NativeAOT builds aren't updated when rebuilding with different MSBuild options

[Sergio0694]

Description

Note: this issue is a follow up from a conversation with @MichalStrehovsky, @tannergooding, @SingleAccretion and others on the C# Discord. I'm aware the culprit here is likely just MSBuild, but opening this just for tracking 🙂

While working on Sergio0694/ComputeSharp#542, I noticed that rebuilding my CLI sample with NAOT using different MSBuild options was just... Not doing anything. And the resulting binary was exactly the same. I have configured a bunch of MSBuild options to build my sample with or without some more size saving options, and my assumptions was that rebuilding after setting up those new environment variables would do "the right thing", but it seems it doesn't 😅

Reproduction Steps

• Clone https://github.com/Sergio0694/ComputeSharp
• Run these commands:

$env:COMPUTESHARP_SWAPCHAIN_CLI_PUBLISH_AOT='true';
dotnet publish samples\ComputeSharp.SwapChain.Cli\ComputeSharp.SwapChain.Cli.csproj -c Release -f net7.0 -r win-x64

• Verify the resulting binary is ~2.3 MB, and has an icon
• Run these commands:

$env:COMPUTESHARP_SWAPCHAIN_CLI_PUBLISH_AOT='true';
$env:COMPUTESHARP_SWAPCHAIN_CLI_SIZE_OPTIMIZED='true';
$env:COMPUTESHARP_SWAPCHAIN_CLI_DISABLE_REFLECTION='true';
dotnet publish samples\ComputeSharp.SwapChain.Cli\ComputeSharp.SwapChain.Cli.csproj -c Release -f net7.0 -r win-x64

• Verify the binary is exactly the same (but it should be ~1.1 MB, and with no icon instead)

Expected behavior

The build should be retriggered with the right properties. The resulting binary should be the same you would get if you tried building with the same exact commands but from a freshly cloned repo instead, not affected by previous builds.

Actual behavior

The resulting binary doesn't change.

Known Workarounds

You can run git clean -fdx before the second build. That works, but isn't ideal.

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Issue Details

---

Description

Note: this issue is a follow up from a conversation with @MichalStrehovsky, @tannergooding, @SingleAccretion and others on the C# Discord. I'm aware the culprit here is likely just MSBuild, but opening this just for tracking 🙂

While working on Sergio0694/ComputeSharp#542, I noticed that rebuilding my CLI sample with NAOT using different MSBuild options was just... Not doing anything. And the resulting binary was exactly the same. I have configured a bunch of MSBuild options to build my sample with or without some more size saving options, and my assumptions was that rebuilding after setting up those new environment variables would do "the right thing", but it seems it doesn't 😅

Reproduction Steps

• Clone https://github.com/Sergio0694/ComputeSharp
• Run these commands:

$env:COMPUTESHARP_SWAPCHAIN_CLI_PUBLISH_AOT='true';
dotnet publish samples\ComputeSharp.SwapChain.Cli\ComputeSharp.SwapChain.Cli.csproj -c Release -f net7.0 -r win-x64

• Verify the resulting binary is ~2.3 MB, and has an icon
• Run these commands:

$env:COMPUTESHARP_SWAPCHAIN_CLI_PUBLISH_AOT='true';
$env:COMPUTESHARP_SWAPCHAIN_CLI_SIZE_OPTIMIZED='true';
$env:COMPUTESHARP_SWAPCHAIN_CLI_DISABLE_REFLECTION='true';
dotnet publish samples\ComputeSharp.SwapChain.Cli\ComputeSharp.SwapChain.Cli.csproj -c Release -f net7.0 -r win-x64

• Verify the binary is exactly the same (but it should be ~1.1 MB, and with no icon instead)

Expected behavior

The build should be retriggered with the right properties. The resulting binary should be the same you would get if you tried building with the same exact commands but from a freshly cloned repo instead, not affected by previous builds.

Actual behavior

The resulting binary doesn't change.

Known Workarounds

You can run git clean -fdx before the second build. That works, but isn't ideal.

Author:	Sergio0694
Assignees:	-
Labels:	untriaged, area-NativeAOT-coreclr, needs-area-label
Milestone:	-

[tannergooding]

There are multiple options available for helping ensure that property inputs impact the rerunability of targets.

What a lot of the SDK does is similar to the following handling for GenerateAssemblyInfo: https://github.com/dotnet/sdk/blob/ce54eaa3bd5a380985825a8c789a5f7d31301884/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.GenerateAssemblyInfo.targets

You can see that there is the main target GenerateAssemblyInfo which has the high level condition and is otherwise empty. It simply inserts itself into the right "BeforeTargets" and adds the relevant DependsOnTargets, one of which is CoreGenerateAssemblyInfo.

That target itself has the inputs/outputs where one of the inputs is GeneratedAssemblyInfoInputsCacheFile which is created by the CreateGeneratedAssemblyInfoInputsCacheFile target.

The CreateGeneratedAssemblyInfoInputsCacheFile target is going to effectively "always" run and it does the minimal steps of basically hashing all the input properties into a file, but with WriteOnlyWhenDifferent=true so the timestamp doesn't change when inputs don't change.

There are of course other options as well, but having the input properties somehow written to a file that is an "input" to the main target is the basic principle behind which it typically operates.