fix: SourceMap::span_to_lines for empty file (#1198)

Co-authored-by: 강동윤 <kdy1997.dev@gmail.com>

common/Cargo.toml

@@ -6,7 +6,7 @@ edition = "2018"
 license = "Apache-2.0/MIT"
 name = "swc_common"
 repository = "https://github.com/swc-project/swc.git"
-version = "0.10.4"
+version = "0.10.5"
 
 [features]
 concurrent = ["parking_lot"]

common/src/source_map.rs

@@ -457,6 +457,14 @@ impl SourceMap {
         }
         assert!(hi.line >= lo.line);
 
+        // Empty file contains no lines
+        if lo.file.src.is_empty() {
+            return Ok(FileLines {
+                file: lo.file,
+                lines: vec![],
+            });
+        }
+
         let mut lines = Vec::with_capacity(hi.line - lo.line + 1);
 
         // The span starts partway through the first line,
@@ -1313,6 +1321,18 @@ mod tests {
         assert_eq!(sstr, "blork.rs:2:1: 2:12");
     }
 
+    #[test]
+    fn t10() {
+        // Test span_to_lines for a span of empty file
+        let sm = SourceMap::new(FilePathMapping::empty());
+        sm.new_source_file(PathBuf::from("blork.rs").into(), "".to_string());
+        let span = Span::new(BytePos(0), BytePos(0), NO_EXPANSION);
+        let file_lines = sm.span_to_lines(span).unwrap();
+
+        assert_eq!(file_lines.file.name, PathBuf::from("blork.rs").into());
+        assert_eq!(file_lines.lines.len(), 0);
+    }
+
     /// Test failing to merge two spans on different lines
     #[test]
     fn span_merging_fail() {