private BoundPatternSwitchLabel BindPatternSwitchSectionLabel(
Binder sectionBinder,
SwitchLabelSyntax node,
LabelSymbol label,
ref BoundPatternSwitchLabel defaultLabel,
DiagnosticBag diagnostics)
{
switch (node.Kind())
{
case SyntaxKind.CaseSwitchLabel:
{
var caseLabelSyntax = (CaseSwitchLabelSyntax)node;
var pattern = sectionBinder.BindConstantAsPattern(
node, SwitchGoverningType, caseLabelSyntax.Value, node.HasErrors, diagnostics, out bool wasExpression);
bool hasErrors = pattern.HasErrors;
SyntaxNode innerValueSyntax = caseLabelSyntax.Value.SkipParens();
if (innerValueSyntax.Kind() == SyntaxKind.DefaultLiteralExpression)
{
diagnostics.Add(ErrorCode.ERR_DefaultInSwitch, innerValueSyntax.Location);
hasErrors = true;
}
pattern.WasCompilerGenerated = true;
var constantValue = pattern.ConstantValue;
if (!hasErrors &&
(object)constantValue != null &&
pattern.Value.Type == SwitchGoverningType &&
this.FindMatchingSwitchCaseLabel(constantValue, caseLabelSyntax) != label)
{
diagnostics.Add(ErrorCode.ERR_DuplicateCaseLabel, node.Location, pattern.ConstantValue.GetValueToDisplay() ?? label.Name);
hasErrors = true;
}
// Until we've determined whether or not the switch label is reachable, we assume it
// is. The caller updates isReachable after determining if the label is subsumed.
const bool isReachable = true;
return(new BoundPatternSwitchLabel(node, label, pattern, null, isReachable, hasErrors));
}
case SyntaxKind.DefaultSwitchLabel:
{
var defaultLabelSyntax = (DefaultSwitchLabelSyntax)node;
var pattern = new BoundWildcardPattern(node);
bool hasErrors = pattern.HasErrors;
if (defaultLabel != null)
{
diagnostics.Add(ErrorCode.ERR_DuplicateCaseLabel, node.Location, label.Name);
hasErrors = true;
}
// We always treat the default label as reachable, even if the switch is complete.
const bool isReachable = true;
// Note that this is semantically last! The caller will place it in the decision tree
// in the final position.
defaultLabel = new BoundPatternSwitchLabel(node, label, pattern, null, isReachable, hasErrors);
return(defaultLabel);
}
case SyntaxKind.CasePatternSwitchLabel:
{
var matchLabelSyntax = (CasePatternSwitchLabelSyntax)node;
var pattern = sectionBinder.BindPattern(
matchLabelSyntax.Pattern, SwitchGoverningType, node.HasErrors, diagnostics);
return(new BoundPatternSwitchLabel(node, label, pattern,
matchLabelSyntax.WhenClause != null ? sectionBinder.BindBooleanExpression(matchLabelSyntax.WhenClause.Condition, diagnostics) : null,
true, node.HasErrors));
}
default:
throw ExceptionUtilities.UnexpectedValue(node);
}
}