llvm-project/clang/test/SemaCXX/warn-unsafe-buffer-usage-warning-data-invocation.cpp

// RUN: %clang_cc1 -std=c++20  -Wno-all -Wunsafe-buffer-usage -Wno-unsafe-buffer-usage-in-container\
// RUN:            -fsafe-buffer-usage-suggestions \
// RUN:            -fblocks -include %s -verify %s

// RUN: %clang -x c++ -frtti -fsyntax-only -fblocks -include %s %s 2>&1 | FileCheck --allow-empty %s
// RUN: %clang_cc1 -std=c++11 -fblocks -include %s %s 2>&1 | FileCheck --allow-empty %s
// RUN: %clang_cc1 -std=c++20 -fblocks -include %s %s 2>&1 | FileCheck --allow-empty %s
// CHECK-NOT: [-Wunsafe-buffer-usage]

#ifndef INCLUDED
#define INCLUDED
#pragma clang system_header

// no spanification warnings for system headers
#else

typedef __INTPTR_TYPE__ intptr_t;

namespace std {
  class type_info;
  class bad_cast;
  class bad_typeid;
}
using size_t = __typeof(sizeof(int));
void *malloc(size_t);

void foo(int v) {
}

void foo(int *p){}

namespace std{
  template <typename T> class span {

   T *elements;
 
   span(T *, unsigned){}

   public:

   constexpr span<T> subspan(size_t offset, size_t count) const {
     return span<T> (elements+offset, count); // expected-warning{{unsafe pointer arithmetic}}
   }

   constexpr T* data() const noexcept {
     return elements;
   }

   constexpr T* hello() const noexcept {
     return elements;
   }
 };

 template <typename T> class vector {

   T *elements;

   public:

   vector(size_t n) {
     elements = new T[n];
   }

   constexpr T* data() const noexcept {
      return elements;
   }

   ~vector() {
     delete[] elements;
   }
 };

 template <class T, size_t N>
 class array {
   T elements[N];

   public:

   constexpr const T* data() const noexcept {
      return elements;
   }

 };

 template <typename T> class span_duplicate {
   span_duplicate(T *, unsigned){}

   T array[10];

   public:

   T* data() {
     return array;
   }

 };
}

using namespace std;

class A {
  int a, b, c;
};

class B {
  int a, b, c;
};

struct Base {
   virtual ~Base() = default;
};

struct Derived: Base {
  int d;
};

void cast_without_data(int *ptr) {
 A *a = (A*) ptr;
 float *p = (float*) ptr;
}

void warned_patterns_span(std::span<int> span_ptr, std::span<Base> base_span, span<int> span_without_qual) {
    A *a1 = (A*)span_ptr.data(); // expected-warning{{unsafe invocation of 'data'}}
    a1 = (A*)span_ptr.data(); // expected-warning{{unsafe invocation of 'data'}}

    a1 = (A*)(span_ptr.data()); // expected-warning{{unsafe invocation of 'data'}}
    A *a2 = (A*) (span_without_qual.data()); // expected-warning{{unsafe invocation of 'data'}}

    a2 = (A*) span_without_qual.data(); // expected-warning{{unsafe invocation of 'data'}}

     // TODO:: Should we warn when we cast from base to derived type?
     Derived *b = dynamic_cast<Derived*> (base_span.data());// expected-warning{{unsafe invocation of 'data'}}

    // TODO:: This pattern is safe. We can add special handling for it, if we decide this
    // is the recommended fixit for the unsafe invocations.
    A *a3 = (A*)span_ptr.subspan(0, sizeof(A)).data(); // expected-warning{{unsafe invocation of 'data'}}
}

void warned_patterns_array(std::array<int, 5> array_ptr, std::array<Base, 10> base_span, span<int> span_without_qual) {
    const A *a1 = (A*)array_ptr.data(); // expected-warning{{unsafe invocation of 'data'}}
    a1 = (A*)array_ptr.data(); // expected-warning{{unsafe invocation of 'data'}}

    a1 = (A*)(array_ptr.data()); // expected-warning{{unsafe invocation of 'data'}}
}

void not_warned_patterns(std::span<A> span_ptr, std::span<Base> base_span) {
    int *p = (int*) span_ptr.data(); // Cast to a smaller type
  
    B *b = (B*) span_ptr.data(); // Cast to a type of same size.

    p = (int*) span_ptr.data();
    A *a = (A*) span_ptr.hello(); // Invoking other methods.
   
     intptr_t k = (intptr_t) span_ptr.data();
    k = (intptr_t) (span_ptr.data());
}

// We do not want to warn about other types
void other_classes(std::span_duplicate<int> span_ptr) {
    int *p;
    A *a = (A*)span_ptr.data();
    a = (A*)span_ptr.data(); 
}

// Potential source for false negatives

A false_negatives(std::span<int> span_pt, span<A> span_A) {
  int *ptr = span_pt.data();

  A *a1 = (A*)ptr; //TODO: We want to warn here eventually.

  A *a2= span_A.data();
  return *a2; // TODO: Can cause OOB if span_pt is empty

}

void test_incomplete_type(std::span<char> S) {
  (struct IncompleteStruct *)S.data(); // expected-warning{{unsafe invocation of 'data'}}
  (class IncompleteClass *)S.data();   // expected-warning{{unsafe invocation of 'data'}}
  (union IncompleteUnion *)S.data();   // expected-warning{{unsafe invocation of 'data'}}
}

void test_complete_type(std::span<long> S) {
  (struct CompleteStruct *)S.data(); // no warn as the struct size is smaller than long
  (class CompleteClass *)S.data();   // no warn as the class size is smaller than long
  (union CompleteUnion *)S.data();   // no warn as the union size is smaller than long

  struct CompleteStruct {};
  class CompleteClass {};
  union CompleteUnion {};
}

#endif