zyounan added a comment.
Thank you for the suggestion and I've updated my patch. :)
================
Comment at: clang/test/CXX/dcl.decl/dcl.meaning/dcl.array/cwg2397.cpp:11
+}
+
+void g() {
----------------
aaron.ballman wrote:
> 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.
Indeed. I will enable it only with C++14 or later. (I didn't come up a way to
get around the restriction for C++11, though.)
================
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]'}}
----------------
aaron.ballman wrote:
> 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.
You're right that such diagnostic looks a bit strange but FYI, GCC now emits
diagnostic like so:
```
auto a[5] = b; // error: unable to deduce 'auto [5]' from 'b'
int c[5] = b; // error: array must be initialized with a brace-enclosed
initializer
```
I agree that what we expect here is to emit messages just like `int a[5] = b;`
would produce with respect to better understandability, however, the
`err_auto_var_deduction_failure` error is actually emitted due to type
deduction failure, whereas `err_array_init_not_init_list` would be produced
**later** by initialization error IIUC. So, IMHO such message makes sence as
per what standard says, that for each type `P`, after being substituted with
deduced `A`, shall be **compatible** with type `A`.
[temp.deduct.type/1](https://eel.is/c++draft/temp.deduct.type#1.sentence-1)
// Feel free to correct me if I'm wrong :)
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D147909/new/
https://reviews.llvm.org/D147909
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