llvm-project/clang/test/SemaCXX/return-stack-addr.cpp

// RUN: %clang_cc1 -std=c++2b -fsyntax-only -verify=expected,cxx2b          %s
// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify=expected,cxx11_20       %s
// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify=expected,cxx11_20,cxx11 %s

int* ret_local() {
  int x = 1;
  return &x; // expected-warning {{address of stack memory}}
}

int* ret_local_array() {
  int x[10];
  return x; // expected-warning {{address of stack memory}}
}

int* ret_local_array_element(int i) {
  int x[10];
  return &x[i]; // expected-warning {{address of stack memory}}
}

int *ret_local_array_element_reversed(int i) {
  int x[10];
  return &i[x]; // expected-warning {{address of stack memory}}
}

int* ret_local_array_element_const_index() {
  int x[10];
  return &x[2];  // expected-warning {{address of stack memory}}
}

int& ret_local_ref() {
  int x = 1;
  return x; // cxx11_20-warning {{reference to stack memory}}
  // cxx2b-error@-1 {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
}

int* ret_local_addrOf() {
  int x = 1;
  return &*&x; // expected-warning {{address of stack memory}}
}

int* ret_local_addrOf_paren() {
  int x = 1;
  return (&(*(&x))); // expected-warning {{address of stack memory}}
}

int* ret_local_addrOf_ptr_arith() {
  int x = 1;
  return &*(&x+1); // expected-warning {{address of stack memory}}
}

int* ret_local_addrOf_ptr_arith2() {
  int x = 1;
  return &*(&x+1); // expected-warning {{address of stack memory}}
}

int* ret_local_field() {
  struct { int x; } a;
  return &a.x; // expected-warning {{address of stack memory}}
}

int& ret_local_field_ref() {
  struct { int x; } a;
  return a.x; // expected-warning {{reference to stack memory}}
}

int* ret_conditional(bool cond) {
  int x = 1;
  int y = 2;
  return cond ? &x // expected-warning {{address of stack memory associated with local variable 'x' returned}}
              : &y; // expected-warning {{address of stack memory associated with local variable 'y' returned}}
}

int* ret_conditional_rhs(int *x, bool cond) {
  int y = 1;
  return cond ? x : &y;  // expected-warning {{address of stack memory}}
}

void* ret_c_cast() {
  int x = 1;
  return (void*) &x;  // expected-warning {{address of stack memory}}
}

int* ret_static_var() {
  static int x = 1;
  return &x;  // no warning.
}

int z = 1;

int* ret_global() {
  return &z;  // no warning.
}

int* ret_parameter(int x) {
  return &x;  // expected-warning {{address of stack memory}}
}


void* ret_cpp_static_cast(short x) {
  return static_cast<void*>(&x); // expected-warning {{address of stack memory}}
}

int* ret_cpp_reinterpret_cast(double x) {
  return reinterpret_cast<int*>(&x); // expected-warning {{address of stack me}}
}

int* ret_cpp_reinterpret_cast_no_warning(long x) {
  return reinterpret_cast<int*>(x); // no-warning
}

int* ret_cpp_const_cast(const int x) {
  return const_cast<int*>(&x);  // expected-warning {{address of stack memory}}
}

struct A { virtual ~A(); }; struct B : A {};
A* ret_cpp_dynamic_cast(B b) {
  return dynamic_cast<A*>(&b); // expected-warning {{address of stack memory}}
}

// PR 7999 - handle the case where a field is itself a reference.
template <typename T> struct PR7999 {
  PR7999(T& t) : value(t) {}
  T& value;
};

struct PR7999_X {};

PR7999_X& PR7999_f(PR7999<PR7999_X> s) { return s.value; } // no-warning
void test_PR7999(PR7999_X& x) { (void)PR7999_f(x); } // no-warning

// PR 8774: Don't try to evaluate parameters with default arguments like
// variables with an initializer, especially in templates where the default
// argument may not be an expression (yet).
namespace PR8774 {
  template <typename U> struct B { };
  template <typename V> V f(typename B<V>::type const &v = B<V>::value()) {
    return v;
  }
  template <> struct B<const char *> {
    typedef const char *type;
    static const char *value();
  };
  void g() {
    const char *t;
    f<const char*>(t);
  }
}

// Don't warn about returning a local variable from a surrounding function if
// we're within a lambda-expression.
void ret_from_lambda() {
  int a;
  int &b = a;
  (void) [&]() -> int& { return a; };
  (void) [&]() -> int& { return b; };
  (void) [=]() mutable -> int& { return a; };
  (void) [=]() mutable -> int& { return b; };
  (void) [&]() -> int& { int a; return a; }; // cxx11_20-warning {{reference to stack}}
  // cxx2b-error@-1 {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
  (void) [=]() -> int& { int a; return a; }; // cxx11_20-warning {{reference to stack}}
  // cxx2b-error@-1 {{non-const lvalue reference to type 'int' cannot bind to a temporary of type 'int'}}
  (void) [&]() -> int& { int &a = b; return a; };
  (void) [=]() mutable -> int& { int &a = b; return a; };

  (void) [] {
    int a;
    return [&] { // expected-warning {{address of stack memory associated with local variable 'a' returned}}
      return a; // expected-note {{implicitly captured by reference due to use here}}
    };
  };
  (void) [] {
    int a;
    return [&a] {}; // expected-warning {{address of stack memory associated with local variable 'a' returned}} expected-note {{captured by reference here}}
  };
  (void) [] {
    int a;
    return [=] {
      return a;
    };
  };
  (void) [] {
    int a;
    return [a] {};
  };
  (void) [] {
    int a;
    // cxx11-warning@+1 {{C++14}}
    return [&b = a] {}; // expected-warning {{address of stack memory associated with local variable 'a' returned}} expected-note {{captured by reference via initialization of lambda capture 'b'}}
  };
  (void) [] {
    int a;
    // cxx11-warning@+1 {{C++14}}
    return [b = &a] {}; // expected-warning {{address of stack memory associated with local variable 'a' returned}} expected-note {{captured via initialization of lambda capture 'b'}}
  };
}

struct HoldsPointer { int *p; };

HoldsPointer ret_via_member_1() {
  int n;
  return {&n}; // expected-warning {{address of stack memory associated with local variable 'n' returned}}
}
HoldsPointer ret_via_member_2() {
  int n;
  return HoldsPointer(HoldsPointer{&n}); // cxx11-warning {{address of stack memory associated with local variable 'n' returned}}
}
// FIXME: We could diagnose this too.
HoldsPointer ret_via_member_3() {
  int n;
  const HoldsPointer hp = HoldsPointer{&n};
  return hp;
}

namespace mem_ptr {
  struct X {};
  int X::*f();
  int &r(X *p) { return p->*f(); }
}

namespace PR47861 {
  struct A {
    A(int i);
    A &operator+=(int i);
  };
  A const &b = A(5) += 5; // expected-warning {{temporary bound to local reference 'b' will be destroyed at the end of the full-expression}}
}