[PATCH] D13330: Implement __attribute__((unique_instantiation))

[Keno Fischer via cfe-commits]

loladiro added inline comments.

================
Comment at: include/clang/Basic/Attr.td:1463
@@ +1462,3 @@
+  let Spellings = [GNU<"unique_instantiation">];
+  let Subjects = SubjectList<[Function, CXXRecord], ErrorDiag>;
+  let Documentation = [UniqueInstantiationDocs];
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loladiro wrote:
> majnemer wrote:
> > They work ok, clang just thinks that it's a declaration of a variable template.  Try this:
> >   template <typename T> T n = T();
> >   extern template int n<int>;
> >   template int n<int>;
> I see. I'll look into adding support for it. Can you explain why my example doesn't work? GCC seems to allow this.
Bump on the question of differences to GCC here.

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Comment at: include/clang/Basic/DiagnosticSemaKinds.td:2456
@@ -2450,1 +2455,3 @@
+def err_unique_instantiation_not_previous : Error<
+  "'unique_instantiation' attribute must be specified for all declarations and definitions of this explicit template instantiation">;
 
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aaron.ballman wrote:
> > They are checking for two different conditions in the spec. One requires that all explicit template instantiations with this attribute have a declaration, the other that every declaration/definition has the attribute.
> 
> Okay, I see now what this diagnostic is attempting to convey. I think it should read:
> ```
> def err_unique_instantiation_no_declaration : Error<
>   "'unique_instantiation' attribute on an explicit instantiation requires a previous explicit instantiation declaration">;
> ```
Sounds good.

================
Comment at: test/SemaCXX/unique-instantiations.cpp:23
@@ +22,2 @@
+extern template struct __attribute__((unique_instantiation)) foo5<int>; // expected-note{{previous explicit instantiation is here}}
+template struct foo5<int>;                                              // expected-error{{must be specified for all declarations}}
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aaron.ballman wrote:
> Missing tests for correct usage of the attribute. Missing tests of the attribute diagnosing when given arguments.
Isn't the correct usage checked for in the CodeGen tests above?


Repository:
  rL LLVM

http://reviews.llvm.org/D13330