[clang] [compiler-rt] [libcxx] [llvm] [clang] Warn about memset/memcpy to NonTriviallyCopyable types (PR #111434)

[Carlos Galvez via cfe-commits]

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@@ -102,7 +102,7 @@ struct __aliasing_iterator_wrapper {
 
     _LIBCPP_HIDE_FROM_ABI _Alias operator*() const _NOEXCEPT {
       _Alias __val;
-      __builtin_memcpy(&__val, std::__to_address(__base_), sizeof(value_type));
+      __builtin_memcpy(&__val, static_cast<const void*>(std::__to_address(__base_)), sizeof(value_type));
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carlosgalvezp wrote:

[cppreference](https://en.cppreference.com/w/cpp/string/byte/memcpy) used to say that it was UB, but now they have changed it to "may be UB":

Honestly, I cannot find any reference in the C++ Standard about this, maybe it's indirectly from [basic.life] of something. The C standard only says:

> The memcpy function copies n characters from the object pointed to by s2 into the object pointed to
by s1. If copying takes place between objects that overlap, the behavior is undefined.

https://github.com/llvm/llvm-project/pull/111434