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Report structural lambda params errors #64960

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merged 7 commits into from
Nov 15, 2022
Merged

Report structural lambda params errors #64960

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c88c03a
Check lambda `params` errors
jjonescz Oct 19, 2022
4640909
Merge branch 'features/lambda-default-parameters' into lambda-params-…
jjonescz Nov 11, 2022
492f103
Update a test
jjonescz Nov 11, 2022
1d9eca7
Use last parameter index instead of count
jjonescz Nov 11, 2022
092b3b9
Use named arguments
jjonescz Nov 11, 2022
e1eac89
Test manual usage of `ParamArrayAttribute`
jjonescz Nov 11, 2022
883d02f
Check independently that `params` is last
jjonescz Nov 11, 2022
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8 changes: 5 additions & 3 deletions src/Compilers/CSharp/Portable/Binder/Binder_Lambda.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -339,10 +339,12 @@ private UnboundLambda BindAnonymousFunction(AnonymousFunctionExpressionSyntax sy
firstDefault = i;
}

ParameterHelpers.GetModifiers(paramSyntax.Modifiers, refnessKeyword: out _, out var paramsKeyword, thisKeyword: out _, scope: out _);
var isParams = paramsKeyword.Kind() != SyntaxKind.None;

// UNDONE: Where do we report improper use of pointer types?
// PROTOTYPE: Set `isParams` to report errors about them.
ParameterHelpers.ReportParameterErrors(owner: null, paramSyntax, ordinal: i, isParams: false, lambda.ParameterTypeWithAnnotations(i),
lambda.RefKind(i), lambda.DeclaredScope(i), containingSymbol: null, thisKeyword: default, paramsKeyword: default, firstDefault, diagnostics);
ParameterHelpers.ReportParameterErrors(owner: null, paramSyntax, ordinal: i, lastParameterIndex: lambda.ParameterCount - 1, isParams: isParams, lambda.ParameterTypeWithAnnotations(i),
lambda.RefKind(i), lambda.DeclaredScope(i), containingSymbol: null, thisKeyword: default, paramsKeyword: paramsKeyword, firstDefault, diagnostics);
}
}

Expand Down
32 changes: 14 additions & 18 deletions src/Compilers/CSharp/Portable/Symbols/Source/ParameterHelpers.cs
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Expand Up @@ -132,7 +132,6 @@ private static ImmutableArray<TParameterSymbol> MakeParameters<TParameterSyntax,
int firstDefault = -1;

var builder = ArrayBuilder<TParameterSymbol>.GetInstance();
var mustBeLastParameter = (ParameterSyntax)null;

foreach (var parameterSyntax in parametersList)
{
Expand All @@ -148,13 +147,6 @@ private static ImmutableArray<TParameterSymbol> MakeParameters<TParameterSyntax,

if (parameterSyntax is ParameterSyntax concreteParam)
{
if (mustBeLastParameter == null &&
(concreteParam.Modifiers.Any(SyntaxKind.ParamsKeyword) ||
concreteParam.Identifier.Kind() == SyntaxKind.ArgListKeyword))
{
mustBeLastParameter = concreteParam;
}

if (concreteParam.IsArgList)
{
arglistToken = concreteParam.Identifier;
Expand All @@ -168,6 +160,12 @@ private static ImmutableArray<TParameterSymbol> MakeParameters<TParameterSyntax,
diagnostics.Add(ErrorCode.ERR_IllegalVarArgs, arglistToken.GetLocation());
}

if (parameterIndex != lastIndex)
{
// CS0257: An __arglist parameter must be the last parameter in a parameter list
diagnostics.Add(ErrorCode.ERR_VarargsLast, concreteParam.GetLocation());
}

continue;
}

Expand All @@ -191,22 +189,13 @@ private static ImmutableArray<TParameterSymbol> MakeParameters<TParameterSyntax,
TParameterSymbol parameter = parameterCreationFunc(withTypeParametersBinder, owner, parameterType, parameterSyntax, refKind, parameterIndex, paramsKeyword, thisKeyword, addRefReadOnlyModifier, scope, diagnostics);

DeclarationScope? declaredScope = parameter is SourceParameterSymbol s ? s.DeclaredScope : null;
ReportParameterErrors(owner, parameterSyntax, parameter.Ordinal, parameter.IsParams, parameter.TypeWithAnnotations,
ReportParameterErrors(owner, parameterSyntax, parameter.Ordinal, lastParameterIndex: lastIndex, parameter.IsParams, parameter.TypeWithAnnotations,
parameter.RefKind, declaredScope, parameter.ContainingSymbol, thisKeyword, paramsKeyword, firstDefault, diagnostics);

builder.Add(parameter);
++parameterIndex;
}

if (mustBeLastParameter != null && mustBeLastParameter != parametersList[lastIndex])
{
diagnostics.Add(
mustBeLastParameter.Identifier.Kind() == SyntaxKind.ArgListKeyword
? ErrorCode.ERR_VarargsLast
: ErrorCode.ERR_ParamsLast,
mustBeLastParameter.GetLocation());
}

ImmutableArray<TParameterSymbol> parameters = builder.ToImmutableAndFree();

if (!parsingFunctionPointer)
Expand Down Expand Up @@ -620,6 +609,7 @@ public static void ReportParameterErrors(
Symbol? owner,
BaseParameterSyntax syntax,
int ordinal,
int lastParameterIndex,
bool isParams,
TypeWithAnnotations typeWithAnnotations,
RefKind refKind,
Expand Down Expand Up @@ -673,6 +663,12 @@ public static void ReportParameterErrors(
diagnostics.Add(ErrorCode.ERR_MethodArgCantBeRefAny, syntax.Location, typeWithAnnotations.Type);
}

if (isParams && ordinal != lastParameterIndex)
{
// error CS0231: A params parameter must be the last parameter in a parameter list
diagnostics.Add(ErrorCode.ERR_ParamsLast, syntax.GetLocation());
}

if (declaredScope == DeclarationScope.ValueScoped && !typeWithAnnotations.IsRefLikeType())
{
diagnostics.Add(ErrorCode.ERR_ScopedRefAndRefStructOnly, syntax.Location);
Expand Down
5 changes: 1 addition & 4 deletions src/Compilers/CSharp/Test/Semantic/Semantics/DelegateTypeTests.cs
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Expand Up @@ -14305,10 +14305,7 @@ void M(int a, int b = 2, params int[] c) { }
Diagnostic(ErrorCode.WRN_OptionalParamValueMismatch, "b").WithArguments("2", "2", "<missing>").WithLocation(1, 20),
// (1,40): warning CS9502: Parameter 3 has params modifier in lambda but not in target delegate type.
// D d1 = (int a, int b = 2, params int[] c) => { }; // 1, 2
Diagnostic(ErrorCode.WRN_ParamsArrayInLambdaOnly, "c").WithArguments("3").WithLocation(1, 40),
// (1,41): error CS1737: Optional parameters must appear after all required parameters
// D d1 = (int a, int b = 2, params int[] c) => { }; // 1, 2
Diagnostic(ErrorCode.ERR_DefaultValueBeforeRequiredValue, ")").WithLocation(1, 41));
Diagnostic(ErrorCode.WRN_ParamsArrayInLambdaOnly, "c").WithArguments("3").WithLocation(1, 40));
}
}
}
59 changes: 55 additions & 4 deletions src/Compilers/CSharp/Test/Semantic/Semantics/LambdaTests.cs
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Expand Up @@ -7921,10 +7921,7 @@ public static void Main()
}
}
""";
CreateCompilation(source).VerifyDiagnostics(
// (5,48): error CS1737: Optional parameters must appear after all required parameters
// var lam = (int i = 3, params int[] args) => i;
Diagnostic(ErrorCode.ERR_DefaultValueBeforeRequiredValue, ")").WithLocation(5, 48));
CreateCompilation(source).VerifyDiagnostics();
}

[Fact]
Expand Down Expand Up @@ -8260,5 +8257,59 @@ public void ParamsArray_Symbol_MultipleParamsArrays()
Assert.False(((SourceParameterSymbol)lambdas[1].Parameters[1]).IsParams);
Assert.True(((SourceParameterSymbol)lambdas[1].Parameters[2]).IsParams);
}

[Fact]
public void ParamsArray_NotLast()
{
var source = """
var lam = (params int[] xs, int y) => xs.Length + y;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,12): error CS0231: A params parameter must be the last parameter in a parameter list
// var lam = (params int[] xs, int y) => xs.Length + y;
Diagnostic(ErrorCode.ERR_ParamsLast, "params int[] xs").WithLocation(1, 12),
// (1,25): warning CS9502: Parameter 1 has params modifier in lambda but not in target delegate type.
// var lam = (params int[] xs, int y) => xs.Length + y;
Diagnostic(ErrorCode.WRN_ParamsArrayInLambdaOnly, "xs").WithArguments("1").WithLocation(1, 25));
}

[Fact]
public void ParamsArray_Multiple()
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{
var source = """
var lam = (params int[] xs, params int[] ys) => xs.Length + ys.Length;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,12): error CS0231: A params parameter must be the last parameter in a parameter list
// var lam = (params int[] xs, params int[] ys) => xs.Length + ys.Length;
Diagnostic(ErrorCode.ERR_ParamsLast, "params int[] xs").WithLocation(1, 12),
// (1,25): warning CS9502: Parameter 1 has params modifier in lambda but not in target delegate type.
// var lam = (params int[] xs, params int[] ys) => xs.Length + ys.Length;
Diagnostic(ErrorCode.WRN_ParamsArrayInLambdaOnly, "xs").WithArguments("1").WithLocation(1, 25));
}

[Fact]
public void ParamsArray_NotArray()
{
var source = """
var lam = (params int x) => x;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,12): error CS0225: The params parameter must be a single dimensional array
// var lam = (params int x) => x;
Diagnostic(ErrorCode.ERR_ParamsMustBeArray, "params").WithLocation(1, 12));
}
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[Fact]
public void ParamsArray_ParamArrayAttribute()
{
var source = """
var lam = ([System.ParamArrayAttribute] int[] xs) => xs;
""";
CreateCompilation(source).VerifyDiagnostics(
// (1,13): error CS0674: Do not use 'System.ParamArrayAttribute'. Use the 'params' keyword instead.
// var lam = ([System.ParamArrayAttribute] int[] xs) => xs;
Diagnostic(ErrorCode.ERR_ExplicitParamArray, "System.ParamArrayAttribute").WithLocation(1, 13));
}
}
}