[Cuis-dev] [bug?] Decompiler does not restore unused temporary variables

[Juan Vuletich]

On 5/5/2025 1:04 PM, Nicolás Papagna Maldonado via Cuis-dev wrote:
> Hi Juan, all!
>
> Thanks for the clarification.
>
> CodeCoverage de-optimizes methods to do its thing, so CodeCoverageTest 
> temporaryVariable is actually a valid use-case (it's used to check 
> whether the temporary variable declaration is marked as 'covered' when 
> the variable is read.
>
> Is there any way I can exclude such tests from DecompilerTests?
> I'm building a custom image where I need to check that I didn't break 
> any tests in the base image and that failing tests is breaking my CI 
> builds, preventing the build from suceeding.
>
> Cheers!
> Nico PM

Yes, you can add it to #expectedFailures . BaseImageTests has some 
examples of this.

Cheers,

>
> On Mon, May 5, 2025 at 12:54 PM Juan Vuletich <juan at cuis.st 
> <mailto:juan at cuis.st>> wrote:
>
>     Hi Nico.
>
>     I don't think this is a bug. Decompiler creates Smalltalk code
>     from actual bytecode. Dead code had been removed when generating
>     the bytecode. Looks fine to me.
>
>     Does it make sense to add some use of the 'a' variable, so it is
>     kept during compilation? I mean, it is difficult to imagine that
>     CodeCoverageTest can do something interesting with a method that
>     had all its code optimized out...
>
>     Cheers,
>
>     On 5/4/2025 1:49 PM, Nicolás Papagna Maldonado via Cuis-dev wrote:
>>     Hi folks,
>>
>>     I don't know if this is a bug or the expected behavior.
>>
>>     Today I ran the tests in BaseImageTests with the CodeCoverage
>>     package (https://github.com/npapagna/cuis-code-coverage) loaded
>>     and one of the DecompilerTests failed.
>>     The reason seems to be that Decompiler does not restore unused
>>     temporary variables.
>>
>>     In particular, DecompilerTests>>#testDecompilerInClassesCNtoCZ
>>     was failing on CodeCoverageTest temporaryVariable:
>>     (For context: this method is needed to reproduce a test scenario
>>     for the CodeCoverage tool)
>>
>>     CodeCoverageTest >> #temporaryVariable
>>         | a |
>>         a.
>>
>>     To reproduce without the CodeCoverage package, evaluate:
>>
>>     Object compile: 'm1 |a| a'.
>>
>>     newCodeString := (Decompiler new
>>         decompile: #m1
>>         in: Object
>>         method: Object >> #m1) decompileString.
>>
>>     Notice that newCodeString is 'm1 ^ self.' and it should be 'm1
>>     |a| a'(if this is really a bug).
>>
>>     The code above was run on HEAD at the moment
>>     (6c13d4eda2e9a8c56362ae3363d7b013917227c5).
>>
>>     Is this something that needs to be fixed?
>>
>>     Best,
>>     Nico PM
>
>
>     -- 
>     Juan Vuletich
>     www.cuis-smalltalk.org  <http://www.cuis-smalltalk.org>
>     https://github.com/Cuis-Smalltalk/Cuis-Smalltalk-Dev
>     https://github.com/jvuletich
>     https://www.linkedin.com/in/juan-vuletich-75611b3
>     https://independent.academia.edu/JuanVuletich
>     https://www.researchgate.net/profile/Juan-Vuletich
>     https://patents.justia.com/inventor/juan-manuel-vuletich
>     https://twitter.com/JuanVuletich
>
>
>
> -- 
>
> Nicolás Papagna


-- 
Juan Vuletich
cuis.st
github.com/jvuletich
researchgate.net/profile/Juan-Vuletich
independent.academia.edu/JuanVuletich
patents.justia.com/inventor/juan-manuel-vuletich
linkedin.com/in/juan-vuletich-75611b3
twitter.com/JuanVuletich

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