[FormatManager] GetCandidateLanguages shouldn't know about ValueObject.

[aprantl]

I'm assuming you already checked that this isn't used in swift-lldb either? Otherwise this obviously LGTM.

[jingham]

In D71236#1776404, @aprantl wrote:

I'm assuming you already checked that this isn't used in swift-lldb either? Otherwise this obviously LGTM.

This is answering the question "which languages have formatters that are compatible with this language." You should not need a live value to determine that, it is a feature of each language. So even if Swift is using the ValueObject version of this, it shouldn't be, and should switch to the LanguageType version.

lldb/include/lldb/DataFormatters/FormatManager.h

public:
   static ConstString GetTypeForCache(ValueObject &, lldb::DynamicValueType);
 
   LanguageCategory *GetCategoryForLanguage(lldb::LanguageType lang_type);
 
   static std::vector<lldb::LanguageType>
   GetCandidateLanguages(lldb::LanguageType lang_type);
 
 private:
-  static std::vector<lldb::LanguageType>
-  GetCandidateLanguages(ValueObject &valobj);
-
   static void GetPossibleMatches(ValueObject &valobj,
                                  CompilerType compiler_type, uint32_t reason,
                                  lldb::DynamicValueType use_dynamic,
                                  FormattersMatchVector &entries,
                                  bool did_strip_ptr, bool did_strip_ref,
                                  bool did_strip_typedef,
                                  bool root_level = false);
 

lldb/source/DataFormatters/FormatClasses.cpp

 using namespace lldb_private;
 
 FormattersMatchData::FormattersMatchData(ValueObject &valobj,
                                          lldb::DynamicValueType use_dynamic)
     : m_valobj(valobj), m_dynamic_value_type(use_dynamic),
       m_formatters_match_vector({}, false), m_type_for_cache(),
       m_candidate_languages() {
   m_type_for_cache = FormatManager::GetTypeForCache(valobj, use_dynamic);
-  m_candidate_languages = FormatManager::GetCandidateLanguages(valobj);
+  m_candidate_languages =
+      FormatManager::GetCandidateLanguages(valobj.GetObjectRuntimeLanguage());
 }
 
 FormattersMatchVector FormattersMatchData::GetMatchesVector() {
   if (!m_formatters_match_vector.second) {
     m_formatters_match_vector.second = true;
     m_formatters_match_vector.first =
         FormatManager::GetPossibleMatches(m_valobj, m_dynamic_value_type);
   }

lldb/source/DataFormatters/FormatManager.cpp

if (non_ptr_type.IsTypedefType()) {
       GetPossibleMatches(
           valobj, deffed_pointed_type,
           reason | lldb_private::eFormatterChoiceCriterionNavigatedTypedefs,
           use_dynamic, entries, did_strip_ptr, did_strip_ref,
           true); // this is not exactly the usual meaning of stripping typedefs
     }
   }
 
-  for (lldb::LanguageType language_type : GetCandidateLanguages(valobj)) {
+  for (lldb::LanguageType language_type :
+       GetCandidateLanguages(valobj.GetObjectRuntimeLanguage())) {
     if (Language *language = Language::FindPlugin(language_type)) {
       for (ConstString candidate :
            language->GetPossibleFormattersMatches(valobj, use_dynamic)) {
         entries.push_back(
             {candidate,
              reason | lldb_private::eFormatterChoiceCriterionLanguagePlugin,
              did_strip_ptr, did_strip_ref, did_strip_typedef});
       }
ConstString FormatManager::GetTypeForCache(ValueObject &valobj,
   if (valobj_sp && valobj_sp->GetCompilerType().IsValid()) {
     if (!valobj_sp->GetCompilerType().IsMeaninglessWithoutDynamicResolution())
       return valobj_sp->GetQualifiedTypeName();
   }
   return ConstString();
 }
 
 std::vector<lldb::LanguageType>
-FormatManager::GetCandidateLanguages(ValueObject &valobj) {
-  lldb::LanguageType lang_type = valobj.GetObjectRuntimeLanguage();
+FormatManager::GetCandidateLanguages(lldb::LanguageType lang_type) {
   switch (lang_type) {
   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: