fix(formatter): skip the leading semicolon when calculating leading lines

Author: Dunqing

crates/oxc_formatter/src/formatter/source_text.rs

@@ -160,6 +160,10 @@ impl<'a> SourceText<'a> {
             && comment.span.end <= start
         {
             start = comment.span.start;
+        } else if start != 0 && matches!(self.byte_at(start - 1), Some(b';')) {
+            // Skip leading semicolon if present
+            // `;(function() {});`
+            start -= 1;
         }
 
         // Count the newlines in the leading trivia of the next node

crates/oxc_formatter/tests/fixtures/js/semicolons/empty-line.js

@@ -0,0 +1,5 @@
+const a = 1
+
+;(function() {
+  const b = 2;
+})()

crates/oxc_formatter/tests/fixtures/js/semicolons/empty-line.js.snap

@@ -0,0 +1,30 @@
+---
+source: crates/oxc_formatter/tests/fixtures/mod.rs
+---
+==================== Input ====================
+const a = 1
+
+;(function() {
+  const b = 2;
+})()
+
+==================== Output ====================
+--------------
+{ semi: true }
+--------------
+const a = 1;
+
+(function () {
+  const b = 2;
+})();
+
+---------------
+{ semi: false }
+---------------
+const a = 1
+
+;(function () {
+  const b = 2
+})()
+
+===================== End =====================

crates/oxc_formatter/tests/fixtures/js/semicolons/options.json

@@ -0,0 +1,8 @@
+[
+  {
+    "semi": true
+  },
+  {
+    "semi": false
+  }
+]