我在检查是否安装.NET 4.5在我们的构建机器上更改了VS 2010生成的IL映像输出。
因为我知道了Foreach的行为已经改变了.NET 4.5以避免因访问修改后的闭包,我选择了一个简单的应用程序来展示这种行为。
class Program
{
private static void Main(string[] args)
{
var contents = new List<Func<int>>();
var s = new StringBuilder();
int[] values = new int[] { 4, 5, 6 };
foreach (int value in values)
{
contents.Add(() => value);
}
for (var k = 0; k < contents.Count; k++)
s.Append(contents[k]());
Console.WriteLine(s);
}
2010年输出*666
2012年输出*456
我在VS 2010中创建了一个控制台应用程序,在VS 2012中创建了一个具有相同代码的控制台应用程序(都是针对目标.NET 4的)。
但是,这两个控制台应用程序都表现出了基于它们构建的IDE的不同行为。在构建输出中,我检查了两者的构建参数几乎相同。所以,我想知道终端可执行文件是如何表现出不同的行为的?.NET 4.5是一个就地升级,因此两个IDE的编译器必须相同.
2010年:建设于2012年12月20日开始
CoreClean: Creating directory "obj\x86\Debug\". GenerateTargetFrameworkMonikerAttribute: Skipping target "GenerateTargetFrameworkMonikerAttribute" because all output files are up-to-date with respect to the input files. CoreCompile:
C:\Windows\Microsoft.NET\Framework\v4.0.30319\Csc.exe /noconfig /nowarn:1701,1702 /nostdlib+ /platform:x86 /errorreport:prompt /warn:4 /define:DEBUG;TRACE /errorendlocation /preferreduilang:en-US /highentropyva- /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\Microsoft.CSharp.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\mscorlib.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Core.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Data.DataSetExtensions.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Data.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Xml.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Xml.Linq.dll" /debug+ /debug:full /filealign:512 /optimize- /out:obj\x86\Debug\TestConsoleApp.exe /target:exe /utf8output Program.cs Properties\AssemblyInfo.cs "C:\Users\105044960\AppData\Local\Temp.NETFramework,Version=v4.0.AssemblyAttributes.cs" _CopyAppConfigFile: Skipping target "_CopyAppConfigFile" because all output files are up-to-date with respect to the input files. CopyFilesToOutputDirectory: Copying file from "obj\x86\Debug\TestConsoleApp.exe" to "bin\Debug\TestConsoleApp.exe". TestConsoleApp -> C:\Users\105044960\Documents\Visual Studio 2010\Projects\TestConsoleApp\TestConsoleApp\bin\Debug\TestConsoleApp.exe Copying file from "obj\x86\Debug\TestConsoleApp.pdb" to "bin\Debug\TestConsoleApp.pdb".
与2012年:
1>CoreClean: 1> Deleting file "c:\users\105044960\documents\visual studio 11\Projects\TestConsoleApp\TestConsoleApp\bin\Debug\TestConsoleApp.exe". 1> Deleting file "c:\users\105044960\documents\visual studio 11\Projects\TestConsoleApp\TestConsoleApp\bin\Debug\TestConsoleApp.pdb". 1> Deleting file "c:\users\105044960\documents\visual studio 11\Projects\TestConsoleApp\TestConsoleApp\obj\Debug\TestConsoleApp.csprojResolveAssemblyReference.cache". 1> Deleting file "c:\users\105044960\documents\visual studio 11\Projects\TestConsoleApp\TestConsoleApp\obj\Debug\TestConsoleApp.exe". 1> Deleting file "c:\users\105044960\documents\visual studio 11\Projects\TestConsoleApp\TestConsoleApp\obj\Debug\TestConsoleApp.pdb". 1>GenerateTargetFrameworkMonikerAttribute: 1>Skipping target "GenerateTargetFrameworkMonikerAttribute" because all output files are up-to-date with respect to the input files. 1>CoreCompile: 1> C:\Windows\Microsoft.NET\Framework\v4.0.30319\Csc.exe /noconfig /nowarn:1701,1702,2008 /nostdlib+ /platform:AnyCPU /errorreport:prompt /warn:4 /define:DEBUG;TRACE /errorendlocation /preferreduilang:en-US /highentropyva- /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\Microsoft.CSharp.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\mscorlib.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Core.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Data.DataSetExtensions.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Data.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Xml.dll" /reference:"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.0\System.Xml.Linq.dll" /debug+ /debug:full /filealign:512 /optimize- /out:obj\Debug\TestConsoleApp.exe /target:exe /utf8output Program.cs Properties\AssemblyInfo.cs "C:\Users\105044960\AppData\Local\Temp.NETFramework,Version=v4.0.AssemblyAttributes.cs" 1>CopyFilesToOutputDirectory: 1> Copying file from "obj\Debug\TestConsoleApp.exe" to "bin\Debug\TestConsoleApp.exe". 1> TestConsoleApp -> C:\Users\105044960\Documents\Visual Studio 11\Projects\TestConsoleApp\TestConsoleApp\bin\Debug\TestConsoleApp.exe 1> Copying file from "obj\Debug\TestConsoleApp.pdb" to "bin\Debug\TestConsoleApp.pdb".
发布于 2018-02-06 10:04:29
VisualStudio使用进程内编译器,所以它知道它使用的是哪个版本的C#。
正如所注意到的,另一方面,命令行中的csc.exe使用它所编译的任何C#版本,因此在示例中它将是C#5.0。因为它是就地升级(就安装目录而言),它可能会破坏依赖于foreach
绑定在整个循环中是相同的(奇怪,但可能)。
注意:错误问题的旧答案:OP知道这一点,并在命令行中测试它。
你链接到的博客已经回答了你的问题。
编译器发生了变化,所以如下所示:
foreach (int value in values)
{
// ...
}
用于生成以下代码:
{
int value;
for (/* iteration */)
{
value = /* get from enumerator */;
// ...
}
}
虽然新的C#编译器现在生成的等效于将变量移动到循环中:
for (/* iteration */)
{
int value = /* get from enumerator */;
// ...
}
这有很大的不同,因为闭包在// ...
将捕获一个新的value
在每个周期中绑定,而不是共享相同的value
以前在循环之外声明的绑定。
问题是,如果希望代码对旧的和新的编译器都正确工作,则必须在foreach
循环:
foreach (int value in values)
{
int newValue = value;
// ...
}
https://stackoverflow.com/questions/-100005248
复制相似问题