private static bool IsRedundantAssignment(ISymbol left, AssignmentExpressionSyntax assignment, SyntaxNodeAnalysisContext context)
{
if (left is IDiscardSymbol ||
assignment.TryFirstAncestor <ObjectCreationExpressionSyntax>(out _))
{
return(false);
}
if (assignment.TryFirstAncestor <MemberDeclarationSyntax>(out var member))
{
if (!(member is ConstructorDeclarationSyntax) &&
context.SemanticModel.TryGetType(assignment.Left, context.CancellationToken, out var type) &&
FieldOrProperty.TryCreate(left, out _))
{
if (type == KnownSymbol.Boolean ||
type.TypeKind == TypeKind.Enum)
{
return(false);
}
}
using (var walker = AssignmentExecutionWalker.For(left, member, Scope.Member, context.SemanticModel, context.CancellationToken))
{
foreach (var candidate in walker.Assignments)
{
if (candidate == assignment)
{
continue;
}
if (!MemberPath.Equals(candidate.Left, assignment.Left))
{
continue;
}
if (candidate.IsExecutedBefore(assignment) == ExecutedBefore.Yes)
{
if (left is IParameterSymbol parameter &&
parameter.RefKind == RefKind.Out &&
assignment.TryFirstAncestor <BlockSyntax>(out var assignmentBlock) &&
candidate.TryFirstAncestor <BlockSyntax>(out var candidateBlock) &&
(candidateBlock.Contains(assignmentBlock) ||
candidateBlock.Statements.Last() is ReturnStatementSyntax))
{
return(false);
}
using (var nameWalker = IdentifierNameWalker.Borrow(assignment.Right))
{
foreach (var name in nameWalker.IdentifierNames)
{
if (left.Name == name.Identifier.ValueText &&
context.SemanticModel.TryGetSymbol(
name,
context.CancellationToken,
out ISymbol symbol) &&
symbol.Equals(left))
{
return(false);
}
}
}
return(true);
}
}
}
}
return(false);
}