[IDE] Decrement the global closure discriminator by one before performing the second code completion pass

Otherwise, the closure discriminator will be incremented by one when the closure witht he code completion token is parsed a second time during the second pass, and thus it would receive a different discriminator during the second pass.

lib/Parse/Parser.cpp

@@ -116,6 +116,11 @@ bool CodeCompletionSecondPassRequest::evaluate(
   if (!parserState->hasCodeCompletionDelayedDeclState())
     return true;
 
+  // Decrement the closure discriminator index by one so a top-level closure
+  // gets the same discriminator as before when being re-parsed in the second
+  // pass.
+  parserState->getTopLevelContext().overrideNextClosureDiscriminator(
+      parserState->getTopLevelContext().claimNextClosureDiscriminator() - 1);
   auto state = parserState->takeCodeCompletionDelayedDeclState();
   auto &Ctx = SF->getASTContext();
 

test/SourceKit/CursorInfo/cursor_in_global_closure.swift

@@ -0,0 +1,6 @@
+// RUN: %sourcekitd-test -req=cursor -pos=4:9 %s -- %s | %FileCheck %s
+
+fileprivate let formatter: DateFormatter = {
+    let formatter
+
+// CHECK: s:24cursor_in_global_closureXefU_9formatterL_Xevp