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Overhaul syntax model for deconstruction decl
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Also update the out var syntax node to use the newly introduced
VariableComponent so it can be extended in the future to allow `out *`
or `out var (x, y)` etc without requiring any further changes to the
syntax model.
Fixes dotnet#12747, dotnet#12664, dotnet#12588, dotnet#1503
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@gafter
gafter committed Aug 3, 2016
1 parent 6647aa5 commit df48ec6
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Showing 59 changed files with 1,324 additions and 1,124 deletions.
118 changes: 66 additions & 52 deletions src/Compilers/CSharp/Portable/Binder/Binder_Deconstruct.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -537,23 +537,66 @@ private BoundBadExpression MissingDeconstruct(BoundExpression receiver, CSharpSy
return BadExpression(syntax, childNode);
}

internal BoundLocalDeconstructionDeclaration BindDeconstructionDeclaration(CSharpSyntaxNode node, VariableDeclarationSyntax declaration, DiagnosticBag diagnostics)
internal BoundLocalDeconstructionDeclaration BindDeconstructionDeclarationStatement(DeconstructionDeclarationStatementSyntax node, DiagnosticBag diagnostics)
{
Debug.Assert(node.Kind() == SyntaxKind.LocalDeclarationStatement || node.Kind() == SyntaxKind.VariableDeclaration);
Debug.Assert(declaration.IsDeconstructionDeclaration);

var value = declaration.Deconstruction.Value;
return new BoundLocalDeconstructionDeclaration(node, BindDeconstructionDeclaration(node, declaration, value, diagnostics));
return new BoundLocalDeconstructionDeclaration(node, BindDeconstructionDeclaration(node, node.Assignment.Declaration, node.Assignment.Value, diagnostics));
}

internal BoundDeconstructionAssignmentOperator BindDeconstructionDeclaration(CSharpSyntaxNode node, VariableDeclarationSyntax declaration, ExpressionSyntax right, DiagnosticBag diagnostics, BoundDeconstructValuePlaceholder rightPlaceholder = null)
internal BoundDeconstructionAssignmentOperator BindDeconstructionDeclaration(CSharpSyntaxNode node, VariableComponentSyntax declaration, ExpressionSyntax right, DiagnosticBag diagnostics, BoundDeconstructValuePlaceholder rightPlaceholder = null)
{
ArrayBuilder<DeconstructionVariable> locals = BindDeconstructionDeclarationLocals(declaration, declaration.Type, diagnostics);
DeconstructionVariable locals = BindDeconstructionDeclarationLocals(declaration, diagnostics);
Debug.Assert(locals.HasNestedVariables);
var result = BindDeconstructionAssignment(node, right, locals.NestedVariables, diagnostics, isDeclaration: true, rhsPlaceholder: rightPlaceholder);
FreeDeconstructionVariables(locals.NestedVariables);
return result;
}

var result = BindDeconstructionAssignment(node, right, locals, diagnostics, isDeclaration: true, rhsPlaceholder: rightPlaceholder);
FreeDeconstructionVariables(locals);
private DeconstructionVariable BindDeconstructionDeclarationLocals(VariableComponentSyntax node, DiagnosticBag diagnostics)
{
switch (node.Kind())
{
case SyntaxKind.TypedVariableComponent:
{
var component = (TypedVariableComponentSyntax)node;
return BindDeconstructionDeclarationLocals(component.Type, component.Designation, diagnostics);
}
case SyntaxKind.TupleDeconstructionVariableComponent:
{
var component = (TupleDeconstructionVariableComponentSyntax)node;
var builder = ArrayBuilder<DeconstructionVariable>.GetInstance();
foreach (var n in component.Variables)
{
builder.Add(BindDeconstructionDeclarationLocals(n, diagnostics));
}
return new DeconstructionVariable(builder, node);
}
default:
throw ExceptionUtilities.UnexpectedValue(node.Kind());
}
}

return result;
private DeconstructionVariable BindDeconstructionDeclarationLocals(TypeSyntax type, VariableDesignationSyntax node, DiagnosticBag diagnostics)
{
switch (node.Kind())
{
case SyntaxKind.SingleVariableDesignation:
{
var single = (SingleVariableDesignationSyntax)node;
return new DeconstructionVariable(BindDeconstructionDeclarationLocal(type, single, diagnostics), node);
}
case SyntaxKind.TupleDeconstructionVariableDesignation:
{
var tuple = (TupleDeconstructionVariableDesignationSyntax)node;
var builder = ArrayBuilder<DeconstructionVariable>.GetInstance();
foreach (var n in tuple.Variables)
{
builder.Add(BindDeconstructionDeclarationLocals(type, n, diagnostics));
}
return new DeconstructionVariable(builder, node);
}
default:
throw ExceptionUtilities.UnexpectedValue(node.Kind());
}
}

/// <summary>
Expand All @@ -562,49 +605,19 @@ internal BoundDeconstructionAssignmentOperator BindDeconstructionDeclaration(CSh
/// Each local is either a simple local (when its type is known) or a deconstruction local pending inference.
/// The caller is responsible for releasing the nested ArrayBuilders.
/// </summary>
private ArrayBuilder<DeconstructionVariable> BindDeconstructionDeclarationLocals(VariableDeclarationSyntax node, TypeSyntax closestTypeSyntax, DiagnosticBag diagnostics)
private ArrayBuilder<DeconstructionVariable> BindDeconstructionDeclarationLocals(DeconstructionDeclarationAssignmentSyntax node, TypeSyntax closestTypeSyntax, DiagnosticBag diagnostics)
{
Debug.Assert(node.IsDeconstructionDeclaration);
SeparatedSyntaxList<VariableDeclarationSyntax> variables = node.Deconstruction.Variables;

// There are four cases for VariableDeclaration:
// - type and declarators are set, but deconstruction is null. This could represent `int x`, which is a single variable.
// - type is null, declarators are set, but deconstruction is null. This could represent `x`, which is a single variable.
// - type is set to 'var', declarators are null, and deconstruction is set. This could represent `var (...)`
// - type and declarators are null, but deconstruction is set. This could represent `(int x, ...)`

var localsBuilder = ArrayBuilder<DeconstructionVariable>.GetInstance(variables.Count);
foreach (var variable in variables)
{
TypeSyntax typeSyntax = variable.Type ?? closestTypeSyntax;

DeconstructionVariable local;
if (variable.IsDeconstructionDeclaration)
{
local = new DeconstructionVariable(BindDeconstructionDeclarationLocals(variable, typeSyntax, diagnostics), variable.Deconstruction);
}
else
{
local = new DeconstructionVariable(BindDeconstructionDeclarationLocal(variable, typeSyntax, diagnostics), variable);
}

localsBuilder.Add(local);
}

return localsBuilder;
var deconstructionVariable = BindDeconstructionDeclarationLocals(node.Declaration, diagnostics);
Debug.Assert(deconstructionVariable.HasNestedVariables);
return deconstructionVariable.NestedVariables;
}

/// <summary>
/// Returns a BoundLocal when the type was explicit, otherwise returns a DeconstructionLocalPendingInference.
/// </summary>
private BoundExpression BindDeconstructionDeclarationLocal(VariableDeclarationSyntax node, TypeSyntax closestTypeSyntax, DiagnosticBag diagnostics)
private BoundExpression BindDeconstructionDeclarationLocal(TypeSyntax typeSyntax, SingleVariableDesignationSyntax designation, DiagnosticBag diagnostics)
{
Debug.Assert(!node.IsDeconstructionDeclaration);
Debug.Assert(node.Variables.Count == 1);

var declarator = node.Variables[0];

var localSymbol = LocateDeclaredVariableSymbol(declarator, closestTypeSyntax);
var localSymbol = LocateDeclaredVariableSymbol(designation, typeSyntax);

// Check for variable declaration errors.
// Use the binder that owns the scope for the local because this (the current) binder
Expand All @@ -614,20 +627,21 @@ private BoundExpression BindDeconstructionDeclarationLocal(VariableDeclarationSy
bool isVar;
bool isConst = false;
AliasSymbol alias;
TypeSymbol declType = BindVariableType(node, diagnostics, closestTypeSyntax, ref isConst, out isVar, out alias);
TypeSymbol declType = BindVariableType(designation, diagnostics, typeSyntax, ref isConst, out isVar, out alias);

if (!isVar)
{
if (node.Type == null)
if (designation.Parent.Kind() == SyntaxKind.TupleDeconstructionVariableDesignation)
{
// An explicit type can only be provided next to the variable
Error(diagnostics, ErrorCode.ERR_DeconstructionVarFormDisallowsSpecificType, node);
Error(diagnostics, ErrorCode.ERR_DeconstructionVarFormDisallowsSpecificType, designation);
hasErrors = true;
}

return new BoundLocal(declarator, localSymbol, constantValueOpt: null, type: declType, hasErrors: node.Type == null);
return new BoundLocal(designation, localSymbol, constantValueOpt: null, type: declType, hasErrors: hasErrors);
}

return new DeconstructionLocalPendingInference(declarator, localSymbol);
return new DeconstructionLocalPendingInference(designation, localSymbol);
}
}
}
4 changes: 2 additions & 2 deletions src/Compilers/CSharp/Portable/Binder/Binder_Expressions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2105,7 +2105,7 @@ private BoundExpression BindArgumentValue(DiagnosticBag diagnostics, ArgumentSyn
}

var declarationExpression = (DeclarationExpressionSyntax)argumentSyntax.Expression;
var declaration = declarationExpression.Declaration;
var declaration = (TypedVariableComponentSyntax)declarationExpression.Declaration;
var typeSyntax = declaration.Type;

bool isConst = false;
Expand Down Expand Up @@ -2299,7 +2299,7 @@ private void CoerceArguments<TMember>(
&& ((MethodSymbol)this.ContainingMemberOrLambda).IsAsync
&& parameterType.IsRestrictedType())
{
var declaration = ((DeclarationExpressionSyntax)argument.Syntax).Declaration;
var declaration = (TypedVariableComponentSyntax)((DeclarationExpressionSyntax)argument.Syntax).Declaration;
Error(diagnostics, ErrorCode.ERR_BadSpecialByRefLocal, declaration.Type, parameterType);
hasErrors = true;
}
Expand Down
48 changes: 29 additions & 19 deletions src/Compilers/CSharp/Portable/Binder/Binder_Statements.cs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,9 @@ public virtual BoundStatement BindStatement(StatementSyntax node, DiagnosticBag
case SyntaxKind.LocalDeclarationStatement:
result = BindLocalDeclarationStatement((LocalDeclarationStatementSyntax)node, diagnostics);
break;
case SyntaxKind.DeconstructionDeclarationStatement:
result = BindDeconstructionDeclarationStatement((DeconstructionDeclarationStatementSyntax)node, diagnostics);
break;
case SyntaxKind.LocalFunctionStatement:
result = BindLocalFunctionStatement((LocalFunctionStatementSyntax)node, diagnostics);
break;
Expand All @@ -65,7 +68,8 @@ public virtual BoundStatement BindStatement(StatementSyntax node, DiagnosticBag
result = BindFor((ForStatementSyntax)node, diagnostics);
break;
case SyntaxKind.ForEachStatement:
result = BindForEach((ForEachStatementSyntax)node, diagnostics);
case SyntaxKind.ForEachComponentStatement:
result = BindForEach((CommonForEachStatementSyntax)node, diagnostics);
break;
case SyntaxKind.BreakStatement:
result = BindBreak((BreakStatementSyntax)node, diagnostics);
Expand Down Expand Up @@ -549,15 +553,7 @@ internal BoundStatement BindLocalDeclarationStatement(LocalDeclarationStatementS
Debug.Assert(binder != null);

BoundStatement bound;
if (node.Declaration.IsDeconstructionDeclaration)
{
bound = binder.BindDeconstructionDeclaration(node, node.Declaration, diagnostics);
}
else
{
bound = binder.BindDeclarationStatementParts(node, diagnostics);
}

bound = binder.BindDeclarationStatementParts(node, diagnostics);
return binder.WrapWithVariablesIfAny(node, bound);
}

Expand All @@ -568,7 +564,7 @@ private BoundStatement BindDeclarationStatementParts(LocalDeclarationStatementSy

bool isVar;
AliasSymbol alias;
TypeSymbol declType = BindVariableType(node, diagnostics, typeSyntax, ref isConst, isVar: out isVar, alias: out alias);
TypeSymbol declType = BindVariableType(node.Declaration, diagnostics, typeSyntax, ref isConst, isVar: out isVar, alias: out alias);

// UNDONE: "possible expression" feature for IDE

Expand Down Expand Up @@ -601,7 +597,10 @@ private BoundStatement BindDeclarationStatementParts(LocalDeclarationStatementSy

private TypeSymbol BindVariableType(CSharpSyntaxNode declarationNode, DiagnosticBag diagnostics, TypeSyntax typeSyntax, ref bool isConst, out bool isVar, out AliasSymbol alias)
{
Debug.Assert(declarationNode.Kind() == SyntaxKind.LocalDeclarationStatement || declarationNode.Kind() == SyntaxKind.DeclarationExpression || declarationNode.Kind() == SyntaxKind.VariableDeclaration);
Debug.Assert(
declarationNode.Kind() == SyntaxKind.SingleVariableDesignation ||
declarationNode.Kind() == SyntaxKind.VariableDeclaration ||
declarationNode.Kind() == SyntaxKind.DeclarationExpression);

// If the type is "var" then suppress errors when binding it. "var" might be a legal type
// or it might not; if it is not then we do not want to report an error. If it is, then
Expand Down Expand Up @@ -638,7 +637,8 @@ private TypeSymbol BindVariableType(CSharpSyntaxNode declarationNode, Diagnostic
// more sense to treat that as "var x = 10; var y = 123.4;" and do each inference
// separately.

if (declarationNode.Kind() == SyntaxKind.LocalDeclarationStatement && ((LocalDeclarationStatementSyntax)declarationNode).Declaration.Variables.Count > 1 && !declarationNode.HasErrors)
if (declarationNode.Parent.Kind() == SyntaxKind.LocalDeclarationStatement &&
((VariableDeclarationSyntax)declarationNode).Variables.Count > 1 && !declarationNode.HasErrors)
{
Error(diagnostics, ErrorCode.ERR_ImplicitlyTypedVariableMultipleDeclarator, declarationNode);
}
Expand Down Expand Up @@ -970,7 +970,17 @@ private ImmutableArray<BoundExpression> BindDeclaratorArguments(VariableDeclarat

private SourceLocalSymbol LocateDeclaredVariableSymbol(VariableDeclaratorSyntax declarator, TypeSyntax typeSyntax)
{
SourceLocalSymbol localSymbol = this.LookupLocal(declarator.Identifier);
return LocateDeclaredVariableSymbol(declarator.Identifier, typeSyntax, declarator.Initializer);
}

private SourceLocalSymbol LocateDeclaredVariableSymbol(SingleVariableDesignationSyntax designation, TypeSyntax typeSyntax)
{
return LocateDeclaredVariableSymbol(designation.Identifier, typeSyntax, null);
}

private SourceLocalSymbol LocateDeclaredVariableSymbol(SyntaxToken identifier, TypeSyntax typeSyntax, EqualsValueClauseSyntax equalsValue)
{
SourceLocalSymbol localSymbol = this.LookupLocal(identifier);

// In error scenarios with misplaced code, it is possible we can't bind the local declaration.
// This occurs through the semantic model. In that case concoct a plausible result.
Expand All @@ -981,9 +991,9 @@ private SourceLocalSymbol LocateDeclaredVariableSymbol(VariableDeclaratorSyntax
this,
RefKind.None,
typeSyntax,
declarator.Identifier,
identifier,
LocalDeclarationKind.RegularVariable,
declarator.Initializer);
equalsValue);
}

return localSymbol;
Expand Down Expand Up @@ -3072,7 +3082,7 @@ internal BoundStatement BindStatementExpressionList(SeparatedSyntaxList<Expressi
}
}

private BoundStatement BindForEach(ForEachStatementSyntax node, DiagnosticBag diagnostics)
private BoundStatement BindForEach(CommonForEachStatementSyntax node, DiagnosticBag diagnostics)
{
Binder loopBinder = this.GetBinder(node);
return this.GetBinder(node.Expression).WrapWithVariablesIfAny(node.Expression, loopBinder.BindForEachParts(diagnostics, loopBinder));
Expand All @@ -3086,9 +3096,9 @@ internal virtual BoundStatement BindForEachParts(DiagnosticBag diagnostics, Bind
/// <summary>
/// Like BindForEachParts, but only bind the deconstruction part of the foreach, for purpose of inferring the types of the declared locals.
/// </summary>
internal virtual void BindForEachDeconstruction(DiagnosticBag diagnostics, Binder originalBinder)
internal virtual BoundStatement BindForEachDeconstruction(DiagnosticBag diagnostics, Binder originalBinder)
{
this.Next.BindForEachDeconstruction(diagnostics, originalBinder);
return this.Next.BindForEachDeconstruction(diagnostics, originalBinder);
}

private BoundStatement BindBreak(BreakStatementSyntax node, DiagnosticBag diagnostics)
Expand Down
2 changes: 1 addition & 1 deletion src/Compilers/CSharp/Portable/Binder/BuckStopsHereBinder.cs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -182,7 +182,7 @@ internal override BoundStatement BindForEachParts(DiagnosticBag diagnostics, Bin
throw ExceptionUtilities.Unreachable;
}

internal override void BindForEachDeconstruction(DiagnosticBag diagnostics, Binder originalBinder)
internal override BoundStatement BindForEachDeconstruction(DiagnosticBag diagnostics, Binder originalBinder)
{
// There's supposed to be a ForEachLoopBinder (or other overrider of this method) in the chain.
throw ExceptionUtilities.Unreachable;
Expand Down
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