fix(plugin): Make span_to_source use dedicated function (#6853)

**Related issue:**

 - Closes #6852.
 - Closes #6404.

.vscode/settings.json

@@ -23,10 +23,14 @@
         "crates/swc_html_parser/tests/html5lib-tests"
     ],
     "eslint.enable": false,
-    "cSpell.allowCompoundWords": true,
-    "cSpell.caseSensitive": true,
-    "rust-analyzer.checkOnSave.command": "clippy",
-    "rust-analyzer.checkOnSave.features": [
+    "rust-analyzer.check.command": "clippy",
+    "rust-analyzer.check.features": [
+        // We use this to make IDE faster
+        "rust-analyzer",
+        "rkyv-impl",
+        "debug"
+    ],
+    "rust-analyzer.cargo.features": [
         // We use this to make IDE faster
         "rust-analyzer",
         "rkyv-impl",

crates/swc_common/src/syntax_pos.rs

@@ -1267,6 +1267,10 @@ pub enum SpanLinesError {
 }
 
 #[derive(Clone, PartialEq, Eq, Debug)]
+#[cfg_attr(
+    any(feature = "rkyv-impl", feature = "rkyv-bytecheck-impl"),
+    derive(rkyv::Archive, rkyv::Serialize, rkyv::Deserialize)
+)]
 pub enum SpanSnippetError {
     DummyBytePos,
     IllFormedSpan(Span),
@@ -1286,6 +1290,10 @@ pub struct DistinctSources {
 }
 
 #[derive(Clone, PartialEq, Eq, Debug)]
+#[cfg_attr(
+    any(feature = "rkyv-impl", feature = "rkyv-bytecheck-impl"),
+    derive(rkyv::Archive, rkyv::Serialize, rkyv::Deserialize)
+)]
 pub struct MalformedSourceMapPositions {
     pub name: FileName,
     pub source_len: usize,

crates/swc_plugin_proxy/src/source_map/plugin_source_map_proxy.rs

@@ -45,6 +45,12 @@ extern "C" {
         span_ctxt: u32,
         allocated_ret_ptr: u32,
     ) -> u32;
+    fn __span_to_source_proxy(
+        span_lo: u32,
+        span_hi: u32,
+        span_ctxt: u32,
+        allocated_ret_ptr: u32,
+    ) -> u32;
     fn __span_to_lines_proxy(
         span_lo: u32,
         span_hi: u32,
@@ -67,49 +73,6 @@ pub struct PluginSourceMapProxy {
 #[cfg(all(feature = "__rkyv", feature = "__plugin_mode", target_arch = "wasm32"))]
 #[swc_trace]
 impl PluginSourceMapProxy {
-    /*
-    fn sss<F, Ret>(&self, sp: Span, extract_source: F) -> Result<Ret, Box<SpanSnippetError>>
-    where
-        F: FnOnce(&str, usize, usize) -> Ret,
-    {
-        if sp.lo() > sp.hi() {
-            return Err(SpanSnippetError::IllFormedSpan(sp));
-        }
-        if sp.lo.is_dummy() || sp.hi.is_dummy() {
-            return Err(SpanSnippetError::DummyBytePos);
-        }
-
-        let local_begin = self.lookup_byte_offset(sp.lo());
-        let local_end = self.lookup_byte_offset(sp.hi());
-
-        if local_begin.sf.start_pos != local_end.sf.start_pos {
-            Err(SpanSnippetError::DistinctSources(DistinctSources {
-                begin: (local_begin.sf.name.clone(), local_begin.sf.start_pos),
-                end: (local_end.sf.name.clone(), local_end.sf.start_pos),
-            }))
-        } else {
-            let pos: BytePos = BytePos(0);
-            let start_index = pos.to_usize();
-            let end_index = local_end.pos.to_usize();
-            let source_len = (local_begin.sf.end_pos - local_begin.sf.start_pos).to_usize();
-
-            if start_index > end_index || end_index > source_len {
-                return Err(SpanSnippetError::MalformedForSourcemap(
-                    MalformedSourceMapPositions {
-                        name: local_begin.sf.name.clone(),
-                        source_len,
-                        begin_pos: local_begin.pos,
-                        end_pos: local_end.pos,
-                    },
-                ));
-            }
-
-            let src = &local_begin.sf.src;
-            Ok(extract_source(src, start_index, end_index))
-        }
-    }
-     */
-
     pub fn span_to_source<F, Ret>(
         &self,
         sp: Span,
@@ -120,50 +83,14 @@ impl PluginSourceMapProxy {
     {
         #[cfg(target_arch = "wasm32")]
         {
-            if sp.lo() > sp.hi() {
-                return Err(Box::new(SpanSnippetError::IllFormedSpan(sp)));
-            }
-            if sp.lo.is_dummy() || sp.hi.is_dummy() {
-                return Err(Box::new(SpanSnippetError::DummyBytePos));
-            }
-
-            let local_begin: SourceFileAndBytePos =
+            let src: Result<String, Box<SpanSnippetError>> =
                 read_returned_result_from_host_fallible(|serialized_ptr| unsafe {
-                    __lookup_byte_offset_proxy(sp.lo().0, serialized_ptr)
+                    __span_to_source_proxy(sp.lo.0, sp.hi.0, sp.ctxt.as_u32(), serialized_ptr)
                 })
-                .expect("Should return begin offset");
-            let local_end: SourceFileAndBytePos =
-                read_returned_result_from_host_fallible(|serialized_ptr| unsafe {
-                    __lookup_byte_offset_proxy(sp.hi().0, serialized_ptr)
-                })
-                .expect("Should return end offset");
-
-            if local_begin.sf.start_pos != local_end.sf.start_pos {
-                Err(Box::new(SpanSnippetError::DistinctSources(
-                    DistinctSources {
-                        begin: (local_begin.sf.name.clone(), local_begin.sf.start_pos),
-                        end: (local_end.sf.name.clone(), local_end.sf.start_pos),
-                    },
-                )))
-            } else {
-                let start_index = local_begin.pos.to_usize();
-                let end_index = local_end.pos.to_usize();
-                let source_len = (local_begin.sf.end_pos - local_begin.sf.start_pos).to_usize();
+                .expect("Host should return source code");
 
-                if start_index > end_index || end_index > source_len {
-                    return Err(Box::new(SpanSnippetError::MalformedForSourcemap(
-                        MalformedSourceMapPositions {
-                            name: local_begin.sf.name.clone(),
-                            source_len,
-                            begin_pos: local_begin.pos,
-                            end_pos: local_end.pos,
-                        },
-                    )));
-                }
-
-                let src = &local_begin.sf.src;
-                return Ok(extract_source(src, start_index, end_index));
-            }
+            let src = src?;
+            return Ok(extract_source(&src, 0, src.len()));
         }
 
         #[cfg(not(target_arch = "wasm32"))]

crates/swc_plugin_runner/src/imported_fn/mod.rs

@@ -83,8 +83,8 @@ use self::{
     },
     source_map::{
         doctest_offset_line_proxy, lookup_byte_offset_proxy, lookup_char_pos_proxy,
-        merge_spans_proxy, span_to_filename_proxy, span_to_lines_proxy, span_to_string_proxy,
-        SourceMapHostEnvironment,
+        merge_spans_proxy, span_to_filename_proxy, span_to_lines_proxy, span_to_source_proxy,
+        span_to_string_proxy, SourceMapHostEnvironment,
     },
 };
 
@@ -281,6 +281,12 @@ pub(crate) fn build_import_object(
         span_to_filename_proxy,
     );
 
+    let span_to_source_fn_decl = Function::new_native_with_env(
+        store,
+        SourceMapHostEnvironment::new(&source_map, &source_map_buffer),
+        span_to_source_proxy,
+    );
+
     let span_to_lines_fn_decl = Function::new_native_with_env(
         store,
         SourceMapHostEnvironment::new(&source_map, &source_map_buffer),
@@ -339,6 +345,7 @@ pub(crate) fn build_import_object(
             "__merge_spans_proxy" => merge_spans_fn_decl,
             "__span_to_string_proxy" => span_to_string_fn_decl,
             "__span_to_filename_proxy" => span_to_filename_fn_decl,
+            "__span_to_source_proxy" => span_to_source_fn_decl,
             "__span_to_lines_proxy" => span_to_lines_fn_decl,
             "__lookup_byte_offset_proxy" => lookup_byte_offset_fn_decl
         }

crates/swc_plugin_runner/src/imported_fn/source_map.rs

@@ -4,7 +4,7 @@ use parking_lot::Mutex;
 use swc_common::{
     plugin::serialized::PluginSerializedBytes,
     source_map::{PartialFileLines, PartialLoc},
-    BytePos, SourceMap, Span, SyntaxContext,
+    BytePos, SourceMap, SourceMapper, Span, SyntaxContext,
 };
 use wasmer::{LazyInit, Memory, NativeFunc};
 
@@ -267,3 +267,37 @@ pub fn span_to_filename_proxy(
         0
     }
 }
+
+#[tracing::instrument(level = "info", skip_all)]
+pub fn span_to_source_proxy(
+    env: &SourceMapHostEnvironment,
+    span_lo: u32,
+    span_hi: u32,
+    span_ctxt: u32,
+    allocated_ret_ptr: u32,
+) -> i32 {
+    if let Some(memory) = env.memory_ref() {
+        let span = Span {
+            lo: BytePos(span_lo),
+            hi: BytePos(span_hi),
+            ctxt: SyntaxContext::from_u32(span_ctxt),
+        };
+        let ret = (env.source_map.lock()).span_to_snippet(span);
+        let serialized_loc_bytes =
+            PluginSerializedBytes::try_serialize(&ret).expect("Should be serializable");
+
+        if let Some(alloc_guest_memory) = env.alloc_guest_memory_ref() {
+            allocate_return_values_into_guest(
+                memory,
+                alloc_guest_memory,
+                allocated_ret_ptr,
+                &serialized_loc_bytes,
+            );
+            1
+        } else {
+            0
+        }
+    } else {
+        0
+    }
+}