Re: "Size of symbol changed" warnings building EPICS Base 3.14.12.2

[Dirk Zimoch <dirk.zimoch@psi.ch>]

Andrew Johnson wrote:
> Hi Dirk,
>
> Interesting, good detective work!
>
> On 2012-03-20 Dirk Zimoch wrote:
> > In cac.cpp we find:
> > #define epicsAssertAuthor "Jeff Hill johill@lanl.gov"
> >
> > But in templateInstances.cpp epicsAssertAuthor is not defined.
> So does defining it there fix the problem?
>
> - Andrew
It will remove the warning. But is that a fix?

Consider code where epicsAssertAuthor is A where the template is inlined 
and B where the template is explicitly instantiated. Depending on the 
Optimization flag, you get different behavior! Here, is it only a 
message text, but it may be worse.
BEWARE: PHILOSOPHY!

It seems that using macros, including 'assert', in any inline code is 
simply wrong programming. However, I cannot remember that I have ever 
seen such a statement in any C++ book. It seems logical when you 
consider what inline means and what macros are made for. They are simply 
incompatible. But typically C++ books only say things like: "With C++ 
inline code, you don't need macros any more. Inline code is much better, 
type safe, etc than macros." Unfortunately that is a lie. It is hard to 
get inline code right and you cannot do everything with inline code that 
you can do with macros.

Of course something like

template <class T>
T max(T a, T b) { return (a < b) ? b : a; }

is better than

#define max(a,b) ( (a) < (b) ? (b) : (a) )

when used in a context like max(getchar(), i++)

But often life is is more complicated than this.

Inline code is better than macros if you are a very experienced and 
professional C++ programmer. Otherwise you will suffer from the one 
million pitfalls in C++. And still you cannot do something like 'assert' 
in C++ inline code.
END PHILOSOPHY.

Maybe this is the wrong part:

#ifndef epicsAssertAuthor
#   define epicsAssertAuthor 0
#endif

In base, only Jeff ever sets epicsAssertAuthor. So we can replace it 
with a constant :-)
Dirk