File can no longer be used with signals since 0.7

[anshap1719]

I have a project I'm migrating from 0.6 to 0.7, and a big hurdle is that the File type that comes from web_sys can no longer be used with a signal, since *mut u8 is not thread-safe. A SendWrapper doesn't work either because then it doesn't implement the Track trait that signals need.

Here's a simple example to reproduce the issue:

let (files, set_files) = signal::<Vec<web_sys::File>>(vec![]);

This produces the following error:

error[E0277]: `*mut u8` cannot be sent between threads safely
    --> src/modules/awdio.rs:34:39
     |
34   |     let (files, set_files) = signal::<Vec<File>>(vec![]);
     |                                       ^^^^^^^^^ `*mut u8` cannot be sent between threads safely
     |
     = help: within `Vec<web_sys::File>`, the trait `Send` is not implemented for `*mut u8`
note: required because it appears within the type `PhantomData<*mut u8>`
    --> /Users/anshulsanghi/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/marker.rs:757:12
     |
757  | pub struct PhantomData<T: ?Sized>;
     |            ^^^^^^^^^^^
note: required because it appears within the type `JsValue`
    --> /Users/anshulsanghi/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wasm-bindgen-0.2.100/src/lib.rs:135:12
     |
135  | pub struct JsValue {
     |            ^^^^^^^
note: required because it appears within the type `wasm_bindgen_futures::js_sys::Object`
    --> /Users/anshulsanghi/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/js-sys-0.3.77/src/lib.rs:3445:14
     |
3445 |     pub type Object;
     |              ^^^^^^
note: required because it appears within the type `web_sys::Blob`
    --> /Users/anshulsanghi/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/web-sys-0.3.77/src/features/gen_Blob.rs:14:14
     |
14   |     pub type Blob;
     |              ^^^^
note: required because it appears within the type `web_sys::File`
    --> /Users/anshulsanghi/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/web-sys-0.3.77/src/features/gen_File.rs:14:14
     |
14   |     pub type File;
     |              ^^^^
note: required because it appears within the type `PhantomData<web_sys::File>`
    --> /Users/anshulsanghi/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/marker.rs:757:12
     |
757  | pub struct PhantomData<T: ?Sized>;
     |            ^^^^^^^^^^^
note: required because it appears within the type `wasm_bindgen::__rt::alloc::raw_vec::RawVec<web_sys::File>`
    --> /Users/anshulsanghi/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/alloc/src/raw_vec.rs:70:19
     |
70   | pub(crate) struct RawVec<T, A: Allocator = Global> {
     |                   ^^^^^^
note: required because it appears within the type `Vec<web_sys::File>`
    --> /Users/anshulsanghi/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/alloc/src/vec/mod.rs:397:12
     |
397  | pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> {
     |            ^^^
note: required by a bound in `leptos::prelude::signal`
    --> /Users/anshulsanghi/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/reactive_graph-0.1.7/src/signal.rs:113:18
     |
113  | pub fn signal<T: Send + Sync + 'static>(
     |                  ^^^^ required by this bound in `signal`

Can anyone please suggest what the best solution would be for this? I don't think I have the option of not using a signal for files.

[benwis]

Have you tried using `signal_local` to create a signal that is not send/sync?

On Sat, Feb 15, 2025, at 11:34 PM, Anshul Sanghi wrote: I have a project I'm migrating from 0.6 to 0.7, and a big hurdle is that the `File` type that comes from `web_sys` can no longer be used with a signal, since *mut u8 is not thread-safe. A SendWrapper doesn't work either because then it doesn't implement the `Track` trait that signals need. Here's a simple example to reproduce the issue: `let (files, set_files) = signal::<Vec<web_sys::File>>(vec![]);

`

This produces the following error: `error[E0277]: `*mut u8` cannot be sent between threads safely --> src/modules/awdio.rs:34:39 | 34 | let (files, set_files) = signal::<Vec<File>>(vec![]); | ^^^^^^^^^ `*mut u8` cannot be sent between threads safely | = help: within `Vec<web_sys::File>`, the trait `Send` is not implemented for `*mut u8` note: required because it appears within the type `PhantomData<*mut u8>` --> /Users/anshulsanghi/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/marker.rs:757:12 | 757 | pub struct PhantomData<T: ?Sized>; | ^^^^^^^^^^^ note: required because it appears within the type `JsValue` --> /Users/anshulsanghi/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wasm-bindgen-0.2.100/src/lib.rs:135:12 | 135 | pub struct JsValue { | ^^^^^^^ note: required because it appears within the type `wasm_bindgen_futures::js_sys::Object` --> /Users/anshulsanghi/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/js-sys-0.3.77/src/lib.rs:3445:14 | 3445 | pub type Object; | ^^^^^^ note: required because it appears within the type `web_sys::Blob` --> /Users/anshulsanghi/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/web-sys-0.3.77/src/features/gen_Blob.rs:14:14 | 14 | pub type Blob; | ^^^^ note: required because it appears within the type `web_sys::File` --> /Users/anshulsanghi/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/web-sys-0.3.77/src/features/gen_File.rs:14:14 | 14 | pub type File; | ^^^^ note: required because it appears within the type `PhantomData<web_sys::File>` --> /Users/anshulsanghi/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/core/src/marker.rs:757:12 | 757 | pub struct PhantomData<T: ?Sized>; | ^^^^^^^^^^^ note: required because it appears within the type `wasm_bindgen::__rt::alloc::raw_vec::RawVec<web_sys::File>` --> /Users/anshulsanghi/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/alloc/src/raw_vec.rs:70:19 | 70 | pub(crate) struct RawVec<T, A: Allocator = Global> { | ^^^^^^ note: required because it appears within the type `Vec<web_sys::File>` --> /Users/anshulsanghi/.rustup/toolchains/nightly-aarch64-apple-darwin/lib/rustlib/src/rust/library/alloc/src/vec/mod.rs:397:12 | 397 | pub struct Vec<T, #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global> { | ^^^ note: required by a bound in `leptos::prelude::signal` --> /Users/anshulsanghi/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/reactive_graph-0.1.7/src/signal.rs:113:18 | 113 | pub fn signal<T: Send + Sync + 'static>( | ^^^^ required by this bound in `signal`

`

…

Can anyone please suggest what the best solution would be for this? I don't think I have the option of not using a signal for files. — Reply to this email directly, view it on GitHub <#3619>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABVBTCICPDLR5SRYD6JIX4D2QA5RHAVCNFSM6AAAAABXHJZWVKVHI2DSMVQWIX3LMV43ERDJONRXK43TNFXW4OZXHE3TCMBYG4>. You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[anshap1719]

Thanks! This works. I should revisit the documentation 😅