[PATCH] D152003: [clang] Fix `static_cast` to array of unknown bound

[Mariya Podchishchaeva via Phabricator via cfe-commits]

Fznamznon added inline comments.


================
Comment at: clang/test/SemaCXX/paren-list-agg-init.cpp:276-285
+namespace gh62863 {
+int (&&arr)[] = static_cast<int[]>(42);
+// beforecxx20-warning at -1 {{aggregate initialization of type 'int[1]' from a parenthesized list of values is a C++20 extension}}
+int (&&arr1)[1] = static_cast<int[]>(42);
+// beforecxx20-warning at -1 {{aggregate initialization of type 'int[1]' from a parenthesized list of values is a C++20 extension}}
+int (&&arrr2)[2] = static_cast<int[]>(42); // expected-error {{reference to type 'int[2]' could not bind to an rvalue of type 'int[1]'}}
+// beforecxx20-warning at -1 {{aggregate initialization of type 'int[1]' from a parenthesized list of values is a C++20 extension}}
----------------
aaron.ballman wrote:
> I'd like to see test coverage for:
> ```
> int (&&arr)[] = (int[])(42);
> int (&&arr1)[1] = (int[])(42);
> int (&&arrr2)[2] = (int[])(42);
> int (&&arr3)[3] = (int[3])(42);
> ```
> where we're using a C-style cast, because: http://eel.is/c++draft/expr.cast#4
Thank you for the review!

Just to double check, so it says:

> The conversions performed by ... *all named casts* can be performed using the cast notation of explicit type conversion.

Does that mean the c-style cast should produce the same thing? And, https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1975r0.html doesn't say anything about c-style casts because it is assumed that it should be able to do anything that `static_cast` can do?

gcc doesn't agree https://godbolt.org/z/Pfq8frdn9 . The funny thing is that the original bug report seems to be using some kind of gcc test.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D152003/new/

https://reviews.llvm.org/D152003