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Merged
omsmith merged 2 commits into from
Oct 16, 2026
Merged

ConstantAttributeAnalyzer: inspect and report tuple conversions #999

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ConstantAttributeAnalyzer: inspect and report tuple conversions
omsmith Oct 16, 2026
89f4258
Analyzers@0.230.0; TestAnalyzers@0.33.0
omsmith Oct 16, 2026
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2 changes: 1 addition & 1 deletion src/D2L.CodeStyle.Analyzers/D2L.CodeStyle.Analyzers.csproj
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@
<Title>D2L.CodeStyle.Analyzers</Title>
<Product>D2L.CodeStyle</Product>
<Description>D2L.CodeStyle analyzers</Description>
<Version>0.229.0</Version>
<Version>0.230.0</Version>
<PackageLicenseExpression>Apache-2.0</PackageLicenseExpression>
<PackageProjectUrl>https://github.com/Brightspace/D2L.CodeStyle</PackageProjectUrl>
<Authors>D2L</Authors>
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2 changes: 1 addition & 1 deletion src/D2L.CodeStyle.TestAnalyzers/D2L.CodeStyle.TestAnalyzers.csproj
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Expand Up @@ -6,7 +6,7 @@
<Title>D2L.CodeStyle.TestAnalyzers</Title>
<Product>D2L.CodeStyle</Product>
<Description>D2L.CodeStyle test analyzers</Description>
<Version>0.32.0</Version>
<Version>0.33.0</Version>
<PackageLicenseExpression>Apache-2.0</PackageLicenseExpression>
<PackageProjectUrl>https://github.com/Brightspace/D2L.CodeStyle</PackageProjectUrl>
<Authors>D2L</Authors>
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81 changes: 63 additions & 18 deletions ...nalyzers.Rule.Constant/D2L.CodeStyle.Analyzers.Rule.Constant/ConstantAttributeAnalyzer.cs
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Expand Up @@ -162,39 +162,84 @@ private static void AnalyzeConversion(
IConversionOperation conversion,
INamedTypeSymbol constantAttribute
) {
// Operand is a constant value or string.Empty, so trust it
IOperation operand = conversion.Operand;
if( operand.ConstantValue.HasValue || IsStringEmpty( operand ) ) {
return;
}

IMethodSymbol @operator = conversion.OperatorMethod;
if( @operator is null ) {
// Operand was defined as [Constant] already, so trust it
ISymbol operandSymbol = conversion.SemanticModel.GetSymbolInfo( operand.Syntax ).Symbol;
if( operandSymbol is not null && HasAttribute( operandSymbol, constantAttribute ) ) {
return;
}
Comment on lines +165 to 175

@omsmith omsmith Oct 16, 2026

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Basically moved to check constant operands first, and anything after that is deciding if the conversion was to something with a [Constant] parameter that we should raise a diagnostic for

if( @operator.Parameters.Length != 1 ) {

AnalyzeConversion(
context,
constantAttribute,
sourceType: conversion.Operand.Type,
targetType: conversion.Type,
conversion.Operand.Syntax
);
}

private static void AnalyzeConversion(
OperationAnalysisContext context,
INamedTypeSymbol constantAttribute,
ITypeSymbol sourceType,
ITypeSymbol targetType,
SyntaxNode diagnosticSyntax
) {
Conversion conversion = context.Compilation.ClassifyConversion(
source: sourceType,
destination: targetType
);

if( !conversion.Exists ) {
return;
}

// Operator parameter is not [Constant], so do nothing
IParameterSymbol parameter = @operator.Parameters[0];
if( !HasAttribute( parameter, constantAttribute ) ) {
if( conversion.MethodSymbol is { } @operator ) {
// Operator parameter is not [Constant], so do nothing
IParameterSymbol parameter = @operator.Parameters[ 0 ];
if( !HasAttribute( parameter, constantAttribute ) ) {
return;
}

// Operand is not constant, so report it
context.ReportDiagnostic(
descriptor: Diagnostics.NonConstantPassedToConstantParameter,
location: diagnosticSyntax.GetLocation(),
messageArgs: [ parameter.Name ]
);
return;
}

// Operand is a constant value or string.Empty, so trust it
IOperation operand = conversion.Operand;
if( operand.ConstantValue.HasValue || IsStringEmpty( operand ) ) {
if( !conversion.IsTupleConversion ) {
return;
}

// Operand was defined as [Constant] already, so trust it
ISymbol operandSymbol = conversion.SemanticModel.GetSymbolInfo( operand.Syntax ).Symbol;
if( operandSymbol is not null && HasAttribute( operandSymbol, constantAttribute ) ) {
if( sourceType is not INamedTypeSymbol namedSourceType ) {
return;
}

// Operand is not constant, so report it
context.ReportDiagnostic(
descriptor: Diagnostics.NonConstantPassedToConstantParameter,
location: operand.Syntax.GetLocation(),
messageArgs: new[] { parameter.Name }
);
if( targetType is not INamedTypeSymbol namedTargetType ) {
return;
}

if( namedSourceType.TypeArguments.Length != namedTargetType.TypeArguments.Length ) {
return;
}

for( int i = 0; i < namedSourceType.TypeArguments.Length; i++ ) {
AnalyzeConversion(
context,
constantAttribute,
sourceType: namedSourceType.TypeArguments[ i ],
targetType: namedTargetType.TypeArguments[ i ],
diagnosticSyntax
);
}
}

private static void AnalyzeCompoundAssignment(
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6 changes: 6 additions & 0 deletions tests/D2L.CodeStyle.Analyzers.Test/Specs/ConstantAttributeAnalyzer.cs
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Expand Up @@ -275,6 +275,12 @@ string untrusted
{ Types.ConstantStruct v = trusted; }
{ Types.ConstantStruct v = /* NonConstantPassedToConstantParameter(value) */ variable /**/; }
{ Types.ConstantStruct v = /* NonConstantPassedToConstantParameter(value) */ untrusted /**/; }
{ (Types.ConstantStruct X, Types.ConstantStruct Y) v = (Constants.String, Constants.String); }
{ (Types.ConstantStruct X, Types.ConstantStruct Y) v = (Constants.String, trusted); }
{ (Types.ConstantStruct X, Types.ConstantStruct Y) v = (Constants.String, /* NonConstantPassedToConstantParameter(value) */ variable /**/); }
{ (Types.ConstantStruct X, Types.ConstantStruct Y) v = (Constants.String, /* NonConstantPassedToConstantParameter(value) */ untrusted /**/); }
Comment on lines +278 to +281

@omsmith omsmith Oct 16, 2026

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These already worked, just adding the tests for it

{ (Types.ConstantStruct X, Types.ConstantStruct Y) v = /* NonConstantPassedToConstantParameter(value) */ true ? (Constants.String, Constants.String) : (Constants.String, Constants.String) /**/; }
{ (Types.ConstantStruct X, Types.ConstantStruct Y) v = /* NonConstantPassedToConstantParameter(value) */ true ? (Constants.String, variable) : (Constants.String, Constants.String) /**/; }
Comment on lines +282 to +283

@omsmith omsmith Oct 16, 2026

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Ideally the former of these two would work, but would require special-casing the ternarys etc. etc. (we similarly don't special case switch expressions or anything)

@omsmith omsmith Oct 16, 2026

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Either of these cases previously fell into conversion.OperatorMethod is null and so we bailed despite the implicit tuple conversion existing.

{
Types.ConstantStruct v = Constants.String;
v += /* NonConstantPassedToConstantParameter(value) */ "abc" /**/;
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