CR feedback

src/Compilers/CSharp/Portable/Binder/Binder.ValueChecks.cs

@@ -1887,6 +1887,7 @@ internal static uint GetValEscape(BoundExpression expr, uint scopeOfTheContainin
                 case BoundKind.Local:
                     return ((BoundLocal)expr).LocalSymbol.ValEscapeScope;
 
+                case BoundKind.StackAllocArrayCreation:
                 case BoundKind.ConvertedStackAllocExpression:
                     return Binder.TopLevelScope;
 
@@ -2054,6 +2055,7 @@ internal static bool CheckValEscape(SyntaxNode node, BoundExpression expr, uint
                     }
                     return true;
 
+                case BoundKind.StackAllocArrayCreation:
                 case BoundKind.ConvertedStackAllocExpression:
                     if (escapeTo < Binder.TopLevelScope)
                     {

src/Compilers/CSharp/Portable/Binder/Binder_Conversions.cs

@@ -75,20 +75,6 @@ internal partial class Binder
                         sourceTuple.HasErrors);
                 }
 
-                // identity stackalloc conversions result in a converted node
-                // to indicate that stackalloc conversions are no longer applicable.
-                // nothing else changes
-                if (source.Kind == BoundKind.StackAllocArrayCreation)
-                {
-                    var sourceStackAlloc = (BoundStackAllocArrayCreation)source;
-                    source = new BoundConvertedStackAllocExpression(
-                        sourceStackAlloc.Syntax,
-                        sourceStackAlloc.ElementType,
-                        sourceStackAlloc.Count,
-                        sourceStackAlloc.Type, 
-                        sourceStackAlloc.HasErrors);
-                }
-
                 // We need to preserve any conversion that changes the type (even identity conversions, like object->dynamic),
                 // or that was explicitly written in code (so that GetSemanticInfo can find the syntax in the bound tree).
                 if (!isCast && source.Type == destination)

src/Compilers/CSharp/Portable/Binder/Binder_Expressions.cs

@@ -3016,9 +3016,9 @@ private void BindArrayInitializerExpressions(InitializerExpressionSyntax initial
             StackAllocArrayCreationExpressionSyntax node, DiagnosticBag diagnostics)
         {
             bool hasErrors = false;
+            var inLegalPosition = (IsInMethodBody || IsLocalFunctionsScopeBinder) && node.IsLegalSpanStackAllocPosition();
 
-            if (!IsInMethodBody && !IsLocalFunctionsScopeBinder ||
-                !node.IsLegalSpanStackAllocPosition())
+            if (!inLegalPosition)
             {
                 hasErrors = true;
                 diagnostics.Add(
@@ -3105,7 +3105,7 @@ private void BindArrayInitializerExpressions(InitializerExpressionSyntax initial
             }
 
             TypeSymbol type = null;
-            if (!node.IsVariableDeclarationInitialization())
+            if (inLegalPosition && !node.IsVariableDeclarationInitialization())
             {
                 CheckFeatureAvailability(node, MessageID.IDS_FeatureRefStructs, diagnostics);
                 GetWellKnownTypeMember(Compilation, WellKnownMember.System_Span_T__ctor, diagnostics, syntax: node);

src/Compilers/CSharp/Test/Semantic/Semantics/StackAllocSpanExpressionsTests.cs

@@ -227,7 +227,7 @@ void M()
         }
 
         [Fact]
-        public void ConditionalExpressionOnSpan_NonConvertible()
+        public void ConditionalExpressionOnSpan_BothStackallocSpans()
         {
             CreateCompilationWithMscorlibAndSpan(@"
 class Test

src/Compilers/CSharp/Test/Semantic/Semantics/UnsafeTests.cs

@@ -7560,13 +7560,7 @@ void M(int* p = stackalloc int[1])
             CreateStandardCompilation(text, options: TestOptions.UnsafeReleaseDll).VerifyDiagnostics(
                 // (4,21): error CS1525: Invalid expression term 'stackalloc'
                 //     void M(int* p = stackalloc int[1])
-                Diagnostic(ErrorCode.ERR_InvalidExprTerm, "stackalloc").WithArguments("stackalloc").WithLocation(4, 21),
-                // (4,21): error CS0656: Missing compiler required member 'System.Span`1..ctor'
-                //     void M(int* p = stackalloc int[1])
-                Diagnostic(ErrorCode.ERR_MissingPredefinedMember, "stackalloc int[1]").WithArguments("System.Span`1", ".ctor").WithLocation(4, 21),
-                // (4,21): error CS0518: Predefined type 'System.Span`1' is not defined or imported
-                //     void M(int* p = stackalloc int[1])
-                Diagnostic(ErrorCode.ERR_PredefinedTypeNotFound, "stackalloc int[1]").WithArguments("System.Span`1").WithLocation(4, 21)
+                Diagnostic(ErrorCode.ERR_InvalidExprTerm, "stackalloc").WithArguments("stackalloc").WithLocation(4, 21)
             );
         }
 

src/Compilers/CSharp/Test/Symbol/Symbols/Source/PropertyTests.cs

@@ -2876,13 +2876,7 @@ static void Main(string[] args)
             CreateStandardCompilation(text, options: new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary, allowUnsafe: true)).VerifyDiagnostics(
                 // (4,30): error CS1525: Invalid expression term 'stackalloc'
                 //     int* property { get; } = stackalloc int[256];
-                Diagnostic(ErrorCode.ERR_InvalidExprTerm, "stackalloc").WithArguments("stackalloc").WithLocation(4, 30),
-                // (4,30): error CS0656: Missing compiler required member 'System.Span`1..ctor'
-                //     int* property { get; } = stackalloc int[256];
-                Diagnostic(ErrorCode.ERR_MissingPredefinedMember, "stackalloc int[256]").WithArguments("System.Span`1", ".ctor").WithLocation(4, 30),
-                // (4,30): error CS0518: Predefined type 'System.Span`1' is not defined or imported
-                //     int* property { get; } = stackalloc int[256];
-                Diagnostic(ErrorCode.ERR_PredefinedTypeNotFound, "stackalloc int[256]").WithArguments("System.Span`1").WithLocation(4, 30)
+                Diagnostic(ErrorCode.ERR_InvalidExprTerm, "stackalloc").WithArguments("stackalloc").WithLocation(4, 30)
                 );
         }
         [Fact]