TODO #1035

#If #EndIf block was not upgraded because the expression %1 did not evaluate to True or was not evaluated.

Description 

The #If #EndIf directives are evaluated by the VB6 AI Migrator preprocessing engine during the preliminary stage of the upgrade process. The current compiler-variable values are taken into consideration to figure out which blocks of code are active and which are inactive. The active blocks are upgraded to .NET while the inactive ones are copied unchanged to the upgraded code and preceded by the 1035 EWI.

Recommendations

Often times conditional compilation directives might be missing and not all code paths will be expressed. Conditional compilation constants can be defined in three different ways in VB6:

Knowing the scope of these constants can help when modifying the code to correct this EWI.

• If the inactive code is small and simple, it can safely be rewritten manually.
• However, if the conditionally compiled code is extensive, an extra migration might be required. Different values of the conditional constants can be used for all valid permutations. This will convert previously inactive blocks of code. The results can then be manually merged to get a fully converted code block.
• In some cases, it might be possible to comment out the conditionally compiled code segments completely. This will only work though, if there are no conflicts and the original code the application can be upgraded without the conditional compilation directives. CAUTION: in order to apply this work around the original code should compile.
• Some inactive blocks of code might no longer be in use. If this is the case then those code segments can be removed.

Special care should be taken when reviewing conditionally compiled code. Locally declared variables have no effect and are not used for evaluation of conditional compilation directives, such as in Example #2.

Sample VB6

#Const ShowMessage = -1 'True

PublicSub ConditionalCompilation()

'ShowMessage is True

#If ShowMessage Then

MsgBox "It will show this message!"

#Else

MsgBox "This text will not show!"

#EndIf

EndSub

PublicSub ImproperConditionalCompilation()

Dim show AsBoolean

Set show = True

' show is a local variable, and is not

' used for conditional compilation

#If show Then

MsgBox "This text will not show!"

#Else

'This message box is shown.

MsgBox "It will show this message!"

#EndIf

EndSub

Target VB.NET

#Const ShowMessage = -1'True

PublicSub ConditionalCompilation()

#If ShowMessage Then

MessageBox.Show("It will show this message!", Application.ProductName)

#Else

'UPGRADE_TODO: (1035) #If #EndIf block was not upgraded because the expression Else did not evaluate to True or was not evaluated.

MsgBox "This text will not show!"

#EndIf

EndSub

PublicSub ImproperConditionalCompilation()

Dim show AsBoolean = True

#If show Then

'UPGRADE_TODO: (1035) #If #EndIf block was not upgraded because the expression show did not evaluate to True or was not evaluated.

MsgBox "This text will not show!"

#Else

MessageBox.Show("It will show this message!", Application.ProductName)

#EndIf

EndSub

Expected VB.NET

#Const ShowMessage = -1'True

PublicSub ConditionalCompilation()

#If ShowMessage Then

MessageBox.Show("It will show this message!", Application.ProductName)

#Else

MessageBox.Show("This text will not show!", Application.ProductName)

#EndIf

EndSub

PublicSub ImproperConditionalCompilation()

Dim show AsBoolean = True

#If show Then

MessageBox.Show("This text will not show!", Application.ProductName)

#Else

MessageBox.Show("It will show this message!", Application.ProductName)

#EndIf

EndSub

Target C#

#undef ShowMessage

staticpublicvoid ConditionalCompilation()

{

#if ShowMessage

MessageBox.Show("It will show this message!", Application.ProductName);

#else

//UPGRADE_TODO: (1035) #If #EndIf block was not upgraded because the expression Else did not evaluate to True or was not evaluated.

MsgBox "This text will not show!"

#endif

}

staticpublicvoid ImproperConditionalCompilation()

{

bool show = true;

#if show

//UPGRADE_TODO: (1035) #If #EndIf block was not upgraded because the expression show did not evaluate to True or was not evaluated.

MsgBox "This text will not show!"

#else

MessageBox.Show("It will show this message!", Application.ProductName);

#endif

}

Expected C#

#define ShowMessage

staticpublicvoid ConditionalCompilation()

{

#if ShowMessage

MessageBox.Show("It will show this message!", Application.ProductName);

#else

MessageBox.Show("This text will not show!");

#endif

}

staticpublicvoid ImproperConditionalCompilation()

{

bool show = true;

#if show

MessageBox.Show("This text will not show!");

#else

MessageBox.Show("It will show this message!", Application.ProductName);

#endif

}