Avoid undefined behavior when subtracting tagged pointers #715
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When compiling with HardwareAddressSanitizer, the top byte of pointers
are tagged, hence subtracting two pointers may overflow. Overflow is
undefined behavior for signed integers, resulting in errors such as:
third_party/nanobind/src/nb_type.cpp:123:50: runtime error: signed integer overflow: -6701078944169102656 - 9079534012674239392 cannot be represented in type 'intptr_t' (aka 'long')
This patch fixes the issue by using unsigned integers, for which
overflow is well-defined.
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When compiling with HardwareAddressSanitizer (https://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html), the top byte of pointers are tagged, hence subtracting two pointers may overflow. Overflow is undefined behavior for signed integers, resulting in errors such as:
This patch fixes the issue by using unsigned integers, for which overflow is well-defined.