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Merged
dotnet-bot merged 1 commit into from
Sep 20, 2022
Merged

Merge main to main-vs-deps #64139

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123 changes: 44 additions & 79 deletions src/Compilers/CSharp/Portable/Binder/Binder.ValueChecks.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,17 +22,20 @@ internal partial class Binder
/// <summary>
/// For the purpose of escape verification we operate with the depth of local scopes.
/// The depth is a uint, with smaller number representing shallower/wider scopes.
/// The 0 and 1 are special scopes -
/// 0 is the "external" or "return" scope that is outside of the containing method/lambda.
/// If something can escape to scope 0, it can escape to any scope in a given method or can be returned.
/// 1 is the "parameter" or "top" scope that is just inside the containing method/lambda.
/// 0, 1 and 2 are special scopes -
/// 0 is the "calling method" scope that is outside of the containing method/lambda.
/// If something can escape to scope 0, it can escape to any scope in a given method through a ref parameter or return.
/// 1 is the "return-only" scope that is outside of the containing method/lambda.
/// If something can escape to scope 1, it can escape to any scope in a given method or can be returned, but it can't escape through a ref parameter.
/// 2 is the "current method" scope that is just inside the containing method/lambda.
/// If something can escape to scope 1, it can escape to any scope in a given method, but cannot be returned.
/// n + 1 corresponds to scopes immediately inside a scope of depth n.
/// Since sibling scopes do not intersect and a value cannot escape from one to another without
/// escaping to a wider scope, we can use simple depth numbering without ambiguity.
/// </summary>
internal const uint ExternalScope = 0;
internal const uint TopLevelScope = 1;
internal const uint ReturnOnlyScope = 1;
internal const uint TopLevelScope = 2;

// Some value kinds are semantically the same and the only distinction is how errors are reported
// for those purposes we reserve lowest 2 bits
Expand Down Expand Up @@ -719,7 +722,7 @@ private static bool CheckLocalRefEscape(SyntaxNode node, BoundLocal local, uint
return true;
}

if (escapeTo == Binder.ExternalScope)
if (escapeTo is Binder.ExternalScope or Binder.ReturnOnlyScope)
{
if (localSymbol.RefKind == RefKind.None)
{
Expand Down Expand Up @@ -794,21 +797,17 @@ private uint GetParameterValEscape(ParameterSymbol parameter)

private uint GetParameterRefEscape(ParameterSymbol parameter)
{
if (UseUpdatedEscapeRules)
{
return parameter.RefKind is RefKind.None || parameter.EffectiveScope != DeclarationScope.Unscoped ? Binder.TopLevelScope : Binder.ExternalScope;
}
else
return parameter switch
{
// byval parameters can escape to method's top level. Others can escape further.
// NOTE: "method" here means nearest containing method, lambda or local function.
return parameter.RefKind == RefKind.None ? Binder.TopLevelScope : Binder.ExternalScope;
}
{ RefKind: RefKind.None } or { EffectiveScope: not DeclarationScope.Unscoped } => Binder.TopLevelScope,
{ Type.IsRefLikeType: true } => Binder.ReturnOnlyScope,
_ => Binder.ExternalScope
};
}

private bool CheckParameterValEscape(SyntaxNode node, BoundParameter parameter, uint escapeTo, BindingDiagnosticBag diagnostics)
{
Debug.Assert(escapeTo == Binder.ExternalScope);
Debug.Assert(escapeTo is Binder.ExternalScope or Binder.ReturnOnlyScope);
if (UseUpdatedEscapeRules)
{
var parameterSymbol = parameter.ParameterSymbol;
Expand All @@ -826,22 +825,32 @@ private bool CheckParameterValEscape(SyntaxNode node, BoundParameter parameter,
}
}

private bool CheckParameterRefEscape(SyntaxNode node, BoundParameter parameter, uint escapeTo, bool checkingReceiver, BindingDiagnosticBag diagnostics)
private bool CheckParameterRefEscape(SyntaxNode node, BoundExpression parameter, ParameterSymbol parameterSymbol, uint escapeTo, bool checkingReceiver, BindingDiagnosticBag diagnostics)
{
var parameterSymbol = parameter.ParameterSymbol;

if (GetParameterRefEscape(parameterSymbol) > escapeTo)
var refSafeToEscape = GetParameterRefEscape(parameterSymbol);
if (refSafeToEscape > escapeTo)
{
var isRefScoped = parameterSymbol.EffectiveScope == DeclarationScope.RefScoped;
Debug.Assert(parameterSymbol.RefKind == RefKind.None || isRefScoped);
if (checkingReceiver)
Debug.Assert(parameterSymbol.RefKind == RefKind.None || isRefScoped || refSafeToEscape == Binder.ReturnOnlyScope);

if (parameter is BoundThisReference)
{
Error(diagnostics, isRefScoped ? ErrorCode.ERR_RefReturnScopedParameter2 : ErrorCode.ERR_RefReturnParameter2, parameter.Syntax, parameterSymbol.Name);
Error(diagnostics, ErrorCode.ERR_RefReturnStructThis, node);
return false;
}
else

#pragma warning disable format
var (errorCode, syntax) = (checkingReceiver, isRefScoped, refSafeToEscape) switch
{
Error(diagnostics, isRefScoped ? ErrorCode.ERR_RefReturnScopedParameter : ErrorCode.ERR_RefReturnParameter, node, parameterSymbol.Name);
}
(checkingReceiver: true, isRefScoped: true, _) => (ErrorCode.ERR_RefReturnScopedParameter2, parameter.Syntax),
(checkingReceiver: true, isRefScoped: false, Binder.ReturnOnlyScope) => (ErrorCode.ERR_RefReturnOnlyParameter, parameter.Syntax),
(checkingReceiver: true, isRefScoped: false, _) => (ErrorCode.ERR_RefReturnParameter2, parameter.Syntax),
(checkingReceiver: false, isRefScoped: true, _) => (ErrorCode.ERR_RefReturnScopedParameter, node),
(checkingReceiver: false, isRefScoped: false, Binder.ReturnOnlyScope) => (ErrorCode.ERR_RefReturnOnlyParameter, node),
(checkingReceiver: false, isRefScoped: false, _) => (ErrorCode.ERR_RefReturnParameter, node)
};
#pragma warning restore format
Error(diagnostics, errorCode, syntax, parameterSymbol.Name);
return false;
}

Expand Down Expand Up @@ -2362,7 +2371,7 @@ private static ErrorCode GetStandardLvalueError(BindValueKind kind)

private static ErrorCode GetStandardRValueRefEscapeError(uint escapeTo)
{
if (escapeTo == Binder.ExternalScope)
if (escapeTo is Binder.ExternalScope or Binder.ReturnOnlyScope)
{
return ErrorCode.ERR_RefReturnLvalueExpected;
}
Expand Down Expand Up @@ -2524,28 +2533,9 @@ internal uint GetRefEscape(BoundExpression expr, uint scopeOfTheContainingExpres
return ((BoundLocal)expr).LocalSymbol.RefEscapeScope;

case BoundKind.ThisReference:
Debug.Assert(this.ContainingMember() is MethodSymbol { ThisParameter: not null });

var thisref = (BoundThisReference)expr;

// "this" is an RValue, unless in a struct.
if (!thisref.Type.IsValueType)
{
break;
}

if (UseUpdatedEscapeRules)
{
if (this.ContainingMember() is MethodSymbol { ThisParameter: var thisParameter } &&
thisParameter.EffectiveScope == DeclarationScope.Unscoped)
{
return Binder.ExternalScope;
}
}

//"this" is not returnable by reference in a struct.
// can ref escape to any other level
return Binder.TopLevelScope;
var thisParam = ((MethodSymbol)this.ContainingMember()).ThisParameter;
Debug.Assert(thisParam.Type.Equals(((BoundThisReference)expr).Type, TypeCompareKind.ConsiderEverything));
return GetParameterRefEscape(thisParam);

case BoundKind.ConditionalOperator:
var conditional = (BoundConditionalOperator)expr;
Expand Down Expand Up @@ -2761,7 +2751,7 @@ internal bool CheckRefEscape(SyntaxNode node, BoundExpression expr, uint escapeF
case BoundKind.RefValueOperator:
// The undocumented __refvalue(tr, T) expression results in an lvalue of type T.
// for compat reasons it is not ref-returnable (since TypedReference is not val-returnable)
if (escapeTo == Binder.ExternalScope)
if (escapeTo is Binder.ExternalScope or Binder.ReturnOnlyScope)
{
break;
}
Expand All @@ -2782,41 +2772,16 @@ internal bool CheckRefEscape(SyntaxNode node, BoundExpression expr, uint escapeF

case BoundKind.Parameter:
var parameter = (BoundParameter)expr;
return CheckParameterRefEscape(node, parameter, escapeTo, checkingReceiver, diagnostics);
return CheckParameterRefEscape(node, parameter, parameter.ParameterSymbol, escapeTo, checkingReceiver, diagnostics);

case BoundKind.Local:
var local = (BoundLocal)expr;
return CheckLocalRefEscape(node, local, escapeTo, checkingReceiver, diagnostics);

case BoundKind.ThisReference:
Debug.Assert(this.ContainingMember() is MethodSymbol { ThisParameter: not null });

var thisref = (BoundThisReference)expr;

// "this" is an RValue, unless in a struct.
if (!thisref.Type.IsValueType)
{
break;
}

//"this" is not returnable by reference in a struct.
if (escapeTo == Binder.ExternalScope)
{
if (UseUpdatedEscapeRules)
{
if (this.ContainingMember() is MethodSymbol { ThisParameter: var thisParameter } &&
thisParameter.EffectiveScope == DeclarationScope.Unscoped)
{
// can ref escape to any other level
return true;
}
}
Error(diagnostics, ErrorCode.ERR_RefReturnStructThis, node);
return false;
}

// can ref escape to any other level
return true;
var thisParam = ((MethodSymbol)this.ContainingMember()).ThisParameter;
Debug.Assert(thisParam.Type.Equals(((BoundThisReference)expr).Type, TypeCompareKind.ConsiderEverything));
return CheckParameterRefEscape(node, expr, thisParam, escapeTo, checkingReceiver, diagnostics);

case BoundKind.ConditionalOperator:
var conditional = (BoundConditionalOperator)expr;
Expand Down
10 changes: 5 additions & 5 deletions src/Compilers/CSharp/Portable/Binder/Binder_Statements.cs
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Expand Up @@ -237,7 +237,7 @@ private BoundStatement BindYieldReturnStatement(YieldStatementSyntax node, Bindi
BoundExpression argument = (node.Expression == null)
? BadExpression(node).MakeCompilerGenerated()
: BindValue(node.Expression, diagnostics, BindValueKind.RValue);
argument = ValidateEscape(argument, ExternalScope, isByRef: false, diagnostics: diagnostics);
argument = ValidateEscape(argument, ReturnOnlyScope, isByRef: false, diagnostics: diagnostics);

if (!argument.HasAnyErrors)
{
Expand Down Expand Up @@ -1546,7 +1546,7 @@ private BoundAssignmentOperator BindAssignment(
var rightEscape = GetRefEscape(op2, LocalScopeDepth);
if (leftEscape < rightEscape)
{
Error(diagnostics, ErrorCode.ERR_RefAssignNarrower, node, getName(op1), op2.Syntax);
Error(diagnostics, rightEscape == Binder.ReturnOnlyScope ? ErrorCode.ERR_RefAssignReturnOnly : ErrorCode.ERR_RefAssignNarrower, node, getName(op1), op2.Syntax);
op2 = ToBadExpression(op2);
}
}
Expand Down Expand Up @@ -2979,7 +2979,7 @@ private BoundStatement BindReturn(ReturnStatementSyntax syntax, BindingDiagnosti
else
{
arg = CreateReturnConversion(syntax, diagnostics, arg, sigRefKind, retType);
arg = ValidateEscape(arg, Binder.ExternalScope, refKind != RefKind.None, diagnostics);
arg = ValidateEscape(arg, Binder.ReturnOnlyScope, refKind != RefKind.None, diagnostics);
}
}
}
Expand Down Expand Up @@ -3421,7 +3421,7 @@ static BoundBlock bindExpressionBodyAsBlockInternal(ArrowExpressionClauseSyntax
ExpressionSyntax expressionSyntax = expressionBody.Expression.CheckAndUnwrapRefExpression(diagnostics, out refKind);
BindValueKind requiredValueKind = bodyBinder.GetRequiredReturnValueKind(refKind);
BoundExpression expression = bodyBinder.BindValue(expressionSyntax, diagnostics, requiredValueKind);
expression = bodyBinder.ValidateEscape(expression, Binder.ExternalScope, refKind != RefKind.None, diagnostics);
expression = bodyBinder.ValidateEscape(expression, Binder.ReturnOnlyScope, refKind != RefKind.None, diagnostics);

return bodyBinder.CreateBlockFromExpression(expressionBody, bodyBinder.GetDeclaredLocalsForScope(expressionBody), refKind, expression, expressionSyntax, diagnostics);
}
Expand All @@ -3439,7 +3439,7 @@ public BoundBlock BindLambdaExpressionAsBlock(ExpressionSyntax body, BindingDiag
var expressionSyntax = body.CheckAndUnwrapRefExpression(diagnostics, out refKind);
BindValueKind requiredValueKind = GetRequiredReturnValueKind(refKind);
BoundExpression expression = bodyBinder.BindValue(expressionSyntax, diagnostics, requiredValueKind);
expression = ValidateEscape(expression, Binder.ExternalScope, refKind != RefKind.None, diagnostics);
expression = ValidateEscape(expression, Binder.ReturnOnlyScope, refKind != RefKind.None, diagnostics);

return bodyBinder.CreateBlockFromExpression(body, bodyBinder.GetDeclaredLocalsForScope(body), refKind, expression, expressionSyntax, diagnostics);
}
Expand Down
9 changes: 9 additions & 0 deletions src/Compilers/CSharp/Portable/CSharpResources.resx
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Expand Up @@ -5077,6 +5077,12 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
<data name="ERR_RefReturnScopedParameter2" xml:space="preserve">
<value>Cannot return by reference a member of parameter '{0}' because it is scoped to the current method</value>
</data>
<data name="ERR_RefReturnOnlyParameter" xml:space="preserve">
<value>Cannot return a parameter by reference '{0}' through a ref parameter; it can only be returned in a return statement</value>
</data>
<data name="ERR_RefReturnOnlyParameter2" xml:space="preserve">
<value>Cannot return by reference a member of parameter '{0}' through a ref parameter; it can only be returned in a return statement</value>
</data>
<data name="ERR_RefReturnLocal" xml:space="preserve">
<value>Cannot return local '{0}' by reference because it is not a ref local</value>
</data>
Expand Down Expand Up @@ -5791,6 +5797,9 @@ To remove the warning, you can use /reference instead (set the Embed Interop Typ
<data name="ERR_RefAssignNarrower" xml:space="preserve">
<value>Cannot ref-assign '{1}' to '{0}' because '{1}' has a narrower escape scope than '{0}'.</value>
</data>
<data name="ERR_RefAssignReturnOnly" xml:space="preserve">
<value>Cannot ref-assign '{1}' to '{0}' because '{1}' can only escape the current method through a return statement.</value>
</data>
<data name="IDS_FeatureEnumGenericTypeConstraint" xml:space="preserve">
<value>enum generic type constraints</value>
</data>
Expand Down
5 changes: 4 additions & 1 deletion src/Compilers/CSharp/Portable/Errors/ErrorCode.cs
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Expand Up @@ -2124,7 +2124,10 @@ internal enum ErrorCode
WRN_ScopedMismatchInParameterOfTarget = 9073,
WRN_ScopedMismatchInParameterOfOverrideOrImplementation = 9074,
ERR_RefReturnScopedParameter = 9075,
ERR_RefReturnScopedParameter2 = 9076
ERR_RefReturnScopedParameter2 = 9076,
ERR_RefReturnOnlyParameter = 9077,
ERR_RefReturnOnlyParameter2 = 9078,
ERR_RefAssignReturnOnly = 9079,

#endregion

Expand Down
3 changes: 3 additions & 0 deletions src/Compilers/CSharp/Portable/Errors/ErrorFacts.cs
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Expand Up @@ -2226,6 +2226,9 @@ internal static bool IsBuildOnlyDiagnostic(ErrorCode code)
case ErrorCode.WRN_ScopedMismatchInParameterOfOverrideOrImplementation:
case ErrorCode.ERR_RefReturnScopedParameter:
case ErrorCode.ERR_RefReturnScopedParameter2:
case ErrorCode.ERR_RefReturnOnlyParameter:
case ErrorCode.ERR_RefReturnOnlyParameter2:
case ErrorCode.ERR_RefAssignReturnOnly:
return false;
default:
// NOTE: All error codes must be explicitly handled in this switch statement
Expand Down
15 changes: 15 additions & 0 deletions src/Compilers/CSharp/Portable/xlf/CSharpResources.cs.xlf
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