/// <summary>
/// Learn from any constant null patterns appearing in the pattern.
/// </summary>
/// <param name="inputType">Type type of the input expression (before nullable analysis).
/// Used to determine which types can contain null.</param>
/// <returns>true if there is a top-level explicit null check</returns>
private void LearnFromAnyNullPatterns(
int inputSlot,
TypeSymbol inputType,
BoundPattern pattern)
{
if (inputSlot <= 0)
{
return;
}
switch (pattern)
{
case BoundConstantPattern cp:
bool isExplicitNullCheck = cp.Value.ConstantValue == ConstantValue.Null;
if (isExplicitNullCheck)
{
LearnFromNullTest(inputSlot, inputType, ref this.State);
}
break;
case BoundDeclarationPattern _:
case BoundDiscardPattern _:
case BoundITuplePattern _:
break; // nothing to learn
case BoundRecursivePattern rp:
{
// for positional part: we only learn from tuples (not Deconstruct)
if (rp.DeconstructMethod is null && !rp.Deconstruction.IsDefault)
{
var elements = inputType.TupleElements;
for (int i = 0, n = Math.Min(rp.Deconstruction.Length, elements.IsDefault ? 0 : elements.Length); i < n; i++)
{
BoundSubpattern item = rp.Deconstruction[i];
FieldSymbol element = elements[i];
LearnFromAnyNullPatterns(GetOrCreateSlot(element, inputSlot), element.Type, item.Pattern);
}
}
// for property part
if (!rp.Properties.IsDefault)
{
for (int i = 0, n = rp.Properties.Length; i < n; i++)
{
BoundSubpattern item = rp.Properties[i];
Symbol symbol = item.Symbol;
if (symbol?.ContainingType.Equals(inputType, TypeCompareKind.AllIgnoreOptions) == true)
{
LearnFromAnyNullPatterns(GetOrCreateSlot(symbol, inputSlot), symbol.GetTypeOrReturnType().Type, item.Pattern);
}
}
}
}
break;
default:
throw ExceptionUtilities.UnexpectedValue(pattern);
}
}
public override BoundNode VisitSubpattern(BoundSubpattern node)
{
Visit(node.Pattern);
return(null);
}
/// <summary>
/// Learn from any constant null patterns appearing in the pattern.
/// </summary>
/// <param name="inputType">Type type of the input expression (before nullable analysis).
/// Used to determine which types can contain null.</param>
private void LearnFromAnyNullPatterns(
int inputSlot,
TypeSymbol inputType,
BoundPattern pattern)
{
if (inputSlot <= 0)
{
return;
}
// https://github.com/dotnet/roslyn/issues/35041 We only need to do this when we're rewriting, so we
// can get information for any nodes in the pattern.
VisitPatternForRewriting(pattern);
switch (pattern)
{
case BoundConstantPattern cp:
bool isExplicitNullCheck = cp.Value.ConstantValue == ConstantValue.Null;
if (isExplicitNullCheck)
{
// Since we're not branching on this null test here, we just infer the top level
// nullability. We'll branch on it later.
LearnFromNullTest(inputSlot, inputType, ref this.State, markDependentSlotsNotNull: false);
}
break;
case BoundDeclarationPattern _:
case BoundDiscardPattern _:
case BoundITuplePattern _:
break; // nothing to learn
case BoundRecursivePattern rp:
{
if (rp.IsExplicitNotNullTest)
{
LearnFromNullTest(inputSlot, inputType, ref this.State, markDependentSlotsNotNull: false);
}
// for positional part: we only learn from tuples (not Deconstruct)
if (rp.DeconstructMethod is null && !rp.Deconstruction.IsDefault)
{
var elements = inputType.TupleElements;
for (int i = 0, n = Math.Min(rp.Deconstruction.Length, elements.IsDefault ? 0 : elements.Length); i < n; i++)
{
BoundSubpattern item = rp.Deconstruction[i];
FieldSymbol element = elements[i];
LearnFromAnyNullPatterns(GetOrCreateSlot(element, inputSlot), element.Type, item.Pattern);
}
}
// for property part
if (!rp.Properties.IsDefault)
{
for (int i = 0, n = rp.Properties.Length; i < n; i++)
{
BoundSubpattern item = rp.Properties[i];
Symbol symbol = item.Symbol;
if (symbol?.ContainingType.Equals(inputType, TypeCompareKind.AllIgnoreOptions) == true)
{
LearnFromAnyNullPatterns(GetOrCreateSlot(symbol, inputSlot), symbol.GetTypeOrReturnType().Type, item.Pattern);
}
}
}
}
break;
default:
throw ExceptionUtilities.UnexpectedValue(pattern);
}
}
private void LearnFromAnyNullPatterns(
int inputSlot,
TypeSymbol inputType,
BoundPattern pattern)
{
if (inputSlot <= 0)
{
return;
}
// https://github.com/dotnet/roslyn/issues/35041 We only need to do this when we're rewriting, so we
// can get information for any nodes in the pattern.
VisitPatternForRewriting(pattern);
switch (pattern)
{
case BoundConstantPattern cp:
bool isExplicitNullCheck = cp.Value.ConstantValue == ConstantValue.Null;
if (isExplicitNullCheck)
{
// Since we're not branching on this null test here, we just infer the top level
// nullability. We'll branch on it later.
LearnFromNullTest(inputSlot, inputType, ref this.State, markDependentSlotsNotNull: false);
}
break;
case BoundDeclarationPattern _:
case BoundDiscardPattern _:
case BoundITuplePattern _:
case BoundRelationalPattern _:
break; // nothing to learn
case BoundTypePattern tp:
if (tp.IsExplicitNotNullTest)
{
LearnFromNullTest(inputSlot, inputType, ref this.State, markDependentSlotsNotNull: false);
}
break;
case BoundRecursivePattern rp:
{
if (rp.IsExplicitNotNullTest)
{
LearnFromNullTest(inputSlot, inputType, ref this.State, markDependentSlotsNotNull: false);
}
// for positional part: we only learn from tuples (not Deconstruct)
if (rp.DeconstructMethod is null && !rp.Deconstruction.IsDefault)
{
var elements = inputType.TupleElements;
for (int i = 0, n = Math.Min(rp.Deconstruction.Length, elements.IsDefault ? 0 : elements.Length); i < n; i++)
{
BoundSubpattern item = rp.Deconstruction[i];
FieldSymbol element = elements[i];
LearnFromAnyNullPatterns(GetOrCreateSlot(element, inputSlot), element.Type, item.Pattern);
}
}
// for property part
if (!rp.Properties.IsDefault)
{
foreach (BoundPropertySubpattern subpattern in rp.Properties)
{
if (subpattern.Member is BoundPropertySubpatternMember member)
{
LearnFromAnyNullPatterns(getExtendedPropertySlot(member, inputSlot), member.Type, subpattern.Pattern);
}
}
}
}
break;
case BoundNegatedPattern p:
LearnFromAnyNullPatterns(inputSlot, inputType, p.Negated);
break;
case BoundBinaryPattern p:
LearnFromAnyNullPatterns(inputSlot, inputType, p.Left);
LearnFromAnyNullPatterns(inputSlot, inputType, p.Right);
break;
default:
throw ExceptionUtilities.UnexpectedValue(pattern);
}
int getExtendedPropertySlot(BoundPropertySubpatternMember member, int inputSlot)
{
if (member.Symbol is null)
{
return(-1);
}
if (member.Receiver is not null)
{
inputSlot = getExtendedPropertySlot(member.Receiver, inputSlot);
}
if (inputSlot < 0)
{
return(inputSlot);
}
return(GetOrCreateSlot(member.Symbol, inputSlot));
}
}
