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c++ - Getting weird warnings

reply "Jim Jennings" <jwjenn mindspring.com> writes:
This program works, but what are these warnings all about? The program
compiles on g++ and bcc32 without complaint. From STL Tutorial and
Reference, Second Edition, Musser, Derge, Saini
 ex02-08.cpp, pp. 29-30

// Demonstrating the generic find algorithm with a deque
#include <iostream>
#include <cassert>
#include <deque>
#include <algorithm>  // For find
using namespace std;
template <typename Container>
Container make(const char s[])
{
  return Container(&s[0], &s[strlen(s)]);
}

int main()
{
  cout << "Demonstrating generic find algorithm with "
       << "a deque." << endl;
  deque<char> deque1 =
    make< deque<char> >("C++ is a better C");

  // Search for the first occurrence of the letter e:
  deque<char>::iterator
    where = find(deque1.begin(), deque1.end(), 'e');
  assert (*where == 'e' && *(where + 1) == 't');
  cout << " --- Ok." << endl;
  return 0;
}:

 C:\dm\bin\sc -Ae -C -WA -S -5 -a8 -o ex02-08.exe
ex02-08.cpp -I\dm\stlport\stlport
ex02-08.cpp(27) : Warning 12: variable 'char ** __cur_node' used before set
ex02-08.cpp(27) : Warning 12: variable 'char ** __cur' used before set
ex02-08.cpp(27) : Warning 12: variable 'char ** __cur' used before set
link ex02-08,ex02-08,,user32+kernel32/noi;
Apr 09 2003
parent reply "Matthew Wilson" <dmd synesis.com.au> writes:
I've had some similar ones from STLPort. I think it's because some STLPort
functions throw as the last action within function bodies, so there's no
return statement.

Oh, no, sorry. That was my errors. Doesn't seem to be the explanation for
yours.

I'd like to put some effort into the STLPort, if no-one else is - if they
are then am more than happy to leave it - but time's not going to be
friendly for a while.

Is there someone that has taken the STLPort under their wing? (Is that
Christof?)



"Jim Jennings" <jwjenn mindspring.com> wrote in message
news:b72m69$1oin$1 digitaldaemon.com...

 This program works, but what are these warnings all about? The program
 compiles on g++ and bcc32 without complaint. From STL Tutorial and
 Reference, Second Edition, Musser, Derge, Saini
  ex02-08.cpp, pp. 29-30

 // Demonstrating the generic find algorithm with a deque
 #include <iostream>
 #include <cassert>
 #include <deque>
 #include <algorithm>  // For find
 using namespace std;
 template <typename Container>
 Container make(const char s[])
 {
   return Container(&s[0], &s[strlen(s)]);
 }

 int main()
 {
   cout << "Demonstrating generic find algorithm with "
        << "a deque." << endl;
   deque<char> deque1 =
     make< deque<char> >("C++ is a better C");

   // Search for the first occurrence of the letter e:
   deque<char>::iterator
     where = find(deque1.begin(), deque1.end(), 'e');
   assert (*where == 'e' && *(where + 1) == 't');
   cout << " --- Ok." << endl;
   return 0;
 }:

  C:\dm\bin\sc -Ae -C -WA -S -5 -a8 -o ex02-08.exe
 ex02-08.cpp -I\dm\stlport\stlport
 ex02-08.cpp(27) : Warning 12: variable 'char ** __cur_node' used before


set

 ex02-08.cpp(27) : Warning 12: variable 'char ** __cur' used before set
 ex02-08.cpp(27) : Warning 12: variable 'char ** __cur' used before set
 link ex02-08,ex02-08,,user32+kernel32/noi;
Apr 09 2003
parent reply Richard Grant <fractal clark.net> writes:
In article <b72obm$1ptq$1 digitaldaemon.com>, Matthew Wilson says...


I'd like to put some effort into the STLPort, if no-one else is - if they
are then am more than happy to leave it - but time's not going to be
friendly for a while.

Is there someone that has taken the STLPort under their wing? (Is that
Christof?)


While I can't speak for Christof, I can say that if I have serious problems with
stlport, Christof is the one I'm going to go begging to.

As for the warnings, I mentioned in a much earlier thread that these were
warnings that appeared whenever a release build was made using deque (and
possibly a few others). I also added that they were annoying, but probably
harmless since no one has tracked them down. Since the thread has appeared
again, they are no longer "harmless" as they are wasting time.. so:

void fn(int i) { }

int main() {
int i;
try {

} catch (...) {
fn(i);
}
}
// Warning 12: variable 'int  i' used before set

This is a design point made in STL for efficiency. __cur_node is assigned inside
the try block, and exceptions can only be thrown after the assignment. 

I don't know what Walter wants to do with this. Warnings are generated for
optimized builds, but not for non optimized builds.

Richard
Apr 10 2003
next sibling parent reply "Jim Jennings" <jwjenn mindspring.com> writes:
"Richard Grant" <fractal clark.net> wrote in message
news:b74gfm$2uo7$1 digitaldaemon.com...

 In article <b72obm$1ptq$1 digitaldaemon.com>, Matthew Wilson says...


 Since the thread has appeared

 again, they are no longer "harmless" as they are wasting time.. so:

 void fn(int i) { }

 int main() {
 int i;
 try {

 } catch (...) {
 fn(i);
 }
 }
 // Warning 12: variable 'int  i' used before set


 Richard


I discovered that the warning messages are caused by the space between
the -o flag and the output file name in the command line:

C:\dm\bin\sc -Ae -C -WA -S -5 -a8 -o ex02-08.exe
ex02-08.cpp -I\dm\stlport\stlport

Take out the space and the warnings go away.
I will not waste any more time of my time.
Jim J.
Apr 10 2003
parent reply "Walter" <walter digitalmars.com> writes:
"Jim Jennings" <jwjenn mindspring.com> wrote in message
news:b74u7v$5rk$1 digitaldaemon.com...

 I discovered that the warning messages are caused by the space between
 the -o flag and the output file name in the command line:

 C:\dm\bin\sc -Ae -C -WA -S -5 -a8 -o ex02-08.exe
 ex02-08.cpp -I\dm\stlport\stlport

 Take out the space and the warnings go away.
 I will not waste any more time of my time.
 Jim J.


-o by itself means "optimize". -ofilename means write the output to
filename.
Apr 10 2003
parent reply "Jim Jennings" <jwjenn mindspring.com> writes:
"Walter" <walter digitalmars.com> wrote in message
news:b753dc$9bu$2 digitaldaemon.com...

 "Jim Jennings" <jwjenn mindspring.com> wrote in message
 news:b74u7v$5rk$1 digitaldaemon.com...

 I discovered that the warning messages are caused by the space between
 the -o flag and the output file name in the command line:

 C:\dm\bin\sc -Ae -C -WA -S -5 -a8 -o ex02-08.exe
 ex02-08.cpp -I\dm\stlport\stlport

 Take out the space and the warnings go away.
 I will not waste any more time of my time.
 Jim J.


 -o by itself means "optimize". -ofilename means write the output to
 filename.


I am using a makefile written for the GNU compiler, that I adapted for dmc.
g++ has an option -o <file> "place output into file", (with space). That's
the way the makefile is written, -o $   -- with a space -- and it compiles
with g++. I think that -ofilename  and -o optimizer flag (whatever they are)
is a very fine distinction. Probably not one person in a thousand coming
over from gcc would be diligent enough to catch the difference.
However, all this is beside the point. Digital Mars is now relegated to file
13. Apparently everyone is happy working around the bugs and gratuitous
warnings. So there is no point in posting them anymore.
Apr 10 2003
parent "Walter" <walter digitalmars.com> writes:
"Jim Jennings" <jwjenn mindspring.com> wrote in message
news:b758nl$cma$1 digitaldaemon.com...

 I am using a makefile written for the GNU compiler, that I adapted for


dmc.

 g++ has an option -o <file> "place output into file", (with space). That's
 the way the makefile is written, -o $   -- with a space -- and it compiles
 with g++. I think that -ofilename  and -o optimizer flag (whatever they


are)

 is a very fine distinction. Probably not one person in a thousand coming
 over from gcc would be diligent enough to catch the difference.
 However, all this is beside the point. Digital Mars is now relegated to


file

 13. Apparently everyone is happy working around the bugs and gratuitous
 warnings. So there is no point in posting them anymore.


If I changed the way the command line worked, it would break innumerable
existing makefiles. It's not really an option to do that. Every compiler has
odd command line syntax in one way or another, there's no standard, it's all
in what you're used to. The existing syntax was not really designed to be
that way, it is an accumulation of 20 years of adding features while
retaining backward compatibility.

In the unix world, it's convention to put a space between a switch and its
argument. In the DOS/Win32 world, the convention is to not have a space
between. Neither is wrong or right, it's just convention.

What I do with projects for multiple compilers is just go ahead and do a
unique makefile for each compiler.
Apr 10 2003
prev sibling parent "Jim Jennings" <jwjenn mindspring.com> writes:
"Richard Grant" <fractal clark.net> wrote in message
news:b74gfm$2uo7$1 digitaldaemon.com...

 In article <b72obm$1ptq$1 digitaldaemon.com>, Matthew Wilson says...


 Since the thread has appeared

 again, they are no longer "harmless" as they are wasting time.. so:

 void fn(int i) { }

 int main() {
 int i;
 try {

 } catch (...) {
 fn(i);
 }
 }
 // Warning 12: variable 'int  i' used before set

 This is a design point made in STL for efficiency. __cur_node is assigned


inside

 the try block, and exceptions can only be thrown after the assignment.

 Richard


I am missing something here? What are you saying? That I should put a
try/catch sequence in my source code to suppress a compiler warning? Or did
I overlook another smiley?
James
Apr 10 2003