GCC Bugzilla Bug 28706

$ cat foo.c
struct rb_node
{
} __attribute__((aligned(sizeof(long))));

extern struct rb_node *rb_prev(struct rb_node *);
extern struct rb_node *rb_prev(struct rb_node *);
 $ gcc -c --combine foo.c foo.c
foo.c:6: error: conflicting types for ‘rb_prev’
foo.c:5: error: previous declaration of ‘rb_prev’ was here

gcc version 4.1.1 20060525 (Red Hat 4.1.1-1.pr27898)

Removing the explicit alignment fixes the problem.

This works in 3.4.0 and 4.0.0 so this is either a regression or a bug in
redhat's compiler or a bug in the patch.

It is a regression.

Subject: Bug 28706

Author: jakub
Date: Sat Sep 23 07:15:37 2006
New Revision: 117167

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=117167
Log:
        PR c/28706
        PR c/28712
        * tree.c (merge_attributes, attribute_list_contained): If both
        TREE_VALUEs are TREE_LISTs, use simple_cst_list_equal instead of
        simple_cst_equal.
        * c-typeck.c (comptypes_internal): Don't consider aggregates
        in different TUs as compatible if there one set of attributes is
        not a subset of the other type's attributes.
        (composite_type): Try harder not to create a new aggregate type.

        * gcc.dg/pr28706.c: New test.
        * gcc.dg/pr28712.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr28706.c
    trunk/gcc/testsuite/gcc.dg/pr28712.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/c-typeck.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree.c

Created an attachment (id=13086) [edit]
backported to gcc 4.1.2

Is there any chance of this fix appearing in a release before 4.3.0? I have
backported it to 4.1.2 successfully. There was a trivial reject (indentation
changes only) and also I had to add { } around the contents of the 2nd hunk in
c-typeck.c

Let me know if I can help further.

How about posting the backported-and-tested patch to gcc-patches, indicating on
which platform you've tested it?

This seems to work as of gcc 4.2.2 (vanilla), using the original commands to
reproduce. Anyone denies/confirms this?

(In reply to comment #6)
> This seems to work as of gcc 4.2.2 (vanilla), using the original commands to
> reproduce. Anyone denies/confirms this?
> 

... and please see bug 34800 .

works for me with 4.3.1 and current trunk

Closing 4.1 branch.