Binding for deconstruction-declaration in 'for' statement #12302
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| var result = new BoundLocalDeconstructionDeclaration(node, BindDeconstructionAssignment(node.Declaration.Deconstruction.Value, node.Declaration.Deconstruction.Value, variables, diagnostics)); | ||
| var result = new BoundLocalDeconstructionDeclaration(statement, BindDeconstructionAssignment(declaration.Deconstruction.Value, declaration.Deconstruction.Value, variables, diagnostics)); |
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Why associate the deconstruction with the entire for statement rather than the Declaration syntax?
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There is a check in BindStatement (in Binder_Statement.cs line 132) that all bound statements should be associated with a statement syntax.
In the for statement, the VariableDeclaration used to initialize the loop is not a statement (it's just an expression).
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But isn't that check for the BoundForStatement in this case rather than any BoundLocalDeconstructionDeclaration within that?
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I'm looking into this more. The binding for for (int i = 0; ...; ...) { ...} avoids this problem, so I should be able to do the same.
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| @@ -616,7 +617,7 @@ private class PossiblyImplicitlyTypedDeconstructionLocalSymbol : SourceLocalSymb | |||
| #if DEBUG | |||
| SyntaxNode parent; | |||
| Debug.Assert(SyntaxFacts.IsDeconstructionIdentifier(identifierToken, out parent)); | |||
| Debug.Assert(parent.Parent?.Kind() == SyntaxKind.LocalDeclarationStatement); | |||
| Debug.Assert(parent.Parent?.Kind() == SyntaxKind.LocalDeclarationStatement || parent.Parent?.Kind() == SyntaxKind.ForStatement); | |||
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Consider asserting parent.Parent != null separately.
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Pushed a change with the PR feedback so far and also some circularity tests to be fixed in a later PR (thanks Chuck for those suggestions!). |
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LGTM |
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Thanks! |
Allows
for(var(x, y) = M(); ..; ...) { ... }The change has two main parts:
BindForPartsIf the VariableDeclarationSyntax for the initialization part of the "for" is a deconstruction-declaration, the initializer bound node will be a
BoundLocalDeconstructionDeclaration(which is the statement introduced in last PR).MakeLocalsWhen scanning the for syntax for locals, if the VariableDeclaration is a deconstruction-declaration, then collect locals from it.
Some of those may have an implicit type, which
PossiblyImplicitlyTypedDeconstructionLocalSymbol.InferTypeOfVarVariableinSourceLocalSymbols.cswill figure out.@dotnet/roslyn-compiler for review.
Issue #11299