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Merged
merged 8 commits into from
Oct 4, 2025
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Merged

Improve error recovery when object initializer uses ':' instead of '=' #80553

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ab15a1b
Implement
Oct 3, 2025
c768433
Merge branch 'main' into feature/80537-improve-error-recovery-on-obj-…
Oct 3, 2025
208a114
Fix pr comments
Oct 4, 2025
6fb9b68
Apply suggestion
Oct 4, 2025
91f99bf
Further simplify
Oct 4, 2025
85c62f6
Add unit test
Oct 4, 2025
8907bb4
Fix pr comments
Oct 4, 2025
839fcf0
Merge branch 'main' into feature/80537-improve-error-recovery-on-obj-…
Oct 4, 2025
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11 changes: 9 additions & 2 deletions src/Compilers/CSharp/Portable/Parser/LanguageParser.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -12999,6 +12999,11 @@ private bool IsNamedAssignment()
return IsTrueIdentifier() && this.PeekToken(1).Kind == SyntaxKind.EqualsToken;
}

private bool IsNamedMemberInitializer()
{
return IsTrueIdentifier() && this.PeekToken(1).Kind is SyntaxKind.EqualsToken or SyntaxKind.ColonToken;
}

private bool IsDictionaryInitializer()
{
return this.CurrentToken.Kind == SyntaxKind.OpenBracketToken;
Expand Down Expand Up @@ -13164,7 +13169,7 @@ private ExpressionSyntax ParseObjectOrCollectionInitializerMember()
// [...] = <expr>
return this.ParseDictionaryInitializer();
}
else if (this.IsNamedAssignment())
else if (this.IsNamedMemberInitializer())
{
// Name = { ... }
// Name = ref <expr>
Expand Down Expand Up @@ -13194,7 +13199,9 @@ private AssignmentExpressionSyntax ParseObjectInitializerNamedAssignment()
return _syntaxFactory.AssignmentExpression(
SyntaxKind.SimpleAssignmentExpression,
this.ParseIdentifierName(),
this.EatToken(SyntaxKind.EqualsToken),
this.CurrentToken.Kind == SyntaxKind.ColonToken
? this.EatTokenAsKind(SyntaxKind.EqualsToken)
: this.EatToken(SyntaxKind.EqualsToken),
this.CurrentToken.Kind == SyntaxKind.OpenBraceToken
? this.ParseObjectOrCollectionInitializer()
: this.ParsePossibleRefExpression());
Expand Down
263 changes: 263 additions & 0 deletions src/Compilers/CSharp/Test/Syntax/Parsing/ExpressionParsingTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -7067,5 +7067,268 @@ public void LinqQueryInConditionalExpression_Incomplete()
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/80537")]
public void ObjectInitializerWithColonInsteadOfEqualsSign()
{
UsingExpression("new Class1 { X: 0 }",
// (1,15): error CS1003: Syntax error, '=' expected
// new Class1 { X: 0 }
Diagnostic(ErrorCode.ERR_SyntaxError, ":").WithArguments("=").WithLocation(1, 15));

N(SyntaxKind.ObjectCreationExpression);
{
N(SyntaxKind.NewKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "Class1");
}
N(SyntaxKind.ObjectInitializerExpression);
{
N(SyntaxKind.OpenBraceToken);
N(SyntaxKind.SimpleAssignmentExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "X");
}
M(SyntaxKind.EqualsToken);
N(SyntaxKind.NumericLiteralExpression);
{
N(SyntaxKind.NumericLiteralToken, "0");
}
}
N(SyntaxKind.CloseBraceToken);
}
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/80537")]
public void ImplicitObjectInitializerWithColonInsteadOfEqualsSign()
{
UsingStatement("Class1 c1 = new() { X: 0 };",
// (1,22): error CS1003: Syntax error, '=' expected
// Class1 c1 = new() { X: 0 };
Diagnostic(ErrorCode.ERR_SyntaxError, ":").WithArguments("=").WithLocation(1, 22));

N(SyntaxKind.LocalDeclarationStatement);
{
N(SyntaxKind.VariableDeclaration);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "Class1");
}
N(SyntaxKind.VariableDeclarator);
{
N(SyntaxKind.IdentifierToken, "c1");
N(SyntaxKind.EqualsValueClause);
{
N(SyntaxKind.EqualsToken);
N(SyntaxKind.ImplicitObjectCreationExpression);
{
N(SyntaxKind.NewKeyword);
N(SyntaxKind.ArgumentList);
{
N(SyntaxKind.OpenParenToken);
N(SyntaxKind.CloseParenToken);
}
N(SyntaxKind.ObjectInitializerExpression);
{
N(SyntaxKind.OpenBraceToken);
N(SyntaxKind.SimpleAssignmentExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "X");
}
M(SyntaxKind.EqualsToken);
N(SyntaxKind.NumericLiteralExpression);
{
N(SyntaxKind.NumericLiteralToken, "0");
}
}
N(SyntaxKind.CloseBraceToken);
}
}
}
}
}
N(SyntaxKind.SemicolonToken);
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/80537")]
public void ObjectInitializerWithColonInsteadOfEqualsSignInNestedInitialization()
{
UsingExpression("new Class1 { X = { Y: 0 } }",
// (1,21): error CS1003: Syntax error, '=' expected
// new Class1 { X = { Y: 0 } }
Diagnostic(ErrorCode.ERR_SyntaxError, ":").WithArguments("=").WithLocation(1, 21));

N(SyntaxKind.ObjectCreationExpression);
{
N(SyntaxKind.NewKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "Class1");
}
N(SyntaxKind.ObjectInitializerExpression);
{
N(SyntaxKind.OpenBraceToken);
N(SyntaxKind.SimpleAssignmentExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "X");
}
N(SyntaxKind.EqualsToken);
N(SyntaxKind.ObjectInitializerExpression);
{
N(SyntaxKind.OpenBraceToken);
N(SyntaxKind.SimpleAssignmentExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "Y");
}
M(SyntaxKind.EqualsToken);
N(SyntaxKind.NumericLiteralExpression);
{
N(SyntaxKind.NumericLiteralToken, "0");
}
}
N(SyntaxKind.CloseBraceToken);
}
}
N(SyntaxKind.CloseBraceToken);
}
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/80537")]
public void ObjectInitializerWithColonInsteadOfEqualsSignInCollectionInitializer()
{
UsingExpression("new Class1 { X = { [0] = { Y: 0 } } }",
// (1,29): error CS1003: Syntax error, '=' expected
// new Class1 { X = { [0] = { Y: 0 } } }
Diagnostic(ErrorCode.ERR_SyntaxError, ":").WithArguments("=").WithLocation(1, 29));

N(SyntaxKind.ObjectCreationExpression);
{
N(SyntaxKind.NewKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "Class1");
}
N(SyntaxKind.ObjectInitializerExpression);
{
N(SyntaxKind.OpenBraceToken);
N(SyntaxKind.SimpleAssignmentExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "X");
}
N(SyntaxKind.EqualsToken);
N(SyntaxKind.ObjectInitializerExpression);
{
N(SyntaxKind.OpenBraceToken);
N(SyntaxKind.SimpleAssignmentExpression);
{
N(SyntaxKind.ImplicitElementAccess);
{
N(SyntaxKind.BracketedArgumentList);
{
N(SyntaxKind.OpenBracketToken);
N(SyntaxKind.Argument);
{
N(SyntaxKind.NumericLiteralExpression);
{
N(SyntaxKind.NumericLiteralToken, "0");
}
}
N(SyntaxKind.CloseBracketToken);
}
}
N(SyntaxKind.EqualsToken);
N(SyntaxKind.ObjectInitializerExpression);
{
N(SyntaxKind.OpenBraceToken);
N(SyntaxKind.SimpleAssignmentExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "Y");
}
M(SyntaxKind.EqualsToken);
N(SyntaxKind.NumericLiteralExpression);
{
N(SyntaxKind.NumericLiteralToken, "0");
}
}
N(SyntaxKind.CloseBraceToken);
}
}
N(SyntaxKind.CloseBraceToken);
}
}
N(SyntaxKind.CloseBraceToken);
}
}
EOF();
}

[Fact, WorkItem("https://github.com/dotnet/roslyn/issues/80537")]
public void ObjectInitializerWithColonAndDashInsteadOfEqualsSigns()
{
UsingExpression("new Class1 { X: 0, Y - 0 }",
// (1,15): error CS1003: Syntax error, '=' expected
// new Class1 { X: 0, Y - 0 }
Diagnostic(ErrorCode.ERR_SyntaxError, ":").WithArguments("=").WithLocation(1, 15));

N(SyntaxKind.ObjectCreationExpression);
{
N(SyntaxKind.NewKeyword);
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "Class1");
}
N(SyntaxKind.ObjectInitializerExpression);
{
N(SyntaxKind.OpenBraceToken);
N(SyntaxKind.SimpleAssignmentExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "X");
}
M(SyntaxKind.EqualsToken);
N(SyntaxKind.NumericLiteralExpression);
{
N(SyntaxKind.NumericLiteralToken, "0");
}
}
N(SyntaxKind.CommaToken);
N(SyntaxKind.SubtractExpression);
{
N(SyntaxKind.IdentifierName);
{
N(SyntaxKind.IdentifierToken, "Y");
}
N(SyntaxKind.MinusToken);
N(SyntaxKind.NumericLiteralExpression);
{
N(SyntaxKind.NumericLiteralToken, "0");
}
}
N(SyntaxKind.CloseBraceToken);
}
}
EOF();
}
}
}