Re: [PATCH v2 01/11] [PR gdb/14441] gdb: gdbtypes: add definitions for rvalue reference type

[Artemiy Volkov <artemiyv@acm.org>]

On Fri, Feb 19, 2016 at 10:49:38AM -0800, Keith Seitz wrote:

[snip]

> >  /* * Instruction-space delimited type.  This is for Harvard architectures
> >     which have separate instruction and data address spaces (and perhaps
> >     others).
> > @@ -767,6 +775,10 @@ struct type
> >  
> >    struct type *reference_type;
> >  
> > +  /* * A C++ rvalue reference type added in C++0x. */
> > +
> > +  struct type *rvalue_reference_type;
> > +
> 
> Why is this new field necessary? AFAICT, it is used exactly the same way
> as the reference_type field above it, and whether a reference type is an
> rvalue type is encoded into the type code.

Do you suggest keeping only the lvalue version of the reference type and
then adjust its type code from TYPE_CODE_REF to TYPE_CODE_RVALUE_REF on
lookup_rvalue_reference_type()? It seems somewhat hacky to me. E.g. how
would we be able to create a struct type for a complex type involving a
T&&, such as a typedef of it?

> 
> >    /* * Variant chain.  This points to a type that differs from this
> >       one only in qualifiers and length.  Currently, the possible
> >       qualifiers are const, volatile, code-space, data-space, and
> > @@ -1229,6 +1241,7 @@ extern void allocate_gnat_aux_type (struct type *);
> >  #define TYPE_TARGET_TYPE(thistype) TYPE_MAIN_TYPE(thistype)->target_type
> >  #define TYPE_POINTER_TYPE(thistype) (thistype)->pointer_type
> >  #define TYPE_REFERENCE_TYPE(thistype) (thistype)->reference_type
> > +#define TYPE_RVALUE_REFERENCE_TYPE(thistype) (thistype)->rvalue_reference_type
> >  #define TYPE_CHAIN(thistype) (thistype)->chain
> >  /* * Note that if thistype is a TYPEDEF type, you have to call check_typedef.
> >     But check_typedef does set the TYPE_LENGTH of the TYPEDEF type,
> 
> If struct type.rvalue_reference_type is superfluous, this is unneeded.
> 
> Keith
>