Print Sendable conformances for clang types

lib/AST/Module.cpp

@@ -909,6 +909,28 @@ SourceFile::getExternalRawLocsForDecl(const Decl *D) const {
 void ModuleDecl::getDisplayDecls(SmallVectorImpl<Decl*> &Results) const {
   // FIXME: Should this do extra access control filtering?
   FORWARD(getDisplayDecls, (Results));
+
+  // Force Sendable on all types, which might synthesize some extensions.
+  // FIXME: We can remove this if @_nonSendable stops creating extensions.
+  for (auto result : Results) {
+    if (auto NTD = dyn_cast<NominalTypeDecl>(result))
+      (void)swift::isSendableType(const_cast<ModuleDecl *>(this),
+                                  NTD->getDeclaredInterfaceType());
+  }
+
+  // Re-add anything from synthesized file units...
+  auto oldCutoff = Results.size();
+  for (auto file : getFiles())
+    if (auto synthFile = dyn_cast<SynthesizedFileUnit>(file))
+      synthFile->getDisplayDecls(Results);
+
+  // And then remove anything that was already in the results.
+  auto oldResults = makeArrayRef(Results).take_front(oldCutoff);
+  auto uniqueEnd = std::remove_if(Results.begin() + oldCutoff, Results.end(),
+                                   [&](auto result) {
+    return llvm::is_contained(oldResults, result);
+  });
+  Results.erase(uniqueEnd, Results.end());
 }
 
 ProtocolConformanceRef