C++ (Cpp) Sema::getStdNamespace Examples

Example #1

File: SemaCoroutine.cpp Project: cling-lang/clang

/// Look up the std::coroutine_traits<...>::promise_type for the given
/// function type.
static QualType lookupPromiseType(Sema &S, const FunctionProtoType *FnType,
                                  SourceLocation Loc) {
  // FIXME: Cache std::coroutine_traits once we've found it.
  NamespaceDecl *Std = S.getStdNamespace();
  if (!Std) {
    S.Diag(Loc, diag::err_implied_std_coroutine_traits_not_found);
    return QualType();
  }

  LookupResult Result(S, &S.PP.getIdentifierTable().get("coroutine_traits"),
                      Loc, Sema::LookupOrdinaryName);
  if (!S.LookupQualifiedName(Result, Std)) {
    S.Diag(Loc, diag::err_implied_std_coroutine_traits_not_found);
    return QualType();
  }

  ClassTemplateDecl *CoroTraits = Result.getAsSingle<ClassTemplateDecl>();
  if (!CoroTraits) {
    Result.suppressDiagnostics();
    // We found something weird. Complain about the first thing we found.
    NamedDecl *Found = *Result.begin();
    S.Diag(Found->getLocation(), diag::err_malformed_std_coroutine_traits);
    return QualType();
  }

  // Form template argument list for coroutine_traits<R, P1, P2, ...>.
  TemplateArgumentListInfo Args(Loc, Loc);
  Args.addArgument(TemplateArgumentLoc(
      TemplateArgument(FnType->getReturnType()),
      S.Context.getTrivialTypeSourceInfo(FnType->getReturnType(), Loc)));
  // FIXME: If the function is a non-static member function, add the type
  // of the implicit object parameter before the formal parameters.
  for (QualType T : FnType->getParamTypes())
    Args.addArgument(TemplateArgumentLoc(
        TemplateArgument(T), S.Context.getTrivialTypeSourceInfo(T, Loc)));

  // Build the template-id.
  QualType CoroTrait =
      S.CheckTemplateIdType(TemplateName(CoroTraits), Loc, Args);
  if (CoroTrait.isNull())
    return QualType();
  if (S.RequireCompleteType(Loc, CoroTrait,
                            diag::err_coroutine_traits_missing_specialization))
    return QualType();

  CXXRecordDecl *RD = CoroTrait->getAsCXXRecordDecl();
  assert(RD && "specialization of class template is not a class?");

  // Look up the ::promise_type member.
  LookupResult R(S, &S.PP.getIdentifierTable().get("promise_type"), Loc,
                 Sema::LookupOrdinaryName);
  S.LookupQualifiedName(R, RD);
  auto *Promise = R.getAsSingle<TypeDecl>();
  if (!Promise) {
    S.Diag(Loc, diag::err_implied_std_coroutine_traits_promise_type_not_found)
      << RD;
    return QualType();
  }

  // The promise type is required to be a class type.
  QualType PromiseType = S.Context.getTypeDeclType(Promise);
  if (!PromiseType->getAsCXXRecordDecl()) {
    // Use the fully-qualified name of the type.
    auto *NNS = NestedNameSpecifier::Create(S.Context, nullptr, Std);
    NNS = NestedNameSpecifier::Create(S.Context, NNS, false,
                                      CoroTrait.getTypePtr());
    PromiseType = S.Context.getElaboratedType(ETK_None, NNS, PromiseType);

    S.Diag(Loc, diag::err_implied_std_coroutine_traits_promise_type_not_class)
      << PromiseType;
    return QualType();
  }

  return PromiseType;
}