hokein added inline comments.
================
Comment at: clang/test/SemaCXX/cxx11-crashes.cpp:117
+ // The missing expression makes A undeduced.
+ static constexpr auto A = ; // expected-error {{expected expression}}
+ Foo<decltype(A)>::type B; // The type of B is also undeduced (wrapped in
Elaborated).
----------------
adamcz wrote:
> hokein wrote:
> > I think the root cause is that this incomplete var declaration is marked
> > valid.
> >
> > Looks like there are a few inconsistencies in clang:
> >
> > ```
> > struct Bar {
> > static constexpr auto A1; // case1: invalid
> > static constexpr auto A2 = ; // case2: valid
> > };
> >
> > // static var decl in global context
> > static constexpr auto A3; // case3: invalid
> > static constexpr auto A4 = ; // case4: invalid
> > ```
> >
> > so it looks like marking case2 valid is a bug, I think we should invalidate
> > it.
> I updated the change to mark a FieldDecl with undeduced type as invalid, thus
> making the record invalid too. Also added a test using -ast-dump to verify
> that both field and record are invalid, but kept the crash test too.
sorry, my comment was not clear enough -- if I understand your new change
correctly, the change makes the field decl `Foo<decltype(A)>::type B;` but not
the decl `A`.
The problem here is `static constexpr auto A = ;`, this declaration (var, not
field) is valid, which causes the field decl below `Foo<decltype(A)>::type B;`
valid. If we invalidate the Decl `A`, then the filed decl B should be
invalidated automatically.
leaving `A` valid is problematic -- we can't have a valid decl with an
undeduced auto type in clang. the following case would lead another crash:
```
struct Bar {
static constexpr auto A = ;
};
constexpr int s = sizeof(Bar::A);
```
So the solution is to make Decl `A` invalid.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D105478/new/
https://reviews.llvm.org/D105478
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