[mcs] Don't reset temporary stack fields too early. Fixes #43265

[mono.git] / mcs / mcs / async.cs

diff --git a/mcs/mcs/async.cs b/mcs/mcs/async.cs
index 797319f62552402040a5b338524748fd257a1e80..39d114fd451cb516dca4d5a8e9679e07ecf6a2ff 100644 (file)
--- a/mcs/mcs/async.cs
+++ b/mcs/mcs/async.cs
@@ -90,6 +90,11 @@ namespace Mono.CSharp
                        if (!stmt.Resolve (bc))
                                return null;
 
+                       if (rc.HasSet (ResolveContext.Options.FinallyScope) && rc.CurrentAnonymousMethod != null) {
+                               var ats = (AsyncTaskStorey)rc.CurrentAnonymousMethod.Storey;
+                               ats.HasAwaitInsideFinally = true;
+                       }
+
                        type = stmt.ResultType;
                        eclass = ExprClass.Variable;
                        return this;
@@ -145,7 +150,7 @@ namespace Mono.CSharp
 
                        public bool ProbingMode { get; set; }
 
-                       protected override void Error_TypeDoesNotContainDefinition (ResolveContext rc, TypeSpec type, string name)
+                       public override void Error_TypeDoesNotContainDefinition (ResolveContext rc, TypeSpec type, string name)
                        {
                                Error_OperatorCannotBeApplied (rc, type);
                        }
@@ -344,7 +349,11 @@ namespace Mono.CSharp
 
                        var errors_printer = new SessionReportPrinter ();
                        var old = bc.Report.SetPrinter (errors_printer);
-                       ama = new Invocation (ama, args).Resolve (bc);
+
+                       //
+                       // The expression await t is classified the same way as the expression (t).GetAwaiter().GetResult(). 
+                       //
+                       ama = new Invocation (new ParenthesizedExpression (ama, Location.Null), args).Resolve (bc);
                        bc.Report.SetPrinter (old);
 
                        if (errors_printer.ErrorsCount > 0 || !MemberAccess.IsValidDotExpression (ama.Type)) {
@@ -536,6 +545,8 @@ namespace Mono.CSharp
 
                #region Properties
 
+               public bool HasAwaitInsideFinally { get; set; }
+
                public Expression HoistedReturnValue { get; set; }
 
                public TypeSpec ReturnType {
@@ -689,6 +700,18 @@ namespace Mono.CSharp
 
                        builder = AddCompilerGeneratedField ("$builder", new TypeExpression (bt, Location));
 
+                       Field rfield;
+                       if (has_task_return_type && HasAwaitInsideFinally) {
+                               //
+                               // Special case async block with return value from finally clause. In such case
+                               // we rewrite all return expresison stores to stfld to $return. Instead of treating
+                               // returns outside of finally and inside of finally differently.
+                               //
+                               rfield = AddCompilerGeneratedField ("$return", new TypeExpression (bt.TypeArguments [0], Location));
+                       } else {
+                               rfield = null;
+                       }
+
                        var set_state_machine = new Method (this, new TypeExpression (Compiler.BuiltinTypes.Void, Location),
                                Modifiers.COMPILER_GENERATED | Modifiers.DEBUGGER_HIDDEN | Modifiers.PUBLIC,
                                new MemberName ("SetStateMachine"),
@@ -726,7 +749,13 @@ namespace Mono.CSharp
                        set_state_machine.Block.AddStatement (new StatementExpression (new Invocation (mg, args)));
 
                        if (has_task_return_type) {
-                               HoistedReturnValue = TemporaryVariableReference.Create (bt.TypeArguments [0], StateMachineMethod.Block, Location);
+                               if (rfield != null) {
+                                       HoistedReturnValue = new FieldExpr (rfield, Location) {
+                                               InstanceExpression = new CompilerGeneratedThis (CurrentType, Location.Null)
+                                       };
+                               } else {
+                                       HoistedReturnValue = TemporaryVariableReference.Create (bt.TypeArguments [0], StateMachineMethod.Block, Location);
+                               }
                        }
 
                        return true;
@@ -944,14 +973,17 @@ namespace Mono.CSharp
                public StackFieldExpr (Field field)
                        : base (field, Location.Null)
                {
+                       AutomaticallyReuse = true;
                }
 
+               public bool AutomaticallyReuse { get; set; }
+
                public bool IsAvailableForReuse {
                        get {
                                var field = (Field) spec.MemberDefinition;
                                return field.IsAvailableForReuse;
                        }
-                       set {
+                       private set {
                                var field = (Field) spec.MemberDefinition;
                                field.IsAvailableForReuse = value;
                        }
@@ -961,7 +993,7 @@ namespace Mono.CSharp
                {
                        base.AddressOf (ec, mode);
 
-                       if (mode == AddressOp.Load) {
+                       if (mode == AddressOp.Load && AutomaticallyReuse) {
                                IsAvailableForReuse = true;
                        }
                }
@@ -970,7 +1002,8 @@ namespace Mono.CSharp
                {
                        base.Emit (ec);
 
-                       PrepareCleanup (ec);
+                       if (AutomaticallyReuse)
+                               PrepareCleanup (ec);
                }
 
                public void EmitLoad (EmitContext ec)