Re: [patchv2] compile: Fix crash on cv-qualified self-reference

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

On Wed, 01 Jul 2015 15:54:21 +0200, Pedro Alves wrote:
> On 07/01/2015 02:24 PM, Jan Kratochvil wrote:
> 
> > I can change it that way but when you ask "isn't cleaner" then no, I think
> > your hack is even a bit more ugly than my ugly hack.
> > 
> > There should be two virtual methods, one pure for 'switch (TYPE_CODE (type))'
> > and the other one checking TYPE_INSTANCE_FLAG* in superclass overriden only by
> > TYPE_CODE_STRUCT and TYPE_CODE_UNION (there would be no TYPE_CODE_*, though).
> 
> What would be the method name?

class Type {
protected:
  virtual GccType convert_unqualified ()=0;
public:
  explicit virtual GccType operator() {
    if (instance_flags==0) return convert_unqualified();
    ...
  }
};

class StructType:public Type {
protected:
  virtual GccType convert_unqualified () { assert(0) }
public:
  explicit virtual GccType operator() override { ... }
};

class IntegerType:public Type {
protected:
  virtual GccType convert_unqualified () { assert(instance_flags==0); ... }
};

Althoughth qualifications could be possibly also subclassed which would look
differently again.

My point was that the current code does not make much sense to clean up as it
cannot be clean in C.


> There's nothing preventing adding a new type_FOO function that takes a type
> pointer as parameter and hides the TYPE_CODE checks inside.  From the
> caller's perspective, it'll be the same.  Once we get to C++ and if we
> consider objectifying type, then converting that function to a method will
> be trivial.

Do you mean simulation of C++ virtual method table by a struct of pointers,
like in other cases in GDB?


Jan