C#•3mo ago

MSBuild : want to detect when files change for the target to be called

I am trying to write targets file that is imported by a project:

    <ItemGroup> 
        <AssetFiles 
                Include="$(AssetsFullPath)/**/*"
                Exclude="$(AssetsFullPath)/bin/*/**;$(AssetsFullPath)/obj/**/*;$(AssetsFullPath)/$(MGCBFileName)"/>
        <AssetsDirItem 
                Include="$(AssetsFullPath)"/>

    </ItemGroup>    
  <Target Name="FenzworkSetup" BeforeTargets="CoreCompile;BeforeBuild">
        
        <PropertyGroup><AssetsTimestampFilePath>$(MSBuildProjectDirectory)/$(IntermediateOutputPath)assets_timestamp.cache</AssetsTimestampFilePath>
        </PropertyGroup>

        <ItemGroup>
            <AssetsTimestamp Include="$(AssetsTimestampFilePath)"/>
        </ItemGroup>
        
        <Touch  Condition="!Exists($(AssetsTimestampFilePath))"
                Files="$(AssetsTimestampFilePath)"
                AlwaysCreate="True"/>

    </Target>
...
    <Target Name="RunGenTool"
        Inputs="@(AssetFiles)"
        Outputs="@(AssetsTimestamp)">
    
        <Message Text="Running GenTool..." Importance="High" />
    
        <Touch Files="@(AssetsTimestamp)" AlwaysCreate="true" />

        <Exec Condition="$(IsUsingSourceGenTool)"
              Command="dotnet &quot;$(GenToolDllPath)&quot; build &quot;%(AssetsConfig.Identity)&quot; &quot;%(AssetsDirItem.Identity)&quot; &quot;$(IntermediateOutputPath)&quot;" />
    </Target>

    <ItemGroup> 
        <AssetFiles 
                Include="$(AssetsFullPath)/**/*"
                Exclude="$(AssetsFullPath)/bin/*/**;$(AssetsFullPath)/obj/**/*;$(AssetsFullPath)/$(MGCBFileName)"/>
        <AssetsDirItem 
                Include="$(AssetsFullPath)"/>

    </ItemGroup>    
  <Target Name="FenzworkSetup" BeforeTargets="CoreCompile;BeforeBuild">
        
        <PropertyGroup><AssetsTimestampFilePath>$(MSBuildProjectDirectory)/$(IntermediateOutputPath)assets_timestamp.cache</AssetsTimestampFilePath>
        </PropertyGroup>

        <ItemGroup>
            <AssetsTimestamp Include="$(AssetsTimestampFilePath)"/>
        </ItemGroup>
        
        <Touch  Condition="!Exists($(AssetsTimestampFilePath))"
                Files="$(AssetsTimestampFilePath)"
                AlwaysCreate="True"/>

    </Target>
...
    <Target Name="RunGenTool"
        Inputs="@(AssetFiles)"
        Outputs="@(AssetsTimestamp)">
    
        <Message Text="Running GenTool..." Importance="High" />
    
        <Touch Files="@(AssetsTimestamp)" AlwaysCreate="true" />

        <Exec Condition="$(IsUsingSourceGenTool)"
              Command="dotnet &quot;$(GenToolDllPath)&quot; build &quot;%(AssetsConfig.Identity)&quot; &quot;%(AssetsDirItem.Identity)&quot; &quot;$(IntermediateOutputPath)&quot;" />
    </Target>

It doesn't call that target when i change the input files at all whatever i tried nothing. The way i know if it actually happend is by looking at that timestamp file Let me know if you need more context.

46 Replies

ero•3mo ago

$(MSBuildProjectDirectory)/$(IntermediateOutputPath) doesn't seem correct to me that would result in D:\Projects\MyProj\src\MyProj\D:\Projects\MyProj\src\MyProj\obj

FenzOP•3mo ago

nope IntermediateOutputPath gave me relative path

ero•3mo ago

interesting, well if it works

FenzOP•3mo ago

i removed it tho

ero•3mo ago

what's running RunGenTool? why this in FenzworkSetup

<ItemGroup>
    <AssetsTimestamp Include="$(AssetsTimestampFilePath)" />
</ItemGroup>

<Touch Condition="!Exists($(AssetsTimestampFilePath))"
        Files="$(AssetsTimestampFilePath)"
        AlwaysCreate="True" />

<ItemGroup>
    <AssetsTimestamp Include="$(AssetsTimestampFilePath)" />
</ItemGroup>

<Touch Condition="!Exists($(AssetsTimestampFilePath))"
        Files="$(AssetsTimestampFilePath)"
        AlwaysCreate="True" />

and then again

<Touch Files="@(AssetsTimestamp)" AlwaysCreate="true" />

<Touch Files="@(AssetsTimestamp)" AlwaysCreate="true" />

in RunGenTool?

FenzOP•3mo ago

its leftover of when i wanted it to create file but it shouldn't serve any purpose yeh

ero•3mo ago

is there anything that executes RunGenTool?

FenzOP•3mo ago

Like CallTarget nope Its like as you see

ero•3mo ago

well then what would possibly run it...?

FenzOP•3mo ago

Inputs outputs ?

MarkPflug•3mo ago

Yeah, there's nothing that's including the RunGenTool target in the targets graph. You probably need to add AfterTargets="FenzworkSetup" and BeforeTargets="BeforeBuild" to the RunGenTool target. There are few ways a target will be run: 1) being listed in the Initial/DefaultsTargets property on a project. 2) being the first target in the project xml graph. (I don't think this would be smart to depend on). 3) being related to 1) or 2) by using DependsOnTargets, BeforeTargets, AfterTargets 4) explicitly invoking via the CallTarget task. Your RunGenTool target doesn't satisfy any of those. Or I guess 5) explicitly specifying the target as a command line parameter to msbuild/dotnet build. But, without before/afterTargets, there's nothing to indicate when your target should run.

FenzOP•3mo ago

Wait so inputs outputs don't call the target they work as conditions?

MarkPflug•3mo ago

Correct. The target will still only be invoked if any of the inputs has a more recent modified date than any of the outputs.

FenzOP•3mo ago

does it detect deletion and creation of input files? it doesn't seem to detect them

MarkPflug•3mo ago

I assume that if an output file is missing, that would trigger the target to run. If an input is missing, I'd assume not. Creation would cause a newer modified date, so I'd expect that to behave normally. But, you have to fully list the inputs and outputs, so if your ourputs are non-deterministic, you might not be able to use the inputs/outputs mechanism. Indeed, the inputs/outputs is really just an opitimization to avoid running targets/tasks that don't need to do anything. But, they should be idempotent, so running them even when not needed should only be a waste of time.

FenzOP•3mo ago

So it can follow the items existence in list ?

        <ItemGroup> 
            <AssetFiles 
                    Include="$(AssetsFullPath)/**/*"
                    Exclude="$(AssetsFullPath)/bin/*/**;$(AssetsFullPath)/obj/**/*;$(AssetsFullPath)/$(MGCBFileName)"/>
        </ItemGroup>

        <ItemGroup> 
            <AssetFiles 
                    Include="$(AssetsFullPath)/**/*"
                    Exclude="$(AssetsFullPath)/bin/*/**;$(AssetsFullPath)/obj/**/*;$(AssetsFullPath)/$(MGCBFileName)"/>
        </ItemGroup>

Like i use this but next call will the content stay the same or reincluded? Like it works when modifying the file but not when deleting or creating a file

MarkPflug•3mo ago

Sorry, I don't understand what you're asking.

FenzOP•3mo ago

AssetsFiles if say has foo/bar;lorem.ipsum;something if something was deleted will it remain in the AssetsFiles?

MarkPflug•3mo ago

Yes. Though, it would be strange for an input file to be deleted during a build...

FenzOP•3mo ago

hmm i might misunderstood how msbuild work so when it wants to build it execute msbuild and all of the properties and items will not be saved across the executions is that how works ?

MarkPflug•3mo ago

No, nothing is saved between executions. The project is re-evaluated from scratch every time

FenzOP•3mo ago

ah i see welp i want to detect when a file is created or deleted that's my goal now

MarkPflug•3mo ago

During the build?

FenzOP•3mo ago

i use CoreCompile

MarkPflug•3mo ago

I don't know what you're trying to accomplish, so I'm not sure how to advise you.

FenzOP•3mo ago

which i don't know exactly when its called but it gets called behind the scene

MarkPflug•3mo ago

If you need to run your code before or after core compile, just tell MSBuild that using the Before/AfterTargets. BeforeTargets="CoreCompile" will cause your target to be invoked before CoreCompile.\

FenzOP•3mo ago

i did but Inputs and Outputs don't seem to see the creation nor deletion of the files

MarkPflug•3mo ago

creation or deletion of what files?

FenzOP•3mo ago

which i put in Inputs

MarkPflug•3mo ago

The inputs/outputs should ideally be deterministic. So, when you start your build all the assets files are the inputs. Why would assets be created/deleted during the build?

FenzOP•3mo ago

i use CoreCompile because it doesn't get called when building i ve heard its usefull to generate code from MSBuild so i used it

MarkPflug•3mo ago

Yes, generating code from MSBuild is very useful. So, your trying to take assets files, turn them into .cs files, and have those .cs files included in the C# compilation?

FenzOP•3mo ago

yeh something like this

MarkPflug•3mo ago

And you're having difficulty getting your Target that does the code gen to run? Have you removed the Inputs/Outputs attributes? I'd remove those first. Like I said, treat those as an optimization after you get everything else working.

FenzOP•3mo ago

but i wanna make sure they work or else i will create real-time tool to do the job maybe

MarkPflug•3mo ago

Make the Inputs/Outputs work after you make everything else work. They are an optimization only. If your process doesn't work, there's nothing to optimize.

MarkPflug•3mo ago

https://learn.microsoft.com/en-us/visualstudio/msbuild/incremental-builds?view=vs-2022

Incremental builds in MSBuild - MSBuild

Explore the incremental build feature in MSBuild, which produces builds that are optimized so up-to-date output files aren't executed.

FenzOP•3mo ago

it works not that it doesn't

MarkPflug•3mo ago

It works? Okay. What are we talking about then?

FenzOP•3mo ago

just need to know if thats worth the effort to make it to work once a file changed or created or removed with MSBuild or not with out the Inputs/Outputs sorry if im confusing

MarkPflug•3mo ago

So, maybe your Inputs/Outputs aren't what you think they are? Have you debugged the content of the Inputs/Outputs collection?

FenzOP•3mo ago

yes wait that's weird it called the target when i removed a file than it stoped doing that

MarkPflug•3mo ago

the file you removed was an input or output file?

FenzOP•3mo ago

oh wait no it worked cause i removed inputs outputs so the outputs is basically just a file that i touch when the target RunGenTool is called

MarkPflug•3mo ago

And you're finding that if you modify an input file (asset) then the target isn't running as you expect?

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MSBuild : want to detect when files change for the target to be called

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