Re: [avr-gcc-list] Wrong excution order in 4.1.1, but not 3.4.5,regression?

[Graham Davies]

David Brown wrote (in part):

> ...  I don't know if the C standard is clear on expressions such as "a = b 
> = c", when some or all of these are volatile ...

It is clear.  The assignment operator has right-to-left associativity so b = 
c is evaluated first.  The result of an assignment is the value assigned. 
So, the value assigned to b is then assigned to a.  I can't see how volatile 
could affect this, but it certainly can't make things less well-defined.

> At the risk of sounding patronising, I'd say that almost any code with
> "a = b = c" expressions is incorrect code because it is far from clear
> what you mean, and if volatiles are involved then it is undoubtedly wrong.

You don't sound patronizing, just wrong.

> When the code is re-written to actually say what you mean, do you still 
> get a difference?

This is a useful question/suggestion, however, and may shed some light on 
the problem.

Graham.