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Merged
AlekseyTs merged 2 commits into from
Jan 31, 2024
Merged

Improve error location of missing object.ToString() for concatenation #71890

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2d37bbc
Improve error location of missing `object.ToString()` for concatenation
DoctorKrolic Jan 31, 2024
0acfa68
Generalize
DoctorKrolic Jan 31, 2024
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14 changes: 8 additions & 6 deletions src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter_StringConcat.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -46,8 +46,8 @@ private BoundExpression RewriteStringConcatenation(SyntaxNode syntax, BinaryOper
}

// Convert both sides to a string (calling ToString if necessary)
loweredLeft = ConvertConcatExprToString(syntax, loweredLeft);
loweredRight = ConvertConcatExprToString(syntax, loweredRight);
loweredLeft = ConvertConcatExprToString(loweredLeft);
loweredRight = ConvertConcatExprToString(loweredRight);

Debug.Assert(loweredLeft.Type is { } && (loweredLeft.Type.IsStringType() || loweredLeft.Type.IsErrorType()) || loweredLeft.ConstantValueOpt?.IsNull == true);
Debug.Assert(loweredRight.Type is { } && (loweredRight.Type.IsStringType() || loweredRight.Type.IsErrorType()) || loweredRight.ConstantValueOpt?.IsNull == true);
Expand Down Expand Up @@ -366,8 +366,10 @@ private BoundExpression RewriteStringConcatInExpressionLambda(SyntaxNode syntax,
/// Returns an expression which converts the given expression into a string (or null).
/// If necessary, this invokes .ToString() on the expression, to avoid boxing value types.
/// </summary>
private BoundExpression ConvertConcatExprToString(SyntaxNode syntax, BoundExpression expr)
private BoundExpression ConvertConcatExprToString(BoundExpression expr)
{
var syntax = expr.Syntax;

// If it's a value type, it'll have been boxed by the +(string, object) or +(object, string)
// operator. Undo that.
if (expr.Kind == BoundKind.Conversion)
Expand Down Expand Up @@ -431,7 +433,7 @@ private BoundExpression ConvertConcatExprToString(SyntaxNode syntax, BoundExpres
// types to all special value types.
if (structToStringMethod != null && (expr.Type.SpecialType != SpecialType.None && !isFieldOfMarshalByRef(expr, _compilation)))
{
return BoundCall.Synthesized(expr.Syntax, expr, initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown, structToStringMethod);
return BoundCall.Synthesized(syntax, expr, initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown, structToStringMethod);
}

// - It's a reference type (excluding unconstrained generics): no copy
Expand All @@ -454,9 +456,9 @@ private BoundExpression ConvertConcatExprToString(SyntaxNode syntax, BoundExpres
{
if (!callWithoutCopy)
{
expr = new BoundPassByCopy(expr.Syntax, expr, expr.Type);
expr = new BoundPassByCopy(syntax, expr, expr.Type);
}
return BoundCall.Synthesized(expr.Syntax, expr, initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown, objectToStringMethod);
return BoundCall.Synthesized(syntax, expr, initialBindingReceiverIsSubjectToCloning: ThreeState.Unknown, objectToStringMethod);
}

if (callWithoutCopy)
Expand Down
64 changes: 63 additions & 1 deletion src/Compilers/CSharp/Test/Symbol/Symbols/MissingSpecialMember.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2403,7 +2403,69 @@ static void Main()
compilation.VerifyEmitDiagnostics(
// (9,27): error CS0656: Missing compiler required member 'System.Object.ToString'
// Console.WriteLine(c + "3");
Diagnostic(ErrorCode.ERR_MissingPredefinedMember, @"c + ""3""").WithArguments("System.Object", "ToString").WithLocation(9, 27)
Diagnostic(ErrorCode.ERR_MissingPredefinedMember, "c").WithArguments("System.Object", "ToString").WithLocation(9, 27)
);
}

[Fact]
public void System_Object__ToString_3Args()
{
var source = """
using System;

public class Test
{
static void Main()
{
char c = 'c';
int i = 2;
Console.WriteLine(c + "3" + i);
}
}
""";

var compilation = CreateCompilationWithMscorlib45(source);
compilation.MakeMemberMissing(SpecialMember.System_Object__ToString);
compilation.VerifyEmitDiagnostics(
// (9,27): error CS0656: Missing compiler required member 'System.Object.ToString'
// Console.WriteLine(c + "3" + i);
Diagnostic(ErrorCode.ERR_MissingPredefinedMember, "c").WithArguments("System.Object", "ToString").WithLocation(9, 27),
// (9,37): error CS0656: Missing compiler required member 'System.Object.ToString'
// Console.WriteLine(c + "3" + i);
Diagnostic(ErrorCode.ERR_MissingPredefinedMember, "i").WithArguments("System.Object", "ToString").WithLocation(9, 37)
);
}

[Fact]
public void System_Object__ToString_4Args()
{
var source = """
using System;

public class Test
{
static void Main()
{
char c = 'c';
int i = 2;
double d = 0.7;
Console.WriteLine(c + "3" + i + d);
}
}
""";

var compilation = CreateCompilationWithMscorlib45(source);
compilation.MakeMemberMissing(SpecialMember.System_Object__ToString);
compilation.VerifyEmitDiagnostics(
// (10,27): error CS0656: Missing compiler required member 'System.Object.ToString'
// Console.WriteLine(c + "3" + i + d);
Diagnostic(ErrorCode.ERR_MissingPredefinedMember, "c").WithArguments("System.Object", "ToString").WithLocation(10, 27),
// (10,37): error CS0656: Missing compiler required member 'System.Object.ToString'
// Console.WriteLine(c + "3" + i + d);
Diagnostic(ErrorCode.ERR_MissingPredefinedMember, "i").WithArguments("System.Object", "ToString").WithLocation(10, 37),
// (10,41): error CS0656: Missing compiler required member 'System.Object.ToString'
// Console.WriteLine(c + "3" + i + d);
Diagnostic(ErrorCode.ERR_MissingPredefinedMember, "d").WithArguments("System.Object", "ToString").WithLocation(10, 41)
);
}

Expand Down