Wasm terminal color always detected as unsupported

[tqwewe]

console/src/wasm_term.rs

Lines 16 to 19 in 02fa5c0

	#[inline]
	pub fn is_a_color_terminal(_out: &Term) -> bool {
	false
	}

In the wasm terminal module, it sets is_a_color_terminal to always return false. But this should use detection similar to native terminals.

In my case, I'm trying to implement console with a wasm runner called lunatic, though coloring doesn't work unless I force it to be enabled, since the compiled module is a wasm module ran by lunatic.

[mitsuhiko]

I would need to look into what WASI wants to do there. There is some discussion about how this is supposed to work over there: WebAssembly/WASI#162

It looks like even if console were to report a color terminal, wasmtime would filter out ANSI codes. I'm unfamiliar with lunatic, not sure how that works. If you have a reference about how lunatic supports ANSI codes I would be interested.

[tqwewe]

Lunatic uses wasmtime under the hood for running the wasm, and just manages multiple "processes". But the main support would be a matter of wasmtime really.

If I force it to be enabled, it prints the colors just fine. I guess wasi just lacks a spec/support for ansi stuff, and sadly that github issue isn't very active.

I guess my best case going forward could be to just copying these lines

console/src/unix_term.rs

Lines 26 to 33 in 02fa5c0

	if env::var("NO_COLOR").is_ok() {
	return false;
	}
	match env::var("TERM") {
	Ok(term) => term != "dumb",
	Err(_) => false,
	}

and setting the color to be enabled based on this

[mitsuhiko]

That is interesting. Because this commit here indicates that ANSI sequences should be filtered by wasmtime: bytecodealliance/wasmtime#684 — it's also documented here as explicitly filtered: https://github.com/bytecodealliance/wasmtime/blob/e4dc9c79443259e40f3e93b9c7815b0645ebd5c4/docs/security.md?plain=1#L98

I would love to get some guidance on what to do with ANSI codes before committing to something. Right now you can already manually force colors on globally by calling console::set_colors_enabled overriding what happens normally.