private ImmutableArray <Diagnostic> AnalyzeSemanticModel(SemanticModelAnalysisContext context, int positionOfFirstReducingNullableDirective, SimpleIntervalTree <TextSpan, TextSpanIntervalIntrospector>?codeBlockIntervalTree, SimpleIntervalTree <TextSpan, TextSpanIntervalIntrospector>?possibleNullableImpactIntervalTree)
{
var root = context.SemanticModel.SyntaxTree.GetCompilationUnitRoot(context.CancellationToken);
using (var simplifier = new NullableImpactingSpanWalker(context.SemanticModel, positionOfFirstReducingNullableDirective, ignoredSpans: codeBlockIntervalTree, context.CancellationToken))
{
simplifier.Visit(root);
possibleNullableImpactIntervalTree ??= new SimpleIntervalTree <TextSpan, TextSpanIntervalIntrospector>(new TextSpanIntervalIntrospector(), values: null);
foreach (var interval in simplifier.Spans)
{
possibleNullableImpactIntervalTree.AddIntervalInPlace(interval);
}
}
using var diagnostics = TemporaryArray <Diagnostic> .Empty;
var compilationOptions = ((CSharpCompilationOptions)context.SemanticModel.Compilation.Options).NullableContextOptions;
DirectiveTriviaSyntax? previousRetainedDirective = null;
NullableContextOptions?retainedOptions = compilationOptions;
DirectiveTriviaSyntax?currentOptionsDirective = null;
var currentOptions = retainedOptions;
for (var directive = root.GetFirstDirective(); directive is not null; directive = directive.GetNextDirective())
{
context.CancellationToken.ThrowIfCancellationRequested();
if (directive.IsKind(SyntaxKind.NullableDirectiveTrivia, out NullableDirectiveTriviaSyntax? nullableDirectiveTrivia))
{
// Once we reach a new directive, check to see if we can remove the previous directive
var removedCurrent = false;
if (IsReducing(retainedOptions, currentOptions))
{
// We can't have found a reducing directive and not know which directive it was
Contract.ThrowIfNull(currentOptionsDirective);
if (possibleNullableImpactIntervalTree is null ||
!possibleNullableImpactIntervalTree.HasIntervalThatOverlapsWith(currentOptionsDirective.Span.End, nullableDirectiveTrivia.SpanStart - currentOptionsDirective.Span.End))
{
diagnostics.Add(Diagnostic.Create(Descriptor, currentOptionsDirective.GetLocation()));
}
}
if (!removedCurrent)
{
previousRetainedDirective = currentOptionsDirective;
retainedOptions = currentOptions;
}
currentOptionsDirective = nullableDirectiveTrivia;
currentOptions = CSharpRemoveRedundantNullableDirectiveDiagnosticAnalyzer.GetNullableContextOptions(compilationOptions, currentOptions, nullableDirectiveTrivia);
}
else if (directive.IsKind(SyntaxKind.IfDirectiveTrivia, SyntaxKind.ElifDirectiveTrivia, SyntaxKind.ElseDirectiveTrivia))
{
possibleNullableImpactIntervalTree ??= new SimpleIntervalTree <TextSpan, TextSpanIntervalIntrospector>(new TextSpanIntervalIntrospector(), values: null);
possibleNullableImpactIntervalTree.AddIntervalInPlace(directive.Span);
}
}
// Once we reach the end of the file, check to see if we can remove the last directive
if (IsReducing(retainedOptions, currentOptions))
{
// We can't have found a reducing directive and not know which directive it was
Contract.ThrowIfNull(currentOptionsDirective);
if (possibleNullableImpactIntervalTree is null ||
!possibleNullableImpactIntervalTree.HasIntervalThatOverlapsWith(currentOptionsDirective.Span.End, root.Span.End - currentOptionsDirective.Span.End))
{
diagnostics.Add(Diagnostic.Create(Descriptor, currentOptionsDirective.GetLocation()));
}
}
return(diagnostics.ToImmutableAndClear());
}
private static ImmutableArray <TextSpan> AnalyzeCodeBlock(CodeBlockAnalysisContext context, int positionOfFirstReducingNullableDirective)
{
using var simplifier = new NullableImpactingSpanWalker(context.SemanticModel, positionOfFirstReducingNullableDirective, ignoredSpans: null, context.CancellationToken);
simplifier.Visit(context.CodeBlock);
return(simplifier.Spans);
}