clang/test/SemaCXX/coro-lifetimebound.cpp

   1 // RUN: %clang_cc1 -triple x86_64-apple-darwin9 %s -std=c++20 -fsyntax-only -verify -Wall -Wextra -Wno-error=unreachable-code -Wno-unused -Wno-c++23-lambda-attributes
   2
   3 #include "Inputs/std-coroutine.h"
   4
   5 using std::suspend_always;
   6 using std::suspend_never;
   7
   8 template <typename T> struct [[clang::coro_lifetimebound, clang::coro_return_type]] Co {
   9   struct promise_type {
  10     Co<T> get_return_object() {
  11       return {};
  12     }
  13     suspend_always initial_suspend();
  14     suspend_always final_suspend() noexcept;
  15     void unhandled_exception();
  16     void return_value(const T &t);
  17
  18     template <typename U>
  19     auto await_transform(const Co<U> &) {
  20       struct awaitable {
  21         bool await_ready() noexcept { return false; }
  22         void await_suspend(std::coroutine_handle<>) noexcept {}
  23         U await_resume() noexcept { return {}; }
  24       };
  25       return awaitable{};
  26     }
  27   };
  28 };
  29
  30 Co<int> foo_coro(const int& b) {
  31   if (b > 0)
  32     co_return 1;
  33   co_return 2;
  34 }
  35
  36 int getInt() { return 0; }
  37
  38 Co<int> bar_coro(const int &b, int c) {
  39   int x = co_await foo_coro(b);
  40   int y = co_await foo_coro(1);
  41   int z = co_await foo_coro(getInt());
  42   auto unsafe1 = foo_coro(1); // expected-warning {{temporary whose address is used as value of local variable}}
  43   auto unsafe2 = foo_coro(getInt()); // expected-warning {{temporary whose address is used as value of local variable}}
  44   auto  safe1 = foo_coro(b);
  45   auto  safe2 = foo_coro(c);
  46   co_return co_await foo_coro(co_await foo_coro(1));
  47 }
  48
  49 [[clang::coro_wrapper]] Co<int> plain_return_co(int b) {
  50   return foo_coro(b); // expected-warning {{address of stack memory associated with parameter}}
  51 }
  52
  53 [[clang::coro_wrapper]] Co<int> safe_forwarding(const int& b) {
  54   return foo_coro(b);
  55 }
  56
  57 [[clang::coro_wrapper]] Co<int> unsafe_wrapper(int b) {
  58   return safe_forwarding(b); // expected-warning {{address of stack memory associated with parameter}}
  59 }
  60
  61 [[clang::coro_wrapper]] Co<int> complex_plain_return(int b) {
  62   return b > 0
  63       ? foo_coro(1)   // expected-warning {{returning address of local temporary object}}
  64       : bar_coro(0, 1); // expected-warning {{returning address of local temporary object}}
  65 }
  66
  67 void lambdas() {
  68   auto unsafe_lambda = [] [[clang::coro_wrapper]] (int b) {
  69     return foo_coro(b); // expected-warning {{address of stack memory associated with parameter}}
  70   };
  71   auto coro_lambda = [] (const int&) -> Co<int> {
  72     co_return 0;
  73   };
  74   auto unsafe_coro_lambda = [&] (const int& b) -> Co<int> {
  75     int x = co_await coro_lambda(b);
  76     auto safe = coro_lambda(b);
  77     auto unsafe1 = coro_lambda(1); // expected-warning {{temporary whose address is used as value of local variable}}
  78     auto unsafe2 = coro_lambda(getInt()); // expected-warning {{temporary whose address is used as value of local variable}}
  79     auto unsafe3 = coro_lambda(co_await coro_lambda(b)); // expected-warning {{temporary whose address is used as value of local variable}}
  80     co_return co_await safe;
  81   };
  82   auto safe_lambda = [](int b) -> Co<int> {
  83     int x = co_await foo_coro(1);
  84     co_return x + co_await foo_coro(b);
  85   };
  86 }
  87 // =============================================================================
  88 // Safe usage when parameters are value
  89 // =============================================================================
  90 namespace by_value {
  91 Co<int> value_coro(int b) { co_return co_await foo_coro(b); }
  92 [[clang::coro_wrapper]] Co<int> wrapper1(int b) { return value_coro(b); }
  93 [[clang::coro_wrapper]] Co<int> wrapper2(const int& b) { return value_coro(b); }
  94 }
  95
  96 // =============================================================================
  97 // Lifetime bound but not a Coroutine Return Type: No analysis.
  98 // =============================================================================
  99 namespace not_a_crt {
 100 template <typename T> struct [[clang::coro_lifetimebound]] CoNoCRT {
 101   struct promise_type {
 102     CoNoCRT<T> get_return_object() {
 103       return {};
 104     }
 105     suspend_always initial_suspend();
 106     suspend_always final_suspend() noexcept;
 107     void unhandled_exception();
 108     void return_value(const T &t);
 109   };
 110 };
 111
 112 CoNoCRT<int> foo_coro(const int& a) { co_return a; }
 113 CoNoCRT<int> bar(int a) {
 114   auto x = foo_coro(a);
 115   co_return 1;
 116 }
 117 } // namespace not_a_crt