[libcxx-commits] [libcxx] [libc++][syncbuf] Implements LWG3253. (PR #99778)

[Louis Dionne via libcxx-commits]

================
@@ -253,7 +255,10 @@ public:
 
   // [syncstream.syncbuf.cons], construction and destruction
 
-  _LIBCPP_HIDE_FROM_ABI explicit basic_syncbuf(streambuf_type* __obuf = nullptr)
+  _LIBCPP_HIDE_FROM_ABI basic_syncbuf()
+      : basic_syncbuf(nullptr) {}
----------------
ldionne wrote:

I think it's possible to test this. Before applying the LWG issue resolution, the following code would not have compiled:

```
basic_syncbuf f() {
  return {};
}
```

But after the LWG issue resolution, this compiles because the default constructor is not explicit. So I think a test like this should work:

```
basic_syncbuf buf = {};
```

https://github.com/llvm/llvm-project/pull/99778