On Mar 26, 2014, at 11:34 AM, Richard Smith <[email protected]> wrote:
> On 20 March 2014 12:04, John McCall <[email protected]> wrote:
> On Mar 20, 2014, at 11:16 AM, Hubert Tong <[email protected]> wrote:
> > John McCall <[email protected]> wrote on 20-03-2014 01:56:10 PM:
> > > From: John McCall <[email protected]>
> > > To: Hubert Tong/Toronto/IBM@IBMCA,
> > > Cc: [email protected]
> > > Date: 20-03-2014 01:56 PM
> > > Subject: Re: [cxx-abi-dev] Missing mangling of elaborated type specifiers
> > >
> > > On Mar 19, 2014, at 9:02 PM, Hubert Tong <[email protected]> wrote:
> > > > It seems that the ABI is missing mangling for elaborated type
> > > > specifiers.
> > > >
> > > > Background:
> > > > As mentioned in Core Issue 1162, elaborated-type-specifiers may be
> > > used to cause SFINAE.
> > >
> > > Good point. I guess this should just be added to <unresolved-name>.
> > > Would you care to make a proposal?
> > >
> >
> > Sure.
>
> Great!
>
> I think I was wrong, by the way; you should add it to to the
> <class-enum-type> grammar as a decoration before we enter <name>.
>
> I think we should leave the 'typename' case alone and change the
> struct/class/union/enum cases, since the latter cases are much less common.
> There seem to be two obvious approaches:
>
> 1) Use a prefix indicating that there was a tag keyword, but don't say which
> one.
> 2) Use a prefix indicating which keyword was used
>
> The first approach seems viable -- we can never have a mangling collision
> where a type is one of struct-or-class, union, or enum in one TU and a
> different one of those three in another TU (and the struct and class cases
> are functionally equivalent).
Sorry, what? Why are any of these the same function template under the ODR?
template <class T> auto f() -> enum T::type;
template <class T> auto f() -> struct T::type;
template <class T> auto f() -> typename T::type;
Template argument deduction can distinguish the first two (and drop them in
favor of the third for typedef members), and the third can be introduced later
or in a different translation unit.
I think we have to take the second approach.
> The second approach seems better for demanglers (and taking that argument to
> its logical conclusion suggests that we should mangle 'class' and 'struct'
> differently).
>
> Strawman:
>
> <class-enum-type> ::= <name> # non-dependent type name or
> typename-specifier
> ::= TC <name> # dependent elaborated class type
> ::= Ts <name> # dependent elaborated struct type
> ::= Tu <name> # dependent elaborated union type
> ::= Te <name> # dependent elaborated enum type
I don’t think distinguishing struct and class is worth it.
John.
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