[lldb][NFC] Explicitly ask for a ClangASTContext in ClangASTSource

ClangASTSource currently takes a clang::ASTContext and keeps that
around, but a lot of LLDB's functionality for doing operations
on a clang::ASTContext is in its ClangASTContext twin class. We
currently constantly recompute the respective ClangASTContext
from the clang::ASTContext while we instead could just pass and
store a ClangASTContext in the ClangASTSource. This also allows
us to get rid of a bunch of unreachable error checking for cases
where recomputation fails for some reason.

lldb/source/Plugins/ExpressionParser/Clang/ClangASTSource.cpp

@@ -57,10 +57,11 @@ ClangASTSource::ClangASTSource(const lldb::TargetSP &target)
   }
 }
 
-void ClangASTSource::InstallASTContext(clang::ASTContext &ast_context,
+void ClangASTSource::InstallASTContext(ClangASTContext &clang_ast_context,
                                        clang::FileManager &file_manager,
                                        bool is_shared_context) {
-  m_ast_context = &ast_context;
+  m_ast_context = clang_ast_context.getASTContext();
+  m_clang_ast_context = &clang_ast_context;
   m_file_manager = &file_manager;
   if (m_target->GetUseModernTypeLookup()) {
     // Configure the ExternalASTMerger.  The merger needs to be able to import
@@ -69,7 +70,7 @@ void ClangASTSource::InstallASTContext(clang::ASTContext &ast_context,
     // AST contexts.
 
     lldbassert(!m_merger_up);
-    clang::ExternalASTMerger::ImporterTarget target = {ast_context,
+    clang::ExternalASTMerger::ImporterTarget target = {*m_ast_context,
                                                        file_manager};
     std::vector<clang::ExternalASTMerger::ImporterSource> sources;
     for (lldb::ModuleSP module_sp : m_target->GetImages().Modules()) {
@@ -132,7 +133,7 @@ void ClangASTSource::InstallASTContext(clang::ASTContext &ast_context,
     m_merger_up =
         std::make_unique<clang::ExternalASTMerger>(target, sources);
   } else {
-    m_ast_importer_sp->InstallMapCompleter(&ast_context, *this);
+    m_ast_importer_sp->InstallMapCompleter(m_ast_context, *this);
   }
 }
 
@@ -775,7 +776,7 @@ void ClangASTSource::FindExternalVisibleDecls(NameSearchContext &context) {
 }
 
 clang::Sema *ClangASTSource::getSema() {
-  return ClangASTContext::GetASTContext(m_ast_context)->getSema();
+  return m_clang_ast_context->getSema();
 }
 
 bool ClangASTSource::IgnoreName(const ConstString name,
@@ -2058,8 +2059,7 @@ CompilerType ClangASTSource::GuardedCopyType(const CompilerType &src_type) {
     // seems to be generating bad types on occasion.
     return CompilerType();
 
-  return CompilerType(ClangASTContext::GetASTContext(m_ast_context),
-                      copied_qual_type.getAsOpaquePtr());
+  return CompilerType(m_clang_ast_context, copied_qual_type.getAsOpaquePtr());
 }
 
 clang::NamedDecl *NameSearchContext::AddVarDecl(const CompilerType &type) {
@@ -2186,10 +2186,9 @@ clang::NamedDecl *NameSearchContext::AddGenericFunDecl() {
       ArrayRef<QualType>(),                     // argument types
       proto_info));
 
-  return AddFunDecl(
-      CompilerType(ClangASTContext::GetASTContext(m_ast_source.m_ast_context),
-                   generic_function_type.getAsOpaquePtr()),
-      true);
+  return AddFunDecl(CompilerType(m_ast_source.m_clang_ast_context,
+                                 generic_function_type.getAsOpaquePtr()),
+                    true);
 }
 
 clang::NamedDecl *

lldb/source/Plugins/ExpressionParser/Clang/ClangASTSource.h

@@ -57,7 +57,7 @@ class ClangASTSource : public ClangExternalASTSourceCommon,
   }
   void MaterializeVisibleDecls(const clang::DeclContext *DC) { return; }
 
-  void InstallASTContext(clang::ASTContext &ast_context,
+  void InstallASTContext(ClangASTContext &ast_context,
                          clang::FileManager &file_manager,
                          bool is_shared_context = false);
 
@@ -408,6 +408,8 @@ class ClangASTSource : public ClangExternalASTSourceCommon,
   const lldb::TargetSP m_target;
   /// The AST context requests are coming in for.
   clang::ASTContext *m_ast_context;
+  /// The ClangASTContext for m_ast_context.
+  ClangASTContext *m_clang_ast_context;
   /// The file manager paired with the AST context.
   clang::FileManager *m_file_manager;
   /// The target's AST importer.

lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp

@@ -1076,12 +1076,9 @@ void ClangExpressionDeclMap::LookupLocalVarNamespace(
   if (!frame_ast)
     return;
 
-  ClangASTContext *map_ast = ClangASTContext::GetASTContext(m_ast_context);
-  if (!map_ast)
-    return;
-
-  clang::NamespaceDecl *namespace_decl = map_ast->GetUniqueNamespaceDeclaration(
-      g_lldb_local_vars_namespace_cstr, nullptr);
+  clang::NamespaceDecl *namespace_decl =
+      m_clang_ast_context->GetUniqueNamespaceDeclaration(
+          g_lldb_local_vars_namespace_cstr, nullptr);
   if (!namespace_decl)
     return;
 
@@ -1724,8 +1721,7 @@ void ClangExpressionDeclMap::AddOneGenericVariable(NameSearchContext &context,
   TypeFromUser user_type(scratch_ast_context->GetBasicType(eBasicTypeVoid)
                              .GetPointerType()
                              .GetLValueReferenceType());
-  ClangASTContext *own_context = ClangASTContext::GetASTContext(m_ast_context);
-  TypeFromParser parser_type(own_context->GetBasicType(eBasicTypeVoid)
+  TypeFromParser parser_type(m_clang_ast_context->GetBasicType(eBasicTypeVoid)
                                  .GetPointerType()
                                  .GetLValueReferenceType());
   NamedDecl *var_decl = context.AddVarDecl(parser_type);
@@ -2003,9 +1999,8 @@ void ClangExpressionDeclMap::AddThisType(NameSearchContext &context,
 
   if (copied_clang_type.IsAggregateType() &&
       copied_clang_type.GetCompleteType()) {
-    ClangASTContext *own_context =
-        ClangASTContext::GetASTContext(m_ast_context);
-    CompilerType void_clang_type = own_context->GetBasicType(eBasicTypeVoid);
+    CompilerType void_clang_type =
+        m_clang_ast_context->GetBasicType(eBasicTypeVoid);
     CompilerType void_ptr_clang_type = void_clang_type.GetPointerType();
 
     CompilerType method_type = ClangASTContext::CreateFunctionType(
@@ -2018,12 +2013,10 @@ void ClangExpressionDeclMap::AddThisType(NameSearchContext &context,
     const bool is_attr_used = true;
     const bool is_artificial = false;
 
-    CXXMethodDecl *method_decl =
-        ClangASTContext::GetASTContext(m_ast_context)
-            ->AddMethodToCXXRecordType(
-                copied_clang_type.GetOpaqueQualType(), "$__lldb_expr", nullptr,
-                method_type, lldb::eAccessPublic, is_virtual, is_static,
-                is_inline, is_explicit, is_attr_used, is_artificial);
+    CXXMethodDecl *method_decl = m_clang_ast_context->AddMethodToCXXRecordType(
+        copied_clang_type.GetOpaqueQualType(), "$__lldb_expr", nullptr,
+        method_type, lldb::eAccessPublic, is_virtual, is_static, is_inline,
+        is_explicit, is_attr_used, is_artificial);
 
     LLDB_LOG(log,
              "  CEDM::AddThisType Added function $__lldb_expr "

lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

@@ -997,7 +997,7 @@ ClangExpressionParser::ParseInternal(DiagnosticManager &diagnostic_manager,
     } else {
       ast_context.setExternalSource(ast_source);
     }
-    decl_map->InstallASTContext(ast_context, m_compiler->getFileManager());
+    decl_map->InstallASTContext(*m_ast_context, m_compiler->getFileManager());
   }
 
   // Check that the ASTReader is properly attached to ASTContext and Sema.

lldb/source/Symbol/ClangASTContext.cpp

@@ -598,7 +598,7 @@ lldb::TypeSystemSP ClangASTContext::CreateInstance(lldb::LanguageType language,
         new ClangASTSource(target->shared_from_this()));
     lldbassert(ast_sp->getFileManager());
     ast_sp->m_scratch_ast_source_up->InstallASTContext(
-        *ast_sp->getASTContext(), *ast_sp->getFileManager(), true);
+        *ast_sp, *ast_sp->getFileManager(), true);
     llvm::IntrusiveRefCntPtr<clang::ExternalASTSource> proxy_ast_source(
         ast_sp->m_scratch_ast_source_up->CreateProxy());
     ast_sp->SetExternalSource(proxy_ast_source);