【buildroot-2011.11】You may have to install 'g++' on your build machine

buildroot - 2011.11 当进行交叉编译。例如像以下错误提及演示：

“You may have to install 'g++' on your build machine”

还提示：toolchain/dependencies/dependencies.sh 121 Error

打开toolchain/dependencies/dependencies.sh，有例如以下一段脚本

# check for host CXX
CXXCOMPILER=$(which $HOSTCXX 2> /dev/null)
if [ -z "$CXXCOMPILER" ] ; then
    CXXCOMPILER=$(which c++ 2> /dev/null)
fi
if [ -z "$CXXCOMPILER" ] ; then
    /bin/echo -e "\nYou may have to install 'g++' on your build machine\n"
    #exit 1
fi
if [ ! -z "$CXXCOMPILER" ] ; then
    CXXCOMPILER_VERSION=$($CXXCOMPILER -v 2>&1 | sed -n '/^gcc version/p' |
        sed -e 's/^gcc version \([0-9\.]\)/\1/g' -e 's/[-\ ].*//g' -e '1q')
    
    if [ -z "$CXXCOMPILER_VERSION" ] ; then
        /bin/echo -e "\nYou may have to install 'g++' on your build machine\n"
    fi

    CXXCOMPILER_MAJOR=$(echo $CXXCOMPILER_VERSION | sed -e "s/\..*//g")
    CXXCOMPILER_MINOR=$(echo $CXXCOMPILER_VERSION | sed -e "s/^$CXXCOMPILER_MAJOR\.//g" -e "s/\..*//g")
    if [ $CXXCOMPILER_MAJOR -lt 3 -o $CXXCOMPILER_MAJOR -eq 2 -a $CXXCOMPILER_MINOR -lt 95 ] ; then
        /bin/echo -e "\nYou have g++ '$CXXCOMPILER_VERSION' installed.  g++ >= 2.95 is required\n"
        exit 1
    fi
fi

有两个地方会打印“You may have to install 'g++' on your build machine”，在这两个地方分别增加调试标记，发现是这里出问题了。

# check for host CXX
CXXCOMPILER=$(which $HOSTCXX 2> /dev/null)
if [ -z "$CXXCOMPILER" ] ; then
    CXXCOMPILER=$(which c++ 2> /dev/null)
fi
if [ -z "$CXXCOMPILER" ] ; then
    /bin/echo -e "\nYou may have to install 'g++' on your build machine\n"
    #exit 1
fi
if [ ! -z "$CXXCOMPILER" ] ; then
    CXXCOMPILER_VERSION=$($CXXCOMPILER -v 2>&1 | sed -n '/^gcc version/p' |
        sed -e 's/^gcc version \([0-9\.]\)/\1/g' -e 's/[-\ ].*//g' -e '1q')
    
    if [ -z "$CXXCOMPILER_VERSION" ] ; then
        /bin/echo -e "\nYou may have to install 'g++' on your build machine\n"
    fi


    CXXCOMPILER_MAJOR=$(echo $CXXCOMPILER_VERSION | sed -e "s/\..*//g")
    CXXCOMPILER_MINOR=$(echo $CXXCOMPILER_VERSION | sed -e "s/^$CXXCOMPILER_MAJOR\.//g" -e "s/\..*//g")
    if [ $CXXCOMPILER_MAJOR -lt 3 -o $CXXCOMPILER_MAJOR -eq 2 -a $CXXCOMPILER_MINOR -lt 95 ] ; then
        /bin/echo -e "\nYou have g++ '$CXXCOMPILER_VERSION' installed.  g++ >= 2.95 is required\n"
        exit 1
    fi
fi

原来他没有检查出来，CXXCOMPILER_VERSION为空。方便起见，我直接输入命令：

c++ -v 2>&1 | sed -n '/^gcc version/p' | sed -e 's/^gcc version \([0-9\.]\)/\1/g' -e 's/[-\ ].*//g' -e '1q'

得到C++的版本号为：4.4.6

我直接在CXXCOMPILER_VERSION上面加一个推理：CXXCOMPILER_VERSION=4.4.6
然后make,直接通过。

OK，问题解决为此。