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Subject: [Bug c++/51427] New: Less-than-useful error message when union/struct tags conflict
Date: Mon, 05 Dec 2011 20:52:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D51427

             Bug #: 51427
           Summary: Less-than-useful error message when union/struct tags
                    conflict
    Classification: Unclassified
           Product: gcc
           Version: 4.6.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ajax@redhat.com
                CC: dodji@gcc.gnu.org


[ajax@f17 tmp]$ cat test.c
#ifdef __cplusplus
extern "C" {
#endif
    typedef struct _GMutex GMutex;
    typedef union _GMutex GMutex;
#ifdef __cplusplus
};
#endif

[ajax@f17 tmp]$ g++ -Wall -c -o test.o test.c
test.c:5:19: error: =E2=80=98union=E2=80=99 tag used in naming =E2=80=98str=
uct _GMutex=E2=80=99 [-fpermissive]

This message is unhelpful.  At the very least it should say where the
conflicting typedef came from, since it could easily be in a different file=
.=20
The text itself is a bit unclear as well, something more like "GMutex alrea=
dy
defined as 'struct _GMutex' at ..." might be better.

Note that the C frontend gets this right already:

[ajax@f17 tmp]$ gcc -Wall -c -o test.o test.c
test.c:5:19: error: =E2=80=98_GMutex=E2=80=99 defined as wrong kind of tag
test.c:5:27: error: conflicting types for =E2=80=98GMutex=E2=80=99
test.c:4:28: note: previous declaration of =E2=80=98GMutex=E2=80=99 was here