clang/test/SemaCXX/this-type-deduction-concept.cpp

   1 // RUN: %clang_cc1 -std=c++23 -verify -fsyntax-only %s
   2 // This test case came up in the review of
   3 // https://reviews.llvm.org/D159126
   4 // when transforming `this` within a
   5 // requires expression, we need to make sure
   6 // the type of this (and its qualifiers) is respected.
   7
   8 // expected-no-diagnostics
   9 namespace D159126 {
  10
  11 template <class _Tp>
  12 concept __member_begin = requires(_Tp __t) {
  13   __t.begin();
  14 };
  15
  16 struct {
  17   template <class _Tp>
  18   requires __member_begin<_Tp>
  19   auto operator()(_Tp &&) {}
  20 } inline begin;
  21
  22 template <class>
  23 concept range = requires {
  24   begin;
  25 };
  26
  27 template <class _Tp>
  28 concept __can_compare_begin = requires(_Tp __t) {
  29   begin(__t);
  30 };
  31
  32 struct {
  33   template <__can_compare_begin _Tp> void operator()(_Tp &&);
  34 } empty;
  35
  36 template <range _Rp> struct owning_view {
  37   _Rp __r_;
  38 public:
  39   void empty() const requires requires { empty(__r_); };
  40 };
  41
  42 template <class T>
  43 concept HasEmpty = requires(T t) {
  44   t.empty();
  45 };
  46
  47 struct ComparableIters {
  48     void begin();
  49 };
  50
  51 static_assert(HasEmpty<owning_view<ComparableIters&>>);
  52 static_assert(HasEmpty<owning_view<ComparableIters&&>>);
  53 static_assert(!HasEmpty<owning_view<const ComparableIters&>>);
  54 static_assert(!HasEmpty<owning_view<const ComparableIters&&>>);
  55
  56 }