https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124003
Bug ID: 124003
Summary: Using an aligned attribute in a typedef used for a
field is not the same as indicating the attribute on
the type of the field
Product: gcc
Version: 15.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: [email protected]
Target Milestone: ---
Created attachment 63608
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=63608&action=edit
Sample file reproducing the problem
First of all, we are not sure that this is a bug. We found it while trying to
replicate the behavior of GCC in an analyzer for C.
The sample file is attached.
The result that we get is:
field_t : size 2 -- align 1
struct S1: size 3 -- align 1
struct S2: size 4 -- align 2
struct S3: size 3 -- align 1
We would have expected to be either:
field_t : size 2 -- align 1
struct S1: size 3 -- align 1
struct S2: size 3 -- align 1
struct S3: size 3 -- align 1
or (even if it would be still surprising) :
field_t : size 2 -- align 1
struct S1: size 4 -- align 2
struct S2: size 4 -- align 2
struct S3: size 3 -- align 1
It seems like when using an attribute in a typedef, if we use it for the type
of a field, the attribute is attached to the field instead of being attached to
the type, which is surprising.
Is it expected? If so, can someone explain the semantics of this code?
I found two issues that may be related, but I am not sure that it is the same:
- https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109824
- https://gcc.gnu.org/bugzilla/show_bug.cgi?id=46354
