[FormatManager] Upstream and test swift bits for GetCandidateLanguages().

[aprantl]

The change looks good with some future refactoring comment inline.

lldb/source/DataFormatters/FormatManager.cpp

588

Unrelated to this change; it seems this should really be a callback into the Language plugin and not hardcoded in LLDB.

[davide]

This is not a bad idea after all. Let me see if I can cook something reasonable without getting burned.

[davide]

Ideally -- if we're able to make this a callback in the language plugins, we don't need this patch at all.

[davide]

Not relevant anymore.

lldb/source/DataFormatters/FormatManager.cpp

if (!valobj_sp->GetCompilerType().IsMeaninglessWithoutDynamicResolution())
       return valobj_sp->GetQualifiedTypeName();
   }
   return ConstString();
 }
 
 std::vector<lldb::LanguageType>
 FormatManager::GetCandidateLanguages(lldb::LanguageType lang_type) {
   switch (lang_type) {
+  case lldb::eLanguageTypeSwift:
+    return {lldb::eLanguageTypeSwift, lldb::eLanguageTypeObjC};
+  case lldb::eLanguageTypeObjC:
+    return {lldb::eLanguageTypeObjC, lldb::eLanguageTypeSwift};
   case lldb::eLanguageTypeC:
   case lldb::eLanguageTypeC89:
   case lldb::eLanguageTypeC99:
   case lldb::eLanguageTypeC11:
   case lldb::eLanguageTypeC_plus_plus:
   case lldb::eLanguageTypeC_plus_plus_03:
   case lldb::eLanguageTypeC_plus_plus_11:
   case lldb::eLanguageTypeC_plus_plus_14:

lldb/unittests/DataFormatter/FormatManagerTests.cpp

EXPECT_EQ(FormatManager::GetCandidateLanguages(eLanguageTypeC_plus_plus),
             candidates);
   EXPECT_EQ(FormatManager::GetCandidateLanguages(eLanguageTypeC_plus_plus_03),
             candidates);
   EXPECT_EQ(FormatManager::GetCandidateLanguages(eLanguageTypeC_plus_plus_11),
             candidates);
   EXPECT_EQ(FormatManager::GetCandidateLanguages(eLanguageTypeC_plus_plus_14),
             candidates);
 
-  candidates = {eLanguageTypeObjC};
+  candidates = {eLanguageTypeObjC, eLanguageTypeSwift};
   EXPECT_EQ(FormatManager::GetCandidateLanguages(eLanguageTypeObjC),
             candidates);
+
+  candidates = {eLanguageTypeSwift, eLanguageTypeObjC};
+  EXPECT_EQ(FormatManager::GetCandidateLanguages(eLanguageTypeSwift),
+            candidates);
 }