| Issue |
75716
|
| Summary |
dereferencing a null pointer in a constant _expression_
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
twoscomplement
|
Should it be possible to dereference a null pointer in a C++20 constant _expression_?
Consider this c++20 code:
```
struct T {
constexpr bool isNull() {
return !this;
}
};
static_assert(((T*)nullptr)->isNull());
constexpr T* t = nullptr;
static_assert((*t).isNull());
```
I would expect this to not compile due to the dereferencing of a null pointer in a constant _expression_.
With reference to https://godbolt.org/z/q53rz5d69
clang-17.0.1 produces errors and warning, by default.
By default, gcc-13.2 compiles without warning. -Wall yields a -Wnonnull warning.
msvc 19.38 compiles without warning.
Potentially relevant context:
[Accessing static data members via null pointer](https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#2748)
[Implicit undefined behavior when dereferencing pointers](https://cplusplus.github.io/CWG/issues/2823.html)
I have submitted the same question for gcc: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113047
![]()
_______________________________________________
llvm-bugs mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
