关于C#7.0: ValueTuple compile error

C# 7 ValueTuple compile error

我正在使用VS2017 RC，我的应用程序目标是NET Framework 4.6.1。

我有两个引用System.ValueTuple 4.3的程序集

我的项目服务我的项目.webapi

在myproject.services中，我有一个类具有这样的方法

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public async Task<(int fCount, int cCount, int aCount)> GetAllStatsAsync()
{
// Some code...
return (fCount, cCount, aCount);
}

在myproject.webapi中，我有一个使用如下方法的控制器：

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public async Task<HttpResponseMessage> GetInfoAsync()
{
// Some code...
var stats = await _myClass.GetAllStatsAsync();

var vm = new ViewModel
{
FCount = stats.fCount,
CCount = stats.cCount,
ACount = stats.aCount
};

return Request.CreateResponse(HttpStatusCode.OK, vm);
}

IntelliSense正在工作并解构元组，但是当我编译它时，它会在错误列表窗口中没有任何错误而失败。在输出窗口中，我有以下错误：

2>MyController.cs(83,31,83,40): error CS1061: 'ValueTuple' does not contain a definition for 'fCount' and no extension
method 'fCount' accepting a first argument of type 'ValueTuple' could be found (are you missing a using directive or an
assembly reference?) 2>MyController.cs(84,39,84,49): error CS1061:
'ValueTuple' does not contain a definition for 'cCount'
and no extension method 'cCount' accepting a first argument of type
'ValueTuple' could be found (are you missing a using
directive or an assembly reference?) 2>MyController.cs(85,35,85,40):
error CS1061: 'ValueTuple' does not contain a
definition for 'aCount' and no extension method 'aCount' accepting a
first argument of type 'ValueTuple' could be found (are
you missing a using directive or an assembly reference?)

我尝试添加demo和demo_实验构建标志，但仍然失败。

知道怎么回事吗？

编辑1：

这段代码可以工作，并且统计数据可以很好地解构。我可能碰到了一只虫子。

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public async Task<HttpResponseMessage> GetInfoAsync()
{
// Some code...
var stats = await _myClass.GetAllStatsAsync();
var tu = stats.ToTuple();
var vm = new ViewModel
{
FCount = tu.Item1,
CCount = tu.Item2,
ACount = tu.Item3
};

return Request.CreateResponse(HttpStatusCode.OK, vm);
}

编辑2：

在GitHub上打开的问题：https://github.com/dotnet/roslyn/issues/16200

相关讨论

我认为这是因为你没有定义fcount、ccount和acount。试试这个

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public async Task<(int fCount, int cCount, int aCount)> GetAllStatsAsync()
{
// Some code...
//fCount, cCount, aCount are not defined here, so you should define them

var fCount = 0;
var cCount= 0;
var aCount = 0;
return (fCount , cCount, aCount );

//Other ways:
//return (fCount : 0, cCount: 0, aCount : 0);
//return new (int fCount , int cCount, int aCount ) { fCount = 0, cCount = 0, aCount = 0 };
}

public async Task<HttpResponseMessage> GetInfoAsync()
{
// Some code...
var stats = await _myClass.GetAllStatsAsync();

var vm = new ViewModel
{
FCount = stats.fCount,
CCount = stats.cCount,
ACount = stats.aCount
};

return Request.CreateResponse(HttpStatusCode.OK, vm);
}

用@swell建议编辑

看看这个帖子