[PATCH] D153542: [C++20][Modules] Implement P2615R1 exported specialization diagnostics.

[Chuanqi Xu via Phabricator via cfe-commits]

ChuanqiXu added inline comments.


================
Comment at: clang/lib/Sema/SemaModule.cpp:848-849
+    if (auto *FD = dyn_cast<FunctionDecl>(D)) {
+      if (FD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization)
+        BadExport = true;
+    } else if (auto *VD = dyn_cast<VarDecl>(D)) {
----------------
ChuanqiXu wrote:
> iains wrote:
> > ChuanqiXu wrote:
> > > Given P2615R1 doesn't allow explicit-instantiation in export block too.
> > I think I must be missing something - I do not see that in the paper - please could you expand your comment?
> See the proposed change in #[module.interface]p1 in the paper, it changed:
> 
> ```
> export declaration
> ```
> 
> to 
> 
> 
> ```
> export named-declaration
> ```
> 
> And the change between the old declaration and the new named declaration is in the proposed change in #[dcl.pre]p1. So it shows the special declarations shouldn't be allowed after `export`.
> 
> Also I noted it is allowed to write `export { declaration-seq_opt }` where the `declaration-seq` may contain special declarations. It looks weird to me. I'll try to check it and ask WG21 when necessary.
I checked the record. And it shows that the current wording reflects the intention. I mean

```
export template<> class A<int>;
```

is not allowed. But,

```
export { template<> class A<int> };
```

is allowed.



Repository:
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  https://reviews.llvm.org/D153542/new/

https://reviews.llvm.org/D153542