[#RSRP-30924] NullReference analysis behaves strangely

ReSharper

NullReference analysis behaves strangely

Created: 01 Nov 06 16:51 Updated: 04 Jun 07 17:52

Component/s:

Code Analysis

Fix Version/s:

Future Versions

Security Level:

Everybody (All jira users)

Original Estimate:

Unknown

Remaining Estimate:

Unknown

Time Spent:

Unknown

Build:

300

Description

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public IClass GetClass(string qualifiedName, ClassCreateHandler classCreateHandler)
    {
      ITypeElement declaredElement = TypeChooser.GetDeclaredElement(qualifiedName);
      if (declaredElement == null && classCreateHandler(qualifiedName))
      {
        IDeclaration declaration = null;
        PsiManager manager = myConstructor.GetManager();
        CommandProcessor.Instance.BeginCommand("Create class");
        try
        {
          TransactionResult result = manager.DoTransaction(delegate
            {
              declaration = LanguageSpecificUtil.GetImplementation(myConstructor).LocateAndCreateClass(myConstructor, qualifiedName);
              if (declaration != null) manager.UpdateCaches();
            });
          if (!result.Succeded) declaration = null;
        }
        finally
        {
          CommandProcessor.Instance.EndCommand();
        }
        return declaration == null ? null : (IClass) declaration.DeclaredElement;
      }
      return declaredElement as IClass;
    }

I have possible null reference on last use of 'declaration', which may seem ok. Now I comment 'if (!result.Succeded) declaration = null;' and possible null reference disappears. Very fishy.

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Eugene Pasynkov - 17 May 07 19:46

Simplified sample:

public delegate void D();
class C
{
  public object Foo(bool cond)
  {
    object declaration = null;
    D d = delegate {declaration = new object();};
    if (cond) declaration = null;
    return declaration == null ? null : declaration.ToString();
  }
}

[ Permlink | « Hide ]

Eugene Pasynkov - 17 May 07 19:50

delegate void D();
class C
{
  public object Foo(bool cond)
  {
    object declaration;
    D d = delegate {declaration = null;};
    declaration = null;
    return declaration == null ? null : declaration.ToString();
  }
}