Add LanguageVersion 10 #54359

jcouv · 2021-06-24T14:53:22Z

This PR:

adds LanguageVersion.CSharp10, makes it the current version and attaches the new feature that are in main already to it
attaches the variance safety feature to C# 9 where it was meant to ship
leaves most usages of LanguageVersion.Preview and TestOptions.RegularPreview in tests as-is
changes the default used by test APIs like CreateCompilation to use LanguageVersion.Preview, so most new tests don't have to specify a language version at all
introduces TestOptions.RegularNext and LanguageVersionFacts.CSharpNext. Those should be used in new tests that are specifically about language version. We'll do a search&replace

jcouv · 2021-06-24T19:35:41Z

src/Compilers/Test/Utilities/CSharp/CSharpTestBase.cs

@@ -876,7 +876,7 @@ public static SyntaxTree Parse(string text, string filename = "", CSharpParseOpt
        {
            if ((object)options == null)
            {
-                options = TestOptions.Regular;
+                options = TestOptions.RegularPreview;


📝 This changes the default for tests using APIs like CreateCompilation.

jcouv · 2021-06-24T19:38:30Z

src/Compilers/Core/MSBuildTask/Microsoft.CSharp.Core.targets

@@ -17,6 +17,10 @@
    <_MaxSupportedLangVersion Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND '$(_TargetFrameworkVersionWithoutV)' == '5.0' AND
                                         '$(_MaxSupportedLangVersion)' == ''">9.0</_MaxSupportedLangVersion>

+    <!-- .NETCoreApp == 6.0 -->
+    <_MaxSupportedLangVersion Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' AND '$(_TargetFrameworkVersionWithoutV)' == '6.0' AND
+                                         '$(_MaxSupportedLangVersion)' == ''">10.0</_MaxSupportedLangVersion>


@chsienki The LanguageVersionGivenTargetFramework test was good at catching the new language version :-)
Can you take a look?

I left GeneratorDriver with a LanguageVersion.Preview check at the moment (based on offline discussion).

sharwell

IDE side LGTM

RikkiGibson · 2021-06-24T20:56:31Z

docs/Language Feature Status.md

 | [Mix declarations and variables in deconstruction](https://github.com/dotnet/csharplang/issues/125) | main | [Merged into 16.10](https://github.com/dotnet/roslyn/issues/47746) | [YairHalberstadt ](https://github.com/YairHalberstadt) | [jcouv](https://github.com/jcouv) | [MadsTorgersen](https://github.com/MadsTorgersen) |
 | [List patterns](https://github.com/dotnet/csharplang/issues/3435) | [list-patterns](https://github.com/dotnet/roslyn/tree/features/list-patterns) | [In Progress](https://github.com/dotnet/roslyn/issues/51289) | [alrz](https://github.com/alrz) | [jcouv](https://github.com/jcouv), [333fred](https://github.com/333fred) | [333fred](https://github.com/333fred) |
+
+# C# 10.0


Should we have individually done this at the time we marked the features merged?

Nah, it's fine. But it would be good if features that get merged following this PR updated this doc individually.

chsienki

LGTM

RikkiGibson · 2021-06-24T21:16:49Z

src/Compilers/CSharp/Test/Emit/CodeGen/CodeGenAsyncMethodBuilderOverrideTests.cs

@@ -115,18 +115,18 @@ class C
 ";
            var compilation = CreateCompilationWithMscorlib45(source, parseOptions: TestOptions.Regular9);
            compilation.VerifyDiagnostics(
-                // (11,25): error CS8652: The feature 'async method builder override' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version.
+                // (11,25): error CS8773: Feature 'async method builder override' is not available in C# 9.0. Please use language version 10.0 or greater.


It feels like even with the new scheme of "use LanguageVersionFacts.CSharpNext" we still have this churn of updating diagnostic IDs when we snap off a new language version.

When we snap a language version, should we also introduce an error code specific to 'C# vNext' which becomes the ERR_FeatureNotAvailableInVersionN error code when the language version gets snapped? (although this perhaps doesn't work for features like static abstracts in interfaces where we don't yet know what language version they are likely to ship in.)

You're right that such diagnostics will still churn. We can explore some mitigations when we start working on C# 11.

cston · 2021-06-24T22:21:48Z

src/Compilers/CSharp/Test/Semantic/SourceGeneration/GeneratorDriverTests.cs

@@ -1337,7 +1339,7 @@ public void Incremental_Generators_Exception_During_Execution()
            var source = @"
 class C { }
 ";
-            var parseOptions = TestOptions.Regular.WithLanguageVersion(LanguageVersion.Preview);
+            var parseOptions = TestOptions.RegularPreview;


RegularPreview

Regular10 or Regular here and below?

The GeneratorDriver only uses incremental general when LangVer==Preview at the moment. That is kept that way intentionally (based on chat with Chris).

PathogenDavid · 2021-06-25T14:39:16Z

@jcouv Just to clarify: The features now listed under C# Next are still (tentatively) planned for C# 10 but just haven't merged to main, right?

jcouv · 2021-06-25T16:35:23Z

@PathogenDavid Yes. Most are still in progress for C# 10. Which one are you asking about?

PathogenDavid · 2021-06-25T17:19:53Z

@jcouv Thanks for confirming!

As boring as it might sound, parameterless struct constructors is the main C# 10 feature I care about.

It's something that'd really help Biohazrd since we wrap arbitrary C++ code and C++ uses parameterless constructors a lot. Currently parameterless constructors are a weird edge case that creates awkward friction, enough so that I was investigating maintaining a soft fork of Roslyn at one point just to build the generated wrappers. (My main sponsor wants to standardize on .NET 6 since it'll be LTS, so it'd be really disappointing to see the feature bumped again.)

It appears to me like the PR for it is purring along smoothly, but if there's anything I can do to help with it definitely let me know.

jcouv · 2021-06-25T21:14:50Z

@PathogenDavid Parameterless struct constructors are still on track for C# 10. Should be in dev17.0p3.

tmat · 2021-06-25T21:33:49Z

docs/Language Feature Status.md

-| [Async method builder override](https://github.com/dotnet/csharplang/issues/1407) | main | [In Progress](https://github.com/dotnet/roslyn/issues/51999) | [jcouv](https://github.com/jcouv) | TBD | [stephentoub](https://github.com/stephentoub) |
+| [Source Generator V2 APIs](https://github.com/dotnet/roslyn/issues/51257) | [features/source-generators](https://github.com/dotnet/roslyn/tree/features/source-generators) | [Merged into 17.0p2](https://github.com/dotnet/roslyn/issues/51257) | [chsienki](https://github.com/chsienki/) | [rikkigibson](https://github.com/rikkigibson), [jaredpar](https://github.com/jaredpar), [cston](https://github.com/cston) | N/A |
+| [Mix declarations and variables in deconstruction](https://github.com/dotnet/csharplang/issues/125) | main | [Merged into 16.10](https://github.com/dotnet/roslyn/issues/47746) | [YairHalberstadt ](https://github.com/YairHalberstadt) | [jcouv](https://github.com/jcouv) | [MadsTorgersen](https://github.com/MadsTorgersen) |
+| [Async method builder override](https://github.com/dotnet/csharplang/issues/1407) | main | [Merged into 17.0p2](https://github.com/dotnet/roslyn/issues/51999) | [jcouv](https://github.com/jcouv) | [cston](https://github.com/cston), [RikkiGibson](https://github.com/RikkiGibson) | [stephentoub](https://github.com/stephentoub) |


Async

#line directives? dotnet/csharplang#4747

PathogenDavid · 2021-06-25T21:40:26Z

@jcouv Excellent news, I'll look forward to using them. Thanks for the info!

…ures/caller-argument-expression * upstream/main: (492 commits) Add nullable ref annotations to SyntaxFactory (#54199) Add 'replace' APIs and hook them up to the IDE (#54270) Allow implicit implementation of non-public interface members (#54182) Make insertion a stage of the official build (#54376) Cleanup Remove unused property Simplify glyph computation Report all-empty top level statements. (#54385) Calculate TypeParameterKind based on the container type (#54200) vert not roaming Split tests Multple matches Report as we get results Fixup tests Update tests Avoid thread dependency in VirtualMemoryNotificationListener constructor Fast progression search. Add LanguageVersion 10 (#54359) Sure, why not ...

JunTaoLuo · 2021-07-02T00:56:22Z

Hey @jcouv I'm trying to use C# 10 features in the dotnet/SDK repo without needing the <LangVersion>preview</LangVersion> setting in my project. I think this PR would allow me to do that.

However, even though it seems like the ingestion of Roslyn bits have been occurring regularly in the SDK repo, e.g. dotnet/sdk#18630, I still encounter errors like:

The feature 'global using directive' is currently in Preview and *unsupported*. To use Preview features, use the 'preview' language version.

What else is needed here so that global usings are supported by default?

FYI @wli3

RikkiGibson · 2021-07-02T01:04:14Z

It would be useful to know the output when #error version is added to your source code.

Does the project where the error occurs actually have a PackageReference to Microsoft.Net.Compilers.Toolset? If not, then the compiler used for the build probably comes from whatever SDK is included in global.json.

JunTaoLuo · 2021-07-02T01:07:47Z

Hmm I see, I'm not too familiar with the workings of the dotnet/SDK repo so let me dig a little.

jcouv · 2021-07-14T17:47:10Z

Recording for future reference:
After we add a new language version, we need to add that version to the release in our documentation.
Here's how that was done for C# 10 (thanks @rbhanda!):

https://dotnet.microsoft.com/download/dotnet/6.0 - This is where it got the update

dotnet/core#6466
https://github.com/dotnet/core/blob/8fe8b54383589e79e94ee338481fd1d1beddf946/release-notes/6.0/releases.json - This is the file which drives dot.net

jcouv added the PR For Personal Review Only The PR doesn’t require anyone other than the developer to review it. label Jun 24, 2021

jcouv self-assigned this Jun 24, 2021

dotnet-issue-labeler bot added the Area-Compilers label Jun 24, 2021

jcouv force-pushed the langver-10 branch 2 times, most recently from 322d150 to bb957a3 Compare June 24, 2021 15:41

jcouv removed the PR For Personal Review Only The PR doesn’t require anyone other than the developer to review it. label Jun 24, 2021

jcouv force-pushed the langver-10 branch 3 times, most recently from 804a63e to f236add Compare June 24, 2021 19:14

Add LangVersion 10

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jcouv force-pushed the langver-10 branch from f236add to 524e26c Compare June 24, 2021 19:17

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jcouv force-pushed the langver-10 branch from 673b671 to 5eb29ed Compare June 24, 2021 19:26

jcouv marked this pull request as ready for review June 24, 2021 19:29

jcouv requested review from a team as code owners June 24, 2021 19:29

jcouv added this to the C# 10 milestone Jun 24, 2021

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Remove LangVer=Preview restriction from CSharpGeneratorDriver #54373

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[main] Update dependencies from dotnet/roslyn dotnet/sdk#18555

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Add global usings for .NET projects (.NET SDK, Web and Worker) dotnet/sdk#18459

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Improve friendliness of constructing/destructing C++ objects MochiLibraries/Biohazrd#161

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Use !! in AddParameterCheck refactoring #57934

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Add LanguageVersion 10 #54359

Add LanguageVersion 10 #54359

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Add LanguageVersion 10 #54359

Add LanguageVersion 10 #54359

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