> On 16 Oct 2018, at 13:19, Akim Demaille <[email protected]> wrote:
>
>> Le 16 oct. 2018 à 11:20, Hans Åberg <[email protected]> a écrit :
>>
>> In Bison 3.1,
>> %define api.value.type {semantic_type}
>
> Actually, what are you trying to achieve? semantic_type is the name
> of the typedef used by bison. So, of course, it’s quite a bad idea
> to use that name. Unless you do mean to use that name, but not
> Bison’s, rather some other definition, coming from some other place,
> in which case you must provide the namespace/path to it.
The minimal example below compiles with clang++6, but not with g++8. One would
think that it should define a qualified name B::A, used as
mu::B::A a;
as in the other cases below. But I have it probably by legacy since when Bison
used YYSTYPE only, though.
A draft version of the C++ standard says:
7.1.3 The typedef specifier [dcl.typedef]
4. In a given class scope, a typedef specifier can be used to redefine any
class-name declared in that scope
that is not also a typedef-name to refer to the type to which it already
refers. [Example:
struct S {
typedef struct A { } A; // OK
typedef struct B B; // OK
typedef A A; // error
};
— end example]
So in the example below, g++8 accepts:
typedef class A A;
typedef mu::A A;
--
namespace mu {
class A {};
class B {
public:
typedef A A;
};
}
int main () {
mu::B::A a;
return 0;
}
--
