[unittests] Remove a use of addTopLevelDecl

Instead, cache the decls as a result of
ParseSourceFileRequest.

unittests/AST/TestContext.cpp

@@ -12,14 +12,14 @@
 
 #include "TestContext.h"
 #include "swift/AST/Module.h"
+#include "swift/AST/ParseRequests.h"
 #include "swift/Strings.h"
 #include "swift/Subsystems.h"
 
 using namespace swift;
 using namespace swift::unittest;
 
-
-static void declareOptionalType(ASTContext &ctx, SourceFile *fileForLookups,
+static Decl *createOptionalType(ASTContext &ctx, SourceFile *fileForLookups,
                                 Identifier name) {
   auto wrapped = new (ctx) GenericTypeParamDecl(fileForLookups,
                                                 ctx.getIdentifier("Wrapped"),
@@ -30,7 +30,7 @@ static void declareOptionalType(ASTContext &ctx, SourceFile *fileForLookups,
   auto decl = new (ctx) EnumDecl(SourceLoc(), name, SourceLoc(),
                                  /*inherited*/{}, params, fileForLookups);
   wrapped->setDeclContext(decl);
-  fileForLookups->addTopLevelDecl(decl);
+  return decl;
 }
 
 TestContext::TestContext(ShouldDeclareOptionalTypes optionals)
@@ -50,8 +50,13 @@ TestContext::TestContext(ShouldDeclareOptionalTypes optionals)
   module->addFile(*FileForLookups);
 
   if (optionals == DeclareOptionalTypes) {
-    declareOptionalType(Ctx, FileForLookups, Ctx.getIdentifier("Optional"));
-    declareOptionalType(Ctx, FileForLookups,
-                        Ctx.getIdentifier("ImplicitlyUnwrappedOptional"));
+    SmallVector<Decl *, 2> optionalTypes;
+    optionalTypes.push_back(createOptionalType(
+        Ctx, FileForLookups, Ctx.getIdentifier("Optional")));
+    optionalTypes.push_back(createOptionalType(
+        Ctx, FileForLookups, Ctx.getIdentifier("ImplicitlyUnwrappedOptional")));
+
+    Ctx.evaluator.cacheOutput(ParseSourceFileRequest{FileForLookups},
+                              Ctx.AllocateCopy(optionalTypes));
   }
 }