[clang] [clang] Add tests for DRs about inheriting constructors (PR #79981)

[via cfe-commits]

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@@ -154,6 +154,47 @@ const D &d3(c); // FIXME ill-formed
 #endif
 }
 
+namespace dr2273 { // dr2273: 3.3
+#if __cplusplus >= 201103L
+struct A {
+  A(int = 0) = delete; // #dr2273-A
+};
+
+struct B : A { // #dr2273-B
+  using A::A;
+};
+
+B b;
+// since-cxx11-error at -1 {{call to implicitly-deleted default constructor of 'B'}}
+//   since-cxx11-note@#dr2273-B {{default constructor of 'B' is implicitly deleted because base class 'A' has a deleted default constructor}}
+//   since-cxx11-note@#dr2273-A {{'A' has been explicitly marked deleted here}}
+#endif
+}
+
+namespace dr2277 { // dr2277: partial
+#if __cplusplus >= 201103L
+struct A {
+  A(int, int = 0);
+  void f(int, int = 0); // #dr2277-A-f
+};
+struct B : A {
+  B(int);
+  using A::A;
+
+  void f(int); // #dr2277-B-f
+  using A::f;
+};
+
+void g() {
+  B b{0};
+  b.f(0); // FIXME: this is well-formed for the same reason as initialization of 'b' above
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cor3ntin wrote:

This in particular looks something we should fix, can you write an issue?

https://github.com/llvm/llvm-project/pull/79981