Init-only & required properties support by vzarytovskii · Pull Request #13490 · dotnet/fsharp

vzarytovskii · 2022-07-11T17:27:16Z

RFC: published
Produce error-level diagnostic on setting init-only IL properties (courtesy of @smoothdeveloper - (experimental) forbid setter call on init properties #11564)
- Test that set_Prop is forbidden too.
- Test if init-properties are only allowed from the constructor, e.g. disallow the following:
  instance.MethodThatReturnsThis(initOnlyProp = 123)
  Which will mutate the instance
Support for CompilerFeatureRequiredAttribute (Roslyn codegen)
Enforcing of required properties initialization (via the properties initialization)

vzarytovskii · 2022-07-14T17:28:05Z

I will need to add one more language feature, and hide init-only checking under it, so F#6 continues to allow current behaviour.

vzarytovskii · 2022-07-15T17:08:34Z

This is ready for a first wave of reviews.
cc @dsyme

dsyme · 2022-07-16T16:04:21Z

System.Exception : Unable to emit C# compilation.
seq
[(26,48): error CS0518: Predefined type 'System.Runtime.CompilerServices.IsExternalInit' is not defined or imported;
(15,43): error CS0518: Predefined type 'System.Runtime.CompilerServices.IsExternalInit' is not defined or imported]

vzarytovskii · 2022-07-16T16:14:14Z

System.Exception : Unable to emit C# compilation.
seq
[(26,48): error CS0518: Predefined type 'System.Runtime.CompilerServices.IsExternalInit' is not defined or imported;
(15,43): error CS0518: Predefined type 'System.Runtime.CompilerServices.IsExternalInit' is not defined or imported]

That is okay, C# compiler cannot find the attribute in the net472 runtime, it's known, i will fix it.

Quote from Jared:

The IsExternalInit type is only included in the net5.0 (and future) target frameworks. When compiling against older target frameworks you will need to manually define this type.

vzarytovskii · 2022-07-22T17:09:05Z

@dsyme Addressed all comments except 1 (not entirely sure whether we should warn user when they place RequiredMemberAttribute or not).

vzarytovskii · 2022-07-25T15:14:04Z

We may want to retarget this feature to 17.4, and update sdk to .NET7-preview, since it will be much easier to test runtime features without the need of adding attributes ourselves.

vzarytovskii · 2022-07-25T16:25:26Z

Added attributes to unsupported ones, compiler will produce a warning for them if used in F# code.

KevinRansom

Nice

0101 · 2022-07-28T09:19:06Z


+    /// Indidcates whether IL property has an init-only setter (i.e. has the `System.Runtime.CompilerServices.IsExternalInit` modifer)
+    member x.IsSetterInitOnly =
+        assert x.HasSetter


This probably shouldn't be here.

Co-authored-by: Petr Pokorny <[email protected]>

dsyme

A couple of small changes needed

dsyme · 2022-07-28T18:12:01Z

@vzarytovskii A couple of small changes needed - Please feel free to clear my review after you've addressed them, no 2nd review needed

As agreed

auduchinok · 2026-02-25T14:57:20Z

+    | Some ([ILAttribElem.String (Some msg); ILAttribElem.Bool isError ], _) when not isByrefLikeTyconRef ->
+        if isError then
+            if g.langVersion.SupportsFeature(LanguageFeature.RequiredPropertiesSupport) then
+                CheckCompilerFeatureRequiredAttribute g cattrs msg m


Does this attribute always come together with Obsolete?
If not, then this path is not going to be executed when there's no Obsolete attribute.

WIP: Added init-only properties error + added some tests

9eedfb7

vzarytovskii self-assigned this Jul 11, 2022

vzarytovskii added the Area-Compiler-ImportAndInterop import of .NET DLLs and interop label Jul 11, 2022

vzarytovskii added this to the July-2022 milestone Jul 11, 2022

vzarytovskii linked an issue Jul 11, 2022 that may be closed by this pull request

Tracking Init properties and required members support #13451

Closed

vzarytovskii added 5 commits July 11, 2022 19:34

WIP: Separate tests

e2d9d68

Added check for explicit setters

2a05ed2

Fix tests

8a7d48c

Forbit calling setters on the methods

bdcab6b

wip: support required attributes

63fc2fb

Added required properties support + apply fantomas

b1ffb44

vzarytovskii commented Jul 15, 2022

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Comment thread src/Compiler/Checking/CheckExpressions.fs Outdated

vzarytovskii commented Jul 15, 2022

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Comment thread src/Compiler/Checking/AttributeChecking.fs Outdated

vzarytovskii changed the title ~~WIP Init-only & required properties support~~ Init-only & required properties support Jul 15, 2022

vzarytovskii requested review from KevinRansom and dsyme July 15, 2022 17:08

Merge branch 'main' into required-and-init

bb8b77a

vzarytovskii removed this from the July-2022 milestone Jul 15, 2022

0101 reviewed Jul 18, 2022

View reviewed changes

Comment thread src/Compiler/FSComp.txt Outdated

Comment thread src/Compiler/Checking/CheckExpressions.fs Outdated

Comment thread src/Compiler/TypedTree/TcGlobals.fs Outdated

dsyme requested changes Jul 18, 2022

View reviewed changes

vzarytovskii added 4 commits July 22, 2022 13:36

Merge remote-tracking branch 'upstream/main' into required-and-init

4c7029f

Moved compilerfeaturerequired check to a method

2681745

Updated

81da22c

fantomas

662186f

Internalize empty

005af55

vzarytovskii added 2 commits July 25, 2022 17:22

Add setter check + add more unsupported attributes

5784869

Merge remote-tracking branch 'upstream/main' into required-and-init

bf2ae5e

vzarytovskii requested review from 0101 and dsyme July 25, 2022 16:24

Fix prop pages

cc928ef

KevinRansom approved these changes Jul 27, 2022

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0101 reviewed Jul 28, 2022

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vzarytovskii and others added 3 commits July 28, 2022 13:08

Update src/Compiler/Checking/CheckExpressions.fs

0ef72fd

Co-authored-by: Petr Pokorny <[email protected]>

Addressed PR comments + added additional tests

07762ca

Merge remote-tracking branch 'upstream/main' into required-and-init

4051bdc

vzarytovskii requested a review from 0101 July 28, 2022 12:43

0101 reviewed Jul 28, 2022

View reviewed changes

Comment thread src/Compiler/Checking/infos.fs Outdated

Comment thread tests/FSharp.Compiler.ComponentTests/Interop/RequiredAndInitOnlyProperties.fs

Comment thread src/Compiler/Checking/CheckExpressions.fs Outdated

0101 approved these changes Jul 28, 2022

View reviewed changes

vzarytovskii and others added 2 commits July 28, 2022 15:39

Update src/Compiler/Checking/infos.fs

3bc625b

Co-authored-by: Petr Pokorny <[email protected]>

Moved condition outside of list expression

66407b2

dsyme reviewed Jul 28, 2022

View reviewed changes

Comment thread src/Compiler/AbstractIL/il.fs Outdated

dsyme reviewed Jul 28, 2022

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Comment thread src/Compiler/Checking/CheckExpressions.fs Outdated

dsyme previously requested changes Jul 28, 2022

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PR fixes

764c158

vzarytovskii closed this Jul 28, 2022

vzarytovskii reopened this Jul 28, 2022

vzarytovskii merged commit efdcde2 into dotnet:main Jul 29, 2022

vzarytovskii deleted the required-and-init branch July 29, 2022 09:48

This was referenced Sep 6, 2022

(experimental) forbid setter call on init properties #11564

Closed

Check expressions: safer init properties check #13892

Merged

auduchinok reviewed Feb 25, 2026

View reviewed changes

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0101 Jul 28, 2022

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vzarytovskii commented Jul 11, 2022 •

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