[PATCH] D11027: [CONCEPTS] Creating Diagnostics for ill-formed function concept declaration

[Hubert Tong]

On Fri, Jul 10, 2015 at 8:30 AM, Aaron Ballman <aaron at aaronballman.com>
wrote:

> Tiny nits, otherwise LGTM, but please wait for Richard to also sign off.
>
Same from my end.


>
> On Fri, Jul 10, 2015 at 12:21 AM, Nathan Wilson <nwilson20 at gmail.com>
> wrote:
> > nwilson updated this revision to Diff 29426.
> > nwilson added a comment.
> >
> > Update phrasing for concept declaration scope diagnostic
> > Fix indentation issue
> > Update comments for function declaration being a definition
> > Adding acceptance tests for concepts in namespace scope and adding
> diagnostic test for variable concept not being in namespace scope
> >
> >
> > http://reviews.llvm.org/D11027
> >
> > Files:
> >   include/clang/Basic/DiagnosticSemaKinds.td
> >   lib/Sema/SemaDecl.cpp
> >   test/SemaCXX/cxx-concept-declaration.cpp
> >
> > Index: test/SemaCXX/cxx-concept-declaration.cpp
> > ===================================================================
> > --- /dev/null
> > +++ test/SemaCXX/cxx-concept-declaration.cpp
> > @@ -0,0 +1,17 @@
> > +// RUN:  %clang_cc1 -std=c++14 -fconcepts-ts -x c++ -verify %s
> > +
> > +namespace A {
> > +  template<typename T> concept bool C1() { return true; }
> > +
> > +  template<typename T> concept bool C2 = true;
> > +}
> > +
> > +template<typename T> concept bool D1(); // expected-error {{can only
> declare a function concept with its definition}}
> > +
> > +struct B {
> > +  template<typename T> concept bool D2() { return true; } //
> expected-error {{concept declarations may only appear in namespace scope}}
> > +};
> > +
> > +struct C {
> > +  template<typename T> static concept bool D3 = true; // expected-error
> {{concept declarations may only appear in namespace scope}}
> > +};
> > Index: lib/Sema/SemaDecl.cpp
> > ===================================================================
> > --- lib/Sema/SemaDecl.cpp
> > +++ lib/Sema/SemaDecl.cpp
> > @@ -4878,6 +4878,17 @@
> >    if (getLangOpts().CPlusPlus)
> >      CheckExtraCXXDefaultArguments(D);
> >
> > +  if (D.getDeclSpec().isConceptSpecified()) {
> > +    // 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
>
> Missing a period.
>
> > +    if (!DC->getRedeclContext()->isFileContext()) {
> > +      Diag(D.getIdentifierLoc(),
> > +           diag::err_concept_decls_may_only_appear_in_namespace_scope);
> > +      return nullptr;
> > +    }
> > +  }
> > +
> >    NamedDecl *New;
> >
> >    bool AddToScope = true;
> > @@ -7223,6 +7234,7 @@
> >      bool isVirtual = D.getDeclSpec().isVirtualSpecified();
> >      bool isExplicit = D.getDeclSpec().isExplicitSpecified();
> >      bool isConstexpr = D.getDeclSpec().isConstexprSpecified();
> > +    bool isConcept = D.getDeclSpec().isConceptSpecified();
> >      isFriend = D.getDeclSpec().isFriendSpecified();
> >      if (isFriend && !isInline && D.isFunctionDefinition()) {
> >        // C++ [class.friend]p5
> > @@ -7439,6 +7451,21 @@
> >          Diag(D.getDeclSpec().getConstexprSpecLoc(),
> diag::err_constexpr_dtor);
> >      }
> >
> > +    if (isConcept) {
> > +      // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier
> shall be
> > +      // applied only to the definition of a function template
> > +      // (we are checking that the declaration is indeed a definition)
>
> Missing a period.
>
I think ellipsis is appropriate. Also, the parenthesized part is redundant
now.


>
> > +      if (!D.isFunctionDefinition()) {
> > +        Diag(D.getDeclSpec().getConceptSpecLoc(),
> > +             diag::err_function_concept_not_defined);
> > +        NewFD->setInvalidDecl();
> > +      }
> > +
> > +      // C++ Concepts TS [dcl.spec.concept]p2: Every concept definition
> is
> > +      // implicity defined to be a constexpr declaration (implicitly
> inline)
> > +      NewFD->setImplicitlyInline();
> > +    }
> > +
> >      // If __module_private__ was specified, mark the function
> accordingly.
> >      if (D.getDeclSpec().isModulePrivateSpecified()) {
> >        if (isFunctionTemplateSpecialization) {
> > Index: include/clang/Basic/DiagnosticSemaKinds.td
> > ===================================================================
> > --- include/clang/Basic/DiagnosticSemaKinds.td
> > +++ include/clang/Basic/DiagnosticSemaKinds.td
> > @@ -1959,6 +1959,12 @@
> >  def note_private_extern : Note<
> >    "use __attribute__((visibility(\"hidden\"))) attribute instead">;
> >
> > +// C++ Concepts TS
> > +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<
> > +  "can only declare a function concept with its definition">;
>
> This reads slightly strange to me. We have another diagnostic that we
> could steal wording from:
>
> def err_invalid_constexpr_var_decl : Error<
>   "constexpr variable declaration must be a definition">;
>
> So perhaps "function concept declaration must be a definition"?
>
That sounds good.


>
> > +
> >  // C++11 char16_t/char32_t
> >  def warn_cxx98_compat_unicode_type : Warning<
> >    "'%0' type specifier is incompatible with C++98">,
>
> ~Aaron
>
> >
> >
> >
> > _______________________________________________
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> > cfe-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
> >
>
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