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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 poss
by scintill76 2y ago
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 2y agoGood 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=109742 https://devblogs.microsoft.com/oldnewthing/20240510-00/?p=10...
- fluoridation 2y agoSo it's actually printing *(const char **)&s?
- twoodfin 2y agoThe first pointer-sized chunk of the string structure is a pointer to the C-string representation. So the cast works as written.
- fluoridation 2y agoWell, no, because (const char *)str is nonsense, if str is an std::string.
- twoodfin 2y agoNot 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.