https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111946
Bug ID: 111946
Summary: bogus cast increases required alignment for a simple
class
Product: gcc
Version: 13.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: objc
Assignee: unassigned at gcc dot gnu.org
Reporter: rm at gnu dot org
Target Milestone: ---
Created attachment 56183
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56183&action=edit
super-trivial class
In the GNUstep project I noticed that I got very often a "warning: cast
increases required alignment of target type [-Wcast-align]" in most files, but
didn't see it always. The classes look fine. I tracked it down to be an
architecture problem. It does not happen e.g. on x86 and amd64, but happens on
sparc64, mips32-le. It happens since many GCC version and it is still present
in 13.2
At the time of writing, I could quickly reproduce it on 7.5.0, 10.2.1 and
13.2.0.
The problem can be reduced to an as trivial class like the attached file. On
more current compiler versions an issue about no root class found is issued,
but in practice this is not the case, we usually use the NSObject root class,
this is just the most minimal trivial example.
Since it happens even with old gcc versions and continues to, I could test on a
variety of platforms.
Compilation command:
gcc Polygon.m -c -Wcast-align
To sum up:
x86 (32bit LE) : NO
amd64 (64bit LE) : NO
MIPS (32bit LE) : YES
sparc (32bit BE) : YES
sparc (64bit BE) : YES
PPC (32bit BE) : NO
I don't see an immediate pattern here
