Squashed commit of the following:

commit 262575b
Author: munrocket <munsocket@protonmail.com>
Date:   Fri May 10 01:16:48 2024 +0400

    add optional extensions

commit de75501
Author: munrocket <munsocket@protonmail.com>
Date:   Thu May 9 21:46:51 2024 +0400

    comment timestamp

src/context.rs

@@ -113,6 +113,10 @@ pub async fn init_wgpu(width: u32, height: u32, bind_id: &str) -> Result<WgpuCon
         })
         .await
         .ok_or("unable to create adapter")?;
+
+    log::info!("adapter.features = {:#?}", adapter.features());
+    log::info!("adapter.limits = {:#?}", adapter.limits());
+
     let (device, queue) = adapter
         .request_device(
             &wgpu::DeviceDescriptor {
@@ -141,7 +145,6 @@ pub async fn init_wgpu(width: u32, height: u32, bind_id: &str) -> Result<WgpuCon
     };
     surface.configure(&device, &surface_config);
 
-    log::info!("adapter.limits = {:#?}", adapter.limits());
     Ok(WgpuContext {
         #[cfg(all(not(target_arch = "wasm32"), feature = "winit"))]
         event_loop: Some(event_loop),

src/lib.rs

@@ -481,7 +481,7 @@ fn passSampleLevelBilinearRepeat(pass_index: int, uv: float2, lod: float) -> flo
 
     pub fn compile(&mut self, source: SourceMap) {
         let now = instant::Instant::now();
-        let prelude = self.prelude(); // prelude must be generated after preprocessor has run
+        let prelude = format!("{}{}", source.extensions, self.prelude());
 
         // FIXME: remove pending resolution of this issue: https://github.com/gfx-rs/wgpu/issues/2130
         let prelude_len = count_newlines(&prelude);

src/pp.rs

@@ -35,6 +35,8 @@ impl WGSLError {
 
 #[wasm_bindgen]
 pub struct SourceMap {
+    #[wasm_bindgen(skip)]
+    pub extensions: String,
     #[wasm_bindgen(skip)]
     pub source: String,
     #[wasm_bindgen(skip)]
@@ -54,6 +56,7 @@ pub struct SourceMap {
 impl SourceMap {
     pub fn new() -> Self {
         Self {
+            extensions: String::new(),
             source: String::new(),
             map: vec![0],
             workgroup_count: HashMap::new(),
@@ -81,7 +84,7 @@ pub struct Preprocessor {
     source: SourceMap,
     storage_count: usize,
     assert_count: usize,
-    enable_strings: bool,
+    special_strings: bool,
 }
 
 static RE_COMMENT: Lazy<Regex> = lazy_regex!(r"(//.*|(?s:/\*.*?\*/))");
@@ -103,7 +106,7 @@ impl Preprocessor {
             source: SourceMap::new(),
             storage_count: 0,
             assert_count: 0,
-            enable_strings: false,
+            special_strings: false,
         }
     }
 
@@ -129,7 +132,11 @@ impl Preprocessor {
     #[async_recursion(?Send)]
     async fn process_line(&mut self, line_orig: &str, n: usize) -> Result<(), WGSLError> {
         let mut line = self.subst_defines(line_orig);
-        if line.trim_start().starts_with('#') {
+        if line.trim_start().starts_with("enable") {
+            line = RE_COMMENT.replace(&line, "").to_string();
+            self.source.extensions.push_str(&line);
+            self.source.extensions.push('\n');
+        } else if line.trim_start().starts_with('#') {
             line = RE_COMMENT.replace(&line, "").to_string();
             let tokens: Vec<&str> = line.trim().split(' ').collect();
             match tokens[..] {
@@ -145,7 +152,7 @@ impl Preprocessor {
                             Some(cap) => {
                                 let path = &cap[1];
                                 if path == "string" {
-                                    self.enable_strings = true;
+                                    self.special_strings = true;
                                 }
                                 fetch_include(format!("std/{path}")).await
                             }
@@ -242,7 +249,7 @@ impl Preprocessor {
                 }
             }
         } else {
-            if self.enable_strings {
+            if self.special_strings {
                 let mut err = None;
                 line = RE_QUOTES.replace(&line, |caps: &Captures| {
                     if let Ok(s) = snailquote::unescape(&caps[0]) {

src/utils.rs

@@ -1,9 +1,7 @@
 use crate::WGSLError;
 
 #[cfg(target_arch = "wasm32")]
-use {
-    cached::proc_macro::cached, std::future::Future, wasm_bindgen::prelude::*,
-};
+use {cached::proc_macro::cached, std::future::Future, wasm_bindgen::prelude::*};
 
 pub fn set_panic_hook() {
     // When the `console_error_panic_hook` feature is enabled, we can call the