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Whats going on with the conversion warning?
- From: Andy H <hutchinsonandy at aim dot com>
- To: GCC Development <gcc at gcc dot gnu dot org>
- Date: Mon, 19 May 2008 22:20:35 -0400
- Subject: Whats going on with the conversion warning?
I came across this odd issue with testsuite test Wconversion-5.c and AVR
target.
I should get warning going from a unsigned value that is wider than
signed result.
As I am not skilled in the art of the all conversions rules. I would
appreciate some guidance before I report this as bug.
FYI AVR has 16 bit int, 16 bit short int and 32 bit long.
I extracted the problematic line with a few variants and compiled -O0
and -Wconversion,
void foo(void)
{
signed char sc;
signed char xi;
xi = (int) (unsigned short int) sc; /* testcase NO WARNING - think
this is bug*/
xi = (unsigned short int) sc; /* NO WARNING - think this is bug*/
xi = (long) (unsigned short int) sc; /* warning: conversion to
'signed char' from 'short unsigned int' may alter its value - correct*/
xi = (long) ( short int) sc; /* NO WARNING - correct */
}
It would seem Wconversion:want to see 32bit result before it gives warning.
That can't be right - can it?
best regards