I would prefer this to generate a warning. The C language standard change you
refer to is a classic example of a misguided change, and any code whose
behavior depends on this deserves a warning message, NOT an option to work one
way or the other.
paul
-----Original Message-----
From: gcc-ow...@gcc.gnu.org [mailto:gcc-ow...@gcc.gnu.org] On Behalf Of Zoltán
Kócsi
Sent: Monday, January 30, 2012 5:03 PM
To: gcc@gcc.gnu.org
Subject: Assignment to volatile objects
Now that the new C standard is out, is there any chance that gcc's behaviour
regarding to volatile lhs in an assignment changes?
This is what it does today:
volatile int a, b;
a = b = 0;
translates to
b = 0;
a = b;
because the standard (up to and including C99) stated that the value of the
assignment operator is the value of the lhs after the assignment.
The C11 standard says the same but then it explicitely states that the compiler
does not have to read back the value of the lhs, not even when the lhs is
volatile.
So it is actually legal now not to read back the lhs. Is there a chance for the
compiler to get a switch which would tell it explicitely not to read the value
back?
Zoltan
