Obsolete Regex.CompileToAssembly

[buyaa-n]

EDIT 9/28/2021 by @stephentoub:
Now that for .NET 7 we have a regex source generator, and as there are no plans to enable CompileToAssembly (which has been and continues to throw PlatformNotSupportedException in Core), we should just obsolete it. This means obsoleting these members:

public class Regex
{
    public static void CompileToAssembly(RegexCompilationInfo[] regexinfos, AssemblyName assemblyname);
    public static void CompileToAssembly(RegexCompilationInfo[] regexinfos, AssemblyName assemblyname, CustomAttributeBuilder[]? attributes);
    public static void CompileToAssembly(RegexCompilationInfo[] regexinfos, AssemblyName assemblyname, CustomAttributeBuilder[]? attributes, string? resourceFile);
}

as well as the whole RegexCompilationInfo class:

public class RegexCompilationInfo { ... }

---

As part of #47228 i am running an analyzer to detect APIs throwing PNSE but not annotated with Obsolete/SupportedOSPlatform/UnsupportedOSPlatform attributes, we need to annotate them so that developers get warnings when they use them unexpectedly

For now, I have results only cross-platform builds, analysis of targeted builds are coming soon which could detect more APIs and will be added here

API	Comment	Suggestion	Location
'RegexAssemblyCompiler.Save()'	Seems not supported on .Net core	add [Obsolete]	libraries\System.Text.RegularExpressions\src\System\Text\RegularExpressions\RegexAssemblyCompiler.cs(246,13)

Note: We are suggesting adding [Obsolete] for the APIs only supported in .Net framework but not supported in .NetCore, with the corresponding Message, DiagnosticId, and UrlFormat

runtime/src/libraries/System.Net.Requests/src/System/Net/AuthenticationManager.cs

Line 17 in cecc76a

[Obsolete(Obsoletions.AuthenticationManagerMessage, DiagnosticId = Obsoletions.AuthenticationManagerDiagId, UrlFormat = Obsoletions.SharedUrlFormat)]

You can claim the next available DiagnosticId from Obsoletions.cs .

EDIT: Annotating internal API is useless, we should add [Obsolete] into Regex.CompileToAssembly(...) overloads instead

cc @jeffhandley @terrajobst @GrabYourPitchforks

[ghost]

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Issue Details

---

As part of #47228 i am running an analyzer to detect APIs throwing PNSE but not annotated with Obsolete/SupportedOSPlatform/UnsupportedOSPlatform attributes, we need to annotate them so that developers get warnings when they use them unexpectedly

For now, I have results only cross-platform and .Net 5.0 or higher builds, analysis of targeted builds or lower envs are coming soon which could detect more APIs and will be added here

API	Comment	Suggestion	Location
'RegexAssemblyCompiler.Save()'	Seems not supported on .Net core	add [Obsolete]	libraries\System.Text.RegularExpressions\src\System\Text\RegularExpressions\RegexAssemblyCompiler.cs(246,13)
'RegexAssemblyCompiler.RegexAssemblyCompiler(AssemblyName, CustomAttributeBuilder[]?, string?)'	throwing condition seems not related to platform	Consider changing the exception to NotSupportedException	libraries\System.Text.RegularExpressions\src\System\Text\RegularExpressions\RegexAssemblyCompiler.cs(28,17)

Note: We are suggesting to add [Obsolete] with the corresponding message for APIs supported in .Net framework but not supported in .NetCore, if it is only supported on a specific platform(s) consider adding [SupportedOSPlatform("platformName")] or if it is unsupported on a specific platform(s) [UnsupportedOSPlatform("platformName")] attribute instead

• Suggestions for changing the exception is optional

cc @jeffhandley @terrajobst @GrabYourPitchforks

Author:	buyaa-n
Assignees:	-
Labels:	area-System.Text.RegularExpressions
Milestone:	6.0.0

[stephentoub]

This is effectively a dup of #30153. Either we implement CompileToAssembly as in #30153, or we mark CompileToAssembly obsolete and throw unconditionally. The methods cited in this issue are internal implementation details below that.

[buyaa-n]

Sorry, seems we should add [obsolete] into Regex.CompileToAssembly overloads instead

[stephentoub]

seems we should add [obsolete] into Regex.CompileToAssembly overloads instead

If we decide to never implement #30153

[buyaa-n]

That was my concern not adding Obsolete initially, but I heard we can remove the Obsolete when we add the support, no?

[stephentoub]

i heard we can remove the Obsolete when we add the support, no?

I hadn't heard any discussions about that, and I'm not sure I've ever seen us do that.

@terrajobst, do we obsolete things even if we think we may want to unobsolete them in the future? I would think we'd only want to obsolete things if we firmly believe they shouldn't be used now or any time in the future (obviously we could change our minds, but based on the knowledge we have at that time, we think it's a permanent thing).

[jeffhandley]

I heard we can remove the Obsolete when we add the support, no?

I asked the question of "why not?" which probably came across as "we can." I don't know of us ever doing it. Do we have any other options here?

<joking> Should we introduce [Obsolete?] ? </joking>

[danmoseley]

Maybe it is time to say we will not do #30153. Source generators are the new way.

[GrabYourPitchforks]

@stephentoub @terrajobst We have un-obsoleted APIs before (in Full Framework, in fact!) in aspnet. I don't remember offhand what API it was since I'd need to diff all the SDK ref asms, but I think it was something like we wanted people to stop using some specific API, then we realized later that it was still popular in some scenario and we didn't have a good alternative, so we un-obsoleted it. So there's precedent, at least.

[stephentoub]

then we realized later

This is the important part. It's one thing to say we made a mistake obsoleting something and then undo that mistake. It's another to say "until we implement xyz, we'll temporarily obsolete it". We shouldn't do the latter. It weakens the meaning of obsolete.

[buyaa-n]

Makes sense, @stephentoub what you think about @danmoseley's point? If we decide not to do #30153 we can obsolete it.

[pgovind]

Maybe it is time to say we will not do #30153. Source generators are the new way.

FWIW, I think this is what we should do and mark these APIs as obsolete. If we realize down the road that source generators won't get us a like for like replacement of RegexCompiler.Save, I think it'd be reasonable to say we made a mistake and un-obsolete these APIs at that point :)

[buyaa-n]

[Brief Meeting Note]:
We have 3 options for handling APIs not supported in .NetCore but having open issue for future support:

• If we decide not to support the API we can close the related issue and add [Obsolete] to the API
• Add support for AllPlatforms scenario to PCA analyzer and annotate the API with [UnsupportedOSPlatform("AllPlatforms")]
• Leave the API un annotated until we decide if we really gonna add support for this

For the APIs in this issue, we are leaving them unannotated until we decide to not support them for sure. @tannergooding will work on that

[marek-safar]

Add support for AllPlatforms scenario to PCA analyzer and annotate the API with [UnsupportedOSPlatform("AllPlatforms")]

I think [SupportedOSPlatform("")] combination would make more sense

[buyaa-n]

I think [SupportedOSPlatform("")] combination would make more sense

We have talked about a variant of using empty constructor for this too, anyway, AllPlatforms is just the idea, for now, we are not exactly doing option 2 as there is not enough API need this, we might consider doing it if more issues found in the future

[eerhardt]

I assume our plan for 6.0 is

Leave the API un annotated until we decide if we really gonna add support for this

And we should just move this issue to 7.0. Is that a fair assumption?

[terrajobst]

Video

• Looks good
  • We should add a diagnostic ID for all these obsoletions.
  • Adjust message as needed to be consistent
• Should we also obsolete the other APIs that persist an assembly to disk, such as
  • AssemblyBuilder.Save

namespace System.Text.RegularExpressions
{
    public partial class Regex
    {
        [Obsolete("This API isn't supported anymore. Please use source generated regexes instead.", DiagnosticId = "TBD")]
        public static void CompileToAssembly(RegexCompilationInfo[] regexinfos, AssemblyName assemblyname);
        [Obsolete("This API isn't supported anymore. Please use source generated regexes instead.", DiagnosticId = "TBD")]
        public static void CompileToAssembly(RegexCompilationInfo[] regexinfos, AssemblyName assemblyname, CustomAttributeBuilder[]? attributes);
        [Obsolete("This API isn't supported anymore. Please use source generated regexes instead.", DiagnosticId = "TBD")]
        public static void CompileToAssembly(RegexCompilationInfo[] regexinfos, AssemblyName assemblyname, CustomAttributeBuilder[]? attributes, string? resourceFile);
    }
    [Obsolete("This API isn't supported anymore. Please use source generated regexes instead.", DiagnosticId = "TBD")]
    public partial class RegexCompilationInfo
    {

    }
}