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

[Aaron Ballman]

On Thu, Jul 9, 2015 at 9:17 AM, Hubert Tong
<hubert.reinterpretcast at gmail.com> wrote:
> On Thu, Jul 9, 2015 at 7:52 AM, Aaron Ballman <aaron at aaronballman.com>
> wrote:
>>
>> On Thu, Jul 9, 2015 at 12:22 AM, Hubert Tong
>> <hubert.reinterpretcast at gmail.com> wrote:
>> > hubert.reinterpretcast added inline comments.
>> >
>> > ================
>> > Comment at: include/clang/Basic/DiagnosticSemaKinds.td:1964
>> > @@ +1963,3 @@
>> > +def err_invalid_concept_scope : Error<
>> > +  "concept declaration required to be in namespace scope">;
>> > +def err_function_concept_not_defined : Error<
>> > ----------------
>> > This error is similar to
>> > `err_objc_decls_may_only_appear_in_global_scope` below, so perhaps it could
>> > be expressed in a similar manner.
>>
>> Can't concepts be declared in a namespace scope that's not the global
>> namespace scope?
>
> Yes. I should have been more specific. The similarity I was referring to did
> not extend to the "global scope" part. Note that I added my comment to the
> message text (not the check, which does allow namespaces other than the
> global one).

I mentioned it because the current patch has:

+def err_concept_decls_may_only_appear_in_global_scope : Error<
+  "function and variable concept declarations may only appear in
global scope">;

which is a misleading diagnostic (both the identifier and the
wording). I probably should have attributed that to the current patch
and not your comment, however. ;-)

~Aaron

>
>>
>>
>> namespace A {
>>   template<typename T> concept bool D1() { return true; }
>> }
>>
>>
>> Either way, this is a test that should be added.
>
> Agreed.
>
>>
>>
>> ~Aaron
>>
>> >
>> > ================
>> > Comment at: include/clang/Basic/DiagnosticSemaKinds.td:1966
>> > @@ +1965,3 @@
>> > +def err_function_concept_not_defined : Error<
>> > +  "function concept requires definition">;
>> > +
>> > ----------------
>> > Perhaps: "can only declare a function concept with its definition".
>> >
>> > The existing wording seems to imply that an earlier definition (of just
>> > one somewhere) is sufficient and that function concepts may be redeclared.
>> >
>> > ================
>> > Comment at: lib/Sema/SemaDecl.cpp:7453
>> > @@ +7452,3 @@
>> > +      // C++ Concepts TS [dcl.spec.concept]p1: A concept definition
>> > refers to a
>> > +      // function concept and its definition
>> > +      if (!D.isFunctionDefinition()) {
>> > ----------------
>> > The quoted text is a definition of the term "concept definition". The
>> > diagnosable rule is established by the quote on line 7444. So there probably
>> > should be a comment here to the effect of "we are checking that the
>> > declaration is indeed a definition".
>> >
>> > ================
>> > Comment at: lib/Sema/SemaDecl.cpp:7460
>> > @@ +7459,3 @@
>> > +
>> > +      // C++ Concepts TS [dcl.spec.concept]p2: Every concepts
>> > definition is
>> > +      // implicity defined to be a constexpr declaration (implicitly
>> > inline)
>> > ----------------
>> > Typo: s/concepts/concept/
>> >
>> > ================
>> > Comment at: test/SemaCXX/cxx-concept-declaration.cpp:3
>> > @@ +2,3 @@
>> > +
>> > +template<typename T> concept bool C1 = true;
>> > +
>> > ----------------
>> > I'm not sure why this is part of the current patch.
>> >
>> > ================
>> > Comment at: test/SemaCXX/cxx-concept-declaration.cpp:5
>> > @@ +4,3 @@
>> > +
>> > +template<typename T> concept decltype(!0) C2 = true;
>> > +
>> > ----------------
>> > Same comment as on line 3.
>> >
>> >
>> > http://reviews.llvm.org/D11027
>> >
>> >
>> >
>> >
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>
>