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From: Martin Str|mberg <ams AT ludd DOT luth DOT se>
Message-Id: <200203171452.g2HEqVZ04604@speedy.ludd.luth.se>
Subject: -Wsign-compare makes gcc complain about bool?unsigned:signed
To: gcc-bugs AT gcc DOT gnu DOT org
Date: Sun, 17 Mar 2002 15:52:31 +0100 (CET)
CC: DJGPP-WORKERS <djgpp-workers AT delorie DOT com>
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Reply-To: djgpp-workers AT delorie DOT com

gcc --version reports:
3.04

My platform is DJGPP (run in WINDOZE 98).

This program

#include <stdio.h>

int main(void)
{
  unsigned int u;
  int s;
  
  unsigned long long ll = u?u:s;

  printf("ll = %llu.\n", ll);

  return( 0 );

}

compiled with "gcc -O2 -g -Wall c.c -o c -Wsign-compare" gives

c.c: In function `main':
c.c:8: warning: signed and unsigned type in conditional expression
c.c:5: warning: `u' might be used uninitialized in this function
c.c:6: warning: `s' might be used uninitialized in this function

I have no problem with line 5 and 6.

But line 8. Why is that wrong? And why does -Wsign-compare trigger
this warning when it's not a comparison?


Right,

						MartinS