Auto-detect wasm target

`wasm-pack build --no-default-features`

The wasm feature still exists for compatibility but is a no-op.

Author: FreezyLemon

Cargo.toml

@@ -57,7 +57,10 @@ tracing = [
 ]
 scenechange = []
 serialize = ["serde", "toml", "v_frame/serialize", "serde-big-array", "av1-grain/serialize"]
-wasm = ["wasm-bindgen"]
+
+# Left here for compatibility reasons.
+# Does not do anything, the wasm target is auto-detected.
+wasm = []
 
 # Enables debug dumping of lookahead computation results, specifically:
 # - i-qres.png: quarter-resolution luma planes,
@@ -106,7 +109,6 @@ console = { version = "0.15", optional = true }
 fern = { version = "0.6", optional = true }
 itertools = "0.12"
 simd_helpers = "0.1"
-wasm-bindgen = { version = "0.2.90", optional = true }
 nom = { version = "7.1.3", optional = true }
 new_debug_unreachable = "1.0.4"
 av1-grain = "0.2.3"
@@ -155,6 +157,10 @@ rand_chacha = "0.3"
 [target.'cfg(any(decode_test, decode_test_dav1d))'.dependencies]
 system-deps = "6"
 
+# WASM
+[target.'cfg(all(target_arch = "wasm32", target_os = "unknown", target_vendor = "unknown"))'.dependencies]
+wasm-bindgen = "0.2.90"
+
 [[bin]]
 name = "rav1e"
 required-features = ["binaries"]

src/lib.rs

@@ -135,7 +135,7 @@ mod serialize {
 
 mod wasm_bindgen {
   cfg_if::cfg_if! {
-    if #[cfg(feature="wasm")] {
+    if #[cfg(all(target_arch = "wasm32", target_os = "unknown", target_vendor = "unknown"))] {
       pub use wasm_bindgen::prelude::*;
     } else {
       pub use noop_proc_macro::wasm_bindgen;