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[Bug c/51568] New: Enum value is not extracted properly via a union
- From: "eugene at hutorny dot in.ua" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 15 Dec 2011 15:55:58 +0000
- Subject: [Bug c/51568] New: Enum value is not extracted properly via a union
- Auto-submitted: auto-generated
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51568
Bug #: 51568
Summary: Enum value is not extracted properly via a union
Classification: Unclassified
Product: gcc
Version: 4.3.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: eugene@hutorny.in.ua
Target: ARM
Created attachment 26103
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26103
Test example
A wrong value is received when a value is assigned via union and read its
member.
Consider the following data structures:
enum en { v0, v1, v2, v3, v4, v5, v6, v7 };
struct rec {
unsigned short w;
unsigned char c;
enum en e;
} __attribute__((__packed__));
union un {
struct rec r;
unsigned v;
} __attribute__((__packed__));
void pass(unsigned v) {
union un u;
u.v = v;
printf("r.w=%X r.c=%d r.e=%d\n", u.r.w, u.r.c, u.r.e );
}
int main(int argc, char** argv) {
union un u;
u.r.c = '8';
u.r.e = v2;
u.r.w = 0xC5FF;
printf("r.w=%X r.c=%d r.e=%d\n", u.r.w, u.r.c, u.r.e );
pass(u.v);
return 0;
}
Sample above compiled with gcc (Debian 4.3.2-1.1) 4.3.2 prints the following:
r.w=C5FF r.c=56 r.e=2
r.w=C5FF r.c=56 r.e=34050
When compiled with arm-linux-gnueabi-gcc (Debian 4.3.2-1.1) 4.3.2 prints:
r.w=C5FF r.c=56 r.e=2
r.w=C5FF r.c=56 r.e=50434