--- Comment #6 from manu at gcc dot gnu dot org 2009-07-07 10:25 ---
(In reply to comment #5)
Thus code is undefined you have an acess of a char array as a struct.
Yes you are only taking the address of an element but it is still
considered an acess by the standards.
I see
--- Comment #7 from mikulas at artax dot karlin dot mff dot cuni dot cz
2009-07-07 16:31 ---
extern int c;
int a(void)
{
return *(short *)(void *)c;
}
This is a very bad example of a false positive as you are acessing an
int as a short; that is undefined. I will
--- Comment #9 from pinskia at gcc dot gnu dot org 2009-07-07 16:54 ---
So you say that converting the char * pointer to struct * pointer is understood
as accessing the stored value by the standard?
No.
Let's look at the code:
char buffer[512];
(void *)((struct structure *)(void
--- Comment #8 from mikulas at artax dot karlin dot mff dot cuni dot cz
2009-07-07 16:45 ---
Thus code is undefined you have an acess of a char array as a struct.
Yes you are only taking the address of an element but it is still
considered an acess by the standards.
Why is it
--- Comment #10 from mikulas at artax dot karlin dot mff dot cuni dot cz
2009-07-07 18:07 ---
So you mean that that -x operator is invalid and break the standard?
Anyway the standard means if you write your code according to the standard =
the code will run correctly, but the inverse
--- Comment #11 from pinskia at gcc dot gnu dot org 2009-07-07 18:18
---
(In reply to comment #10)
For example, you write unsigned char *framebuffer = vga_getgraphmem(); and
now you want to access the framebuffer. According to the standard, you could
only do it by bytes. But that
--- Comment #12 from mikulas at artax dot karlin dot mff dot cuni dot cz
2009-07-07 19:40 ---
So if there was char *buffer = malloc(512) instead of char buffer[512], would
it be correct to cast it to the pointer to structure?
And it is not about the cast between the pointer types
--- Comment #13 from pinskia at gcc dot gnu dot org 2009-07-07 20:24
---
(In reply to comment #12)
So if there was char *buffer = malloc(512) instead of char buffer[512], would
it be correct to cast it to the pointer to structure?
Yes.
And it is not about the cast between the
--- Comment #1 from mikulas at artax dot karlin dot mff dot cuni dot cz
2009-07-07 01:22 ---
Created an attachment (id=18145)
-- (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18145action=view)
a bug in -Wstrict-aliasing=3
This is an example of a flaw in -Wstrict-aliasing=3 (this
--- Comment #2 from mikulas at artax dot karlin dot mff dot cuni dot cz
2009-07-07 01:34 ---
Created an attachment (id=18146)
-- (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18146action=view)
a bug in -Wstrict-aliasing=3
This is an example of a flaw in -Wstrict-aliasing=3 (this
--- Comment #3 from pinskia at gmail dot com 2009-07-07 03:44 ---
Subject: Re: New: dereferencing type-punned pointer warnings cannot be
disabled
Sent from my iPhone
On Jul 6, 2009, at 6:12 PM, mikulas at artax dot karlin dot mff dot
cuni dot cz gcc-bugzi...@gcc.gnu.org wrote:
Sent from my iPhone
On Jul 6, 2009, at 6:34 PM, mikulas at artax dot karlin dot mff dot
cuni dot cz gcc-bugzi...@gcc.gnu.org wrote:
--- Comment #2 from mikulas at artax dot karlin dot mff dot cuni
dot cz 2009-07-07 01:34 ---
Created an attachment (id=18146)
--
--- Comment #4 from pinskia at gmail dot com 2009-07-07 03:48 ---
Subject: Re: dereferencing type-punned pointer warnings cannot be disabled
Sent from my iPhone
On Jul 6, 2009, at 6:34 PM, mikulas at artax dot karlin dot mff dot
cuni dot cz gcc-bugzi...@gcc.gnu.org wrote:
Thus code is undefined you have an acess of a char array as a struct.
Yes you are only taking the address of an element but it is still
considered an acess by the standards.
Sent from my iPhone
On Jul 6, 2009, at 6:34 PM, mikulas at artax dot karlin dot mff dot
cuni dot cz
--- Comment #5 from pinskia at gmail dot com 2009-07-07 03:50 ---
Subject: Re: dereferencing type-punned pointer warnings cannot be disabled
Thus code is undefined you have an acess of a char array as a struct.
Yes you are only taking the address of an element but it is still
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