[lldb] NFC modernize codebase with modernize-use-nullptr

Summary:
NFC = [[ https://llvm.org/docs/Lexicon.html#nfc | Non functional change ]]

This commit is the result of modernizing the LLDB codebase by using
`nullptr` instread of `0` or `NULL`. See
https://clang.llvm.org/extra/clang-tidy/checks/modernize-use-nullptr.html
for more information.

This is the command I ran and I to fix and format the code base:

```
run-clang-tidy.py \
	-header-filter='.*' \
	-checks='-*,modernize-use-nullptr' \
	-fix ~/dev/llvm-project/lldb/.* \
	-format \
	-style LLVM \
	-p ~/llvm-builds/debug-ninja-gcc
```

NOTE: There were also changes to `llvm/utils/unittest` but I did not
include them because I felt that maybe this library shall be updated in
isolation somehow.

NOTE: I know this is a rather large commit but it is a nobrainer in most
parts.

Reviewers: martong, espindola, shafik, #lldb, JDevlieghere

Reviewed By: JDevlieghere

Subscribers: arsenm, jvesely, nhaehnle, hiraditya, JDevlieghere, teemperor, rnkovacs, emaste, kubamracek, nemanjai, ki.stfu, javed.absar, arichardson, kbarton, jrtc27, MaskRay, atanasyan, dexonsmith, arphaman, jfb, jsji, jdoerfert, lldb-commits, llvm-commits

Tags: #lldb, #llvm

Differential Revision: https://reviews.llvm.org/D61847

llvm-svn: 361484
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
index e5bc63b..8ec64db 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp
@@ -175,7 +175,7 @@
 
   SymbolVendor *
   GetSymbolVendor(bool can_create = true,
-                  lldb_private::Stream *feedback_strm = NULL) override {
+                  lldb_private::Stream *feedback_strm = nullptr) override {
     // Scope for locker
     if (m_symfile_up.get() || !can_create)
       return m_symfile_up.get();
@@ -197,7 +197,7 @@
                   symbol_vendor->GetSymbolFile());
 
           if (!oso_symfile)
-            return NULL;
+            return nullptr;
 
           ObjectFile *exe_objfile = exe_module_sp->GetObjectFile();
           SymbolVendor *exe_sym_vendor = exe_module_sp->GetSymbolVendor();
@@ -213,7 +213,7 @@
         }
       }
     }
-    return NULL;
+    return nullptr;
   }
 
 protected:
@@ -368,12 +368,12 @@
                           oso_symbol->GetName().GetCString());
           }
         } else {
-          if (oso_symbol == NULL)
+          if (oso_symbol == nullptr)
             m_obj_file->GetModule()->ReportError(
                 "N_OSO symbol[%u] can't be found, please file a bug and attach "
                 "the binary listed in this error",
                 oso_idx);
-          else if (so_symbol == NULL)
+          else if (so_symbol == nullptr)
             m_obj_file->GetModule()->ReportError(
                 "N_SO not found for N_OSO symbol[%u], please file a bug and "
                 "attach the binary listed in this error",
@@ -398,7 +398,7 @@
   const uint32_t cu_count = GetNumCompileUnits();
   if (oso_idx < cu_count)
     return GetModuleByCompUnitInfo(&m_compile_unit_infos[oso_idx]);
-  return NULL;
+  return nullptr;
 }
 
 Module *SymbolFileDWARFDebugMap::GetModuleByCompUnitInfo(
@@ -428,7 +428,7 @@
               ") since this executable was linked, file will be ignored",
               oso_file.GetPath().c_str(), llvm::to_string(oso_mod_time).c_str(),
               llvm::to_string(comp_unit_info->oso_mod_time).c_str());
-          return NULL;
+          return nullptr;
         }
 
       } else {
@@ -436,7 +436,7 @@
 
         if (!ObjectFile::SplitArchivePathWithObject(oso_path, oso_file,
                                                     oso_object, must_exist)) {
-          return NULL;
+          return nullptr;
         }
       }
       // Always create a new module for .o files. Why? Because we use the debug
@@ -462,7 +462,7 @@
   }
   if (comp_unit_info->oso_sp)
     return comp_unit_info->oso_sp->module_sp.get();
-  return NULL;
+  return nullptr;
 }
 
 bool SymbolFileDWARFDebugMap::GetFileSpecForSO(uint32_t oso_idx,
@@ -480,7 +480,7 @@
   Module *oso_module = GetModuleByOSOIndex(oso_idx);
   if (oso_module)
     return oso_module->GetObjectFile();
-  return NULL;
+  return nullptr;
 }
 
 SymbolFileDWARF *
@@ -493,7 +493,7 @@
   CompileUnitInfo *comp_unit_info = GetCompUnitInfo(comp_unit);
   if (comp_unit_info)
     return GetSymbolFileByCompUnitInfo(comp_unit_info);
-  return NULL;
+  return nullptr;
 }
 
 ObjectFile *SymbolFileDWARFDebugMap::GetObjectFileByCompUnitInfo(
@@ -501,7 +501,7 @@
   Module *oso_module = GetModuleByCompUnitInfo(comp_unit_info);
   if (oso_module)
     return oso_module->GetObjectFile();
-  return NULL;
+  return nullptr;
 }
 
 uint32_t SymbolFileDWARFDebugMap::GetCompUnitInfoIndex(
@@ -521,7 +521,7 @@
   unsigned size = m_compile_unit_infos.size();
   if (oso_idx < size)
     return GetSymbolFileByCompUnitInfo(&m_compile_unit_infos[oso_idx]);
-  return NULL;
+  return nullptr;
 }
 
 SymbolFileDWARF *
@@ -529,7 +529,7 @@
   if (sym_file &&
       sym_file->GetPluginName() == SymbolFileDWARF::GetPluginNameStatic())
     return (SymbolFileDWARF *)sym_file;
-  return NULL;
+  return nullptr;
 }
 
 SymbolFileDWARF *SymbolFileDWARFDebugMap::GetSymbolFileByCompUnitInfo(
@@ -540,7 +540,7 @@
     if (sym_vendor)
       return GetSymbolFileAsSymbolFileDWARF(sym_vendor->GetSymbolFile());
   }
-  return NULL;
+  return nullptr;
 }
 
 uint32_t SymbolFileDWARFDebugMap::CalculateAbilities() {
@@ -609,7 +609,7 @@
     if (comp_unit == m_compile_unit_infos[i].compile_unit_sp.get())
       return &m_compile_unit_infos[i];
   }
-  return NULL;
+  return nullptr;
 }
 
 size_t SymbolFileDWARFDebugMap::GetCompUnitInfosForModule(
@@ -706,7 +706,7 @@
   SymbolFileDWARF *oso_dwarf = GetSymbolFileByOSOIndex(oso_idx);
   if (oso_dwarf)
     return oso_dwarf->ResolveTypeUID(type_uid);
-  return NULL;
+  return nullptr;
 }
 
 llvm::Optional<SymbolFile::ArrayInfo>
@@ -750,7 +750,7 @@
       sc.symbol =
           symtab->SymbolAtIndex(debug_map_entry->data.GetExeSymbolIndex());
 
-      if (sc.symbol != NULL) {
+      if (sc.symbol != nullptr) {
         resolved_flags |= eSymbolContextSymbol;
 
         uint32_t oso_idx = 0;
@@ -930,7 +930,7 @@
 SymbolFileDWARFDebugMap::GetCompileUnitInfoForSymbolWithIndex(
     uint32_t symbol_idx, uint32_t *oso_idx_ptr) {
   const uint32_t oso_index_count = m_compile_unit_infos.size();
-  CompileUnitInfo *comp_unit_info = NULL;
+  CompileUnitInfo *comp_unit_info = nullptr;
   if (oso_index_count) {
     comp_unit_info = (CompileUnitInfo *)bsearch(
         &symbol_idx, &m_compile_unit_infos[0], m_compile_unit_infos.size(),
@@ -939,7 +939,7 @@
   }
 
   if (oso_idx_ptr) {
-    if (comp_unit_info != NULL)
+    if (comp_unit_info != nullptr)
       *oso_idx_ptr = comp_unit_info - &m_compile_unit_infos[0];
     else
       *oso_idx_ptr = UINT32_MAX;
@@ -951,7 +951,7 @@
 SymbolFileDWARFDebugMap::GetCompileUnitInfoForSymbolWithID(
     user_id_t symbol_id, uint32_t *oso_idx_ptr) {
   const uint32_t oso_index_count = m_compile_unit_infos.size();
-  CompileUnitInfo *comp_unit_info = NULL;
+  CompileUnitInfo *comp_unit_info = nullptr;
   if (oso_index_count) {
     comp_unit_info = (CompileUnitInfo *)::bsearch(
         &symbol_id, &m_compile_unit_infos[0], m_compile_unit_infos.size(),
@@ -960,7 +960,7 @@
   }
 
   if (oso_idx_ptr) {
-    if (comp_unit_info != NULL)
+    if (comp_unit_info != nullptr)
       *oso_idx_ptr = comp_unit_info - &m_compile_unit_infos[0];
     else
       *oso_idx_ptr = UINT32_MAX;
@@ -1058,7 +1058,7 @@
                      type_mask);
 
   uint32_t initial_size = type_list.GetSize();
-  SymbolFileDWARF *oso_dwarf = NULL;
+  SymbolFileDWARF *oso_dwarf = nullptr;
   if (sc_scope) {
     SymbolContext sc;
     sc_scope->CalculateSymbolContext(&sc);
@@ -1103,7 +1103,7 @@
     m_supports_DW_AT_APPLE_objc_complete_type = eLazyBoolNo;
     ForEachSymbolFile([&](SymbolFileDWARF *oso_dwarf) -> bool {
       if (skip_dwarf_oso != oso_dwarf &&
-          oso_dwarf->Supports_DW_AT_APPLE_objc_complete_type(NULL)) {
+          oso_dwarf->Supports_DW_AT_APPLE_objc_complete_type(nullptr)) {
         m_supports_DW_AT_APPLE_objc_complete_type = eLazyBoolYes;
         return true;
       }
@@ -1122,7 +1122,7 @@
   // contain the implementation definition since it will be scoped inside the
   // N_SO and we can then locate the SymbolFileDWARF that corresponds to that
   // N_SO.
-  SymbolFileDWARF *oso_dwarf = NULL;
+  SymbolFileDWARF *oso_dwarf = nullptr;
   TypeSP type_sp;
   ObjectFile *module_objfile = m_obj_file->GetModule()->GetObjectFile();
   if (module_objfile) {
@@ -1143,7 +1143,7 @@
           if (source_file_symbol_idx != UINT32_MAX) {
             CompileUnitInfo *compile_unit_info =
                 GetCompileUnitInfoForSymbolWithIndex(source_file_symbol_idx,
-                                                     NULL);
+                                                     nullptr);
             if (compile_unit_info) {
               oso_dwarf = GetSymbolFileByCompUnitInfo(compile_unit_info);
               if (oso_dwarf) {
@@ -1268,7 +1268,7 @@
       }
     }
   }
-  return NULL;
+  return nullptr;
 }
 
 void SymbolFileDWARFDebugMap::SetCompileUnit(SymbolFileDWARF *oso_dwarf,
@@ -1414,7 +1414,7 @@
   CompileUnitInfo *cu_info = GetCompileUnitInfo(oso_dwarf);
   if (cu_info)
     return line_table->LinkLineTable(cu_info->GetFileRangeMap(this));
-  return NULL;
+  return nullptr;
 }
 
 size_t