[Refactoring] Replace attributes when converting to an async function

The replacement range was `FunctionDecl::getRange`, which does not
include attributes. This would cause attributes to be duplicated when
converting a function to async. Override the start with the attribute
start instead so that they are replaced as well.

Resolves rdar://74063741

Author: bnbarham

lib/IDE/Refactoring.cpp

@@ -4721,10 +4721,15 @@ class AsyncConversionStringBuilder : private SourceEntityWalker {
     Placeholders.insert(TopHandler.Handler);
   }
 
-  void replace(ASTNode Node, SourceEditConsumer &EditConsumer) {
-    CharSourceRange Range =
-        Lexer::getCharSourceRangeFromSourceRange(SM, Node.getSourceRange());
-    EditConsumer.accept(SM, Range, Buffer.str());
+  void replace(ASTNode Node, SourceEditConsumer &EditConsumer,
+               SourceLoc StartOverride = SourceLoc()) {
+    SourceRange Range = Node.getSourceRange();
+    if (StartOverride.isValid()) {
+      Range = SourceRange(StartOverride, Range.End);
+    }
+    CharSourceRange CharRange =
+        Lexer::getCharSourceRangeFromSourceRange(SM, Range);
+    EditConsumer.accept(SM, CharRange, Buffer.str());
     Buffer.clear();
   }
 
@@ -5285,7 +5290,7 @@ bool RefactoringActionConvertToAsync::performChange() {
   if (DiagEngine.hadAnyError())
     return true;
 
-  Builder.replace(FD, EditConsumer);
+  Builder.replace(FD, EditConsumer, FD->getSourceRangeIncludingAttrs().Start);
   return false;
 }
 

test/refactoring/ConvertAsync/convert_function.swift

@@ -22,6 +22,20 @@ func nested() {
 // NESTED-NEXT: print(str2)
 // NESTED-NEXT: }
 
+// RUN: %refactor -convert-to-async -dump-text -source-filename %s -pos=%(line+2):9 | %FileCheck -check-prefix=ATTRIBUTES %s
+@available(*, deprecated, message: "Deprecated")
+private func functionWithAttributes() {
+  simple { str in
+    print(str)
+  }
+}
+// ATTRIBUTES: convert_function.swift [[# @LINE-6]]:1 -> [[# @LINE-1]]:2
+// ATTRIBUTES-NEXT: @available(*, deprecated, message: "Deprecated")
+// ATTRIBUTES-NEXT: private func functionWithAttributes() async {
+// ATTRIBUTES-NEXT: let str = await simple()
+// ATTRIBUTES-NEXT: print(str)
+// ATTRIBUTES-NEXT: }
+
 // RUN: %refactor -convert-to-async -dump-text -source-filename %s -pos=%(line+1):1 | %FileCheck -check-prefix=MANY-NESTED %s
 func manyNested() {
   simple { str1 in