yaxunl added a comment.
In D84364#2168036 <https://reviews.llvm.org/D84364#2168036>, @tra wrote:
> One side effect of this change is that we'll probably stop producing
> diagnostics for the code that is known to be wrong, but happens to be unused.
>
> E.g.
>
> __host__ __device__ static void hd() {
> no_such_type_t t;
> }
>
>
> We obviously can never compile this function on either side of the
> compilation and clang currently does diagnose it on both sides.
> However, if all diagnostics in HD functions are postponed until codegen,
> this error will go unreported.
>
> What if I have a syntax error in a HD function? I'd still want it to be
> diagnosed.
> It's going to be interesting to see how it affects parsing subsequent code.
> E.g https://godbolt.org/z/1vfPcc -- clang complains about the error in
> `innocent` due to an error in `hd`. If all diags issues in `hd` are postponed
> and the user only sees `error: function definition is not allowed here`, it
> will be rather confusing, because the `innocent` itself is perfectly fine.
A diagnostic will be deferred only if clang successfully parsed a function
declaration and the current context is a function declaration.
In the above situation, clang fails to parse the function and the current
context is not a function, therefore the error is emitted immediately, like
before.
I have added a lit test for such situation.
> Also, this patch may need more eyes on it. I'm sure there are more corner
> cases we may need to think about.
> E.g. how would it affect SFINAE? Will it allow some things to succeed where
> they would've failed previously? If so, is it always the right thing to do?
We only defer diagnostics happen inside a host device function. My guess is
that SFINAE will work as before since it happens not in a function scope,
therefore it is not deferred. I will add some tests.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D84364/new/
https://reviews.llvm.org/D84364
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