xref: /llvm-project/clang/test/CodeGenCXX/cxx2c-decomposition.cpp (revision abc8812df02599fc413d9ed77b992f8236ed2af9)
1 // RUN: %clang_cc1 -std=c++26 -triple x86_64-linux-gnu -emit-llvm -o - %s | FileCheck %s
2 
3 namespace std {
4   using size_t = decltype(sizeof(0));
5   template<typename> struct tuple_size;
6   template<size_t, typename> struct tuple_element;
7 }
8 
9 struct Y { int n; };
10 struct X { X(); X(Y); X(const X&); ~X(); };
11 
12 struct A { int a : 13; bool b; };
13 
14 struct B {};
15 template<> struct std::tuple_size<B> { enum { value = 2 }; };
16 template<> struct std::tuple_element<0,B> { using type = X; };
17 template<> struct std::tuple_element<1,B> { using type = const int&; };
18 template<int N> auto get(B) {
19   if constexpr (N == 0)
20     return Y();
21   else
22     return 0.0;
23 }
24 
25 using C = int[2];
26 
27 template<typename T> T &make();
28 
29 // CHECK-LABEL: define {{.*}} @_Z8big_testIiEiv()
30 template <typename T>
31 int big_test() {
32   A& a = make<A>();
33 A:
34   auto &[...an] = a;
35   an...[0] = 5;
36   // CHECK: %[[a1:.*]].load = load i16, ptr %[[BITFIELD:.*]],
37   // CHECK: %[[a1]].clear = and i16 %[[a1]].load, -8192
38   // CHECK: %[[a1]].set = or i16 %[[a1]].clear, 5
39   // CHECK: store i16 %[[a1]].set, ptr %[[BITFIELD]],
40 B:
41   auto [b1, ...bn] = make<B>();
42   // CHECK: @_Z4makeI1BERT_v()
43   //   CHECK: call i32 @_Z3getILi0EEDa1B()
44   //   CHECK: call void @_ZN1XC1E1Y(ptr {{[^,]*}} %[[b1:.*]], i32
45   //
46   //   CHECK: call noundef double @_Z3getILi1EEDa1B()
47   //   CHECK: %[[cvt:.*]] = fptosi double %{{.*}} to i32
48   //   CHECK: store i32 %[[cvt]], ptr %[[b2:.*]],
49   //   CHECK: store ptr %[[b2]], ptr %[[b2ref:.*]],
50   int bn2 = bn...[0];
51   // CHECK load ptr, ptr %[[b2ref]]
52 
53   return 0;
54 }
55 
56 int g = big_test<int>();
57