Bug 28712 - [4.1 Regression] Compile failure with --combine and packed structures.
Summary: [4.1 Regression] Compile failure with --combine and packed structures.
Status: RESOLVED FIXED
Alias: None
Product: gcc
Classification: Unclassified
Component: c (show other bugs)
Version: 4.1.1
: P2 normal
Target Milestone: 4.2.0
Assignee: Jakub Jelinek
URL: http://gcc.gnu.org/ml/gcc-patches/200...
Keywords: rejects-valid
Depends on:
Blocks: 28779
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Reported: 2006-08-13 23:36 UTC by David Woodhouse
Modified: 2008-07-04 15:49 UTC (History)
4 users (show)

See Also:
Host:
Target:
Build:
Known to work: 3.4.0 4.2.0
Known to fail: 4.0.0 4.0.4 4.1.0 4.1.3
Last reconfirmed: 2006-08-14 17:47:00

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Description David Woodhouse 2006-08-13 23:36:00 UTC 
$ cat foo.i
struct tss_struct;

extern struct tss_struct *doublefault_tss;

struct tss_struct {
} __attribute__((packed));

 $ gcc -c --combine foo.i foo.i
 $ gcc -c --combine foo.i foo.i foo.i
foo.i:3: error: conflicting types for ‘doublefault_tss’
foo.i:3: error: previous declaration of ‘doublefault_tss’ was here

Removing the packed attribute, or compiling only _two_ of them together, makes it work.

Seen with ppc->i686 GCC 4.1.0 and also
Fedora PowerPC gcc version 4.1.1 20060525 (Red Hat 4.1.1-1.pr27898)

(Both with Alex's patch for pr27898).
Comment 1 Andrew Pinski 2006-08-13 23:46:15 UTC 
Confirmed, this worked in 3.4.0.
Comment 2 Joseph S. Myers 2006-08-15 16:03:27 UTC 
The C front end part of the patch is OK.
Comment 3 Jakub Jelinek 2006-09-23 07:15:49 UTC 
Subject: Bug 28712

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
Comment 4 Gabriel Dos Reis 2007-02-03 18:55:21 UTC 
won't fix in GCC-4.0.x.  Adjusting milestone.
Comment 5 Alexandre Pereira Nunes 2008-01-15 17:58:50 UTC 
(In reply to comment #4)
> won't fix in GCC-4.0.x.  Adjusting milestone.
> 

For anyone interested, I think this is fixed for at least gcc 4.2.2; I couldn't reproduce it.
Comment 6 Joseph S. Myers 2008-07-04 15:49:38 UTC 
Closing 4.1 branch.