private ForEachEnumeratorInfo(TypeSymbol iterableType,
TypeSymbolWithAnnotations elementType,
TypeSymbol iteratorType,
MethodSymbol iterateBegin,
MethodSymbol iterateHasCurrent,
MethodSymbol iterateCurrent,
MethodSymbol iterateNext,
MethodSymbol iterateEnd,
bool needsDisposal,
AwaitableInfo disposeAwaitableInfo,
BinderFlags location)
{
Debug.Assert((object)iterableType != null, "Field 'collectionType' cannot be null");
Debug.Assert(!elementType.IsNull, "Field 'elementType' cannot be null");
Debug.Assert((object)iteratorType != null, "Field 'stateType' cannot be null");
Debug.Assert((object)iterateBegin != null, "Field 'iterateBegin' cannot be null");
Debug.Assert((object)iterateNext != null, "Field 'iterateItem' cannot be null");
Debug.Assert((object)iterateHasCurrent != null, "Field 'iterateNext' cannot be null");
Debug.Assert((object)iterateEnd != null, "Field 'iterateEnd' cannot be null");
this.IterableType = iterableType;
this.ElementType = elementType;
this.IteratorType = iteratorType;
this.IterateBegin = iterateBegin;
this.IterateHasCurrent = iterateHasCurrent;
this.IterateCurrent = iterateCurrent;
this.IterateNext = iterateNext;
this.IterateEnd = iterateEnd;
this.NeedsDisposal = needsDisposal;
this.DisposeAwaitableInfo = disposeAwaitableInfo;
this.Location = location;
}
private ForEachEnumeratorInfo(
TypeSymbol collectionType,
TypeSymbolWithAnnotations elementType,
MethodSymbol getEnumeratorMethod,
MethodSymbol currentPropertyGetter,
MethodSymbol moveNextMethod,
bool needsDisposal,
AwaitableInfo disposeAwaitableInfo,
MethodSymbol disposeMethod,
Conversion collectionConversion,
Conversion currentConversion,
Conversion enumeratorConversion,
BinderFlags location)
{
Debug.Assert((object)collectionType != null, "Field 'collectionType' cannot be null");
Debug.Assert(!elementType.IsNull, "Field 'elementType' cannot be null");
Debug.Assert((object)getEnumeratorMethod != null, "Field 'getEnumeratorMethod' cannot be null");
Debug.Assert((object)currentPropertyGetter != null, "Field 'currentPropertyGetter' cannot be null");
Debug.Assert((object)moveNextMethod != null, "Field 'moveNextMethod' cannot be null");
this.CollectionType = collectionType;
this.ElementType = elementType;
this.GetEnumeratorMethod = getEnumeratorMethod;
this.CurrentPropertyGetter = currentPropertyGetter;
this.MoveNextMethod = moveNextMethod;
this.NeedsDisposal = needsDisposal;
this.DisposeAwaitableInfo = disposeAwaitableInfo;
this.DisposeMethod = disposeMethod;
this.CollectionConversion = collectionConversion;
this.CurrentConversion = currentConversion;
this.EnumeratorConversion = enumeratorConversion;
this.Location = location;
}
private BoundAwaitExpression BindAwait(BoundExpression expression, SyntaxNode node, DiagnosticBag diagnostics)
{
bool hasErrors = false;
AwaitableInfo info = BindAwaitInfo(expression, node, node.Location, diagnostics, ref hasErrors);
// Spec 7.7.7.2:
// The expression await t is classified the same way as the expression (t).GetAwaiter().GetResult(). Thus,
// if the return type of GetResult is void, the await-expression is classified as nothing. If it has a
// non-void return type T, the await-expression is classified as a value of type T.
TypeSymbol awaitExpressionType = info.GetResult?.ReturnType.TypeSymbol ?? (hasErrors ? CreateErrorType() : Compilation.DynamicType);
return(new BoundAwaitExpression(node, expression, info, awaitExpressionType, hasErrors));
}
private BoundStatement MakeDeclarationUsingStatement(SyntaxNode syntax,
BoundBlock body,
ImmutableArray <LocalSymbol> locals,
BoundLocalDeclaration declaration,
Conversion iDisposableConversion,
MethodSymbol disposeMethodOpt,
AwaitableInfo awaitOpt,
SyntaxToken awaitKeyword)
{
Debug.Assert(declaration != null);
BoundBlock result = body;
result = RewriteDeclarationUsingStatement(syntax, declaration, result, iDisposableConversion, awaitKeyword, awaitOpt, disposeMethodOpt);
// Declare all locals in a single, top-level block so that the scope is correct in the debugger
// (Dev10 has them all come into scope at once, not per-declaration.)
return(new BoundBlock(
syntax,
locals,
ImmutableArray.Create <BoundStatement>(result)));
}
private BoundExpression GenerateDisposeCall(SyntaxNode syntax, BoundExpression disposedExpression, MethodSymbol methodOpt, AwaitableInfo awaitOpt, SyntaxToken awaitKeyword)
{
Debug.Assert(awaitOpt is null || awaitKeyword != default);
// If we don't have an explicit dispose method, try and get the special member for IDiposable/IAsyncDisposable
if (methodOpt is null)
{
if (awaitOpt is null)
{
// IDisposable.Dispose()
Binder.TryGetSpecialTypeMember(_compilation, SpecialMember.System_IDisposable__Dispose, syntax, _diagnostics, out methodOpt);
}
else
{
// IAsyncDisposable.DisposeAsync()
TryGetWellKnownTypeMember(syntax: null, WellKnownMember.System_IAsyncDisposable__DisposeAsync, out methodOpt, location: awaitKeyword.GetLocation());
}
}
BoundExpression disposeCall;
if (methodOpt is null)
{
disposeCall = new BoundBadExpression(syntax, LookupResultKind.NotInvocable, ImmutableArray <Symbol> .Empty, ImmutableArray.Create(disposedExpression), ErrorTypeSymbol.UnknownResultType);
}
else
{
disposeCall = MakeCallWithNoExplicitArgument(syntax, disposedExpression, methodOpt);
if (!(awaitOpt is null))
{
// await local.DisposeAsync()
_sawAwaitInExceptionHandler = true;
TypeSymbol awaitExpressionType = awaitOpt.GetResult?.ReturnType.TypeSymbol ?? _compilation.DynamicType;
disposeCall = RewriteAwaitExpression(syntax, disposeCall, awaitOpt, awaitExpressionType, false);
}
}
return(disposeCall);
}
private BoundStatement RewriteUsingStatementTryFinally(SyntaxNode syntax, BoundBlock tryBlock, BoundLocal local, SyntaxToken awaitKeywordOpt, AwaitableInfo awaitOpt, MethodSymbol methodOpt)
{
// SPEC: When ResourceType is a non-nullable value type, the expansion is:
// SPEC:
// SPEC: {
// SPEC: ResourceType resource = expr;
// SPEC: try { statement; }
// SPEC: finally { ((IDisposable)resource).Dispose(); }
// SPEC: }
// SPEC:
// SPEC: Otherwise, when Resource type is a nullable value type or
// SPEC: a reference type other than dynamic, the expansion is:
// SPEC:
// SPEC: {
// SPEC: ResourceType resource = expr;
// SPEC: try { statement; }
// SPEC: finally { if (resource != null) ((IDisposable)resource).Dispose(); }
// SPEC: }
// SPEC:
// SPEC: Otherwise, when ResourceType is dynamic, the expansion is:
// SPEC: {
// SPEC: dynamic resource = expr;
// SPEC: IDisposable d = (IDisposable)resource;
// SPEC: try { statement; }
// SPEC: finally { if (d != null) d.Dispose(); }
// SPEC: }
// SPEC:
// SPEC: An implementation is permitted to implement a given using statement
// SPEC: differently -- for example, for performance reasons -- as long as the
// SPEC: behavior is consistent with the above expansion.
//
// In the case of using-await statement, we'll use "IAsyncDisposable" instead of "IDisposable", "await DisposeAsync()" instead of "Dispose()"
//
// And we do in fact generate the code slightly differently than precisely how it is
// described above.
//
// First: if the type is a non-nullable value type then we do not do the
// *boxing conversion* from the resource to IDisposable. Rather, we do
// a *constrained virtual call* that elides the boxing if possible.
//
// Now, you might wonder if that is legal; isn't skipping the boxing producing
// an observable difference? Because if the value type is mutable and the Dispose
// mutates it, then skipping the boxing means that we are now mutating the original,
// not the boxed copy. But this is never observable. Either (1) we have "using(R r = x){}"
// and r is out of scope after the finally, so it is not possible to observe the mutation,
// or (2) we have "using(x) {}". But that has the semantics of "using(R temp = x){}",
// so again, we are not mutating x to begin with; we're always mutating a copy. Therefore
// it doesn't matter if we skip making *a copy of the copy*.
//
// This is what the dev10 compiler does, and we do so as well.
//
// Second: if the type is a nullable value type then we can similarly elide the boxing.
// We can generate
//
// {
// ResourceType resource = expr;
// try { statement; }
// finally { if (resource.HasValue) resource.GetValueOrDefault().Dispose(); }
// }
//
// Where again we do a constrained virtual call to Dispose, rather than boxing
// the value to IDisposable.
//
// Note that this optimization is *not* what the native compiler does; in this case
// the native compiler behavior is to test for HasValue, then *box* and convert
// the boxed value to IDisposable. There's no need to do that.
//
// Third: if we have "using(x)" and x is dynamic then obviously we need not generate
// "{ dynamic temp1 = x; IDisposable temp2 = (IDisposable) temp1; ... }". Rather, we elide
// the completely unnecessary first temporary.
Debug.Assert((awaitKeywordOpt == default) == (awaitOpt == default(AwaitableInfo)));
BoundExpression disposedExpression;
bool isNullableValueType = local.Type.IsNullableType();
if (isNullableValueType)
{
MethodSymbol getValueOrDefault = UnsafeGetNullableMethod(syntax, local.Type, SpecialMember.System_Nullable_T_GetValueOrDefault);
// local.GetValueOrDefault()
disposedExpression = BoundCall.Synthesized(syntax, local, getValueOrDefault);
}
else
{
// local
disposedExpression = local;
}
BoundExpression disposeCall = GenerateDisposeCall(syntax, disposedExpression, methodOpt, awaitOpt, awaitKeywordOpt);
// local.Dispose(); or await variant
BoundStatement disposeStatement = new BoundExpressionStatement(syntax, disposeCall);
BoundExpression ifCondition;
if (isNullableValueType)
{
// local.HasValue
ifCondition = MakeNullableHasValue(syntax, local);
}
else if (local.Type.IsValueType)
{
ifCondition = null;
}
else
{
// local != null
ifCondition = MakeNullCheck(syntax, local, BinaryOperatorKind.NotEqual);
}
BoundStatement finallyStatement;
if (ifCondition == null)
{
// local.Dispose(); or await variant
finallyStatement = disposeStatement;
}
else
{
// if (local != null) local.Dispose();
// or
// if (local.HasValue) local.GetValueOrDefault().Dispose();
// or
// await variants
finallyStatement = RewriteIfStatement(
syntax: syntax,
rewrittenCondition: ifCondition,
rewrittenConsequence: disposeStatement,
rewrittenAlternativeOpt: null,
hasErrors: false);
}
// try { ... } finally { if (local != null) local.Dispose(); }
// or
// nullable or await variants
BoundStatement tryFinally = new BoundTryStatement(
syntax: syntax,
tryBlock: tryBlock,
catchBlocks: ImmutableArray <BoundCatchBlock> .Empty,
finallyBlockOpt: BoundBlock.SynthesizedNoLocals(syntax, finallyStatement));
return(tryFinally);
}
/// <summary>
/// Lower "using [await] (ResourceType resource = expression) statement" to a try-finally block.
/// </summary>
/// <remarks>
/// Assumes that the local symbol will be declared (i.e. in the LocalsOpt array) of an enclosing block.
/// Assumes that using statements with multiple locals have already been split up into multiple using statements.
/// </remarks>
private BoundBlock RewriteDeclarationUsingStatement(SyntaxNode usingSyntax, BoundLocalDeclaration localDeclaration, BoundBlock tryBlock, Conversion iDisposableConversion, SyntaxToken awaitKeywordOpt, AwaitableInfo awaitOpt, MethodSymbol methodSymbol)
{
SyntaxNode declarationSyntax = localDeclaration.Syntax;
LocalSymbol localSymbol = localDeclaration.LocalSymbol;
TypeSymbol localType = localSymbol.Type.TypeSymbol;
Debug.Assert((object)localType != null); //otherwise, there wouldn't be a conversion to IDisposable
BoundLocal boundLocal = new BoundLocal(declarationSyntax, localSymbol, localDeclaration.InitializerOpt.ConstantValue, localType);
BoundStatement rewrittenDeclaration = (BoundStatement)Visit(localDeclaration);
// If we know that the expression is null, then we know that the null check in the finally block
// will fail, and the Dispose call will never happen. That is, the finally block will have no effect.
// Consequently, we can simply skip the whole try-finally construct and just create a block containing
// the new declaration.
if (boundLocal.ConstantValue == ConstantValue.Null)
{
//localSymbol will be declared by an enclosing block
return(BoundBlock.SynthesizedNoLocals(usingSyntax, rewrittenDeclaration, tryBlock));
}
if (localType.IsDynamic())
{
TypeSymbol iDisposableType = awaitOpt is null?
_compilation.GetSpecialType(SpecialType.System_IDisposable) :
_compilation.GetWellKnownType(WellKnownType.core_IAsyncDisposable);
BoundExpression tempInit = MakeConversionNode(
declarationSyntax,
boundLocal,
iDisposableConversion,
iDisposableType,
@checked: false);
BoundAssignmentOperator tempAssignment;
BoundLocal boundTemp = _factory.StoreToTemp(tempInit, out tempAssignment, kind: SynthesizedLocalKind.Using);
BoundStatement tryFinally = RewriteUsingStatementTryFinally(usingSyntax, tryBlock, boundTemp, awaitKeywordOpt, awaitOpt, methodSymbol);
return(new BoundBlock(
syntax: usingSyntax,
locals: ImmutableArray.Create <LocalSymbol>(boundTemp.LocalSymbol), //localSymbol will be declared by an enclosing block
statements: ImmutableArray.Create <BoundStatement>(
rewrittenDeclaration,
new BoundExpressionStatement(declarationSyntax, tempAssignment),
tryFinally)));
}
else
{
BoundStatement tryFinally = RewriteUsingStatementTryFinally(usingSyntax, tryBlock, boundLocal, awaitKeywordOpt, awaitOpt, methodSymbol);
// localSymbol will be declared by an enclosing block
return(BoundBlock.SynthesizedNoLocals(usingSyntax, rewrittenDeclaration, tryFinally));
}
}
private BoundExpression RewriteAwaitExpression(SyntaxNode syntax, BoundExpression rewrittenExpression, AwaitableInfo awaitableInfo, TypeSymbol type, bool used)
{
return(RewriteAwaitExpression(new BoundAwaitExpression(syntax, rewrittenExpression, awaitableInfo, type)
{
WasCompilerGenerated = true
}, used));
}
/// <summary>
/// Lower "using [await] (ResourceType resource = expression) statement" to a try-finally block.
/// </summary>
/// <remarks>
/// Assumes that the local symbol will be declared (i.e. in the LocalsOpt array) of an enclosing block.
/// Assumes that using statements with multiple locals have already been split up into multiple using statements.
/// </remarks>
private BoundBlock RewriteDeclarationUsingStatement(SyntaxNode usingSyntax, BoundLocalDeclaration localDeclaration, BoundBlock tryBlock, Conversion iDisposableConversion, SyntaxToken awaitKeywordOpt, AwaitableInfo awaitOpt, MethodSymbol methodSymbol)
{
SyntaxNode declarationSyntax = localDeclaration.Syntax;
LocalSymbol localSymbol = localDeclaration.LocalSymbol;
TypeSymbol localType = localSymbol.Type.TypeSymbol;
Debug.Assert((object)localType != null); //otherwise, there wouldn't be a conversion to IDisposable
BoundLocal boundLocal = new BoundLocal(declarationSyntax, localSymbol, localDeclaration.InitializerOpt.ConstantValue, localType);
BoundStatement rewrittenDeclaration = (BoundStatement)Visit(localDeclaration);
// If we know that the expression is null, then we know that the null check in the finally block
// will fail, and the Dispose call will never happen. That is, the finally block will have no effect.
// Consequently, we can simply skip the whole try-finally construct and just create a block containing
// the new declaration.
if (boundLocal.ConstantValue == ConstantValue.Null)
{
//localSymbol will be declared by an enclosing block
return(BoundBlock.SynthesizedNoLocals(usingSyntax, rewrittenDeclaration, tryBlock));
}
BoundStatement tryFinally = RewriteUsingStatementTryFinally(usingSyntax, tryBlock, boundLocal, awaitKeywordOpt, awaitOpt, methodSymbol);
// localSymbol will be declared by an enclosing block
return(BoundBlock.SynthesizedNoLocals(usingSyntax, rewrittenDeclaration, tryFinally));
}
internal static BoundStatement BindUsingStatementOrDeclarationFromParts(SyntaxNode syntax, SyntaxToken usingKeyword, SyntaxToken awaitKeyword, Binder originalBinder, UsingStatementBinder usingBinderOpt, DiagnosticBag diagnostics)
{
bool isUsingDeclaration = syntax.Kind() == SyntaxKind.LocalDeclarationStatement;
bool isExpression = !isUsingDeclaration && syntax.Kind() != SyntaxKind.VariableDeclaration;
bool hasAwait = awaitKeyword != default;
Debug.Assert(isUsingDeclaration || usingBinderOpt != null);
TypeSymbol disposableInterface = getDisposableInterface(hasAwait);
Debug.Assert((object)disposableInterface != null);
bool hasErrors = ReportUseSiteDiagnostics(disposableInterface, diagnostics, hasAwait ? awaitKeyword : usingKeyword);
Conversion iDisposableConversion = Conversion.NoConversion;
BoundLocalDeclaration declarationOpt = default;
BoundExpression expressionOpt = null;
AwaitableInfo awaitOpt = null;
TypeSymbol declarationTypeOpt = null;
MethodSymbol disposeMethodOpt = null;
TypeSymbol awaitableTypeOpt = null;
if (isExpression)
{
expressionOpt = usingBinderOpt.BindTargetExpression(diagnostics, originalBinder);
hasErrors |= !populateDisposableConversionOrDisposeMethod(fromExpression: true);
}
else
{
VariableDeclarationSyntax declarationSyntax = isUsingDeclaration ? ((LocalDeclarationStatementSyntax)syntax).Declaration : (VariableDeclarationSyntax)syntax;
declarationOpt = originalBinder.BindForOrUsingOrFixedDeclarations(declarationSyntax, LocalDeclarationKind.UsingVariable, diagnostics);
Debug.Assert(declarationOpt != null);
declarationTypeOpt = declarationOpt.DeclaredType.Type;
hasErrors |= !populateDisposableConversionOrDisposeMethod(fromExpression: false);
}
if (hasAwait)
{
BoundAwaitableValuePlaceholder placeholderOpt;
if (awaitableTypeOpt is null)
{
placeholderOpt = null;
}
else
{
hasErrors |= ReportUseSiteDiagnostics(awaitableTypeOpt, diagnostics, awaitKeyword);
placeholderOpt = new BoundAwaitableValuePlaceholder(syntax, awaitableTypeOpt).MakeCompilerGenerated();
}
// even if we don't have a proper value to await, we'll still report bad usages of `await`
awaitOpt = originalBinder.BindAwaitInfo(placeholderOpt, syntax, awaitKeyword.GetLocation(), diagnostics, ref hasErrors);
}
// This is not awesome, but its factored.
// In the future it might be better to have a seperate shared type that we add the info to, and have the callers create the appropriate bound nodes from it
if (isUsingDeclaration)
{
return(new BoundUsingLocalDeclaration(syntax, disposeMethodOpt, iDisposableConversion, awaitOpt, declarationOpt, hasErrors));
}
else
{
BoundStatement boundBody = originalBinder.BindPossibleEmbeddedStatement(usingBinderOpt._syntax.Statement, diagnostics);
return(new BoundUsingStatement(
usingBinderOpt._syntax,
usingBinderOpt.Locals,
declarationOpt,
expressionOpt,
iDisposableConversion,
boundBody,
awaitOpt,
disposeMethodOpt,
hasErrors));
}
// initializes iDisposableConversion, awaitableTypeOpt and disposeMethodOpt
bool populateDisposableConversionOrDisposeMethod(bool fromExpression)
{
HashSet <DiagnosticInfo> useSiteDiagnostics = null;
iDisposableConversion = classifyConversion(fromExpression, disposableInterface, ref useSiteDiagnostics);
diagnostics.Add(syntax, useSiteDiagnostics);
if (iDisposableConversion.IsImplicit)
{
if (hasAwait)
{
awaitableTypeOpt = originalBinder.Compilation.GetWellKnownType(WellKnownType.core_Threading_Tasks_ValueTask);
}
return(true);
}
TypeSymbol type = fromExpression ? expressionOpt.Type : declarationTypeOpt;
// If this is a ref struct, or we're in a valid asynchronous using, try binding via pattern.
// We won't need to try and bind a second time if it fails, as async dispose can't be pattern based (ref structs are not allowed in async methods)
if (!(type is null) && (type.IsRefLikeType || hasAwait))
{
BoundExpression receiver = fromExpression
? expressionOpt
: new BoundLocal(syntax, declarationOpt.LocalSymbol, null, type)
{
WasCompilerGenerated = true
};
disposeMethodOpt = originalBinder.TryFindDisposePatternMethod(receiver, syntax, hasAwait, diagnostics);
if (!(disposeMethodOpt is null))
{
if (hasAwait)
{
awaitableTypeOpt = disposeMethodOpt.ReturnType.TypeSymbol;
}
return(true);
}
}
if (type is null || !type.IsErrorType())
{
// Retry with a different assumption about whether the `using` is async
TypeSymbol alternateInterface = getDisposableInterface(!hasAwait);
HashSet <DiagnosticInfo> ignored = null;
Conversion alternateConversion = classifyConversion(fromExpression, alternateInterface, ref ignored);
bool wrongAsync = alternateConversion.IsImplicit;
ErrorCode errorCode = wrongAsync
? (hasAwait ? ErrorCode.ERR_NoConvToIAsyncDispWrongAsync : ErrorCode.ERR_NoConvToIDispWrongAsync)
: (hasAwait ? ErrorCode.ERR_NoConvToIAsyncDisp : ErrorCode.ERR_NoConvToIDisp);
Error(diagnostics, errorCode, syntax, declarationTypeOpt ?? expressionOpt.Display);
}
return(false);
}
Conversion classifyConversion(bool fromExpression, TypeSymbol targetInterface, ref HashSet <DiagnosticInfo> diag)
{
return(fromExpression ?
originalBinder.Conversions.ClassifyImplicitConversionFromExpression(expressionOpt, targetInterface, ref diag) :
originalBinder.Conversions.ClassifyImplicitConversionFromType(declarationTypeOpt, targetInterface, ref diag));
}
TypeSymbol getDisposableInterface(bool isAsync)
{
return(isAsync
? originalBinder.Compilation.GetWellKnownType(WellKnownType.core_IAsyncDisposable)
: originalBinder.Compilation.GetSpecialType(SpecialType.System_IDisposable));
}
}
internal AwaitExpressionInfo(AwaitableInfo awaitableInfo)
{
Debug.Assert(awaitableInfo != null);
_awaitableInfo = awaitableInfo;
}