[cfe-dev] Late parsing of CXX11 attributes

[Javier López via cfe-dev]

Hi Eric, I wrote a workaround for that issue a few months ago (as part of the
implementation of P0542R5, now included in the current C++ working
draft).  These attributes are manually moved to the attribute list of the
declarator.  To illustrate this, a patch is included in this mail.
--- a/tools/clang/lib/Sema/SemaType.cpp+++
b/tools/clang/lib/Sema/SemaType.cpp@@ -7039,6 +7039,14 @@ static void
processTypeAttrs(TypeProcessingState &state, QualType &type,           <<
attr.getName();       break; +    // These attributes appertain to the
declarator, although they occur+    //  void identifier(void)
[[here]];+    case AttributeList::AT_Expects:+    case
AttributeList::AT_Ensures:+      moveAttrFromListToList(attr,
state.getCurrentAttrListRef(),+                             state.getDeclarato
r().getAttrListRef());+      break;+
Regards.
El mié, 27-06-2018 a las 04:15 -0600, Eric Fiselier escribió:
> Wooh! Thanks for working on this.
> Clang's `diagnose_if` attribute would certainly benefit from this change.
> Currently it's usable only
> as a GCC attribute.
> 
> I tried working on this a while back. IIRC the main issue is that C++11
> attributes placed at the end of
> a function declaration apply to the function type and not the declaration
> itself. (See [dcl.spec]p1).
> 
> After discussing this with Richard and Aaron about attributes appearing
> after a function-specifier, I believe the
> consensus was to only apply the attribute to the type if said attribute is a
> "type attribute". Otherwise the
> attribute would apply to the entity being declared. For example, I think we
> should accept `int foo() [[noreturn]];`
> 
> /Eric
> On Wed, Jun 27, 2018 at 2:20 AM, Javier López via cfe-dev <cfe-dev at lists.llv
> m.org> wrote:
> > OK, unless Aaron replies that someone is currently implementing this, I
> > will be working on a patch.
> > 
> > I know :-)  I have been working for months in the implementation of P0542
> > in Clang.  Late parsing is one of the missing features.
> > 
> > El mar, 26-06-2018 a las 17:05 -0700, Richard Smith escribió:
> > > I'm not aware of anyone working on this (CC'd Aaron, who might know if
> > > someone is). Patches would be very much welcome :)
> > > Also relevant is http://wg21.link/p0542r5 (voted into the current C++
> > > working draft a couple of weeks ago), which requires late parsing for
> > > C++11 attributes within a class.
> > > On 21 June 2018 at 04:16, Javier López via cfe-dev <cfe-dev at lists.llvm.o
> > > rg> wrote:
> > > > Hello everyone,
> > > > 
> > > > AFAIK, GNU attributes can be late parsed within a class (see
> > > > ParseDecl.cpp, Parser::ParseGNUAttributes), but late parsing of CXX11
> > > > attributes is not yet implemented. 
> > > > 
> > > > Is there any plans to do it or anyone already working on it?  Anyway,
> > > > if no one is owning that issue, I could work on it.
> > > > 
> > > > Thanks, 
> > > > -- 
> > > > Javier López
> > > > 2.2.B.08 ARCOS lab, Computer Architecture Group
> > > > University Carlos III of Madrid
> > > > e-mail: jalopezg at inf.uc3m.es
> > > > _______________________________________________
> > > > 
> > > > cfe-dev mailing list
> > > > 
> > > > cfe-dev at lists.llvm.org
> > > > 
> > > > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
> > > > 
> > > > 
> > -- 
> > Javier López
> > 2.2.B.08 ARCOS lab, Computer Architecture Group
> > University Carlos III of Madrid
> > e-mail: jalopezg at inf.uc3m.es
> > _______________________________________________
> > 
> > cfe-dev mailing list
> > 
> > cfe-dev at lists.llvm.org
> > 
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
> > 
> > 
-- 
Javier López
2.2.B.08 ARCOS lab, Computer Architecture Group
University Carlos III of Madrid
e-mail: jalopezg at inf.uc3m.es
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