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* [Bug c++/40751] New: G++ never packs typedef'd enums
@ 2009-07-14 19:02 bryce dot schober at gmail dot com
2009-07-14 19:09 ` [Bug c++/40751] " bryce dot schober at gmail dot com
2009-07-14 22:31 ` bryce dot schober at gmail dot com
0 siblings, 2 replies; 3+ messages in thread
From: bryce dot schober at gmail dot com @ 2009-07-14 19:02 UTC (permalink / raw)
To: gcc-bugs
The following enumerated type definitions packs to one byte as expected in C,
but not in C++:
typedef enum __attribute__ ((packed)) {
ZERO = 0,
ONE,
TWO
} my_enum_t;
The enum will pack as expected if using -fshort-enums, but that doesn't allow
me to pack on a per-enum basis. Neither will the above enum pack as a packed
member in a structure or as a member in a packed structure.
Test case to follow.
--
Summary: G++ never packs typedef'd enums
Product: gcc
Version: 4.3.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: bryce dot schober at gmail dot com
GCC build triplet: i486-linux-gnu
GCC host triplet: i486-linux-gnu
GCC target triplet: i486-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40751
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c++/40751] G++ never packs typedef'd enums
2009-07-14 19:02 [Bug c++/40751] New: G++ never packs typedef'd enums bryce dot schober at gmail dot com
@ 2009-07-14 19:09 ` bryce dot schober at gmail dot com
2009-07-14 22:31 ` bryce dot schober at gmail dot com
1 sibling, 0 replies; 3+ messages in thread
From: bryce dot schober at gmail dot com @ 2009-07-14 19:09 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from bryce dot schober at gmail dot com 2009-07-14 19:09 -------
Created an attachment (id=18196)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18196&action=view)
test case
Built without warnings, to try to make sure I'm not doing something marginal:
gcc -Wall -Wextra -pedantic -lstdc++ -0 size size.c size.gcc
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40751
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c++/40751] G++ never packs typedef'd enums
2009-07-14 19:02 [Bug c++/40751] New: G++ never packs typedef'd enums bryce dot schober at gmail dot com
2009-07-14 19:09 ` [Bug c++/40751] " bryce dot schober at gmail dot com
@ 2009-07-14 22:31 ` bryce dot schober at gmail dot com
1 sibling, 0 replies; 3+ messages in thread
From: bryce dot schober at gmail dot com @ 2009-07-14 22:31 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from bryce dot schober at gmail dot com 2009-07-14 22:31 -------
I now see that the following syntax packs as expected:
typedef enum {
ZERO = 0,
ONE,
TWO
} __attribute__ ((packed)) my_enum_t;
I have been unable to find a concise definition of how attributes are supposed
to be used with types in either the Type-Attributes or Attribute-Syntax
sections of the GCC manual. I guess this location for the attribute is a bit
more logical in the sense that the type isn't "complete" until the closing
brace.
It remains unclear whether both attribute locations are supposed to be
supported in both C and C++ or not. Either way, it's certainly not clear from
the docs.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40751
^ permalink raw reply [flat|nested] 3+ messages in thread
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2009-07-14 19:02 [Bug c++/40751] New: G++ never packs typedef'd enums bryce dot schober at gmail dot com
2009-07-14 19:09 ` [Bug c++/40751] " bryce dot schober at gmail dot com
2009-07-14 22:31 ` bryce dot schober at gmail dot com
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