gcc -Wconversion
なにが警告されているのかわからない。。
conversion.c
----------------------------------------
int main(void)
{
signed short ss;
unsigned short us;
ss = (signed short)0xFFFF;
ss &= (signed short)0xFF00;
us = (unsigned short)0xFFFFU;
us &= (unsigned short)0xFF00U;
return 0;
}
----------------------------------------
$ gcc-4 -Wconversion conversion.c
conversion.c: In function 'main':
conversion.c:8: warning: conversion to 'short unsigned int' from 'int' may alter its value
$ gcc-4 -v
Using built-in specs.
Target: i686-pc-cygwin
Configured with: /gnu/gcc/release/gcc4-4.3.2-1/src/gcc-4.3.2/configure --srcdir=/gnu/gcc/release/gcc4-4.3.2-1/src/gcc-4.3.2 --prefix=/usr --exec-prefix=/usr --bindir=/usr/bin --sbindir=/usr/sbin --libexecdir=/usr/sbin --localstatedir=/var --sysconfdir=/etc --datadir=/usr/share --infodir=/usr/share/info --mandir=/usr/share/man -v --with-gmp=/usr --with-mpfr=/usr --enable-bootstrap --enable-version-specific-runtime-libs --with-slibdir=/usr/bin --libexecdir=/usr/lib --enable-static --enable-shared --enable-shared-libgcc --enable-__cxa_atexit --with-gnu-ld --with-gnu-as --with-dwarf2 --disable-sjlj-exceptions --enable-languages=ada,c,c++,fortran,java,objc,obj-c++ --disable-symvers --enable-libjava --program-suffix=-4
Thread model: single
gcc version 4.3.2 20080827 (alpha-testing) 1 (GCC)