[clang] Reapply "[Clang][CWG1815] Support lifetime extension of temporary created by aggregate initialization using a default member initializer" (PR #92527)

[Zequan Wu via cfe-commits]

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@@ -27,6 +27,80 @@ class MemInit {
   C m = s;
 };
 
+namespace std {
+typedef decltype(sizeof(int)) size_t;
+
+// libc++'s implementation
+template <class _E> class initializer_list {
+  const _E *__begin_;
+  size_t __size_;
+
+  initializer_list(const _E *__b, size_t __s) : __begin_(__b), __size_(__s) {}
+
+public:
+  typedef _E value_type;
+  typedef const _E &reference;
+  typedef const _E &const_reference;
+  typedef size_t size_type;
+
+  typedef const _E *iterator;
+  typedef const _E *const_iterator;
+
+  initializer_list() : __begin_(nullptr), __size_(0) {}
+
+  size_t size() const { return __size_; }
+  const _E *begin() const { return __begin_; }
+  const _E *end() const { return __begin_ + __size_; }
+};
+} // namespace std
+
+#if __cplusplus >= 201703L
+namespace test_rebuild {
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ZequanWu wrote:

Thanks!

https://github.com/llvm/llvm-project/pull/92527