util: keep function name for mapped call sites

Signed-off-by: Lazizbek Ergashev <lazerg2@gmail.com>

Author: lazerg

lib/util.js

@@ -515,8 +515,7 @@ function reconstructCallSite(callSite) {
   if (!entry?.originalSource) return;
   return {
     __proto__: null,
-    // If the name is not found, it is an empty string to match the behavior of `util.getCallSite()`
-    functionName: entry.name ?? '',
+    functionName: entry.name ?? callSite.functionName,
     scriptName: entry.originalSource,
     lineNumber: entry.originalLine + 1,
     column: entry.originalColumn + 1,

test/fixtures/source-map/get-call-sites-named-mapped.js

@@ -0,0 +1,6 @@
+{
+  "version": 3,
+  "sources": ["get-call-sites-named-original.js"],
+  "names": [],
+  "mappings": "AAUA"
+}

test/fixtures/source-map/get-call-sites-named-mapped.map

@@ -39,6 +39,23 @@ const fixtures = require('../common/fixtures');
   assert.strictEqual(callSite.columnNumber, 1);
 }
 
+// The generated function name is kept when the source map has no name entry
+// for the call site.
+{
+  const file = fixtures.path('source-map', 'get-call-sites-named-mapped.js');
+  const { status, stderr, stdout } = spawnSync(
+    process.execPath,
+    ['--enable-source-maps', file],
+  );
+  assert.strictEqual(status, 0, stderr.toString());
+  const callSite = JSON.parse(stdout.toString());
+  assert.ok(
+    callSite.scriptName.endsWith('get-call-sites-named-original.js'),
+    `expected original source in scriptName, got "${callSite.scriptName}"`,
+  );
+  assert.strictEqual(callSite.functionName, 'foo');
+}
+
 // Without --enable-source-maps the generated file path is preserved.
 {
   const file = fixtures.path('source-map', 'get-call-sites-mapped.js');