一位同事在运行时向我发送了一个有趣的代码示例，该代码示例与InvalidProgramException（“CLR检测到无效程序”）崩溃。
问题似乎发生在JIT时间，因为这编译得很好但是在调用“违规”行的方法之前抛出异常 - 我猜是因为它是JIT'd。
有问题的行是调用Enumerable.ToDictionary并传入Func作为第二个参数。
如果使用lambda完全指定了Func参数，它就可以工作;如果将其指定为方法组，则失败。当然这两个是等价的吗？
这让我感到难过（以及发现它的同事！） - 这看起来肯定是一个JIT错误。
[编辑：对不起 - 我在代码示例中得到了错误的方式的通过和失败案例 - 现已更正（上面的描述是正确的）]
有没有人有解释？
using System;
using System.Linq;
internal class Program
{
private static void Main(string[] args)
{
Test.Try();
}
}
public class Test
{
public static readonly int[] integers = new[] { 1, 3, 5 };
public static void Try()
{
var line = new Line { A = 3, B = 5 };
// PASSES
var dict = integers.ToDictionary<int, int, decimal>(i => i, i => line.Compute(i));
// FAILS
//var dict = integers.ToDictionary<int, int, decimal>(i => i, line.Compute);
Console.WriteLine(string.Join(" ", dict.Select(kv => kv.Key + "-" + kv.Value)));
}
}
public class Line
{
public decimal A;
public decimal B;
}
public static class SimpleCompute
{
public static decimal Compute(this Line line, int value)
{
return line.A*value + line.B;
}
}
答案 0 :(得分：15)
编译器错误。
有关信息，我有异步CTP，可能是相关的; csc报告：4.0.30319.440
似乎是区别：
public static void TryTwo() // fails
{
var line = new Line {A = 3, B = 5};
var dict = integers.ToDictionary<int, int, decimal>(i => i, line.Compute);
Console.WriteLine("TryTwo complete");
}
public static void TryFive() // works
{
var line = new Line { A = 3, B = 5 };
Func<int, decimal> func = line.Compute;
var dict = integers.ToDictionary<int, int, decimal>(i => i, func);
Console.WriteLine("TryFour complete");
}
所以让我们看看反射器：
.method public hidebysig static void TryTwo() cil managed
{
.maxstack 4
.locals init (
[0] class Line <>g__initLocal6)
L_0000: newobj instance void Line::.ctor()
L_0005: stloc.0
L_0006: ldloc.0
L_0007: ldc.i4.3
L_0008: newobj instance void [mscorlib]System.Decimal::.ctor(int32)
L_000d: stfld valuetype [mscorlib]System.Decimal Line::A
L_0012: ldloc.0
L_0013: ldc.i4.5
L_0014: newobj instance void [mscorlib]System.Decimal::.ctor(int32)
L_0019: stfld valuetype [mscorlib]System.Decimal Line::B
L_001e: ldsfld int32[] Test::integers
L_0023: ldsfld class [mscorlib]System.Func`2<int32, int32> Test::CS$<>9__CachedAnonymousMethodDelegate8
L_0028: brtrue.s L_003b
L_002a: ldnull
L_002b: ldftn int32 Test::<TryTwo>b__7(int32)
L_0031: newobj instance void [mscorlib]System.Func`2<int32, int32>::.ctor(object, native int)
L_0036: stsfld class [mscorlib]System.Func`2<int32, int32> Test::CS$<>9__CachedAnonymousMethodDelegate8
L_003b: ldsfld class [mscorlib]System.Func`2<int32, int32> Test::CS$<>9__CachedAnonymousMethodDelegate8
L_0040: call class [mscorlib]System.Collections.Generic.Dictionary`2<!!1, !!2> [System.Core]System.Linq.Enumerable::ToDictionary<int32, int32, valuetype [mscorlib]System.Decimal>(class [mscorlib]System.Collections.Generic.IEnumerable`1<!!0>, class [mscorlib]System.Func`2<!!0, !!1>, class [mscorlib]System.Func`2<!!0, !!2>)
L_0045: pop
L_0046: ldstr "TryTwo complete"
L_004b: call void [mscorlib]System.Console::WriteLine(string)
L_0050: ret
}
VS
.method public hidebysig static void TryFive() cil managed
{
.maxstack 4
.locals init (
[0] class Line line,
[1] class [mscorlib]System.Func`2<int32, valuetype [mscorlib]System.Decimal> func,
[2] class Line <>g__initLocal9)
L_0000: newobj instance void Line::.ctor()
L_0005: stloc.2
L_0006: ldloc.2
L_0007: ldc.i4.3
L_0008: newobj instance void [mscorlib]System.Decimal::.ctor(int32)
L_000d: stfld valuetype [mscorlib]System.Decimal Line::A
L_0012: ldloc.2
L_0013: ldc.i4.5
L_0014: newobj instance void [mscorlib]System.Decimal::.ctor(int32)
L_0019: stfld valuetype [mscorlib]System.Decimal Line::B
L_001e: ldloc.2
L_001f: stloc.0
L_0020: ldloc.0
L_0021: ldftn valuetype [mscorlib]System.Decimal SimpleCompute::Compute(class Line, int32)
L_0027: newobj instance void [mscorlib]System.Func`2<int32, valuetype [mscorlib]System.Decimal>::.ctor(object, native int)
L_002c: stloc.1
L_002d: ldsfld int32[] Test::integers
L_0032: ldsfld class [mscorlib]System.Func`2<int32, int32> Test::CS$<>9__CachedAnonymousMethodDelegateb
L_0037: brtrue.s L_004a
L_0039: ldnull
L_003a: ldftn int32 Test::<TryFive>b__a(int32)
L_0040: newobj instance void [mscorlib]System.Func`2<int32, int32>::.ctor(object, native int)
L_0045: stsfld class [mscorlib]System.Func`2<int32, int32> Test::CS$<>9__CachedAnonymousMethodDelegateb
L_004a: ldsfld class [mscorlib]System.Func`2<int32, int32> Test::CS$<>9__CachedAnonymousMethodDelegateb
L_004f: ldloc.1
L_0050: call class [mscorlib]System.Collections.Generic.Dictionary`2<!!1, !!2> [System.Core]System.Linq.Enumerable::ToDictionary<int32, int32, valuetype [mscorlib]System.Decimal>(class [mscorlib]System.Collections.Generic.IEnumerable`1<!!0>, class [mscorlib]System.Func`2<!!0, !!1>, class [mscorlib]System.Func`2<!!0, !!2>)
L_0055: pop
L_0056: ldstr "TryFour complete"
L_005b: call void [mscorlib]System.Console::WriteLine(string)
L_0060: ret
}
如果查看损坏的版本，只会加载一个代理。编译器错误，基本上是：
L_0023: ldsfld class [mscorlib]System.Func`2<int32, int32> Test::CS$<>9__CachedAnonymousMethodDelegate8
L_0028: brtrue.s L_003b
L_002a: ldnull
L_002b: ldftn int32 Test::<TryTwo>b__7(int32)
L_0031: newobj instance void [mscorlib]System.Func`2<int32, int32>::.ctor(object, native int)
L_0036: stsfld class [mscorlib]System.Func`2<int32, int32> Test::CS$<>9__CachedAnonymousMethodDelegate8
L_003b: ldsfld class [mscorlib]System.Func`2<int32, int32> Test::CS$<>9__CachedAnonymousMethodDelegate8
L_0040: call class [mscorlib]System.Collections.Generic.Dictionary`2<!!1, !!2> [System.Core]System.Linq.Enumerable::ToDictionary<int32, int32, valuetype [mscorlib]System.Decimal>(class [mscorlib]System.Collections.Generic.IEnumerable`1<!!0>, class [mscorlib]System.Func`2<!!0, !!1>, class [mscorlib]System.Func`2<!!0, !!2>)
以上所有内容都是“检查缓存的i => i是否存在;如果不存在，则加载它”。 永远不会对第二个代表做任何事情。因此，堆栈上没有足够的值来调用方法。