contains the definition for Bytes (2 definitions, namely scoped to: abc::types::types::Bytes and abc::compression::compression::Bytes) that can be used by the local rust code.

On the wasmtime embedded host side, the bindgen! macro seems unable to find/resolve the shared types across packages (in this case, between package abc:compression@0.1.0 and package abc:types@0.1.0, where abc:types@0.1.0 contains a type bytes that should be shared across other packages, including to the abc:compression@0.1.0 package.

On the host, the bindgen! looks like:

bindgen!({
    path: "wit/deps/compression",
    world: "imports",
});

The error coming from the compilation of the host is as follows:

   Compiling wasmtime-test v1.0.0 (/home/abc/Projects/abc-project/bin/wasmtime-test)
error: failed to resolve directory while parsing WIT for path [/home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression]

       Caused by:
           package 'abc:types@0.1.0' not found. known packages:
               abc:compression@0.1.0

                --> /home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression/compression.wit:6:9
                 |
               6 |     use fusing:types/types@0.1.0.{bytes};
                 |         ^-----------
  --> bin/wasmtime-test/src/platform_implementations/compression/compression.rs:15:1
   |
15 | / bindgen!({
16 | |     path: "wit/deps/compression",
17 | |     world: "imports",
...  |
26 | | });
   | |__^

Notes:

On the guest wasm bytecode project side, the following had to be included in the Cargo.toml file:

[package.metadata.component.target.dependencies]
"abc:compression" = { path = "../../bin/wasmtime-test/wit/deps/compression" }
"abc:types" = { path = "../../bin/wasmtime-test/wit/deps/types" }

I've tried adding these to the Cargo.toml inside the host wasmtime embedding project but to no avail (I'm guessing that the bindgen! macro doesn't use these).

Also for the guest, a single world.wit WIT file, defined as:

package component:wasm-component;

interface run {
    run: func();
}

world client {
    import abc:compression/compression@0.1.0;
    import abc:types/types@0.1.0;
    export run;
}

Is there something I'm missing for the bindgen! macro options (or for the Cargo.toml on the host side)?

Wasmtime GitHub notifications bot (Sep 05 2025 at 18:49):

fuzing edited issue #11627:

I'm trying to share types across packages in WIT definitions. The functionality defined in the WIT files is provided by an embedded wasmtime host (Rust). There is also a wasm guest that consumes the functionality.

I have 2 projects that consume the WIT definitions, namely:

• a rust project that provides the embedded wasmtime runtime (I'll refer to this as host)
• a project that generates wasm bytecode that will run inside the wasmtime host (I'll refer to this as guest)

I have the following file structure for my WIT files (WIT files are defined within the host project)

  wit/package.wit
  wit/deps/types/world.wit
  wit/deps/types/types.wit
  wit/deps/compression/compression.wit
  wit/deps/compression/world.wit

My shared types WIT files look like these:

wit/deps/types/world.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import types;
}

wit/deps/types/types.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    type bytes = list<u8>;
}

Note that it's the bytes type that I need to share with (in this case) the compression package

The package attempting to access the above shared types look like these:

wit/deps/compression/compression.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface compression {
    @since(version = 0.1.0)
    use abc:types/types@0.1.0.{bytes};

    @since(version = 0.1.0)
    use types.{compression-level, compression-type};

    @since(version = 0.1.0)
    compress: func(compression-type: compression-type, compression-level: compression-level, data: bytes) -> bytes;

    @since(version = 0.1.0)
    decompress: func(compression-type: compression-type, data: bytes) -> bytes;
}

wit/deps/compression/world.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import abc:types/types@0.1.0;

    @since(version = 0.1.0)
    import types;

    @since(version = 0.1.0)
    import compression;
}

wit/deps/compression/types.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    enum compression-level {
        ultra-low,
        low,
        medium,
        high,
        ultra-high,
    }

    @since(version = 0.1.0)
    enum compression-type {
        zstd,
        deflate,
    }
}

On the guest side, the component builds fine using the following steps:

1. cargo component bindings
2. cargo component build --release --target wasm32-unknown-unknown

Step 1 above seems to parse the WIT files as I'd anticipate, and the resulting bindings.rs contains the definition for Bytes (2 definitions, namely scoped to: abc::types::types::Bytes and abc::compression::compression::Bytes) that can be used by the local rust code.

On the wasmtime embedded host side, the bindgen! macro seems unable to find/resolve the shared types across packages (in this case, between package abc:compression@0.1.0 and package abc:types@0.1.0, where abc:types@0.1.0 contains a type bytes that should be shared across other packages, including to the abc:compression@0.1.0 package.

On the host, the bindgen! looks like:

bindgen!({
    path: "wit/deps/compression",
    world: "imports",
});

The error coming from the compilation of the host is as follows:

   Compiling wasmtime-test v1.0.0 (/home/abc/Projects/abc-project/bin/wasmtime-test)
error: failed to resolve directory while parsing WIT for path [/home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression]

       Caused by:
           package 'abc:types@0.1.0' not found. known packages:
               abc:compression@0.1.0

                --> /home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression/compression.wit:6:9
                 |
               6 |     use fusing:types/types@0.1.0.{bytes};
                 |         ^-----------
  --> bin/wasmtime-test/src/platform_implementations/compression/compression.rs:15:1
   |
15 | / bindgen!({
16 | |     path: "wit/deps/compression",
17 | |     world: "imports",
...  |
26 | | });
   | |__^

Notes:

On the guest wasm bytecode project side, the following had to be included in the Cargo.toml file:

[package.metadata.component.target.dependencies]
"abc:compression" = { path = "../../bin/wasmtime-test/wit/deps/compression" }
"abc:types" = { path = "../../bin/wasmtime-test/wit/deps/types" }

I've tried adding these to the Cargo.toml inside the host wasmtime embedding project but to no avail (I'm guessing that the bindgen! macro doesn't use these).

Also for the guest, a single world.wit WIT file, defined as:

package component:wasm-component;

interface run {
    run: func();
}

world client {
    import abc:compression/compression@0.1.0;
    import abc:types/types@0.1.0;
    export run;
}

Is there something I'm missing for the bindgen! macro options (or for the Cargo.toml on the host side)?

Wasmtime GitHub notifications bot (Sep 05 2025 at 18:51):

fuzing edited issue #11627:

I'm trying to share types across packages in WIT definitions. The functionality defined in the WIT files is provided by an embedded wasmtime host (Rust). There is also a wasm guest that consumes the functionality.

I have 2 projects that consume the WIT definitions, namely:

• a rust project that provides the embedded wasmtime runtime (I'll refer to this as host)
• a project that generates wasm bytecode that will run inside the wasmtime host (I'll refer to this as guest)

I have the following file structure for my WIT files (WIT files are defined within the host project)

  wit/package.wit
  wit/deps/types/world.wit
  wit/deps/types/types.wit
  wit/deps/compression/compression.wit
  wit/deps/compression/world.wit

My shared types WIT files look like these:

wit/deps/types/world.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import types;
}

wit/deps/types/types.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    type bytes = list<u8>;
}

Note that it's the bytes type that I need to share with (in this case) the compression package

The package attempting to access the above shared types look like these:

wit/deps/compression/compression.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface compression {
    @since(version = 0.1.0)
    use abc:types/types@0.1.0.{bytes};

    @since(version = 0.1.0)
    use types.{compression-level, compression-type};

    @since(version = 0.1.0)
    compress: func(compression-type: compression-type, compression-level: compression-level, data: bytes) -> bytes;

    @since(version = 0.1.0)
    decompress: func(compression-type: compression-type, data: bytes) -> bytes;
}

wit/deps/compression/world.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import abc:types/types@0.1.0;

    @since(version = 0.1.0)
    import types;

    @since(version = 0.1.0)
    import compression;
}

wit/deps/compression/types.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    enum compression-level {
        ultra-low,
        low,
        medium,
        high,
        ultra-high,
    }

    @since(version = 0.1.0)
    enum compression-type {
        zstd,
        deflate,
    }
}

On the guest side, the component builds fine using the following steps:

1. cargo component bindings
2. cargo component build --release --target wasm32-unknown-unknown

Step 1 above seems to parse the WIT files as I'd anticipate, and the resulting bindings.rs contains the definition for Bytes (2 definitions, namely scoped to: abc::types::types::Bytes and abc::compression::compression::Bytes) that can be used by the local rust code.

On the wasmtime embedded host side, the bindgen! macro seems unable to find/resolve the shared types across packages (in this case, between package abc:compression@0.1.0 and package abc:types@0.1.0, where abc:types@0.1.0 contains a type bytes that should be shared across other packages, including to the abc:compression@0.1.0 package.

On the host, the bindgen! looks like:

bindgen!({
    path: "wit/deps/compression",
    world: "imports",
});

The error coming from the compilation of the host is as follows:

   Compiling wasmtime-test v1.0.0 (/home/abc/Projects/abc-project/bin/wasmtime-test)
error: failed to resolve directory while parsing WIT for path [/home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression]

       Caused by:
           package 'abc:types@0.1.0' not found. known packages:
               abc:compression@0.1.0

                --> /home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression/compression.wit:6:9
                 |
               6 |     use abc:types/types@0.1.0.{bytes};
                 |         ^-----------
  --> bin/wasmtime-test/src/platform_implementations/compression/compression.rs:15:1
   |
15 | / bindgen!({
16 | |     path: "wit/deps/compression",
17 | |     world: "imports",
...  |
26 | | });
   | |__^

Notes:

On the guest wasm bytecode project side, the following had to be included in the Cargo.toml file:

[package.metadata.component.target.dependencies]
"abc:compression" = { path = "../../bin/wasmtime-test/wit/deps/compression" }
"abc:types" = { path = "../../bin/wasmtime-test/wit/deps/types" }

I've tried adding these to the Cargo.toml inside the host wasmtime embedding project but to no avail (I'm guessing that the bindgen! macro doesn't use these).

Also for the guest, a single world.wit WIT file, defined as:

package component:wasm-component;

interface run {
    run: func();
}

world client {
    import abc:compression/compression@0.1.0;
    import abc:types/types@0.1.0;
    export run;
}

Is there something I'm missing for the bindgen! macro options (or for the Cargo.toml on the host side)?

Wasmtime GitHub notifications bot (Sep 05 2025 at 18:54):

fuzing edited issue #11627:

I'm trying to share types across packages in WIT definitions. The functionality defined in the WIT files is provided by an embedded wasmtime host (Rust). There is also a wasm guest that consumes the functionality.

I have 2 projects that consume the WIT definitions, namely:

• a rust project that provides the embedded wasmtime runtime (I'll refer to this as host)
• a project that generates wasm bytecode that will run inside the wasmtime host (I'll refer to this as guest)

I have the following file structure for my WIT files (WIT files are defined within the host project)

  wit/package.wit
  wit/deps/types/world.wit
  wit/deps/types/types.wit
  wit/deps/compression/compression.wit
  wit/deps/compression/types.wit
  wit/deps/compression/world.wit

My shared types WIT files look like these:

wit/deps/types/world.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import types;
}

wit/deps/types/types.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    type bytes = list<u8>;
}

Note that it's the bytes type that I need to share with (in this case) the compression package

The package attempting to access the above shared types look like these:

wit/deps/compression/compression.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface compression {
    @since(version = 0.1.0)
    use abc:types/types@0.1.0.{bytes};

    @since(version = 0.1.0)
    use types.{compression-level, compression-type};

    @since(version = 0.1.0)
    compress: func(compression-type: compression-type, compression-level: compression-level, data: bytes) -> bytes;

    @since(version = 0.1.0)
    decompress: func(compression-type: compression-type, data: bytes) -> bytes;
}

wit/deps/compression/world.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import abc:types/types@0.1.0;

    @since(version = 0.1.0)
    import types;

    @since(version = 0.1.0)
    import compression;
}

wit/deps/compression/types.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    enum compression-level {
        ultra-low,
        low,
        medium,
        high,
        ultra-high,
    }

    @since(version = 0.1.0)
    enum compression-type {
        zstd,
        deflate,
    }
}

On the guest side, the component builds fine using the following steps:

1. cargo component bindings
2. cargo component build --release --target wasm32-unknown-unknown

Step 1 above seems to parse the WIT files as I'd anticipate, and the resulting bindings.rs contains the definition for Bytes (2 definitions, namely scoped to: abc::types::types::Bytes and abc::compression::compression::Bytes) that can be used by the local rust code.

On the wasmtime embedded host side, the bindgen! macro seems unable to find/resolve the shared types across packages (in this case, between package abc:compression@0.1.0 and package abc:types@0.1.0, where abc:types@0.1.0 contains a type bytes that should be shared across other packages, including to the abc:compression@0.1.0 package.

On the host, the bindgen! looks like:

bindgen!({
    path: "wit/deps/compression",
    world: "imports",
});

The error coming from the compilation of the host is as follows:

   Compiling wasmtime-test v1.0.0 (/home/abc/Projects/abc-project/bin/wasmtime-test)
error: failed to resolve directory while parsing WIT for path [/home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression]

       Caused by:
           package 'abc:types@0.1.0' not found. known packages:
               abc:compression@0.1.0

                --> /home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression/compression.wit:6:9
                 |
               6 |     use abc:types/types@0.1.0.{bytes};
                 |         ^-----------
  --> bin/wasmtime-test/src/platform_implementations/compression/compression.rs:15:1
   |
15 | / bindgen!({
16 | |     path: "wit/deps/compression",
17 | |     world: "imports",
...  |
26 | | });
   | |__^

Notes:

On the guest wasm bytecode project side, the following had to be included in the Cargo.toml file:

[package.metadata.component.target.dependencies]
"abc:compression" = { path = "../../bin/wasmtime-test/wit/deps/compression" }
"abc:types" = { path = "../../bin/wasmtime-test/wit/deps/types" }

I've tried adding these to the Cargo.toml inside the host wasmtime embedding project but to no avail (I'm guessing that the bindgen! macro doesn't use these).

Also for the guest, a single world.wit WIT file, defined as:

package component:wasm-component;

interface run {
    run: func();
}

world client {
    import abc:compression/compression@0.1.0;
    import abc:types/types@0.1.0;
    export run;
}

Is there something I'm missing for the bindgen! macro options (or for the Cargo.toml on the host side)?

Wasmtime GitHub notifications bot (Sep 05 2025 at 20:08):

fuzing edited issue #11627:

I'm trying to share types across packages in WIT definitions. The functionality defined in the WIT files is provided by an embedded wasmtime host (Rust). There is also a wasm guest that consumes the functionality.

I have 2 projects that consume the WIT definitions, namely:

• a rust project that provides the embedded wasmtime runtime (I'll refer to this as host)
• a project that generates wasm bytecode that will run inside the wasmtime host (I'll refer to this as guest)

I have the following file structure for my WIT files (WIT files are defined within the host project)

  wit/package.wit
  wit/deps/types/world.wit
  wit/deps/types/types.wit
  wit/deps/compression/compression.wit
  wit/deps/compression/types.wit
  wit/deps/compression/world.wit

My shared types WIT files look like these:

wit/deps/types/world.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import types;
}

wit/deps/types/types.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    type bytes = list<u8>;
}

Note that it's the bytes type that I need to share with (in this case) the compression package

The package attempting to access the above shared types look like these:

wit/deps/compression/compression.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface compression {
    @since(version = 0.1.0)
    use abc:types/types@0.1.0.{bytes};

    @since(version = 0.1.0)
    use types.{compression-level, compression-type};

    @since(version = 0.1.0)
    compress: func(compression-type: compression-type, compression-level: compression-level, data: bytes) -> bytes;

    @since(version = 0.1.0)
    decompress: func(compression-type: compression-type, data: bytes) -> bytes;
}

wit/deps/compression/world.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import abc:types/types@0.1.0;

    @since(version = 0.1.0)
    import types;

    @since(version = 0.1.0)
    import compression;
}

wit/deps/compression/types.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    enum compression-level {
        ultra-low,
        low,
        medium,
        high,
        ultra-high,
    }

    @since(version = 0.1.0)
    enum compression-type {
        zstd,
        deflate,
    }
}

On the guest side, the component builds fine using the following steps:

1. cargo component bindings
2. cargo component build --release --target wasm32-unknown-unknown

Step 1 above seems to parse the WIT files as I'd anticipate, and the resulting bindings.rs contains the definition for Bytes (2 definitions, namely scoped to: abc::types::types::Bytes and abc::compression::compression::Bytes) that can be used by the local rust code.

On the wasmtime embedded host side, the bindgen! macro seems unable to find/resolve the shared types across packages (in this case, between package abc:compression@0.1.0 and package abc:types@0.1.0, where abc:types@0.1.0 contains a type bytes that should be shared across other packages, including to the abc:compression@0.1.0 package.

On the host, I'm using bindgen! inside each Host implementation source file. For the compression host implementor, the bindgen! looks like:

bindgen!({
    path: "wit/deps/compression",
    world: "imports",
});

The error coming from the compilation of the host is as follows:

   Compiling wasmtime-test v1.0.0 (/home/abc/Projects/abc-project/bin/wasmtime-test)
error: failed to resolve directory while parsing WIT for path [/home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression]

       Caused by:
           package 'abc:types@0.1.0' not found. known packages:
               abc:compression@0.1.0

                --> /home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression/compression.wit:6:9
                 |
               6 |     use abc:types/types@0.1.0.{bytes};
                 |         ^-----------
  --> bin/wasmtime-test/src/platform_implementations/compression/compression.rs:15:1
   |
15 | / bindgen!({
16 | |     path: "wit/deps/compression",
17 | |     world: "imports",
...  |
26 | | });
   | |__^

Notes:

On the guest wasm bytecode project side, the following had to be included in the Cargo.toml file:

[package.metadata.component.target.dependencies]
"abc:compression" = { path = "../../bin/wasmtime-test/wit/deps/compression" }
"abc:types" = { path = "../../bin/wasmtime-test/wit/deps/types" }

I've tried adding these to the Cargo.toml inside the host wasmtime embedding project but to no avail (I'm guessing that the bindgen! macro doesn't use these).

Also for the guest, a single world.wit WIT file, defined as:

package component:wasm-component;

interface run {
    run: func();
}

world client {
    import abc:compression/compression@0.1.0;
    import abc:types/types@0.1.0;
    export run;
}

Is there something I'm missing for the bindgen! macro options (or for the Cargo.toml on the host side)?

Wasmtime GitHub notifications bot (Sep 05 2025 at 20:27):

alexcrichton commented on issue #11627:

Can you try changing:

bindgen!({
    path: "wit/deps/compression",
    world: "imports",
});

to

bindgen!({
    world: "abc:compression/imports",
});

and does that fix your issue?

Wasmtime GitHub notifications bot (Sep 05 2025 at 21:49):

fuzing commented on issue #11627:

It does indeed - thank you so much, and enjoy your weekend!

Wasmtime GitHub notifications bot (Sep 05 2025 at 21:49):

fuzing closed issue #11627:

I'm trying to share types across packages in WIT definitions. The functionality defined in the WIT files is provided by an embedded wasmtime host (Rust). There is also a wasm guest that consumes the functionality.

I have 2 projects that consume the WIT definitions, namely:

• a rust project that provides the embedded wasmtime runtime (I'll refer to this as host)
• a project that generates wasm bytecode that will run inside the wasmtime host (I'll refer to this as guest)

I have the following file structure for my WIT files (WIT files are defined within the host project)

  wit/package.wit
  wit/deps/types/world.wit
  wit/deps/types/types.wit
  wit/deps/compression/compression.wit
  wit/deps/compression/types.wit
  wit/deps/compression/world.wit

My shared types WIT files look like these:

wit/deps/types/world.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import types;
}

wit/deps/types/types.wit

package abc:types@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    type bytes = list<u8>;
}

Note that it's the bytes type that I need to share with (in this case) the compression package

The package attempting to access the above shared types look like these:

wit/deps/compression/compression.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface compression {
    @since(version = 0.1.0)
    use abc:types/types@0.1.0.{bytes};

    @since(version = 0.1.0)
    use types.{compression-level, compression-type};

    @since(version = 0.1.0)
    compress: func(compression-type: compression-type, compression-level: compression-level, data: bytes) -> bytes;

    @since(version = 0.1.0)
    decompress: func(compression-type: compression-type, data: bytes) -> bytes;
}

wit/deps/compression/world.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
world imports {
    @since(version = 0.1.0)
    import abc:types/types@0.1.0;

    @since(version = 0.1.0)
    import types;

    @since(version = 0.1.0)
    import compression;
}

wit/deps/compression/types.wit

package abc:compression@0.1.0;

@since(version = 0.1.0)
interface types {
    @since(version = 0.1.0)
    enum compression-level {
        ultra-low,
        low,
        medium,
        high,
        ultra-high,
    }

    @since(version = 0.1.0)
    enum compression-type {
        zstd,
        deflate,
    }
}

On the guest side, the component builds fine using the following steps:

1. cargo component bindings
2. cargo component build --release --target wasm32-unknown-unknown

Step 1 above seems to parse the WIT files as I'd anticipate, and the resulting bindings.rs contains the definition for Bytes (2 definitions, namely scoped to: abc::types::types::Bytes and abc::compression::compression::Bytes) that can be used by the local rust code.

On the wasmtime embedded host side, the bindgen! macro seems unable to find/resolve the shared types across packages (in this case, between package abc:compression@0.1.0 and package abc:types@0.1.0, where abc:types@0.1.0 contains a type bytes that should be shared across other packages, including to the abc:compression@0.1.0 package.

On the host, I'm using bindgen! inside each Host implementation source file. For the compression host implementor, the bindgen! looks like:

bindgen!({
    path: "wit/deps/compression",
    world: "imports",
});

The error coming from the compilation of the host is as follows:

   Compiling wasmtime-test v1.0.0 (/home/abc/Projects/abc-project/bin/wasmtime-test)
error: failed to resolve directory while parsing WIT for path [/home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression]

       Caused by:
           package 'abc:types@0.1.0' not found. known packages:
               abc:compression@0.1.0

                --> /home/abc/Projects/abc-project/bin/wasmtime-test/wit/deps/compression/compression.wit:6:9
                 |
               6 |     use abc:types/types@0.1.0.{bytes};
                 |         ^-----------
  --> bin/wasmtime-test/src/platform_implementations/compression/compression.rs:15:1
   |
15 | / bindgen!({
16 | |     path: "wit/deps/compression",
17 | |     world: "imports",
...  |
26 | | });
   | |__^

Notes:

On the guest wasm bytecode project side, the following had to be included in the Cargo.toml file:

[package.metadata.component.target.dependencies]
"abc:compression" = { path = "../../bin/wasmtime-test/wit/deps/compression" }
"abc:types" = { path = "../../bin/wasmtime-test/wit/deps/types" }

I've tried adding these to the Cargo.toml inside the host wasmtime embedding project but to no avail (I'm guessing that the bindgen! macro doesn't use these).

Also for the guest, a single world.wit WIT file, defined as:

package component:wasm-component;

interface run {
    run: func();
}

world client {
    import abc:compression/compression@0.1.0;
    import abc:types/types@0.1.0;
    export run;
}

Is there something I'm missing for the bindgen! macro options (or for the Cargo.toml on the host side)?

Last updated: Dec 06 2025 at 07:03 UTC