pbrt::SplitString triggers dereferencing asserts

[pierremoreau]

Visual Studio (2019, 16.8.5) has asserts checking that dereferencing a string-view iterator occurs within the range of the string-view.

pbrt::SplitString() expects the string-view to end with a '\0', however when constructing std::string the '\0' character does not count as being part of the string even if space is allocated for it.
For example,

std::string str = "Geometry/Disks";
std::cout << str.size() << '\n'; // Outputs: 14, i.e. the length of the string without the final '\0'.
assert(str.c_str()[str.size()] == '\0'); // Valid since C++11, and is true.

So once pbrt::SplitString("Geometry/Disks", '/') has pushed the string "Disks", end and begin now both point to the 15th character of str (i.e. the '\0') which also corresponds to str.end(), so when running if (*begin == ch) it tries to get the character at index 14 which is no longer < str.size() as str.size() == 14 and the assert fails.
Since the value at that position is guaranteed to be '\0' since C++11 (unless the user decided to modify it), the program will not end up reading undefined memory and will perform as expected, assuming the string_view was constructed from std::string and not something else.

It would probably be safer to change if (*begin == ch) to if (end != str.end() && *begin == ch).

[mmp]

Thanks for reporting this! I've rewritten the logic (and slightly simplified it) in a way that I think should fix this. Please let me know if it takes care of it for you, though.

[pierremoreau]

I can finally confirm that the rework fixed it. Thank you for the quick fix!