[PATCH] D147909: [clang] Implement CWG 2397

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added a reviewer: clang-language-wg.
aaron.ballman added a comment.

The changes need a release note, but also this should have changes to `clang/test/CXX/drs/dr23xx.cpp` with the proper dr markings and update `clang/www/cxx_dr_status.html`.



================
Comment at: clang/test/CXX/dcl.decl/dcl.meaning/dcl.array/cwg2397.cpp:11
+}
+
+void g() {
----------------
I think it'd be good to also show a constexpr test, like:
```
constexpr int foo() {
  int a[] = { 1, 2, 3 };
  auto (&c)[3] = a;

  return c[2];
}

static_assert(foo() == 3, "");
```
to prove that we actually perform the assignment properly, not just figure out the deduced type correctly.


================
Comment at: clang/test/CXX/dcl.decl/dcl.meaning/dcl.array/p1-cxx0x.cpp:5
   int b[5];
-  auto a[5] = b; // expected-error{{'a' declared as array of 'auto'}}
-  auto *c[5] = b; // expected-error{{'c' declared as array of 'auto *'}}
+  auto a[5] = b; // expected-error{{variable 'a' with type 'auto[5]' has incompatible initializer of type 'int[5]'}}
+  auto *c[5] = b; // expected-error{{variable 'c' with type 'auto *[5]' has incompatible initializer of type 'int[5]'}}
----------------
I've seen worse diagnostics, but the phrasing here is interesting -- if you use `int a[5] = b;` instead of `auto`, you get `array initializer must be an initializer list` as a diagnostic, so I wonder why we're getting such a drastically different diagnostic for `auto`. Same for the diagnostic below.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D147909/new/

https://reviews.llvm.org/D147909