Update:我已经提交了一份错误报告 https://connect.microsoft.com/VisualStudio/feedback/details/558649/c-is-type-check-on-struct-odd-net-4-0-x86-optimization-behavior与 Microsoft Connect,请投票!
更新2:微软已将该错误报告标记为已修复
微软发布于 18/08/2010 at 17:25
此错误将在
运行时的未来版本。我是
恐怕现在判断是否如此还为时过早
将在服务包或下一个
主要版本。
自从升级到 VS2010 以来,我在使用“is”关键字时遇到了一些非常奇怪的行为。
下面的程序 (test.cs) 在调试模式下编译时(对于 x86)输出 True,在启用优化的情况下编译时输出 False(对于 x86)。在 x64 或 AnyCPU 中编译所有组合会得到预期结果 True。
在 .NET 3.5 下编译的所有组合都会给出预期结果 True。
我使用下面的批处理文件 (runtest.bat) 使用编译器 .NET 框架的各种组合来编译和测试代码。
- 还有其他人在 .NET 4.0 下见过此类问题吗?
- 运行 runtests.bat 时,其他人是否在他们的计算机上看到与我相同的行为?
-
@$@#$??
- 有解决办法吗?
test.cs
using System;
public class Program
{
public static bool IsGuid(object item)
{
return item is Guid;
}
public static void Main()
{
Console.Write(IsGuid(Guid.NewGuid()));
}
}
运行测试.bat
@echo off
rem Usage:
rem runtest -- runs with csc.exe x86 .NET 4.0
rem runtest 64 -- runs with csc.exe x64 .NET 4.0
rem runtest v3.5 -- runs with csc.exe x86 .NET 3.5
rem runtest v3.5 64 -- runs with csc.exe x64 .NET 3.5
set version=v4.0.30319
set platform=Framework
for %%a in (%*) do (
if "%%a" == "64" (set platform=Framework64)
if "%%a" == "v3.5" (set version=v3.5)
)
echo Compiler: %platform%\%version%\csc.exe
set csc="C:\Windows\Microsoft.NET\%platform%\%version%\csc.exe"
set make=%csc% /nologo /nowarn:1607 test.cs
rem CS1607: Referenced assembly targets a different processor
rem This happens if you compile for x64 using csc32, or x86 using csc64
%make% /platform:x86
test.exe
echo =^> x86
%make% /platform:x86 /optimize
test.exe
echo =^> x86 (Optimized)
%make% /platform:x86 /debug
test.exe
echo =^> x86 (Debug)
%make% /platform:x86 /debug /optimize
test.exe
echo =^> x86 (Debug + Optimized)
%make% /platform:x64
test.exe
echo =^> x64
%make% /platform:x64 /optimize
test.exe
echo =^> x64 (Optimized)
%make% /platform:x64 /debug
test.exe
echo =^> x64 (Debug)
%make% /platform:x64 /debug /optimize
test.exe
echo =^> x64 (Debug + Optimized)
%make% /platform:AnyCPU
test.exe
echo =^> AnyCPU
%make% /platform:AnyCPU /optimize
test.exe
echo =^> AnyCPU (Optimized)
%make% /platform:AnyCPU /debug
test.exe
echo =^> AnyCPU (Debug)
%make% /platform:AnyCPU /debug /optimize
test.exe
echo =^> AnyCPU (Debug + Optimized)
检测结果
运行 runtest.bat 时,我在 Win7 x64 安装上得到以下结果。
> runtest 32 v4.0
Compiler: Framework\v4.0.30319\csc.exe
False => x86
False => x86 (Optimized)
True => x86 (Debug)
False => x86 (Debug + Optimized)
True => x64
True => x64 (Optimized)
True => x64 (Debug)
True => x64 (Debug + Optimized)
True => AnyCPU
True => AnyCPU (Optimized)
True => AnyCPU (Debug)
True => AnyCPU (Debug + Optimized)
> runtest 64 v4.0
Compiler: Framework64\v4.0.30319\csc.exe
False => x86
False => x86 (Optimized)
True => x86 (Debug)
False => x86 (Debug + Optimized)
True => x64
True => x64 (Optimized)
True => x64 (Debug)
True => x64 (Debug + Optimized)
True => AnyCPU
True => AnyCPU (Optimized)
True => AnyCPU (Debug)
True => AnyCPU (Debug + Optimized)
> runtest 32 v3.5
Compiler: Framework\v3.5\csc.exe
True => x86
True => x86 (Optimized)
True => x86 (Debug)
True => x86 (Debug + Optimized)
True => x64
True => x64 (Optimized)
True => x64 (Debug)
True => x64 (Debug + Optimized)
True => AnyCPU
True => AnyCPU (Optimized)
True => AnyCPU (Debug)
True => AnyCPU (Debug + Optimized)
> runtest 64 v3.5
Compiler: Framework64\v3.5\csc.exe
True => x86
True => x86 (Optimized)
True => x86 (Debug)
True => x86 (Debug + Optimized)
True => x64
True => x64 (Optimized)
True => x64 (Debug)
True => x64 (Debug + Optimized)
True => AnyCPU
True => AnyCPU (Optimized)
True => AnyCPU (Debug)
True => AnyCPU (Debug + Optimized)
tl;dr