[Mono-bugs] [Bug 518707] New: gmcs fails to unbox 'var' to check it against generic constraints

bugzilla_noreply at novell.com bugzilla_noreply at novell.com
Thu Jul 2 09:07:09 EDT 2009


           Summary: gmcs fails to unbox 'var' to check it against generic
    Classification: Mono
           Product: Mono: Compilers
           Version: SVN
          Platform: x86
        OS/Version: All
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: C#
        AssignedTo: mono-bugs at lists.ximian.com
        ReportedBy: skolima at gmail.com
         QAContact: mono-bugs at lists.ximian.com
          Found By: ---

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; pl; rv:1.9.1)
Gecko/20090624 Firefox/3.5 (.NET CLR 3.5.30729)

The following code does not compile properly with gmcs 2.0.1, 2.4.2 and
svn-r137273. When the code is compiled with MS.Net and run on Mono, the
expected result is produced. Comparing the IL produced, the gmcs fails to unbox
the Object parameter stored in a 'var' to check it's type against generic Type

Reproducible: Always

Steps to Reproduce:
Compile this code with gmcs and run on either Mono or MS.Net:

using System;

namespace Spike
    class Program
        static void Main(string[] args)
            Tester<int> t = new Tester<int>();

        private class Tester<T> where T : struct, IConvertible
            public T Get(object data)
                var val = data;
                if (val is T)
                    return (T)val;
                return default(T);

Actual Results:  
During compilation:
"Program.cs(19,41): warning CS0184: The given expression is never of the
 (`T') type
Program.cs(20,41): warning CS0162: Unreachable code detected
Compilation succeeded - 2 warning(s)"
During execution:

Expected Results:  
No warnings during compilation.
Execution produces:

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