10000 Filter out compiler generated types for `Add-Type -PassThru` by daxian-dbw · Pull Request #18095 · PowerShell/PowerShell · GitHub
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Merged
merged 2 commits into from
Sep 15, 2022
Merged

Filter out compiler generated types for Add-Type -PassThru #18095

merged 2 commits into from
Sep 15, 2022

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daxian-dbw
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@daxian-dbw daxian-dbw commented Sep 14, 2022 •
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PR Summary

Only return types that are not auto-generated by compiler with Add-Type -PassThru.

An improvement was made to Microsoft.CodeAnalysis.CSharp to allow compiler to generate private helper class sometimes for performance reason (see an example below). Passing through all types from the assembly cause one of our tests to fail:

https://dev.azure.com/powershell/PowerShell/_build/results?buildId=108821&view=logs&j=77295986-da6b-5a15-d60e-dfb16acd57ef&t=a58f8c58-10a4-5f19-f6fe-df1d6acdd5db&l=685

This PR makes -PassThru to only return types that are not compiler generated. It's technically a breaking change, but should be in "Bucket 3 - gray area".

$classDefinition = @'
using System;
using System.Management.Automation;
using System.Management.Automation.Runspaces;
using System.Threading;
namespace StackTest {
    public class StackDepthTest {
        public static PowerShell ps;
        public static int size = 512 * 1024;
        public static void CauseError() {
            Thread t = new Thread(RunPS, size);
            t.Start();
            t.Join();
        }

        public static void RunPS() {
            InitialSessionState iss = InitialSessionState.CreateDefault2();
            iss.ThreadOptions = PSThreadOptions.UseCurrentThread;
            ps = PowerShell.Create(iss);
            ps.AddScript("function recurse { recurse }; recurse").Invoke();
        }

        public static void GetPSError() {
            if ( ps.Streams.Error.Count > 0) {
                throw ps.Streams.Error[0].Exception.InnerException;
            }
        }
    }
}
'@

Add-Type -PassThru -TypeDefinition $classDefinition

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     False    StackDepthTest                           System.Object
False    False    <>O                                      System.Object

PR Checklist

@daxian-dbw daxian-dbw added CL-BreakingChange Indicates that a PR should be marked as a breaking change in the Change Log CL-General Indicates that a PR should be marked as a general cmdlet change in the Change Log labels Sep 14, 2022
@daxian-dbw daxian-dbw self-assigned this Sep 14, 2022
@daxian-dbw
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@SeeminglyScience Can you please take a look and see if this will cause any problem to VSCode Extension?

@daxian-dbw daxian-dbw added the Review - Committee The PR/Issue needs a review from the PowerShell Committee label Sep 14, 2022
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@SeeminglyScience Can you please take a look and see if this will cause any problem to VSCode Extension?

I think all is good on the VSCode side 🎉

Though, I can imagine someone generating p/invokes as internal and doing (Add-Type -Passthru)[0]::PInvokeName() or something like that to avoid polluting type resolution.

Would definitely be slower, but maybe worth considering looking for CompilerGeneratedAttribute decorations as a filter

@iSazonov
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A breaking change is made to new versions of Microsoft.CodeAnalysis.CSharp to make the compiler generate private helper class sometimes (see an example below).

Looks like a bug. Why should we hide it?

The fix looks like very sensitive breaking change in the cmdlet.

PaulHigin
PaulHigin approved these changes Sep 15, 2022
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LGTM

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A breaking change is made to new versions of Microsoft.CodeAnalysis.CSharp to make the compiler generate private helper class sometimes (see an example below).

Looks like a bug. Why should we hide it?

The fix looks like very sensitive breaking change in the cmdlet.

Roslyn has always created private helper types in certain conditions, typically for performance reasons. I don't think they would consider this change breaking, they expect all tooling that reads types to ignore anything decorated with CompilerGeneratedAttribute when the exclusion of them is required.

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A breaking change is made to new versions of Microsoft.CodeAnalysis.CSharp to make the compiler generate private helper class sometimes (see an example below).

Looks like a bug. Why should we hide it?
The fix looks like very sensitive breaking change in the cmdlet.

Roslyn has always created private helper types in certain conditions, typically for performance reasons. I don't think they would consider this change breaking, they expect all tooling that reads types to ignore anything decorated with CompilerGeneratedAttribute when the exclusion of them is required.

Maybe they lost the attribute for member we see? :-)

And your comment raises the same question - why should we hide if they don't?

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This PR has 5 quantified lines of changes. In general, a change size of upto 200 lines is ideal for the best PR experience!

Quantification details 

Label      : Extra Small
Size       : +4 -1
Percentile : 2%

Total files changed: 1

Change summary by file extension:
.cs : +4 -1

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@daxian-dbw
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daxian-dbw commented Sep 15, 2022 •
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Would definitely be slower, but maybe worth considering looking for CompilerGeneratedAttribute decorations as a filter

I like this👍
It's about 60 ms slower when filtering on CompilerGeneratedAttribute than calling GetTypes()/ExportedTypes for the assembly System.Management.Automation. But in practice, I believe when -PassThru is specified, the assembly to be inspected will most likely contain a small number of types, so the additional perf cost won't be much.

SeeminglyScience
SeeminglyScience approved these changes Sep 15, 2022
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LGTM! ❤️

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daxian-dbw commented Sep 15, 2022 •
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Maybe they lost the attribute for member we see? :-)
And your comment raises the same question - why should we hide if they don't?

Nope, nothing is hidden. It's an improvement to the emitted code.

  • The assembly generated from the same source code in PS 7.2.6 doesn't do any optimization around wrapping RunPS to a delegate -- every time CauseError is called, the static method RunPS will be wrapped to a new delegate.
  • With the improvement in the new Microsoft.CodeAnalysis.CSharp, a helper class is generated to hold the delegate, so the delegate gets created only once.

I have updated the PR description to say it's an improvement, instead of a breaking change :)

@daxian-dbw daxian-dbw changed the title Only return public types with Add-Type -PassThru Filter out compiler generated types for Add-Type -PassThru Sep 15, 2022
@adityapatwardhan adityapatwardhan merged commit d0a9147 into PowerShell:master Sep 15, 2022
@daxian-dbw daxian-dbw removed Review - Committee The PR/Issue needs a review from the PowerShell Committee CL-BreakingChange Indicates that a PR should be marked as a breaking change in the Change Log labels Sep 15, 2022
@daxian-dbw daxian-dbw deleted the addtype branch September 15, 2022 20:59
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/backport to release/v7.3.0-rc.1

@github-actions github-actions bot mentioned this pull request Sep 15, 2022
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ghost commented Sep 20, 2022

🎉v7.3.0-preview.8 has been released which incorporates this pull request.:tada:

Handy links:

@TravisEz13 TravisEz13 mentioned this pull request Sep 30, 2022
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@iSazonov iSazonov iSazonov left review comments

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@PaulHigin PaulHigin PaulHigin approved these changes

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