Different results on all three versions of g++ [2.95.3, 3.3.3, 4.0.0].
Only 2.95.3 produces the desired output.
After investigating the bug list, several potential duplicates have been
dismissed as not being the same issue, as listed below:
8542
10156
11098
24526
The issue was first noticed on a SunOS 5.8 SunFire V210 server when trying to
upgrade from gcc 2.95.2 to gcc 3.3.3. All of the following scenarios are
reproducible on gdb 6.3 and 6.4.
When trying to debug the following block of code, some of the function's local
variables can not be displayed using display, print, or info scope [function].
Display and print will work after a certain point within the stack frame of the
function foo(), but long after the variables are initialized. Please examine
the following source code and output.
#include <string>
using std::string;
#include <map>
using std::map;
class myElem
{
};
class myMap : public map<string, myElem>
{
};
class myClass
{
};
int
foo(myClass& asset)
{
int rcode(0);
unsigned int n;
n = 0;
switch(n)
{
default:
break;
}
#ifndef GOODDBG
map<string, myElem> nfacts;
#endif
myElem mfacts;
return rcode;
}
int
main(int argc, char *argv[])
{
myClass c;
foo( c );
return 0;
}
-------------------------------
!!! MISSING THREE SYMBOLS !!!
> g++3.3.3 -Wno-deprecated -gstabs+ -o test test.C
> gdb test
GNU gdb 6.3
Copyright 200....
(gdb) info scope foo
Scope for foo:
Symbol asset is an argument at stack/frame offset 68, length 4.
Symbol mfacts is a local variable at frame offset -41, length 1.
!!! MISSING ONE SYMBOL !!!
> g++3.3.3 -Wno-deprecated -gstabs+ -DGOODDBG -o test test.C
> gdb test
GNU gdb 6.3
Copyright 200....
(gdb) info scope foo
Scope for foo:
Symbol asset is an argument at stack/frame offset 68, length 4.
Symbol rcode is a local variable at frame offset -20, length 4.
Symbol n is a local variable at frame offset -24, length 4.
Symbol mfacts is a local variable at frame offset -25, length 1.
!!! MISSING ONE SYMBOL !!!
> g++4.0.0 -Wno-deprecated -gstabs+ -o test test.C
> gdb test
GNU gdb 6.3
Copyright 200....
(gdb) info scope foo
Scope for foo:
Symbol asset is an argument at stack/frame offset 68, length 4.
Symbol rcode is a local variable at frame offset -24, length 4.
Symbol n is a local variable at frame offset -20, length 4.
Symbol nfacts is a local variable at frame offset -48, length 24.
!!! WORKS CORRECTLY !!!
> g++2.95.2 -Wno-deprecated -gstabs+ -o test test.C
> gdb test
GNU gdb 6.3
Copyright 200....
(gdb) info scope foo
Scope for foo:
Symbol asset is an argument at stack/frame offset 68, length 4.
Symbol rcode is a local variable at frame offset -20, length 4.
Symbol n is a local variable at frame offset -24, length 4.
Symbol nfacts is a local variable at frame offset -40, length 12.
Symbol mfacts is a local variable at frame offset -41, length 1.
Based on the fact that changing the GOODDBG flag alters the appearance of
unrelated symbols in the debugger, it seems like this is not the desired effect
due to optimization or for any other logical reason.
--
Summary: [2.95.2/3.3.3/4.0.0 Regression] g++ fails to emit debug
information for SOME local variables in class member
function that has templated local variables
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: debug
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: schaudhu at blackrock dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25234
