[Bug c/60069] New: Different warning messages for -Wconversion with different optimization levels

["chengniansun at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60069

            Bug ID: 60069
           Summary: Different warning messages for -Wconversion with
                    different optimization levels
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: chengniansun at gmail dot com

For the following code, gcc with -O0 emits a conversion warning, and gcc with
-O1 emits an overflow warning. 

Does gcc have a similar policy to Clang that warnings should be not affected by
optimization levels? 


$: cat s.c
void fn1() {
  unsigned short *l_432;
  const long l_448 = 70758;
  *l_432 = +l_448;
}
$: gcc-trunk -O0 -c -Wconversion s.c
s.c: In function âfn1â:
s.c:4:12: warning: conversion to âshort unsigned intâ from âlong intâ may alter
its value [-Wconversion]
   *l_432 = +l_448;
            ^
$: gcc-trunk -O1 -c -Wconversion s.c
s.c: In function âfn1â:
s.c:4:12: warning: large integer implicitly truncated to unsigned type
[-Woverflow]
   *l_432 = +l_448;
            ^
$: gcc-trunk --version
gcc-trunk (GCC) 4.9.0 20140204 (experimental)
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.