fix: comments with # macros should also be appropriately indented

Author: vinu-vanjari

Sources/SwiftSyntaxMacroExpansion/MacroSystem.swift

@@ -137,13 +137,13 @@ private func adjustIndentationOfFreestandingMacro(expandedCode: String, node: so
   var indentedSource =
     expandedCode
     .indented(by: indentationOfFirstLine)
-    .wrappingInTrivia(from: node)
 
-  // if the experssion started in middle of the line, then remove indentation of the first line
-  if !node.leadingTrivia.contains(where: \.isNewline) {
+  if indentedSource.count >= indentationOfFirstLine.sourceLength.utf8Length {
     indentedSource.removeFirst(indentationOfFirstLine.sourceLength.utf8Length)
   }
 
+  indentedSource = indentedSource.wrappingInTrivia(from: node)
+
   return indentedSource
 }
 
@@ -1274,9 +1274,7 @@ private extension String {
   /// user should think about it as just replacing the `#...` expression without
   /// any trivia.
   func wrappingInTrivia(from node: some SyntaxProtocol) -> String {
-    // We need to remove the indentation from the last line because the macro
-    // expansion buffer already contains the indentation.
-    return node.leadingTrivia.removingIndentationOnLastLine.description
+    return node.leadingTrivia.description
       + self
       + node.trailingTrivia.description
   }

Tests/SwiftSyntaxMacroExpansionTest/LexicalContextTests.swift

@@ -287,6 +287,40 @@ final class LexicalContextTests: XCTestCase {
       macros: ["function": FunctionMacro.self],
       indentationWidth: indentationWidth
     )
+
+    assertMacroExpansion(
+      """
+      func f(a: Int, _: Double, c: Int) {
+        print(/*comment*/#function)
+      }
+      """,
+      expandedSource: """
+        func f(a: Int, _: Double, c: Int) {
+          print(/*comment*/"f(a:_:c:)")
+        }
+        """,
+      macros: ["function": FunctionMacro.self],
+      indentationWidth: indentationWidth
+    )
+
+    assertMacroExpansion(
+      """
+      var computed: String {
+        get {
+          /*comment*/#function
+        }
+      }
+      """,
+      expandedSource: """
+        var computed: String {
+          get {
+            /*comment*/"computed"
+          }
+        }
+        """,
+      macros: ["function": FunctionMacro.self],
+      indentationWidth: indentationWidth
+    )
   }
 
   func testPoundMultilineFunction() {
@@ -385,6 +419,44 @@ final class LexicalContextTests: XCTestCase {
       macros: ["function": MultilineFunctionMacro.self],
       indentationWidth: indentationWidth
     )
+
+    assertMacroExpansion(
+      """
+      func f(a: Int, _: Double, c: Int) {
+        print(/*comment*/#function)
+      }
+      """,
+      expandedSource: """
+        func f(a: Int, _: Double, c: Int) {
+          print(/*comment*/{
+            "f(a:_:c:)"
+          })
+        }
+        """,
+      macros: ["function": MultilineFunctionMacro.self],
+      indentationWidth: indentationWidth
+    )
+
+    assertMacroExpansion(
+      """
+      var computed: String {
+        get {
+          /*comment*/#function // another comment
+        }
+      }
+      """,
+      expandedSource: """
+        var computed: String {
+          get {
+            /*comment*/{
+              "computed"
+            } // another comment
+          }
+        }
+        """,
+      macros: ["function": MultilineFunctionMacro.self],
+      indentationWidth: indentationWidth
+    )
   }
 
   func testAllLexicalContexts() {