[Mono-bugs] [Bug 504791] New: NRE in FileSystem.FileOpen due to compiler problem

bugzilla_noreply at novell.com bugzilla_noreply at novell.com
Mon May 18 11:09:23 EDT 2009


http://bugzilla.novell.com/show_bug.cgi?id=504791


           Summary: NRE in FileSystem.FileOpen due to compiler problem
    Classification: Mono
           Product: Mono: Compilers
           Version: 2.4.x
          Platform: Other
        OS/Version: Other
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: Basic
        AssignedTo: rkvinge at novell.com
        ReportedBy: andyhume32 at yahoo.co.uk
         QAContact: mono-bugs at lists.ximian.com
          Found By: ---


User-Agent:       Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR
2.0.50727; .NET CLR 1.1.4322; .NET CLR 3.0.04506.30; .NET CLR 3.0.04506.648;
NET CLR 3.5.21022; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)

Calling FileSystem.FileOpen on the Mono Runtime fails with a fault in the Mono
VBRuntime.
[[
Class UseVbrtFileSystemFileOpen
  Shared Sub Main
    FileSystem.FileOpen(1, "foo.txt", OpenMode.Append)
  End Sub
End Class
]]

Fails with:
[[
Unhandled Exception: System.NullReferenceException: Object reference not set to
an instance of an object
  at Microsoft.VisualBasic.FileSystem.FileOpen (Int32 FileNumber, System.String
FileName, OpenMode Mode, OpenAccess Access, OpenShare Share, Int32
RecordLength) [0x00000]
  at UseVbrtFileSystemFileOpen.Main () [0x00000]
]]

Inspecting the runtime library code shows that incorrect IL has been generated,
the first If statement in the FileOpen method being badly mangled, with some
clauses having their conditions reversed, and other clauses skipped.


I can't see any workaround.  (One would need to make m_OpenFiles non-null, but
it is only assigned by that method).

Reproducible: Always

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