What is

a pointer to ... uninitialized memory

"uninitialized memory" refers to memory that never has any objects on it.

I think we do not have such things because we implicitly create objects. Also, my question was about pointer, not about memory.

@blackteahamburger , please give a code example.

I think we do not have such things because we implicitly create objects.

Just call a function that doesn't do IOC:

void* p = __builtin_malloc(1);
new (p) char;
*static_cast<char*>(p) = 'c'; // UB
 __builtin_free(p);

p is a pointer to uninitialized memory.

@blackteahamburger , this is not a conforming C++ program; its behavior is not specified by the standard. Do you have an example of a conforming program?

Just call a function that doesn't do IOC

IOC functions are not limited to those specified in the standard. Well, ofc, an implementation should define them as IOC, but implementations often ignore the requirement to specify implementation-defined things. I'd say you can treat __builtin_malloc as IOC.

I forgot that IOC do not start the lifetimes of subobjects of such objects that are not themselves of implicit-lifetime types... Just use std::string:

void* p = operator new(sizeof(std::string));    // does not implicitly create a std::string object
std::string* pstr = new (p) std::string;
*static_cast<std::string*>(p) = "str1";    // undefined behavior
*pstr = "str2";    // OK

@blackteahamburger your concern is [basic.life]/8's

after the lifetime of an object has ended

condition, and that the lifetime of the first element of the implicitly-created std::string[1] has never started?

@languagelawyer But I think they are related.
So, where do you think a better place is?

I think the

after the lifetime of an object has ended

condition is slightly misspelled. It does not mean that there necessarily shall be lifetime end, but that if there is lifetime end, it shall be properly synchronized (new object creation shall happen-after the lifetime end).

I'm not sure if there's an editorial issue here. Please reopen if you have a clear improvement in mind.