[PATCH] D11490: [Concepts] Add diagnostic: non template declaration

[Hubert Tong]

Thanks Aaron for copying the similar messages here. I'd still like the use
"definition of", but with Aaron's suggestion as the base.
I considered using plural nouns instead of singular ones to match the
existing messages better, but the result was clunky.

"'concept' can only appear on the definition of a function template or
variable template"

On Fri, Jul 24, 2015 at 3:37 PM, Aaron Ballman <aaron at aaronballman.com>
wrote:

> On Fri, Jul 24, 2015 at 3:27 PM, Nathan Wilson <nwilson20 at gmail.com>
> wrote:
> >
> >
> > On Fri, Jul 24, 2015 at 2:14 PM, Aaron Ballman <aaron at aaronballman.com>
> > wrote:
> >>
> >> On Fri, Jul 24, 2015 at 2:43 PM, Nathan Wilson <nwilson20 at gmail.com>
> >> wrote:
> >> > nwilson created this revision.
> >> > nwilson added reviewers: rsmith, faisalv, fraggamuffin,
> >> > hubert.reinterpretcast.
> >> > nwilson added a subscriber: cfe-commits.
> >> >
> >> > Adding diagnostic for concepts declared as non template (function or
> >> > variable)
> >> >
> >> > http://reviews.llvm.org/D11490
> >>
> >> >
> >> > Files:
> >> >   include/clang/Basic/DiagnosticSemaKinds.td
> >> >   lib/Sema/SemaDecl.cpp
> >> >   test/SemaCXX/cxx-concept-declaration.cpp
> >> >
> >> > Index: test/SemaCXX/cxx-concept-declaration.cpp
> >> > ===================================================================
> >> > --- test/SemaCXX/cxx-concept-declaration.cpp
> >> > +++ test/SemaCXX/cxx-concept-declaration.cpp
> >> > @@ -15,3 +15,7 @@
> >> >  struct C {
> >> >    template<typename T> static concept bool D3 = true; //
> expected-error
> >> > {{concept declarations may only appear in namespace scope}}
> >> >  };
> >> > +
> >> > +concept bool D4() { return true; } // expected-error {{concept can
> only
> >> > be applied to a function or variable template definition}}
> >> > +
> >> > +concept bool D5 = true; // expected-error {{concept can only be
> applied
> >> > to a function or variable template definition}}
> >> > Index: lib/Sema/SemaDecl.cpp
> >> > ===================================================================
> >> > --- lib/Sema/SemaDecl.cpp
> >> > +++ lib/Sema/SemaDecl.cpp
> >> > @@ -4865,6 +4865,12 @@
> >> >      // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier
> >> > shall be
> >> >      // applied only to the definition of a function template or
> >> > variable
> >> >      // template, declared in namespace scope
> >> > +    if (!TemplateParamLists.size()) {
> >> > +      Diag(D.getDeclSpec().getConceptSpecLoc(),
> >> > +           diag::err_concept_decl_non_template);
> >> > +      return nullptr;
> >> > +    }
> >> > +
> >> >      if (!DC->getRedeclContext()->isFileContext()) {
> >> >        Diag(D.getIdentifierLoc(),
> >> >
>  diag::err_concept_decls_may_only_appear_in_namespace_scope);
> >> > Index: include/clang/Basic/DiagnosticSemaKinds.td
> >> > ===================================================================
> >> > --- include/clang/Basic/DiagnosticSemaKinds.td
> >> > +++ include/clang/Basic/DiagnosticSemaKinds.td
> >> > @@ -1966,6 +1966,8 @@
> >> >    "use __attribute__((visibility(\"hidden\"))) attribute instead">;
> >> >
> >> >  // C++ Concepts TS
> >> > +def err_concept_decl_non_template : Error<
> >> > +  "concept can only be applied to a function or variable template
> >> > definition">;
> >>
> >> Since we are using "concept" as a grammar term, I think we want to
> >> quote it. Similar diagnostics suggest phrasing like:
> >>
> >> "'concept' can only appear on a function template or variable template
> >> definition"
> >>
> >> This also reduces some ambiguity over how "function or variable
> template"
> >> binds.
> >>
> >> ~Aaron
> >
> >
> > May we apply both this suggestion and Hubert's? So it would be:
> >
> > "the 'concept' specifier may only be applied to the definition of a
> function
> > or variable template"
>
> I don't have a strong preference, but I think "specifier may only be"
> is kind of wordy without adding much value. For comparison:
>
> def err_inline_non_function : Error<
>   "'inline' can only appear on functions">;
> def err_noreturn_non_function : Error<
>   "'_Noreturn' can only appear on functions">;
> def err_virtual_non_function : Error<
>   "'virtual' can only appear on non-static member functions">;
> def err_explicit_non_function : Error<
>   "'explicit' can only appear on non-static member functions">;
>
> ~Aaron
>
> >
> >>
> >>
> >> >  def err_concept_decls_may_only_appear_in_namespace_scope : Error<
> >> >    "concept declarations may only appear in namespace scope">;
> >> >  def err_function_concept_not_defined : Error<
> >> >
> >> >
> >> >
> >> > _______________________________________________
> >> > cfe-commits mailing list
> >> > cfe-commits at cs.uiuc.edu
> >> > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
> >> >
> >
> >
>
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