[wasm][build] Don't use GetTempFileName; emit webcil to subdir of obj

[lambdageek]

Instead of using GetTempFileName (which can run out of temp file names on Windows after 64K files, see #73793), emit the temporary webcil files to a directory in IntermediateOutputPath before copying them to the final location, if they changed (which is elsewhere in IntermediateOutputPath).

An example of the failure with the old implementation:

Error MSB4018     The "ConvertDllsToWebCil" task failed unexpectedly.
System.IO.IOException: The file exists.
 
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.Path.InternalGetTempFileName(Boolean checkHost)
   at Microsoft.NET.Sdk.WebAssembly.ConvertDllsToWebCil.Execute()
   at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
   at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext() Wasm.Prerendered.Client C:\Users\jacalvar\.nuget\packages\microsoft.net.sdk.webassembly.pack\8.0.0-preview.5.23276.2\build\Microsoft.NET.Sdk.WebAssembly.Browser.targets      221   

[ghost]

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Issue Details

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Instead of using GetTempFileName (which can run out of temp file names on Windows after 64K files, see #73793), emit the temporary webcil files to a directory in IntermediateOutputPath before copying them to the final location, if they changed (which is elsewhere in IntermediateOutputPath).

Author:	lambdageek
Assignees:	lambdageek
Labels:	arch-wasm, area-Build-mono
Milestone:	-

[lambdageek]

/cc @javiercn

[danmoseley]

which can run out of temp file names on Windows after 64K files, see #73793

The above issue was fixed. It can't run out any more.

[lewing]

which can run out of temp file names on Windows after 64K files, see #73793

The above issue was fixed. It can't run out any more.

This runs in application publish and msbuild tasks use framework when run from VS. It worked fine from the cli

[lewing]

wbt failures are known. not sure why they aren't getting tagged by build analysis