Do not zero out "With" statement target expression locals referenced within a lambda. (#22223)

Fixes #16968.

Do not zero out "With" statement target expression locals referenced within a lambda. (#22223)
Fixes #16968.
f827f7a8 · AlekseyTs · GitHub · a0d9ead3 · f827f7a8 · f827f7a8
2 changed file
--- a/src/Compilers/VisualBasic/Portable/Lowering/LocalRewriter/LocalRewriter_With.vb
+++ b/src/Compilers/VisualBasic/Portable/Lowering/LocalRewriter/LocalRewriter_With.vb
@@ -98,38 +98,36 @@ Namespace Microsoft.CodeAnalysis.VisualBasic
                initStatements.Add(RegisterUnstructuredExceptionHandlingNonThrowingResumeTarget(syntax))
            End If

-            'TODO: what is the purpose of this? 
-            '      Is this code adding dead-stores that optimizer will most likely remove?
-            '      Also, what happens if the temps are lifted into a closure and are still alive?
-            '      
            ' Cleanup code for locals which need it
-            For Each _local In locals
-                Dim localType As TypeSymbol = _local.Type
-
-                ' Only for locals of reference type or type parameter type or non-primitive structs 
-                If Not _local.IsByRef AndAlso LocalOrFieldNeedsToBeCleanedUp(localType) Then
-                    initStatements.Add(
-                        New BoundExpressionStatement(
-                            syntax,
-                            VisitExpression(
-                                New BoundAssignmentOperator(
-                                    syntax,
-                                    New BoundLocal(syntax, _local, isLValue:=True, type:=localType).MakeCompilerGenerated(),
-                                    New BoundConversion(
+            If Not node.Binder.ExpressionIsAccessedFromNestedLambda Then
+                For Each _local In locals
+                    Dim localType As TypeSymbol = _local.Type
+
+                    ' Only for locals of reference type or type parameter type or non-primitive structs 
+                    If Not _local.IsByRef AndAlso LocalOrFieldNeedsToBeCleanedUp(localType) Then
+                        initStatements.Add(
+                            New BoundExpressionStatement(
+                                syntax,
+                                VisitExpression(
+                                    New BoundAssignmentOperator(
                                        syntax,
-                                        New BoundLiteral(syntax, ConstantValue.Nothing, Nothing).MakeCompilerGenerated(),
-                                        ConversionKind.WideningNothingLiteral,
-                                        checked:=False,
-                                        explicitCastInCode:=False,
-                                        type:=localType).MakeCompilerGenerated(),
-                                    suppressObjectClone:=True,
-                                    type:=localType
-                                ).MakeCompilerGenerated()
-                            )
-                        ).MakeCompilerGenerated()
-                    )
-                End If
-            Next
+                                        New BoundLocal(syntax, _local, isLValue:=True, type:=localType).MakeCompilerGenerated(),
+                                        New BoundConversion(
+                                            syntax,
+                                            New BoundLiteral(syntax, ConstantValue.Nothing, Nothing).MakeCompilerGenerated(),
+                                            ConversionKind.WideningNothingLiteral,
+                                            checked:=False,
+                                            explicitCastInCode:=False,
+                                            type:=localType).MakeCompilerGenerated(),
+                                        suppressObjectClone:=True,
+                                        type:=localType
+                                    ).MakeCompilerGenerated()
+                                )
+                            ).MakeCompilerGenerated()
+                        )
+                    End If
+                Next
+            End If

            ' Create a new block
            Dim newBlock As New BoundBlock(syntax, Nothing, locals, initStatements.ToImmutableAndFree())

--- a/src/Compilers/VisualBasic/Test/Emit/CodeGen/CodeGenWithBlock.vb
+++ b/src/Compilers/VisualBasic/Test/Emit/CodeGen/CodeGenWithBlock.vb
@@ -1999,7 +1999,7 @@ expectedOutput:="A = 2; B = 6/6/2006; C = ?")
            c.VerifyDiagnostics()
            c.VerifyIL("C2..ctor", <![CDATA[
 {
-  // Code size      119 (0x77)
+  // Code size      112 (0x70)
  .maxstack  4
  IL_0000:  ldarg.0
  IL_0001:  initobj    "C2"
@@ -2025,19 +2025,16 @@ expectedOutput:="A = 2; B = 6/6/2006; C = ?")
  IL_003e:  ldelema    "C2.ABC"
  IL_0043:  ldfld      "C2.ABC.A As Integer"
  IL_0048:  stfld      "C2._Closure$__4-0.$W3 As Integer"
-  IL_004d:  dup
-  IL_004e:  ldftn      "Sub C2._Closure$__4-0._Lambda$__0()"
-  IL_0054:  newobj     "Sub VB$AnonymousDelegate_0..ctor(Object, System.IntPtr)"
-  IL_0059:  callvirt   "Sub VB$AnonymousDelegate_0.Invoke()"
-  IL_005e:  ldnull
-  IL_005f:  stfld      "C2._Closure$__4-0.$W2 As C2.ABC()"
-  IL_0064:  ldarg.0
-  IL_0065:  ldarg.0
-  IL_0066:  ldfld      "C2.ARR As C2.ABC()"
-  IL_006b:  ldc.i4.1
-  IL_006c:  ldelem     "C2.ABC"
-  IL_0071:  call       "Sub C2.Print(C2.ABC)"
-  IL_0076:  ret
+  IL_004d:  ldftn      "Sub C2._Closure$__4-0._Lambda$__0()"
+  IL_0053:  newobj     "Sub VB$AnonymousDelegate_0..ctor(Object, System.IntPtr)"
+  IL_0058:  callvirt   "Sub VB$AnonymousDelegate_0.Invoke()"
+  IL_005d:  ldarg.0
+  IL_005e:  ldarg.0
+  IL_005f:  ldfld      "C2.ARR As C2.ABC()"
+  IL_0064:  ldc.i4.1
+  IL_0065:  ldelem     "C2.ABC"
+  IL_006a:  call       "Sub C2.Print(C2.ABC)"
+  IL_006f:  ret
 }
 ]]>)
            c.VerifyIL("C2._Closure$__4-0._Lambda$__0", <![CDATA[
@@ -3091,7 +3088,7 @@ End Structure

            c.VerifyIL("Clazz.TEST", <![CDATA[
 {
-  // Code size       89 (0x59)
+  // Code size       82 (0x52)
  .maxstack  3
  .locals init (Clazz._Closure$__1-0 V_0) //$VB$Closure_0
  IL_0000:  newobj     "Sub Clazz._Closure$__1-0..ctor()"
@@ -3118,10 +3115,7 @@ End Structure
  IL_0041:  ldftn      "Sub Clazz._Closure$__1-0._Lambda$__0()"
  IL_0047:  newobj     "Sub System.Action..ctor(Object, System.IntPtr)"
  IL_004c:  callvirt   "Sub System.Action.Invoke()"
-  IL_0051:  ldloc.0
-  IL_0052:  ldnull
-  IL_0053:  stfld      "Clazz._Closure$__1-0.$W2 As Clazz()"
-  IL_0058:  ret
+  IL_0051:  ret
 }
 ]]>)
            c.VerifyIL("Clazz._Closure$__1-0._Lambda$__0", <![CDATA[
@@ -3179,7 +3173,7 @@ End Structure

            c.VerifyIL("Clazz.TEST", <![CDATA[
 {
-  // Code size       89 (0x59)
+  // Code size       82 (0x52)
  .maxstack  3
  .locals init (Clazz._Closure$__1-0 V_0) //$VB$Closure_0
  IL_0000:  newobj     "Sub Clazz._Closure$__1-0..ctor()"
@@ -3206,10 +3200,7 @@ End Structure
  IL_0041:  ldftn      "Sub Clazz._Closure$__1-0._Lambda$__0()"
  IL_0047:  newobj     "Sub System.Action..ctor(Object, System.IntPtr)"
  IL_004c:  callvirt   "Sub System.Action.Invoke()"
-  IL_0051:  ldloc.0
-  IL_0052:  ldnull
-  IL_0053:  stfld      "Clazz._Closure$__1-0.$W2 As Clazz()"
-  IL_0058:  ret
+  IL_0051:  ret
 }
 ]]>)
            c.VerifyIL("Clazz._Closure$__1-0._Lambda$__0", <![CDATA[
@@ -3277,7 +3268,7 @@ End Structure
            c.VerifyDiagnostics()
            c.VerifyIL("Clazz.TEST", <![CDATA[
 {
-  // Code size      154 (0x9a)
+  // Code size      142 (0x8e)
  .maxstack  3
  .locals init (Clazz V_0, //$W0
                Clazz V_1, //$W1
@@ -3316,14 +3307,11 @@ End Structure
  IL_006e:  call       "Function System.Linq.Enumerable.Select(Of Char, String)(System.Collections.Generic.IEnumerable(Of Char), System.Func(Of Char, String)) As System.Collections.Generic.IEnumerable(Of String)"
  IL_0073:  call       "Function System.Linq.Enumerable.FirstOrDefault(Of String)(System.Collections.Generic.IEnumerable(Of String)) As String"
  IL_0078:  call       "Sub System.Console.Write(String)"
-  IL_007d:  ldloc.2
-  IL_007e:  ldflda     "Clazz._Closure$__3-0.$W2 As Clazz"
-  IL_0083:  initobj    "Clazz"
-  IL_0089:  ldloca.s   V_1
-  IL_008b:  initobj    "Clazz"
-  IL_0091:  ldloca.s   V_0
-  IL_0093:  initobj    "Clazz"
-  IL_0099:  ret
+  IL_007d:  ldloca.s   V_1
+  IL_007f:  initobj    "Clazz"
+  IL_0085:  ldloca.s   V_0
+  IL_0087:  initobj    "Clazz"
+  IL_008d:  ret
 }
 ]]>)
            c.VerifyIL("Clazz._Closure$__3-0._Lambda$__0",
@@ -3420,6 +3408,45 @@ Hello, World
 ]]>)
        End Sub

+        <Fact()>
+        <WorkItem(16968, "https://github.com/dotnet/roslyn/issues/16968")>
+        Public Sub WithExpressionIsAccessedFromLambdaExecutedAfterTheBlock()
+            CompileAndVerify(
+<compilation>
+    <file name="a.vb">
+Module Module1
+
+    Private f As EventOwner
+
+    Sub Main()
+
+        f = New EventOwner()
+        With f
+            AddHandler .Baz, Sub()
+                                 .Bar = "called"
+                             End Sub
+        End With
+
+        f.RaiseBaz()
+        System.Console.WriteLine(f.Bar)
+    End Sub
+
+End Module
+
+Class EventOwner
+
+    Public Property Bar As String
+
+    Public Event Baz As System.Action
+
+    Public Sub RaiseBaz()
+        RaiseEvent Baz()
+    End Sub
+End Class
+    </file>
+</compilation>, expectedOutput:="called")
+        End Sub
+
    End Class

 End Namespace