[lldb] Fix TestClangASTContext.TestFunctionTemplateInRecordConstruction in Debug builds

[teemperor]

Summary

In Debug builds we call VerifyDecl in ClangASTContext::CreateFunctionDeclaration which in turn
calls getAccess on the created FunctionDecl. As we passed in a RecordDecl as the DeclContext
for the FunctionDecl, we end up hitting the assert in getAccess that checks that we never have
a Decl inside a Record without a valid AccessSpecifier. FunctionDecls are never in RecordDecls
(that would be a CXXMethodDecl) so setting a access specifier would not be the correct way to
fix this.

Instead this patch does the same thing that DWARFASTParserClang::ParseSubroutine is doing:
We pass in the FunctionDecl with the TranslationUnit as the DeclContext. That's not ideal but
it is how we currently do it when creating our debug info AST, so the unit test should do
the same.

[shafik]

LGTM

lldb/unittests/Symbol/TestClangASTContext.cpp

TEST_F(TestClangASTContext, TestFunctionTemplateConstruction) {
   EXPECT_EQ("foo", func_template->getName());
   EXPECT_EQ(clang::AccessSpecifier::AS_none, func_template->getAccess());
 }
 
 TEST_F(TestClangASTContext, TestFunctionTemplateInRecordConstruction) {
   // Tests creating a function template inside a record.
 
   CompilerType int_type = m_ast->GetBasicType(lldb::eBasicTypeInt);
+  clang::TranslationUnitDecl *TU = m_ast->GetTranslationUnitDecl();
 
   // Create a record we can put the function template int.
   CompilerType record_type =
       clang_utils::createRecordWithField(*m_ast, "record", int_type, "field");
   clang::TagDecl *record = ClangUtil::GetAsTagDecl(record_type);
 
   // Prepare the declarations/types we need for the template.
   CompilerType clang_type =
       m_ast->CreateFunctionType(int_type, nullptr, 0U, false, 0U);
+  // We create the FunctionDecl for the template in the TU DeclContext because:
+  // 1. FunctionDecls can't be in a Record (only CXXMethodDecls can).
+  // 2. It is mirroring the behavior of DWARFASTParserClang::ParseSubroutine.
   FunctionDecl *func =
-      m_ast->CreateFunctionDeclaration(record, "foo", clang_type, 0, false);
+      m_ast->CreateFunctionDeclaration(TU, "foo", clang_type, 0, false);
   ClangASTContext::TemplateParameterInfos empty_params;
 
   // Create the actual function template.
   clang::FunctionTemplateDecl *func_template =
       m_ast->CreateFunctionTemplateDecl(record, func, "foo", empty_params);
 
   EXPECT_EQ(record, func_template->getDeclContext());
   EXPECT_EQ("foo", func_template->getName());
   EXPECT_EQ(clang::AccessSpecifier::AS_public, func_template->getAccess());
 }