[NAntC-Dev] [ nantcontrib-Bugs-1082302 ] Vb6task ignors references when parsing the project.

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Bugs item #1082302, was opened at 2004-12-09 18:32
Message generated for change (Comment added) made by drieseng
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Category: Tasks
Group: 0.85
Status: Open
Resolution: None
Priority: 5
Submitted By: Hani Atassi (haniatassi)
Assigned to: Nobody/Anonymous (nobody)
Summary: Vb6task ignors references when parsing the project.

Initial Comment:
I noticed this problem when my project is not compiled, 
even though there was a reference file that has 
changed. Vb6task didnt detect any changes that 
require compilation but there was a change.

I tracked the problem down to the function 
ParseProjectFile. One TLB file couldnt be found and the 
API function QueryPathOfRegTypeLib failed to find it. 
The comment afterward in the code says Typelib wasn't 
found - vb6 will barf when the compile happens, but we 
won't worry about it. This is not totally correct because 
vb6 compiles my project. So whats the problem!!

After some investigation with VB, I found the following 
behavior:

1. Once you add a reference in VB, the version wont 
change in the project file even if you update the type 
library to a newer version. The version will change only if 
you unselect the old reference and select the new one.
So, consider you originally have your project set to use 
ver 1.0 of TestObj.tlb. Later on, you created ver 2.0 and 
unregistered ver 1.0. If you open the project, you will 
notice that you are using by default the newer version 
even that the project file says that you are using ver 
1.0.

2. The minor version sometimes is a hex number, even 
though this is not indicated by MSDN documentation. 
Some of the references that I am using has a version 
similar to 1.a, 1.b, 1.14,  These versions can actually 
be treated as 1.10, 1.11, 1.20 You can figure this 
easily by calling QueryPathOfRegTypeLib with the 
following:
* major: 1
minor: 10
The function will return the TLB for 1.a
* major: 1
minor: 14
The function will return the TLB for 1.14 (here 14 is 
treated as decimal)
* major: 1
minor: 20
The function will return the TLB for 1.14 (because 14 in 
hex equals 20)
The regular expression (referenceRegEx) actually ignores 
the reference file if it has a hex minor version.  Example 
of this would be (Common Language Runtime Library 
v1.1.4322 has a TLB version 1.a)

3. VB has a weird behavior in choosing the TLB library to 
compile against. Even with this behavior that I will 
describe next, Vb6task should copy the same behavior in 
checking for reference out-of-date:

VB6 uses a special algorithm to search for the typelib 
file. It doesn't rely on the API function 
QueryPathOfRegTypeLib, because VB could use a newer 
version of the TLB.
The algorithm used by VB is not perfect and has some 
flaws, that you could get a newer version even if your 
requested version is installed. This is because the 
algorithm iterates the registry beneath the Guid - entry 
by entry - from the beginning and returns the first TLB 
version that is higher or equal to the requested version.

So, if you have the following versions installed for a 
specific tlb Guid under the registery key 
HKEY_CLASSES_ROOT\TypeLib\{Guid}:
2.0
5.0
If your project requesting version 1.0, VB will use tlb ver 
2.0. 
If your project requesting version 4.0, VB will use tlb ver 
5.0. 
If your project requesting version 8.0, VB will fail and will 
say the object is MISSING.

Now consider the following situation where the versions 
are like the following:
5.0
2.0
If your project requesting version 1.0, VB will use tlb ver 
5.0. 
If your project requesting version 2.0, VB will use tlb ver 
5.0. (Notice that 2.0 exist but its been recorded after 
5.0 somehow by installing an older version after the 
newer version)
If your project requesting version 8.0, VB will fail and will 
say the object is MISSING.

You can check out this behavior by playing with the 
registry and VB project file.

I came up with the following pseudo code that describes 
how VB searches for the TLB to use:
1. open the key HKEY_CLASSES_ROOT\TypeLib\{Guid}
        2. If the key exists:
                3. Foreach version under the key that has 
the requested culture entry
                        4. If the version higher or equal to the 
requested version:
                                5. Get the TLB filename and 
returns it

Hope what Ive just said makes since. I patched the file 
Vb6task.cs, with the previous problems. I dont think 
that this change would break anything. Take a look at it.

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>Comment By: Gert Driesen (drieseng)
Date: 2004-12-09 21:59

Message:
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A repro would be great too.

Ian, do you still have VB6 installed, or should I consider 
creating a VMWare images with VB6 for test purposes ?

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Comment By: Ian MacLean (ianm74)
Date: 2004-12-09 20:17

Message:
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Would you mind posting an updated patch with those changes ?
That will make it easier to commit somthing that you have tested

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Comment By: Hani Atassi (haniatassi)
Date: 2004-12-09 20:07

Message:
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Yeah u could ignore the temp fix, this is for my machine.. 

Please also, include the capital letters A-F in the regular 
expression along with a-f.

Thanks,

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Comment By: Ian MacLean (ianm74)
Date: 2004-12-09 20:02

Message:
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Hani,
I assume the sections marked "I added this as a temprorary
fix for Bug ID 1081472" can come out of this patch if your
tlb finding algorithm is correct.
- comments of the form : //      12.8.04 (ha) -  do not
require the date -- cvs history will always be able to tell
us that. 
- opening braces should be in the same line - if (foo) {
- otherwise the patch looks good. If you address the above
we can probably commit. I'm not a big vb6 user and neither
are the other admins so we'll most likely add the change and
let vb6 users out there find any issues that there might be.

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