[libcxx-commits] [libcxx] [llvm] [libcxx] Remove ASan container overflow checks for SSO strings (PR #194208)

[Nikolas Klauser via libcxx-commits]

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@@ -56,16 +56,35 @@ TEST_CONSTEXPR bool is_double_ended_contiguous_container_asan_correct(const std:
 #endif
 
 #if TEST_HAS_FEATURE(address_sanitizer) && _LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS_FOR_STRING
+template <typename S>
+bool is_string_short(S const& s) {
+  // We do not have access to __is_long(), but we can check if strings
+  // buffer is inside strings memory. If strings memory contains its content,
+  // SSO is in use. To check it, we can just confirm that the beginning is in
+  // the string object memory block.
+  // &s    - beginning of objects memory
+  // &s[0] - beginning of the buffer
+  // (&s+1) - end of objects memory
+  return (void*)std::addressof(s) <= (void*)std::addressof(s[0]) &&
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philnik777 wrote:

We should use `std::less` (or friends) here, since they're defined globally and not just within the same range.

https://github.com/llvm/llvm-project/pull/194208