[SourceKit] Don’t set the code completion offset when doing completion-like cursor info

Author: ahoppen

test/SourceKit/CursorInfo/cursor_in_top_level_closure.swift

@@ -0,0 +1,24 @@
+// RUN: %empty-directory(%t/split)
+// RUN: %{python} %utils/split_file.py -o %t/split %s
+// RUN: %empty-directory(%t/build)
+// RUN: %sourcekitd-test -req=cursor -pos=5:9 %t/split/MovieRow.swift -- %t/split/MovieRow.swift %t/split/Color.swift | %FileCheck %s
+
+// BEGIN Color.swift
+
+extension Invalid {}
+
+// BEGIN MovieRow.swift
+
+struct Bar {}
+
+fileprivate let bar: Bar = {
+    let bar = Bar()
+    return bar
+}()
+
+
+// CHECK: source.lang.swift.decl.var.local (5:9-5:12)
+// CHECK-NEXT: bar
+// CHECK: RELATED BEGIN
+// CHECK-NEXT: <RelatedName usr="s:4main3bar33_F48676AE0C86F007C79C860E40EDA2D3LLAA3BarVvp">bar</RelatedName>
+// CHECK-NEXT: RELATED END

tools/SourceKit/lib/SwiftLang/SwiftSourceDocInfo.cpp

@@ -1996,9 +1996,11 @@ void SwiftLangSupport::getCursorInfo(
           [&](CancellableResult<CompletionLikeOperationParams> ParmsResult) {
             ParmsResult.mapAsync<CursorInfoResults>(
                 [&](auto &Params, auto DeliverTransformed) {
+                  // Set offset = ~0U to indicate that w did not insert a code
+                  // completiom token into the source file.
                   getCompletionInstance()->cursorInfo(
                       Params.Invocation, Args, fileSystem,
-                      Params.completionBuffer, Offset, Params.DiagC,
+                      Params.completionBuffer, /*Offset=*/~0U, Params.DiagC,
                       Params.CancellationFlag, DeliverTransformed);
                 },
                 [&](auto Result) {