Implicit field initialization in struct constructors #59788

RikkiGibson · 2022-02-26T01:00:45Z

Related to #60167

This design introduces a set of "disabled by default" diagnostics for definite assignment analysis of 'this' in struct constructors. Currently, in order to enable the diagnostics, the user would need to do something like the following:

# .editorconfig
dotnet_diagnostic.CS9018.severity = warning
dotnet_diagnostic.CS9019.severity = warning
dotnet_diagnostic.CS9020.severity = warning
dotnet_diagnostic.CS9021.severity = warning
dotnet_diagnostic.CS9022.severity = warning

I considered introducing some kind of shorthand which would allow specifying this whole set of diagnostics at once, but it feels like it might be worth waiting for user feedback before we add something like that.

src/Compilers/CSharp/Test/Semantic/Semantics/StructConstructorTests.cs

RikkiGibson · 2022-03-03T20:20:43Z

src/Compilers/CSharp/Portable/FlowAnalysis/FlowAnalysisPass.cs

+            var builder = ArrayBuilder<BoundStatement>.GetInstance(implicitlyInitializedFields.Length + 1);
+            foreach (var field in implicitlyInitializedFields)
+            {
+                builder.Add(new BoundExpressionStatement(


Do we need a use site diagnostic here? see CodeGenTupleTests.CustomValueTuple_StructWithConstructor in this branch.

It might make more sense to give a "Missing compiler required member" on the tuple declaration which is missing the well-known fields.

I'm leaning toward allowing the current behavior here. Declaring your own ValueTuple is a pretty rare thing to do and I wasn't able to find a decent way to introduce the use site diagnostics here without adding redundant use site diagnostics in other scenarios.

…assignment

src/Compilers/CSharp/Portable/Errors/DiagnosticBagExtensions.cs

src/Compilers/CSharp/Portable/FlowAnalysis/DefiniteAssignment.cs

src/Compilers/CSharp/Test/Semantic/Semantics/StructConstructorTests.cs

RikkiGibson · 2022-03-21T20:02:38Z

@cston @jcouv for another review pass

src/Compilers/CSharp/Portable/FlowAnalysis/DefiniteAssignment.cs

src/Compilers/CSharp/Portable/Errors/ErrorCode.cs

src/Compilers/CSharp/Portable/Errors/ErrorFacts.cs

docs/Language Feature Status.md

src/Compilers/CSharp/Test/Symbol/Symbols/Source/EventTests.cs

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

src/Compilers/CSharp/Test/Semantic/Semantics/WarningVersionTests.cs

jcouv

Done with review pass (iteration 32). Overall, looks very nice

jcouv

LGTM Thanks (iteration 33)

jcouv · 2022-03-23T23:00:27Z

src/Compilers/CSharp/Test/Semantic/Semantics/WarningVersionTests.cs

+                references: moduleReference,
+                options: TestOptions.DebugDll.WithWarningLevel(5),
+                parseOptions: TestOptions.Regular10,
+                verify: Verification.Skipped);


Consider modifying those tests to also verify execution (expectedOutput: should show reads of auto-defaulted values)

cston · 2022-03-24T20:39:28Z

src/Compilers/CSharp/Portable/FlowAnalysis/DefiniteAssignment.cs

+            {
+                var associatedSymbol = fieldSymbol.AssociatedSymbol;
+                var hasAssociatedProperty = associatedSymbol?.Kind == SymbolKind.Property;
+                var symbolName = associatedSymbol?.Kind == SymbolKind.Property ? associatedSymbol.Name : fieldSymbol.Name;


associatedSymbol?.Kind == SymbolKind.Property

Minor: hasAssociatedProperty

cston · 2022-03-24T21:00:28Z

src/Compilers/CSharp/Portable/FlowAnalysis/DefiniteAssignment.cs

+                while (true)
+                {
+                    var containingSlot = variableBySlot[fieldSlot].ContainingSlot;
+                    if (containingSlot == fieldSlot)


containingSlot == fieldSlot

Minor: This seems surprising to check that fieldSlot is the same as its containingSlot. Could we simply check if (fieldSlot == 0) instead, and before using variableBySlot[fieldSlot].ContainingSlot?

…t-definite-assignment

src/EditorFeatures/CSharpTest/ConvertTupleToStruct/ConvertTupleToStructTests.cs

RikkiGibson · 2022-03-26T04:19:03Z

This is should be ready to go now @jaredpar. There are some test plan items that can be addressed in the coming weeks.

…t-definite-assignment

WIP

b2ba13b

dotnet-issue-labeler bot added the Area-Compilers label Feb 26, 2022

Fix bugs. Update semantic tests.

e167c09

runfoapp bot mentioned this pull request Mar 1, 2022

Timeout on Microsoft.VisualStudio.LanguageServices.CSharp.UnitTests.dll tests #55638

Open

RikkiGibson added 2 commits March 1, 2022 17:36

Fix remaining semantic tests

741403b

Fix more tests

3fbe7e6

RikkiGibson mentioned this pull request Mar 2, 2022

Implicit struct initialization: handle fields at any depth? #59890

Open

RikkiGibson added 2 commits March 2, 2022 14:31

Address most prototype comments

c1b4562

PROTOTYPE -> TODO

e942cad

RikkiGibson commented Mar 2, 2022

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don't give use site diagnostics for now

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RikkiGibson commented Mar 3, 2022

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Merge branch 'main' of github.com:dotnet/roslyn into struct-definite-…

5f23f47

…assignment

RikkiGibson marked this pull request as ready for review March 3, 2022 20:23

RikkiGibson requested review from a team as code owners March 3, 2022 20:23

cston reviewed Mar 7, 2022

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RikkiGibson and others added 2 commits March 7, 2022 16:18

Address feedback

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Update src/Compilers/CSharp/Portable/FlowAnalysis/DefiniteAssignment.cs

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cston reviewed Mar 8, 2022

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RikkiGibson added 2 commits March 18, 2022 12:27

Address prototype. Move error codes for now.

e16572c

Update ErrorFacts.Generated.cs

307fcab

jcouv reviewed Mar 21, 2022

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jcouv reviewed Mar 21, 2022

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Address feedback. Make diagnostic messages consistent.

4c13809

jcouv approved these changes Mar 22, 2022

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cston reviewed Mar 24, 2022

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RikkiGibson added 2 commits March 25, 2022 21:11

Merge branch 'release/dev17.3' of github.com:dotnet/roslyn into struc…

0bb7707

…t-definite-assignment

Address feedback and pack error codes

6bcda83

RikkiGibson commented Mar 26, 2022

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This was referenced Mar 28, 2022

csharpcodedefinitionwindow.codedefinitionwindowopensmetadataassource failing #60363

Closed

csharpcodedefinitionwindow.codedefinitionwindowopensmetadataassource failing #60364

Closed

Merge branch 'release/dev17.3' of github.com:dotnet/roslyn into struc…

99fad4e

…t-definite-assignment

jaredpar approved these changes Mar 28, 2022

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davidwengier approved these changes Mar 28, 2022

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RikkiGibson enabled auto-merge (squash) March 28, 2022 21:59

RikkiGibson merged commit 65d5234 into dotnet:release/dev17.3 Mar 28, 2022

RikkiGibson deleted the struct-definite-assignment branch March 28, 2022 23:08

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Implicit field initialization in struct constructors #59788

Implicit field initialization in struct constructors #59788

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RikkiGibson commented Mar 26, 2022

Implicit field initialization in struct constructors #59788

Implicit field initialization in struct constructors #59788

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