[Mono-bugs] [Bug 688008] New: Mono fails to run F# code involving native pointers that works on .NET

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https://bugzilla.novell.com/show_bug.cgi?id=688008

https://bugzilla.novell.com/show_bug.cgi?id=688008#c0


           Summary: Mono fails to run F# code involving native pointers
                    that works on .NET
    Classification: Mono
           Product: Mono: Runtime
           Version: SVN
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: JIT
        AssignedTo: lupus at novell.com
        ReportedBy: st at quanttec.com
         QAContact: mono-bugs at lists.ximian.com
          Found By: ---
           Blocker: ---


Created an attachment (id=425276)
 --> (http://bugzilla.novell.com/attachment.cgi?id=425276)
A compiled version of the test program

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 6.1; en-GB; rv:1.9.2.16)
Gecko/20110319 Firefox/3.6.16

Mono rejects IL generated by the F# compiler for the following code involving a
native pointer:

let test (chars: char[]) =
    let handle = System.Runtime.InteropServices.GCHandle.Alloc(chars,
System.Runtime.InteropServices.GCHandleType.Pinned)
    let cp = &&chars.[0]
    System.Console.WriteLine(new string(cp, 0, chars.Length))
    handle.Free()

test("test".ToCharArray())

The generated IL for the test functions is:

method public static void test(char[] chars) cil managed
{
    .maxstack 5
    .locals init (
        [0] valuetype [mscorlib]System.Runtime.InteropServices.GCHandle handle,
        [1] native int cp)
    L_0000: nop 
    L_0001: ldarg.0 
    L_0002: ldc.i4.3 
    L_0003: call valuetype [mscorlib]System.Runtime.InteropServices.GCHandle
[mscorlib]System.Runtime.InteropServices.GCHandle::Alloc(object, valuetype
[mscorlib]System.Runtime.InteropServices.GCHandleType)
    L_0008: stloc.0 
    L_0009: ldarg.0 
    L_000a: ldc.i4.0 
    L_000b: ldelema char
    L_0010: stloc.1 
    L_0011: ldloc.1 
    L_0012: ldc.i4.0 
    L_0013: ldarg.0 
    L_0014: ldlen 
    L_0015: conv.i4 
    L_0016: newobj instance void [mscorlib]System.String::.ctor(char*, int32,
int32)
    L_001b: call void [mscorlib]System.Console::WriteLine(string)
    L_0020: ldloca.s handle
    L_0022: call instance void
[mscorlib]System.Runtime.InteropServices.GCHandle::Free()
    L_0027: ret 
}

Mono fails with: 

Unhandled Exception: System.InvalidProgramException: Invalid IL code in
Test.Test:test (char[]): IL_0010: stloc.1   

This code works fine on .NET. Using a signed native int for storing a pointer
value is certainly an odd choice, but I'm not sure that the ECMA standard
prohibits this.

Reproducible: Always

Steps to Reproduce:
See details.
Actual Results:  
See details.

Expected Results:  
See details.

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