feat(plugin): Implement proxy for dummy_with_cmt (#4268)

crates/swc_common/src/syntax_pos.rs

@@ -6,7 +6,7 @@ use std::{
     hash::{Hash, Hasher},
     ops::{Add, Sub},
     path::PathBuf,
-    sync::atomic::{AtomicU32, Ordering},
+    sync::atomic::AtomicU32,
 };
 
 #[cfg(feature = "parking_lot")]
@@ -68,6 +68,7 @@ pub const DUMMY_SP: Span = Span {
 #[derive(Default)]
 pub struct Globals {
     hygiene_data: Mutex<hygiene::HygieneData>,
+    #[allow(unused)]
     dummy_cnt: AtomicU32,
 }
 
@@ -199,6 +200,10 @@ pub struct MultiSpan {
     span_labels: Vec<(Span, String)>,
 }
 
+extern "C" {
+    fn __span_dummy_with_cmt_proxy() -> u32;
+}
+
 impl Span {
     #[inline]
     pub fn lo(self) -> BytePos {
@@ -438,14 +443,30 @@ impl Span {
     /// Dummy span, both position are extremely large numbers so they would be
     /// ignore by sourcemap, but can still have comments
     pub fn dummy_with_cmt() -> Self {
-        GLOBALS.with(|globals| {
-            let lo = BytePos(globals.dummy_cnt.fetch_add(1, Ordering::SeqCst));
+        #[cfg(all(feature = "plugin-mode", target_arch = "wasm32"))]
+        {
+            let lo = BytePos(unsafe { __span_dummy_with_cmt_proxy() });
+
+            return Span {
+                lo,
+                hi: lo,
+                ctxt: SyntaxContext::empty(),
+            };
+        }
+
+        #[cfg(not(all(feature = "plugin-mode", target_arch = "wasm32")))]
+        return GLOBALS.with(|globals| {
+            let lo = BytePos(
+                globals
+                    .dummy_cnt
+                    .fetch_add(1, std::sync::atomic::Ordering::SeqCst),
+            );
             Span {
                 lo,
                 hi: lo,
                 ctxt: SyntaxContext::empty(),
             }
-        })
+        });
     }
 }
 

crates/swc_plugin_runner/src/imported_fn/mod.rs

@@ -57,6 +57,7 @@ use crate::{
             take_leading_comments_proxy, take_trailing_comments_proxy, CommentHostEnvironment,
         },
         set_transform_result::{set_transform_result, TransformResultHostEnvironment},
+        span::span_dummy_with_cmt_proxy,
     },
 };
 
@@ -64,6 +65,7 @@ mod comments;
 mod handler;
 mod hygiene;
 mod set_transform_result;
+mod span;
 
 use handler::*;
 use hygiene::*;
@@ -114,6 +116,9 @@ pub(crate) fn build_import_object(
     let syntax_context_outer_fn_decl =
         Function::new_native(wasmer_store, syntax_context_outer_proxy);
 
+    // Span
+    let span_dummy_with_cmt_fn_decl = Function::new_native(wasmer_store, span_dummy_with_cmt_proxy);
+
     // comments
     let comment_buffer = Arc::new(Mutex::new(vec![]));
 
@@ -209,6 +214,8 @@ pub(crate) fn build_import_object(
             "__syntax_context_apply_mark_proxy" => syntax_context_apply_mark_fn_decl,
             "__syntax_context_remove_mark_proxy" => syntax_context_remove_mark_fn_decl,
             "__syntax_context_outer_proxy" => syntax_context_outer_fn_decl,
+            // span
+            "__span_dummy_with_cmt_proxy" => span_dummy_with_cmt_fn_decl,
             // comments
             "__copy_comment_to_host_env" => copy_comment_to_host_env_fn_decl,
             "__add_leading_comment_proxy" => add_leading_comment_fn_decl,

crates/swc_plugin_runner/src/imported_fn/span.rs

@@ -0,0 +1,4 @@
+pub fn span_dummy_with_cmt_proxy() -> u32 {
+    // Instead of trying to serialize whole span, send bytepos only
+    swc_common::Span::dummy_with_cmt().lo.0
+}