Re: [PATCH 00/19] cleanup of memory stats prototypes

[Trevor Saunders <tbsaunde at tbsaunde dot org>]

On Mon, Jul 31, 2017 at 02:56:40PM -0600, Martin Sebor wrote:
> On 07/27/2017 02:30 AM, tbsaunde+gcc@tbsaunde.org wrote:
> > From: Trevor Saunders <tbsaunde+gcc@tbsaunde.org>
> > 
> > The preC++ way of passing information about the call site of a function was to
> > use a macro that passed __file__, __LINE__, and __FUNCTION__ to a function with
> > the same name with _stat appended to it.  The way this is now done with C++ is
> > to have arguments where the default value is __LINE__, __FILE__, and
> > __FUNCTION__ in the caller.  This has the significant advantage that if you
> > look for "^function (" you find the correct function, where in the C way of
> > doing things you need to realize its a macro and check the definition of the
> > macro to see what to look for next.  So this removes a layer of indirection,
> > and makes things somewhat more consistant in using the C++ way of doing things.
> 
> So that's what these things are for! :)
> 
> I must be missing something either about the macros or about your
> changes.  The way I read the changes it seems that it's no longer
> possible to call, say,
> 
>   t = make_node (code);
> 
> and have __FILE__, __LINE__, and __FUNCTION__ passed as arguments
> behind the scenes.
> 
> Instead, to achieve that, make_node has to be called like so
> 
>   t = make_node (code PASS_MEM_STAT);
> 
> Otherwise calling make_node() with just one argument will end up
> calling it with the defaults.

calling it with the defaults will do the same thing the macro used to
do, so its fine unless you want to pass in a location that you got as an
argument.

I'm guessing you are missing that the functions when used as the default
argument provide the location of the call site of the function, not the
location of the prototype.  Which is not the most obvious thing.

Trev

> 
> Martin
>