[PATCH] D59754: [Sema] Add c++2a designated initializer warnings

[Nicolas Lesser via Phabricator via cfe-commits]

Rakete1111 added inline comments.


================
Comment at: clang/test/SemaCXX/cxx2a-initializer-aggregates.cpp:30
+// out of order designators
+A a1 = {.y = 1, .x = 2}; // expected-warning {{designated initializers are a C99 feature}}
+
----------------
hintonda wrote:
> lebedev.ri wrote:
> > hintonda wrote:
> > > Rakete1111 wrote:
> > > > Those warnings are misleading, since C++20 does have designated initializers; they just don't support some stuff that C99 does. It would be better  IMO if you could separate them. As in, the above should give you: `out-of-order designated initializers are a C99 feature` or something like that.
> > > I think that would be a good idea as well, but wanted to get advise first.
> > > As in, the above should give you: out-of-order designated initializers are a C99 feature or something like that.
> > 
> > I suppose also the question is, whether to error-out, or support them as an extension?
> > 
> Although most of them seem fine, the nested ones can be problematic.  Please see https://reviews.llvm.org/D17407 for a proposal on how to fix them.
> I suppose also the question is, whether to error-out, or support them as an extension?

Yes that's true. gcc doesn't support them at all in C++, and it seems like we accept it as well, but only for C classes (constructors make clang crash).

But making it an error now breaks backwards compatibility. So I think the best solution is to accept it for now, as an extension.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D59754/new/

https://reviews.llvm.org/D59754