hintonda marked an inline comment as done.
hintonda added inline comments.
================
Comment at: clang/lib/Sema/SemaInit.cpp:2069-2072
+ if (!VerifyOnly && HasDesignatedInit && SemaRef.getLangOpts().CPlusPlus2a)
{
+ SemaRef.Diag(Init->getBeginLoc(), diag::ext_c20_designated_init)
+ << "mixed" << Init->getSourceRange();
+ }
----------------
rsmith wrote:
> I think it would be preferable to diagnose the "mixed" case in the parser
> rather than here (it's a grammatical restriction in C++, after all). I'm
> worried that handling it here will get some cases wrong, such as perhaps:
>
> ```
> struct A {
> union { int x, y; };
> int z;
> };
> A a = { .x = 123, 456 }; // should be rejected, but I think this patch might
> accept
> ```
>
> ... and it might also get template instantiation cases wrong for a case like:
>
> ```
> struct Q { Q(); };
> struct A { Q x, y; };
> template<typename T> void f() {
> A a = {.y = Q()};
> }
> void g() { f<int>(); }
> ```
>
> ... where we might possibly end up passing an `InitListExpr` representing
> `{Q(), .y = Q()}` into `InitListChecker`.
>
> I think the only C++20 restriction that it makes sense to check in
> `InitListChecker` is that the field names are in the right order; everything
> else should be checked earlier. This would also match the semantics of
> overload resolution, for which the "fields are in the right order" check is
> deferred until after a function is selected, whereas all the other checks are
> performed eagerly.
Will work on moving these to the parser.
Btw, the first one is diagnosed correctly, but doesn't complain about the
second. Not sure I grok the problem there either since Q has a default ctor.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D59754/new/
https://reviews.llvm.org/D59754
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