[twoodfin]

If your std::string was using a short string optimization, that would explain the “accident”.

Some implementations even put char[0] at the first byte in the optimized form.

[scintill76]

That explanation doesn't work IMO, unless `str` is a std::string pointer, which is contrary to the syntax GP suggested with `str.c_str()`.

It doesn't seem possible in actual C++ that the cast from non-pointer to pointer would work at all (even if a small string happens to be inlined at offset 0.) Like GP, I looked for a conversion operator, and I don't think it's there. Maybe it is a feature of the gdb parser.

[twoodfin]

Good point, but if it’s a long string, 2/3 of the most common implementations would make the first word the c_str()-equivalent pointer:

https://devblogs.microsoft.com/oldnewthing/20240510-00/?p=10...

[fluoridation]

So it's actually printing *(const char **)&s?

[twoodfin]

The first pointer-sized chunk of the string structure is a pointer to the C-string representation. So the cast works as written.

[fluoridation]

Well, no, because (const char *)str is nonsense, if str is an std::string.

[twoodfin]

Not to the debugger. If the first 8 bytes of the object referenced by str is a char* the debugger is perfectly capable of using it that way.