[Bug c/60018] New: Bogus conversion warning with optimization flag -O1

[chengniansun at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60018

            Bug ID: 60018
           Summary: Bogus conversion warning with optimization flag -O1
           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

The -Wconversion should not be affected by the optimization flags. 

For the following code, Gcc emits no warning with flag -O0, but one conversion
warning with flag -O1. 



$: cat s.c
extern void fn1(unsigned);
extern void fn3(void);
void fn2(void);
void fn2() {
  fn1((fn3(), 0) || 0);
}
$: gcc-trunk -c -Wconversion -std=c11 -O0 s.c
$: gcc-trunk -c -Wconversion -std=c11 -O1 s.c
s.c: In function ‘fn2’:
s.c:5:7: warning: conversion to ‘unsigned int’ from ‘int’ may change the sign
of the result [-Wsign-conversion]
   fn1((fn3(), 0) || 0);
       ^
$: gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/home/chengniansun/tools/gcc-trunk-binaries/libexec/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure --enable-languages=c,c++
--disable-multilib --prefix=/home/chengniansun/tools/gcc-trunk-binaries :
(reconfigured) ../gcc-trunk/configure --enable-languages=c,c++
--disable-multilib --prefix=/home/chengniansun/tools/gcc-trunk-binaries :
(reconfigured) ../gcc-trunk/configure --enable-languages=c,c++
--disable-multilib --prefix=/home/chengniansun/tools/gcc-trunk-binaries
Thread model: posix
gcc version 4.9.0 20140131 (experimental) (GCC)