[cxx-abi-dev] Mangling for noexcept operator

[John McCall]

On Sep 4, 2012, at 11:30 AM, David Vandevoorde wrote:
> On Sep 4, 2012, at 2:17 PM, John McCall wrote:
>> On Sep 4, 2012, at 6:39 AM, Mike Herrick wrote:
>>> We don't seem to have a mangling for the new noexcept operator.  
>>> 
>>> How's this:
>>> 
>>> <operator-name> ::= nx		# noexcept (an expression)
>>> 
>>> For example:
>>> 
>>> void f(int) noexcept;
>>> void f(float) throw (int);
>>> template <class T> auto g(T p) -> decltype((int (*)[noexcept(f(p))])0);
>>> int main() {
>>>  g(1);
>>> }
>>> 
>>> Which would provide a mangled name of: _Z1gIiEDTcvPAnxcl1ffp_E_iLi0EET_ for g.
>> 
>> This seems like a fine mangling, but it shouldn't be an <operator-name>.
>> Let's just do:
>> <expression> ::= nx <expression>
> 
> It would be odd not to follow the pattern of sizeof and alignof here, no?

Heh.  I was following the pattern of typeid and throw. :)  I didn't actually notice that sizeof and alignof are only <expression>s directly in the type variant.

> (I can kind of see an argument to distinguish the "operators" that cannot be the basis of a <base-unresolved-name>, but I'm not sure it's worth the complication.)

Well, they also can't be the names of declarations, at least until the committee inevitably adds an operator sizeof. :)

I withdraw my tweak, although I may just move these using editorial discretion unless you really object.  Neither seems inherently less complicated, and having (e.g.) both sizeof rules in the same place has some merit.

John.