Hi all,
I have two problems (maybe I misunderstanding something, or maybe I
don't know something).
1) Is it possible to pack structure in c++11 instead of using attribute
packed (__attribute__((packed)))? There is alignas keyword for
structures and classes but using alignas(1) doesn't change structure.
alignas with '1' value is accepted by compiler but default align is used.
2) What is going on third line exactly (for x86_64/i686/avr machine):
/*0:*/ typedef uint8_t u8;
/*1:*/ static u8 MAIN_DDR;
/*2:*/ constexpr u8 BV(u8 v) { return static_cast<u8>(1 << v); }
/*3:*/ inline void setPinAsOut(u8 PIN) { MAIN_DDR |= BV(PIN); }
I want use -Wconversion option, but this option raises warning
for third line:
warning: conversion to ‘u8 {aka unsigned char}’ from ‘int’ may alter its
value [-Wconversion]
inline void setPinAsOut(u8 PIN) { MAIN_DDR |= BV(PIN); }
But types operates on 8 bits, so why compiler uses here bigger type? Or
maybe it's a bug?
This line can be resolved by:
MAIN_DDR = MAIN_DDR | BV(PIN);
or by adding static_cast, but IMO it's not good;-/
The same to & operator, but changing line to:
MAIN_DDR = MAIN_DDR & BV(PIN);
doesn't resolve problem.
I'm using compilers in versions: 4.7.2, 4.8.3, 4.9.
Regards
Zygmunt
