When compiling eframe in wasm32-unknown-emscripten, an error occurred. What should I do?

[Aladdinslamp]

The issue with Emscripten compilation is as follows:
cargo build --target=wasm32-unknown-emscripten
--> D:\RustEnv\CargoCache\registry\src\index.crates.io-6f17d22bba15001f\eframe-0.27.0\src\web\web_painter_glow.rs:118:29
|
118 | let gl = glow::Context::from_webgl1_context(gl1_ctx);
| ^^^^^^^^^^^^^^^^^^^ function or associated item not found in Context
|
note: if you're trying to build a new glow::Context consider using one of the following associated functions:
glow::Context::from_loader_function_cstr
glow::Context::from_loader_function
--> D:\RustEnv\CargoCache\registry\src\index.crates.io-6f17d22bba15001f\glow-0.13.1\src\native.rs:42:5
|
42 | / pub unsafe fn from_loader_function_cstr(mut loader_function: F) -> Self
43 | | where
44 | | F: FnMut(&CStr) -> *const std::os::raw::c_void,
| |_^
...
104 | / pub unsafe fn from_loader_function(mut loader_function: F) -> Self
105 | | where
106 | | F: FnMut(&str) -> *const std::os::raw::c_void,
| |^

error[E0599]: no function or associated item named from_webgl2_context found for struct glow::Context in the current scope
--> D:\RustEnv\CargoCache\registry\src\index.crates.io-6f17d22bba15001f\eframe-0.27.0\src\web\web_painter_glow.rs:134:29
|
134 | let gl = glow::Context::from_webgl2_context(gl2_ctx);
| ^^^^^^^^^^^^^^^^^^^ function or associated item not found in Context
|
note: if you're trying to build a new glow::Context consider using one of the following associated functions:
glow::Context::from_loader_function_cstr
glow::Context::from_loader_function
--> D:\RustEnv\CargoCache\registry\src\index.crates.io-6f17d22bba15001f\glow-0.13.1\src\native.rs:42:5
|
42 | / pub unsafe fn from_loader_function_cstr(mut loader_function: F) -> Self
43 | | where
44 | | F: FnMut(&CStr) -> *const std::os::raw::c_void,
| |_^
...
104 | / pub unsafe fn from_loader_function(mut loader_function: F) -> Self
105 | | where
106 | | F: FnMut(&str) -> *const std::os::raw::c_void,
| |^

[YgorSouza]

It looks like the glow API for emscripten is the same as for native, and different from other wasm32.

https://github.com/grovesNL/glow/blob/e4a9a702111c425abdf9febef3ec2f2ce4822c26/src/lib.rs#L15-L26

And eframe does not make this distinction.

egui/crates/eframe/src/lib.rs

Lines 158 to 168 in 78dfdb3

	#[cfg(target_arch = "wasm32")]
	pub use wasm_bindgen;
	#[cfg(target_arch = "wasm32")]
	pub use web_sys;
	#[cfg(target_arch = "wasm32")]
	pub mod web;
	#[cfg(target_arch = "wasm32")]
	pub use web::{WebLogger, WebRunner};

The wgpu backend also has a similar problem. So it seems like eframe is not compatible with the emscripten target at the moment. You could open an issue about it, to at least document that it doesn't work.