Bug 56119
| Summary: | Segfault from code (w/ libstdc++) the compiler likes. | ||
|---|---|---|---|
| Product: | [Retired] Red Hat Linux | Reporter: | Ali-Reza Anghaie <ali> |
| Component: | libstdc++ | Assignee: | Jakub Jelinek <jakub> |
| Status: | CLOSED ERRATA | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | 7.2 | ||
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | i386 | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2001-11-28 12:19:08 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
Stuff I was too stupid to include the first time around:
$ rpm -q gcc libstdc++
gcc-2.96-98
libstdc++-2.96-98
And this:
#include <iostream.h>
#include <typeinfo>
using namespace std;
int main(){
cout << typeid(cout).name() << endl;
ostream& cref=cout;
cout << typeid(cref).name() << endl;
}
Behaves only marginally better. If it helps any....
Should be fixed by:
2001-11-28 Jakub Jelinek <jakub>
* stdstreams.cc (_fake_istream, _fake_ostream): Add vptr as
separate field.
(_vptr_ostream, _vptr_istream): New externs.
(OSTREAM_DEF, ISTREAM_DEF): Set vptr for standard streams.
* g++.old-deja/g++.other/rtti6.C: New test.
--- gcc/testsuite/g++.old-deja/g++.other/rtti6.C.jj Wed Nov 28 14:26:43 2001
+++ gcc/testsuite/g++.old-deja/g++.other/rtti6.C Wed Nov 28 14:27:27 2001
@@ -0,0 +1,14 @@
+// test whether rtti works correctly on cout
+// Special g++ Options: -O2
+
+#include <iostream>
+#include <typeinfo>
+
+using namespace std;
+
+int main ()
+{
+ typeid (cout);
+ ostream &cref=cout;
+ typeid (cref);
+}
--- libio/stdstreams.cc.jj Sat Sep 4 17:08:50 1999
+++ libio/stdstreams.cc Wed Nov 28 14:16:24 2001
@@ -78,7 +78,12 @@ struct _fake_istream {
#endif
} mine;
_ios_fields base;
+#if !defined(__GNUC__) || __GNUC__ != 2 || __GNUC_MINOR__ != 96
char filler[sizeof(struct istream)-sizeof(struct _ios_fields)+PAD];
+#else
+ char *vptr;
+ void *filler, *filler2;
+#endif
};
struct _fake_ostream {
struct myfields {
@@ -88,7 +93,12 @@ struct _fake_ostream {
_ios_fields *vb; /* pointer to virtual base class ios */
} mine;
_ios_fields base;
+#if !defined(__GNUC__) || __GNUC__ != 2 || __GNUC_MINOR__ != 96
char filler[sizeof(struct ostream)-sizeof(struct _ios_fields)+PAD];
+#else
+ void *vptr;
+ void *filler;
+#endif
};
@@ -101,14 +111,33 @@ struct _fake_ostream {
#endif
#ifdef __GNUC__
-#define OSTREAM_DEF(NAME, SBUF, TIE, EXTRA_FLAGS, ASM) \
+# if __GNUC__ == 2 && __GNUC_MINOR__ == 96
+# if defined(__i386__) || defined(__ia64__) || defined(__sparc__)
+extern char _vptr_ostream[] __asm ("__vt_22_IO_ostream_withassign.3ios");
+extern char _vptr_istream[] __asm ("__vt_22_IO_istream_withassign.3ios");
+# elif defined(__alpha__)
+extern char _vptr_ostream[] __asm ("__vt_22_IO_ostream_withassign$3ios");
+extern char _vptr_istream[] __asm ("__vt_22_IO_istream_withassign$3ios");
+# else
+# define _vptr_ostream NULL
+# define _vptr_istream NULL
+# endif
+# define OSTREAM_DEF(NAME, SBUF, TIE, EXTRA_FLAGS, ASM) \
+ _fake_ostream NAME ASM = { {&NAME.base}, {STD_STR(SBUF, TIE, EXTRA_FLAGS) }, \
+ _vptr_ostream };
+# define ISTREAM_DEF(NAME, SBUF, TIE, EXTRA_FLAGS) \
+ _fake_istream NAME = { {&NAME.base}, {STD_STR(SBUF, TIE, EXTRA_FLAGS) }, \
+ _vptr_istream };
+# else
+# define OSTREAM_DEF(NAME, SBUF, TIE, EXTRA_FLAGS, ASM) \
_fake_ostream NAME ASM = { {&NAME.base}, {STD_STR(SBUF, TIE, EXTRA_FLAGS) }};
-#define ISTREAM_DEF(NAME, SBUF, TIE, EXTRA_FLAGS) \
+# define ISTREAM_DEF(NAME, SBUF, TIE, EXTRA_FLAGS) \
_fake_istream NAME = { {&NAME.base}, {STD_STR(SBUF, TIE, EXTRA_FLAGS) }};
+# endif
#else
-#define OSTREAM_DEF(NAME, SBUF, TIE, EXTRA_FLAGS) \
+# define OSTREAM_DEF(NAME, SBUF, TIE, EXTRA_FLAGS) \
_fake_ostream NAME = { {0, &NAME.base}, {STD_STR(SBUF, TIE, EXTRA_FLAGS) }};
-#define ISTREAM_DEF(NAME, SBUF, TIE, EXTRA_FLAGS) \
+# define ISTREAM_DEF(NAME, SBUF, TIE, EXTRA_FLAGS) \
_fake_istream NAME = {{0, 0, &NAME.base}, {STD_STR(SBUF, TIE, EXTRA_FLAGS)}};
#endif
(standard streams were missing their vptr pointers in libio).
For gcc3+ this is not relevant, since for now it doesn't use libio at all.
I'll include this patch into gcc-2.96-102.
Seems to work in Valhalla but I forgot to try it in Skipjack I or II. I guess I'll close the bug. Thanks for the fix. An errata has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on the solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHBA-2002-055.html |
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.5) Gecko/20011012 Description of problem: Take this innocent snippet of code: #include <iostream> #include <typeinfo> using namespace std; int main(){ typeid(cout); ostream& cref=cout; typeid(cref); } $ g++ foo.cpp $ ./a.out Segmentation fault And the same thing happens with explicit std::cout as well. This happens with GCC 2.95.x and 2.96RH. Not able to reproduce in 3.0.x. Version-Release number of selected component (if applicable): How reproducible: Always Steps to Reproduce: 1. Copy code to <somefile>.cpp 2. g++ <somefile>.cpp 3. ./a.out Additional info: